Patent Publication Number: US-2023164450-A1

Title: Image processing method, image processing system, electronic device, and readable storage medium

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of International Application No. PCT/CN2020/120025, filed Oct. 9, 2020, which claims priority to Chinese Patent Application No. 202010833968.8, filed Aug. 18, 2020, the entire disclosures of which are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to the field of image processing technology, and in particular to a method and system for image processing and an electronic device. 
     BACKGROUND 
     Cameras can be configured in electronic devices such as mobile phones to take pictures. An image sensor for receiving light can be disposed in the camera. The image sensor can be provided with a filter array. 
     SUMMARY 
     A method for image processing is provided in implementations of the disclosure. The method is applied to an image sensor. The image sensor includes a pixel array that includes multiple panchromatic photosensitive pixels and multiple color photosensitive pixels. The color photosensitive pixels include a first-color photosensitive pixel, a second-color photosensitive pixel, and a third-color photosensitive pixel having different spectral responses from one another. The color photosensitive pixels each have a narrower spectral response than the panchromatic photosensitive pixels. The second-color photosensitive pixel and the third-color photosensitive pixel each have a narrower spectral response than the first-color photosensitive pixel. The method includes the following. A first image is obtained by exposing the pixel array, where the first image contains panchromatic image pixels generated by the panchromatic photosensitive pixels, a first-color image pixel generated by the first-color photosensitive pixel, a second-color image pixel generated by the second-color photosensitive pixel, and a third-color image pixel generated by the third-color photosensitive pixel. A second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels. A third image is obtained by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels. A second-color intermediate image and a third-color intermediate image are obtained by processing the third image according to the first image, where the second-color intermediate image contains second-color image pixels, the third-color intermediate image contains third-color image pixels. A target image is obtained by merging the third image, the second-color intermediate image, and the third-color intermediate image, where the target image contains multiple color image pixels arranged in a Bayer array. 
     A system for image processing is provided in implementations of the disclosure. The system includes an image sensor and a processor. The image sensor includes a pixel array. The pixel array includes multiple panchromatic photosensitive pixels and multiple color photosensitive pixels. The color photosensitive pixels include a first-color photosensitive pixel, a second-color photosensitive pixel, and a third-color photosensitive pixel having different spectral responses from one another. The color photosensitive pixels each have a narrower spectral response than the panchromatic photosensitive pixels. The second-color photosensitive pixel and the third-color photosensitive pixel each have a narrower spectral response than the first-color photosensitive pixel. The image sensor is configured to obtain a first image by exposing the pixel array, where the first image contains panchromatic image pixels generated by the panchromatic photosensitive pixels, a first-color image pixel generated by the first-color photosensitive pixel, a second-color image pixel generated by the second-color photosensitive pixel, and a third-color image pixel generated by the third-color photosensitive pixel. The processor is configured to: obtain a second image by converting the panchromatic image pixels in the first image into first-color image pixels; obtain a third image by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels; obtain a second-color intermediate image and a third-color intermediate image by processing the third image according to the first image, the second-color intermediate image containing second-color image pixels, the third-color intermediate image containing third-color image pixels; and obtain a target image by merging the third image, the second-color intermediate image, and the third-color intermediate image, the target image containing multiple color image pixels arranged in a Bayer array. 
     An electronic device is provided in implementations of the disclosure. The electronic device includes a lens, a housing, and the system for image processing described above. The lens and the system are integrated in the housing, and the lens and the image sensor of the system cooperate for imaging. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or additional aspects and advantages of the present disclosure will become apparent and easily understood from the description of the implementations in conjunction with the following drawings. 
         FIG.  1    is a schematic flowchart of a method for image processing in implementations of the disclosure. 
         FIG.  2    is a schematic structural diagram of a system for image processing in implementations of the disclosure. 
         FIG.  3    is a schematic diagram of a pixel array in implementations of the disclosure. 
         FIG.  4    is a schematic sectional diagram of a photosensitive pixel in implementations of the disclosure. 
         FIG.  5    is a circuit diagram of a photosensitive pixel in implementations of the disclosure. 
         FIG.  6    is a schematic diagram illustrating an arrangement of a minimal repeating unit in a pixel array in implementations of the disclosure. 
         FIG.  7    is a schematic diagram illustrating an arrangement of a minimal repeating unit in another pixel array in implementations of the disclosure. 
         FIG.  8    is a schematic diagram illustrating an arrangement of a minimal repeating unit in another pixel array in implementations of the disclosure. 
         FIG.  9    is a schematic diagram illustrating an arrangement of a minimal repeating unit in another pixel array in implementations of the disclosure. 
         FIG.  10    is a schematic diagram illustrating an arrangement of a minimal repeating unit in another pixel array in implementations of the disclosure. 
         FIG.  11    is a schematic diagram illustrating an arrangement of a minimal repeating unit in another pixel array in implementations of the disclosure. 
         FIG.  12    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  13    is a schematic diagram illustrating conversion from a panchromatic image pixel to a first-color image pixel in implementations of the disclosure. 
         FIG.  14    is another schematic diagram illustrating conversion from a panchromatic image pixel to a first-color image pixel in implementations of the disclosure. 
         FIG.  15    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  16    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  17    is a schematic diagram illustrating obtaining of a feature direction in implementations of the disclosure. 
         FIG.  18    is another schematic diagram illustrating conversion from a panchromatic image pixel to a first-color image pixel in implementations of the disclosure. 
         FIG.  19    is another schematic diagram illustrating conversion from a panchromatic image pixel to a first-color image pixel in implementations of the disclosure. 
         FIG.  20    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  21    is another schematic diagram illustrating conversion from a panchromatic image pixel to a first-color image pixel in implementations of the disclosure. 
         FIG.  22    is another schematic diagram illustrating conversion from a panchromatic image pixel to a first-color image pixel in implementations of the disclosure. 
         FIG.  23    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  24    is another schematic diagram illustrating conversion from a panchromatic image pixel to a first-color image pixel in implementations of the disclosure. 
         FIG.  25    is another schematic diagram illustrating conversion from a panchromatic image pixel to a first-color image pixel in implementations of the disclosure. 
         FIG.  26    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  27    is another schematic diagram illustrating conversion from a panchromatic image pixel to a first-color image pixel in implementations of the disclosure. 
         FIG.  28    is a schematic diagram of a fifth weighting matrix in implementations of the disclosure. 
         FIG.  29    is a schematic diagram illustrating conversion from a first image to a third image in implementations of the disclosure. 
         FIG.  30    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  31    is a schematic diagram illustrating conversion from a second-color image pixel to a first-color image pixel in implementations of the disclosure. 
         FIG.  32    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  33    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  34    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  35    is a schematic flowchart illustrating obtaining of a second-color intermediate image and a third-color intermediate image according to a first image and a third image in implementations of the disclosure. 
         FIG.  36    is a schematic flowchart of another method for image processing in implementations of the disclosure. 
         FIG.  37    and  FIG.  38    are schematic flowcharts illustrating obtaining of a second-color intermediate image and a third-color intermediate image according to a first image and a third image in implementations of the disclosure. 
         FIG.  39    is a schematic diagram illustrating merging of a third image, a second-color intermediate image and a third-color intermediate image in implementations of the disclosure. 
         FIG.  40    is a schematic structural diagram of an electronic device in implementations of the disclosure. 
         FIG.  41    is a schematic diagram illustrating interaction between a non-transitory computer-readable storage medium and a processor in implementations of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Implementations of the present disclosure are described in detail below, examples of which are illustrated in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The implementations described below with reference to the drawings are exemplary and only for explaining the implementations of the disclosure, and should not be construed as limiting the implementations of the disclosure. 
     Referring to  FIG.  1    and  FIG.  3   , a method for image processing is provided, which is applied to an image sensor  10 . The image sensor  10  includes a pixel array  11  that includes multiple panchromatic photosensitive pixels W and multiple color photosensitive pixels. The color photosensitive pixels include a first-color photosensitive pixel A, a second-color photosensitive pixel B, and a third-color photosensitive pixel C having different spectral responses from one another. The color photosensitive pixels each have a narrower spectral response than the panchromatic photosensitive pixels W. The second-color photosensitive pixel B and the third-color photosensitive pixel C each have a narrower spectral response than the first-color photosensitive pixel A. The method includes the following. 
     At block  01 , a first image is obtained by exposing the pixel array  11 , where the first image contains panchromatic image pixels generated by the panchromatic photosensitive pixels, a first-color image pixel generated by the first-color photosensitive pixel, a second-color image pixel generated by the second-color photosensitive pixel, and a third-color image pixel generated by the third-color photosensitive pixel. 
     At block  02 , a second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels. 
     At block  03 , a third image is obtained by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels. 
     At block  04 , a second-color intermediate image and a third-color intermediate image are obtained by processing the third image according to the first image, where the second-color intermediate image contains second-color image pixels, the third-color intermediate image contains third-color image pixels. 
     At block  05 , a target image is obtained by merging the third image, the second-color intermediate image, and the third-color intermediate image, where the target image contains multiple color image pixels arranged in a Bayer array. 
     Referring to  FIG.  1    and  FIG.  12   , in some implementations, operations at block  02  where the second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels includes the following. 
     At block  0202 , when the panchromatic image pixel is in a flat region, a first calculating window centered on the panchromatic image pixel to-be-converted is preset. 
     At block  0203 , pixel values of all pixels in the first calculating window are obtained. 
     At block  0204 , a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted is obtained according to the pixel values of all pixels in the first calculating window, a pixel value of the panchromatic image pixel to-be-converted, a preset first weighting matrix, and a preset second weighting matrix. 
     Referring to  FIG.  1    and  FIG.  15   , in some implementations, operations at block  02  where the second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels includes the following. 
     At block  0205 , when the panchromatic image pixel is in a non-flat region, a feature direction of the panchromatic image pixel to-be-converted is obtained. 
     At block  0206 , when the feature direction is a first direction and a first-color image pixel closest to the panchromatic image pixel to-be-converted in the feature direction is at a first side of the panchromatic image pixel to-be-converted, a first offset is obtained according to a pixel value of the panchromatic image pixel to-be-converted and a pixel value of a panchromatic image pixel adjacent to the panchromatic image pixel to-be-converted at the first side, and a second offset is obtained according to the pixel value of the panchromatic image pixel to-be-converted and pixel values of two panchromatic image pixels adjacent to the panchromatic image pixel to-be-converted at a second side opposite to the first side. 
     At block  0207 , a first weight is obtained according to the first offset and a preset weighting function, and a second weight is obtained according to the second offset and the weighting function. 
     At block  0208 , a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted is obtained according to the first weight, the second weight, the pixel value of the first-color image pixel closest to the panchromatic image pixel to-be-converted at the first side, and a pixel value of a first-color image pixel adjacent to the panchromatic image pixel to-be-converted at the second side. 
     Referring to  FIG.  1    and  FIG.  20   , in some implementations, operations at block  02  where the second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels includes the following. 
     At block  0205 , when the panchromatic image pixel is in a non-flat region, a feature direction of the panchromatic image pixel to-be-converted is obtained. 
     At block  0209 , when the feature direction is a first direction and a first-color image pixel closest to the panchromatic image pixel to-be-converted in the feature direction is at a second side of the panchromatic image pixel to-be-converted, a third offset is obtained according to a pixel value of the panchromatic image pixel to-be-converted and a pixel value of a panchromatic image pixel adjacent to the panchromatic image pixel to-be-converted at the second side, and a fourth offset is obtained according to the pixel value of the panchromatic image pixel to-be-converted and pixel values of two panchromatic image pixels adjacent to the panchromatic image pixel to-be-converted at a first side opposite to the second side. 
     At block  0210 , a third weight is obtained according to the third offset and a preset weighting function, and a fourth weight is obtained according to the fourth offset and the weighting function 
     At block  0211 , a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted is obtained according to the third weight, the fourth weight, a pixel value of a first-color image pixel adjacent to the panchromatic image pixel to-be-converted at the first side, and the pixel value of the first-color image pixel closest to the panchromatic image pixel to-be-converted at the second side. 
     Referring to  FIG.  1    and  FIG.  23   , in some implementations, operations at block  02  where the second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels includes the following. 
     At block  0205 , when the panchromatic image pixel is in a non-flat region, a feature direction of the panchromatic image pixel to-be-converted is obtained. 
     At block  0212 , when the feature direction is a second direction, a second calculating window centered on the panchromatic image pixel to-be-converted is preset. 
     At block  0213 , pixel values of all pixels in the second calculating window are obtained. 
     At block  0214 , a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted is obtained according to the pixel values of all pixels in the second calculating window, a pixel value of the panchromatic image pixel to-be-converted, a preset third weighting matrix, and a preset fourth weighting matrix. 
     Referring to  FIG.  1    and  FIG.  26   , in some implementations, operations at block  02  where the second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels includes the following. 
     At block  0205 , when the panchromatic image pixel is in a non-flat region, a feature direction of the panchromatic image pixel to-be-converted is obtained. 
     At block  0215 , when the feature direction is a third direction, a third calculating window centered on the panchromatic image pixel to-be-converted is preset. 
     At block  0216 , pixel values of all pixels in the third calculating window are obtained, and a transformed pixel value of each first-color image pixel in the third calculating window is obtained according to pixel values of multiple panchromatic image pixels around the first-color image pixel. 
     At block  0217 , a fifth weighting matrix is obtained according to the transformed pixel value of each first-color image pixel, a pixel value of the panchromatic image pixel to-be-converted, and a preset weighting function. 
     At block  0218 , a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted is obtained according to the transformed pixel value of each first-color image pixels, the fifth weighting matrix, and a distance weight. 
     Referring to  FIG.  16   , in some implementations, operations of when the panchromatic image pixel is in the non-flat region, obtaining the feature direction of the panchromatic image pixel to-be-converted include the following. 
     At block  02051 , gradient values in multiple directions at the panchromatic image pixel to-be-converted are obtained, and a direction corresponding to a smallest gradient value is selected as the feature direction of the panchromatic image pixel. 
     In some implementations, operations of obtaining the third image by converting the second-color image pixel and the third-color image pixel in the second image into the first-color image pixels include the following. When the second-color image pixel is in a flat region, a pixel value of a first-color image pixel converted from the second-color image pixel to-be-converted is obtained according to pixel values of first-color image pixels adjacent to the second-color image pixel to-be-converted in multiple directions. Optionally, when the third-color image pixel is in a flat region, a pixel value of a first-color image pixel converted from the third-color image pixel to-be-converted is obtained according to pixel values of first-color image pixels adjacent to the third-color image pixel to-be-converted in multiple directions. 
     Referring to  FIG.  1    and  FIG.  32   , in some implementations, operations at block  03  where the third image is obtained by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels include the following. 
     At block  033 , when the second-color image pixel is in a non-flat region, a feature direction of the second-color image pixel to-be-converted is obtained. 
     At block  034 , a pixel value of a first-color image pixel converted from the second-color image pixel to-be-converted is obtained according to pixel values of two first-color image pixels adjacent to the second-color image pixel to-be-converted in the feature direction. 
     Referring to  FIG.  1    and  FIG.  33   , in some implementations, operations at block  03  where the third image is obtained by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels include the following. 
     At block  037 , when the third-color image pixel is in a non-flat region, a feature direction of the third-color image pixel to-be-converted is obtained. 
     At block  038 , a pixel value of a first-color image pixel converted from the third-color image pixel to-be-converted is obtained according to pixel values of two first-color image pixels adjacent to the third-color image pixel to-be-converted in the feature direction. 
     In some implementations, operations of when the second-color image pixel is in the non-flat region, obtaining the feature direction of the second-color image pixel to-be-converted include obtaining gradient values at the second-color image pixel to-be-converted in multiple directions, and selecting a direction corresponding to a smallest gradient value as the feature direction of the second-color image pixel. Operations of when the third-color image pixel is in the non-flat region, obtaining the feature direction of the third-color image pixel to-be-converted include obtaining gradient values at the third-color image pixel to-be-converted in multiple directions, and selecting a direction corresponding to a smallest gradient value as the feature direction of the third-color image pixel. 
     Referring to  FIG.  36   , in some implementations, operations at block  04  where the second-color intermediate image and the third-color intermediate image are obtained by processing the third image according to the first image include the following. 
     At block  041 , the second-color intermediate image and the third-color intermediate image are obtained by performing bilateral filtering on the third image according to the first image. 
     In conjunction with  FIG.  1    and  FIG.  2   , the disclosure further provides a system  100  for image processing. The system  100  for image processing includes an image sensor  10  and a processor  20 . The image sensor  10  includes a pixel array  11  (as illustrated in  FIG.  3   ). The pixel array  11  includes multiple panchromatic photosensitive pixels w and multiple color photosensitive pixels. The color photosensitive pixels include a first-color photosensitive pixel A, a second-color photosensitive pixel B, and a third-color photosensitive pixel C having different spectral responses from one another. The color photosensitive pixels each have a narrower spectral response than the panchromatic photosensitive pixels. The second-color photosensitive pixel B and the third-color photosensitive pixel C each have a narrower spectral response than the first-color photosensitive pixel A. The image sensor is configured to obtain a first image by exposing the pixel array, where the first image contains panchromatic image pixels generated by the panchromatic photosensitive pixels, a first-color image pixel generated by the first-color photosensitive pixel, a second-color image pixel generated by the second-color photosensitive pixel, and a third-color image pixel generated by the third-color photosensitive pixel. The processor is configured to: obtain a second image by converting the panchromatic image pixels in the first image into first-color image pixels; obtain a third image by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels; obtain a second-color intermediate image and a third-color intermediate image by processing the third image according to the first image, the second-color intermediate image containing second-color image pixels, the third-color intermediate image containing third-color image pixels; and obtain a target image by merging the third image, the second-color intermediate image, and the third-color intermediate image, the target image containing multiple color image pixels arranged in a Bayer array. 
     Referring to  FIG.  2    and  FIG.  12   , in some implementations, the processor  20  is further configured to: when the panchromatic image pixel is in the flat region, preset a first calculating window centered on the panchromatic image pixel to-be-converted; obtain pixel values of all pixels in the first calculating window; and obtain a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted, according to the pixel values of all pixels in the first calculating window, a pixel value of the panchromatic image pixel to-be-converted, a preset first weighting matrix, and a preset second weighting matrix. 
     Referring to  FIG.  2    and  FIG.  15   , in some implementations, the processor  20  is further configured to: when the panchromatic image pixel is in a non-flat region, obtain a feature direction of the panchromatic image pixel to-be-converted; when the feature direction is a first direction and a first-color image pixel closest to the panchromatic image pixel to-be-converted in the feature direction is at a first side of the panchromatic image pixel to-be-converted, obtain a first offset according to a pixel value of the panchromatic image pixel to-be-converted and a pixel value of a panchromatic image pixel adjacent to the panchromatic image pixel to-be-converted at the first side, and obtain a second offset according to the pixel value of the panchromatic image pixel to-be-converted and pixel values of two panchromatic image pixels adjacent to the panchromatic image pixel to-be-converted at a second side opposite to the first side; obtain a first weight according to the first offset and a preset weighting function, and obtain a second weight according to the second offset and the weighting function; and obtain a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted, according to the first weight, the second weight, the pixel value of the first-color image pixel closest to the panchromatic image pixel to-be-converted at the first side, and a pixel value of a first-color image pixel adjacent to the panchromatic image pixel to-be-converted at the second side. 
     Referring to  FIG.  2    and  FIG.  20   , in some implementations, the processor  20  is further configured to: when the panchromatic image pixel is in a non-flat region, obtain a feature direction of the panchromatic image pixel to-be-converted; when the feature direction is a first direction and a first-color image pixel closest to the panchromatic image pixel to-be-converted in the feature direction is at a second side of the panchromatic image pixel to-be-converted, obtain a third offset according to a pixel value of the panchromatic image pixel to-be-converted and a pixel value of a panchromatic image pixel adjacent to the panchromatic image pixel to-be-converted at the second side, and obtain a fourth offset according to the pixel value of the panchromatic image pixel to-be-converted and pixel values of two panchromatic image pixels adjacent to the panchromatic image pixel to-be-converted at a first side opposite to the second side; obtain a third weight according to the third offset and a preset weighting function, and obtain a fourth weight according to the fourth offset and the weighting function; and obtain a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted, according to the third weight, the fourth weight, a pixel value of a first-color image pixel adjacent to the panchromatic image pixel to-be-converted at the first side, and the pixel value of the first-color image pixel closest to the panchromatic image pixel to-be-converted at the second side. 
     Referring to  FIG.  2    and  FIG.  23   , in some implementations, the processor  20  is further configured to: when the panchromatic image pixel is in a non-flat region, obtain a feature direction of the panchromatic image pixel to-be-converted; when the feature direction is a second direction, preset a second calculating window centered on the panchromatic image pixel to-be-converted, where the second direction intersects with the first direction of the first image; obtain pixel values of all pixels in the second calculating window; and obtain a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted, according to the pixel values of all pixels in the second calculating window, a pixel value of the panchromatic image pixel to-be-converted, a preset third weighting matrix, and a preset fourth weighting matrix. 
     Referring to  FIG.  2    and  FIG.  26   , in some implementations, the processor  20  is further configured to: when the panchromatic image pixel is in a non-flat region, obtain a feature direction of the panchromatic image pixel to-be-converted; when the feature direction is a third direction, preset a third calculating window centered on the panchromatic image pixel to-be-converted; obtain pixel values of all pixels in the third calculating window, and obtain a transformed pixel value of each first-color image pixel in the third calculating window according to pixel values of multiple panchromatic image pixels around the first-color image pixel; obtain a fifth weighting matrix according to the transformed pixel value of each first-color image pixel, a pixel value of the panchromatic image pixel to-be-converted, and a preset weighting function; and obtain a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted, according to the transformed pixel value of each first-color image pixels, the fifth weighting matrix, and a distance weight. 
     Referring to  FIG.  2    and  FIG.  16   , in some implementations, the processor  20  is further configured to: obtain gradient values in multiple directions at the panchromatic image pixel to-be-converted, and select a direction corresponding to a smallest gradient value as the feature direction of the panchromatic image pixel. 
     In some implementations, the processor  20  is further configured to: when the second-color image pixel is in the flat region, obtain a pixel value of a first-color image pixel converted from the second-color image pixel to-be-converted, according to pixel values of first-color image pixels adjacent to the second-color image pixel to-be-converted in multiple directions; and/or when the third-color image pixel is in the flat region, obtain a pixel value of a first-color image pixel converted from the third-color image pixel to-be-converted, according to pixel values of first-color image pixels adjacent to the third-color image pixel to-be-converted in multiple directions. 
     Referring to  FIG.  2    and  FIG.  32   , in some implementations, the processor  20  is further configured to: when the second-color image pixel is in the non-flat region, obtain a feature direction of the second-color image pixel to-be-converted; and obtain a pixel value of a first-color image pixel converted from the second-color image pixel to-be-converted, according to pixel values of two first-color image pixels adjacent to the second-color image pixel to-be-converted in the feature direction. 
     Referring to  FIG.  2    and  FIG.  33   , in some implementations, the processor  20  is further configured to: when the third-color image pixel is in the non-flat region, obtain a feature direction of the third-color image pixel to-be-converted; and obtain a pixel value of a first-color image pixel converted from the third-color image pixel to-be-converted, according to pixel values of two first-color image pixels adjacent to the third-color image pixel to-be-converted in the feature direction. 
     In some implementations, the processor  20  is further configured to: obtain gradient values at the second-color image pixel to-be-converted in multiple directions, and select a direction corresponding to a smallest gradient value as the feature direction of the second-color image pixel, and obtain gradient values at the third-color image pixel to-be-converted in multiple directions, and select a direction corresponding to a smallest gradient value as the feature direction of the third-color image pixel. 
     Referring to  FIG.  2    and  FIG.  36   , in some implementations, the processor  20  is further configured to: obtain the second-color intermediate image and the third-color intermediate image by performing bilateral filtering on the third image according to the first image. 
     Referring to  FIG.  40   , the disclosure further provides an electronic device  1000 . The electronic device  1000  in implementations of the disclosure includes a lens  300 , a housing  200 , and the system for image process  100  in any of implementations above. The lens  300 , the system for image processing  100  are integrated in the housing  200 . The lens  300  and the image sensor  10  of the system for image processing  100  cooperate for imaging. 
     Referring to  FIG.  41   , the disclosure further provides a non-transitory computer-readable storage medium  400  that includes a computer program. When executed by a processor  60 , the computer program causes the processor  60  to execute the method for image processing in any implementation described above. 
     Referring to  FIG.  1    and  FIG.  3   , a method for image processing is provided, which is applied to an image sensor  10 . The image sensor  10  includes a pixel array  11  that includes multiple panchromatic photosensitive pixels W and multiple color photosensitive pixels. The color photosensitive pixels include a first-color photosensitive pixel A, a second-color photosensitive pixel B, and a third-color photosensitive pixel C having different spectral responses from one another. The color photosensitive pixels each have a narrower spectral response than the panchromatic photosensitive pixels W. The second-color photosensitive pixel B and the third-color photosensitive pixel C each have a narrower spectral response than the first-color photosensitive pixel A. The method includes the following. 
     At block  01 , a first image is obtained by exposing the pixel array  11 , where the first image contains panchromatic image pixels generated by the panchromatic photosensitive pixels, a first-color image pixel generated by the first-color photosensitive pixel, a second-color image pixel generated by the second-color photosensitive pixel, and a third-color image pixel generated by the third-color photosensitive pixel. 
     At block  02 , a second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels. 
     At block  03 , a third image is obtained by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels. 
     At block  04 , a second-color intermediate image and a third-color intermediate image are obtained by processing the third image according to the first image, where the second-color intermediate image contains second-color image pixels, the third-color intermediate image contains third-color image pixels. 
     At block  05 , a target image is obtained by merging the third image, the second-color intermediate image, and the third-color intermediate image, where the target image contains multiple color image pixels arranged in a Bayer array. 
     In conjunction with  FIG.  1    and  FIG.  2   , the disclosure further provides a system  100  for image processing. The system  100  for image processing includes an image sensor  10  and a processor  20 . The image sensor  10  includes a pixel array  11  (as illustrated in  FIG.  3   ). The pixel array  11  includes multiple panchromatic photosensitive pixels w and multiple color photosensitive pixels. The color photosensitive pixels include a first-color photosensitive pixel A, a second-color photosensitive pixel B, and a third-color photosensitive pixel C having different spectral responses from one another. The color photosensitive pixels each have a narrower spectral response than the panchromatic photosensitive pixels. The second-color photosensitive pixel B and the third-color photosensitive pixel C each have a narrower spectral response than the first-color photosensitive pixel A. The image sensor is configured to obtain a first image by exposing the pixel array, where the first image contains panchromatic image pixels generated by the panchromatic photosensitive pixels, a first-color image pixel generated by the first-color photosensitive pixel, a second-color image pixel generated by the second-color photosensitive pixel, and a third-color image pixel generated by the third-color photosensitive pixel. The processor is configured to: obtain a second image by converting the panchromatic image pixels in the first image into first-color image pixels; obtain a third image by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels; obtain a second-color intermediate image and a third-color intermediate image by processing the third image according to the first image, the second-color intermediate image containing second-color image pixels, the third-color intermediate image containing third-color image pixels; and obtain a target image by merging the third image, the second-color intermediate image, and the third-color intermediate image, the target image containing multiple color image pixels arranged in a Bayer array. 
     According to the method for image processing, the system  100  for image processing, the electronic device  1000 , and the computer-readable storage medium  400  in implementations of the disclosure, by introducing panchromatic photosensitive pixels W in the pixel array  11 , the panchromatic image pixels W can be interpolated to be color image pixels with a relatively wide spectral response to obtain the second image, and then the second image can be processed to obtain the target image in a Bayer array. In this way, the problem that the image processor cannot directly process the images with image pixels arranged in a non-Bayer array can be solved. In addition, since the panchromatic photosensitive pixels W are introduced to the pixel array  11 , the resolution and signal-to-noise ratio of the finally obtained image can be improved, thus improving the photographing effect at night. 
       FIG.  3    is a schematic diagram of an image sensor  10  in implementations of the disclosure. The image sensor  10  includes a pixel array  11 , a vertical drive unit  12 , a control unit  13 , a column processing unit  14 , and a horizontal drive unit  15 . 
     For example, the image sensor  10  may be a complex metal oxide semiconductor (CMOS) sensor or a charge coupled device (CCD) sensor. 
     For example, the pixel array  11  includes multiple photosensitive pixels  110  (illustrated in  FIG.  4   ) arranged in a two-dimensional array (i.e., arranged in a two-dimensional matrix), and each photosensitive pixel  110  includes a photoelectric conversion element  1111  (illustrated in  FIG.  5   ). Each photosensitive pixel  110  converts light into charge according to the intensity of light incident on the pixel. 
     For example, the vertical drive unit  12  includes a shift register and an address decoder. The vertical drive unit  12  has functions of readout scanning and reset scanning. The readout scanning refers to sequentially scanning per photosensitive pixel  110  line by line, and reading signals line by line from per photosensitive pixel  110 . For example, the signal output by each photosensitive pixel  110  in the selected and scanned row of photosensitive pixels is transmitted to the column processing unit  14 . The reset scanning is used to reset the charge, in which photo charges of the photoelectric conversion element are discarded, so that accumulation of photo charges can be restarted. 
     For example, the signal processing performed by the column processing unit  14  is correlation double sampling (CDS) processing. In CDS processing, a reset level and a signal level output from each photosensitive pixel  110  in the selected photosensitive pixel row are extracted, and a level difference is calculated. Thus, signals of the photosensitive pixels  110  in the row are obtained. The column processing unit  14  may have an analog-to-digital (A/D) conversion function for converting analog pixel signals into digital formats. 
     For example, the horizontal drive unit  15  includes a shift register and an address decoder. The horizontal drive unit  15  sequentially scans the pixel array  11  column by column. Through the selection scanning operation performed by the horizontal drive unit  15 , each column of photosensitive pixels is sequentially processed by the column processing unit  14  for sequentially output. 
     For example, the control unit  13  configures timing signals according to the operation mode, and uses a variety of timing signals to control the vertical drive unit  12 , the column processing unit  14 , and the horizontal drive unit  15  to cooperate. 
       FIG.  4    is a schematic diagram of a photosensitive pixel  110  in implementations of the disclosure. The photosensitive pixel  110  includes a pixel circuit  111 , a filter  112 , and a micro lens  113 . Along a light receiving direction of the photosensitive pixel  110 , the micro lens  113 , the filter  112 , and the pixel circuit  111  are sequentially arranged. The micro lens  113  is configured to gather light, and the filter  112  is configured to pass light within a certain band and filter out light within other bands. The pixel circuit  111  is configured to convert the received light into an electrical signal and provide the generated electrical signal to the column processing unit  14  illustrated in  FIG.  3   . 
       FIG.  5    is a schematic diagram of a pixel circuit  111  of a photosensitive pixel  110  in implementations of the disclosure. The pixel circuit  111  in  FIG.  5    can be applied to each photosensitive pixel  110  (illustrated in  FIG.  4   ) in the pixel array  11  illustrated in  FIG.  3   . The operating principle of the pixel circuit  111  will be described below with reference to  FIG.  3    to  FIG.  5   . 
     As illustrated in  FIG.  5   , the pixel circuit  111  includes a photoelectric conversion element  1111  (for example, a photodiode), an exposure control circuit (for example, a transfer transistor  1112 ), a reset circuit (for example, a reset transistor  1113 ), an amplifying circuit (for example, an amplifying transistor  1114 ), and a selecting circuit (for example, a selecting transistor  1115 ). In implementations of the disclosure, the transfer transistor  1112 , the reset transistor  1113 , the amplifying transistor  1114 , and the selecting transistor  1115  are each, for example, a MOS transistor, but are not limited thereto. 
     For example, the photoelectric conversion element  117  includes the photodiode, and the anode of the photodiode is connected to ground, for example. The photodiode converts the received light into charges. The cathode of the photodiode is connected to a floating diffusion unit FD through the exposure control circuit (for example, the transfer transistor  1112 ). The floating diffusion unit FD is connected to the gate of the amplifying transistor  1114  and the source of the reset transistor  1113 . 
     For example, the exposure control circuit is the transfer transistor  1112 , and the control terminal TG of the exposure control circuit is the gate of the transfer transistor  1112 . When a pulse of an effective level (for example, VPIX level) is transmitted to the gate of the transfer transistor  1112  through the exposure control line, the transfer transistor  1112  is turned on. The transfer transistor  1112  transmits the charges generated from photoelectric conversion by the photodiode to the floating diffusion unit FD. 
     For example, the drain of the reset transistor  1113  is connected to a pixel power supply VPIX. The source of the reset transistor  1113  is connected to the floating diffusion unit FD. Before the charges are transferred from the photodiode to the floating diffusion unit FD, a pulse of an effective reset level is transmitted to the gate of the reset transistor  1113  through the reset line, and the reset transistor  1113  is turned on. The reset transistor  1113  resets the floating diffusion unit FD to the pixel power supply VPIX. 
     For example, the gate of the amplifying transistor  1114  is connected to the floating diffusion unit FD. The drain of the amplifying transistor  1114  is connected to the pixel power supply VPIX. After the floating diffusion unit FD is reset by the reset transistor  1113 , the amplifying transistor  1114  outputs a reset level through an output terminal OUT via the selecting transistor  1115 . After the charges of the photodiode are transferred by the transfer transistor  1112 , the amplifying transistor  1114  outputs a signal level through the output terminal OUT via the selecting transistor  1115 . 
     For example, the drain of the selecting transistor  1115  is connected to the source of the amplifying transistor  1114 . The source of selecting transistor  1115  is connected to the column processing unit  14  illustrated in  FIG.  3    through the output terminal OUT. When a pulse of an effective level is transmitted to the gate of selecting transistor  1115  through the selecting line, the selecting transistor  1115  is turned on. The signal outputted from the amplifying transistor  1114  is transmitted to the column processing unit  14  through the selecting transistor  1115 . 
     It should be noted that the pixel structure of the pixel circuit  111  in the implementations of the disclosure is not limited to the structure illustrated in  FIG.  5   . For example, the pixel circuit  111  may have a three-transistor pixel structure, in which the functions of the amplifying transistor  1114  and the selecting transistor  1115  are realized by a single transistor. For example, the exposure control circuit is also not limited to one transfer transistor  1112 , and other electronic elements or structures with control terminals to control the conduction function can be used as the exposure control circuit in the implementations of the disclosure. The implementation of a single transfer transistor  1112  is simple, low cost, and easy to control. 
     Specifically, for example,  FIG.  6    illustrates an arrangement of photosensitive pixels  110  (illustrated in  FIG.  4   ) in a minimal repeating unit in implementations of the disclosure. The minimal repeating unit has 16 photosensitive pixels  110  in 4 rows and 4 columns, and each subunit has 4 photosensitive pixels in 2 rows and 2 columns. The 16 pixels are arranged as follows: 
                                                    W B W A               B W A W               W A W C               A W C W                        
where W represents a panchromatic photosensitive pixel, A represents a first-color photosensitive pixel in multiple color photosensitive pixels, B represents a second-color photosensitive pixel in the multiple photosensitive color pixels, and C represents a third-color photosensitive pixel in the multiple color photosensitive pixels.
 
     As illustrated in  FIG.  6   , the panchromatic pixels W are arranged in a first diagonal direction D 1  (that is, a direction connecting the upper left corner and the lower right corner in  FIG.  6   ). The color pixels are arranged in a second diagonal direction D 2  (such as a direction connecting the lower left corner and the upper right corner in  FIG.  6   ). The first diagonal direction D 1  is different from the second diagonal direction D 2 . 
     It should be noted that the first diagonal direction D 1  and the second diagonal direction D 2  are not limited to the diagonal lines, but also include directions parallel to the diagonal lines. The same interpretation applies for the first diagonal direction D 1  and the second diagonal direction D 2  illustrated in  FIG.  7    to  FIG.  11   . The “direction” herein is not a single direction, but can be understood as the concept of a “straight line” indicating the arrangement, and can be a two-way direction indicated at both ends of the straight line. 
     It should be understood that the orientation or positional relationship indicated by the terms “upper”, “lower”, “left”, “right”, etc. here and below are based on the orientation or positional relationship illustrated in the drawings, which are only for ease of description rather than indicating or implying that the device or element referred to must have a particular orientation or be constructed and operate in a particular orientation, and thus should not be construed as limiting the present disclosure. 
     For example,  FIG.  7    illustrates an arrangement of photosensitive pixels  110  (illustrated in  FIG.  4   ) in a minimal repeating unit in implementations of the disclosure. The minimal repeating unit has 16 photosensitive pixels  110  in 4 rows and 4 columns, and each subunit has 4 photosensitive pixels  110  in 2 rows and 2 columns. The 16 pixels are arranged as follows: 
                                                    B W A W               W B W A               A W C W               W A W C                        
where W represents a panchromatic photosensitive pixel, A represents a first-color photosensitive pixel in multiple color photosensitive pixels, B represents a second-color photosensitive pixel in the multiple photosensitive color pixels, and C represents a third-color photosensitive pixel in the multiple color photosensitive pixels.
 
     For example, as illustrated in  FIG.  7   , the panchromatic pixels W are arranged in a second diagonal direction D 2  (that is, a direction connecting the upper right corner and the lower left corner in  FIG.  7   ). The color pixels are arranged in a first diagonal direction D 1  (such as a direction connecting the lower right corner and the upper left corner in  FIG.  7   ). For example, the first diagonal direction is perpendicular to the second diagonal direction. 
     For example,  FIG.  8    illustrates an arrangement of photosensitive pixels  110  (illustrated in  FIG.  4   ) in a minimal repeating unit in implementations of the disclosure. The minimal repeating unit has 36 photosensitive pixels  110  in 6 rows and 6 columns, and each subunit has 4 photosensitive pixels  110  in 2 rows and 2 columns. The 36 pixels are arranged as follows: 
                                                    W B W A W A               B W B W A W               W B W A W A               A W A W C W               W A W C W C               A W A W C W                        
where W represents a panchromatic photosensitive pixel, A represents a first-color photosensitive pixel in multiple color photosensitive pixels, B represents a second-color photosensitive pixel in the multiple photosensitive color pixels, and C represents a third-color photosensitive pixel in the multiple color photosensitive pixels.
 
     For example, as illustrated in  FIG.  8   , the panchromatic pixels W are arranged in a first diagonal direction D 1  (that is, a direction connecting the upper left corner and the lower right corner in  FIG.  8   ). The color pixels are arranged in a second diagonal direction D 2  (such as a direction connecting the lower left corner and the upper right corner in  FIG.  8   ). The first diagonal direction D 1  is different from the second diagonal direction D 2 . 
     For example,  FIG.  9    illustrates an arrangement of photosensitive pixels  110  (illustrated in  FIG.  4   ) in a minimal repeating unit in implementations of the disclosure. The minimal repeating unit has 36 photosensitive pixels  110  in 6 rows and 6 columns, and each subunit has 4 photosensitive pixels  110  in 2 rows and 2 columns. The 36 pixels are arranged as follows: 
                                                    B W B W A W               W B W A W A               B W B W A W               W A W C W C               A W A W C W               W A W C W C                        
where W represents a panchromatic photosensitive pixel, A represents a first-color photosensitive pixel in multiple color photosensitive pixels, B represents a second-color photosensitive pixel in the multiple photosensitive color pixels, and C represents a third-color photosensitive pixel in the multiple color photosensitive pixels.
 
     For example, as illustrated in  FIG.  9   , the panchromatic pixels W are arranged in a second diagonal direction D 2  (that is, a direction connecting the upper right corner and the lower left corner in  FIG.  9   ). The color pixels are arranged in a first diagonal direction D 1  (such as a direction connecting the lower right corner and the upper left corner in  FIG.  9   ). For example, the first diagonal direction is perpendicular to the second diagonal direction. 
     For example,  FIG.  10    illustrates an arrangement of photosensitive pixels  110  (illustrated in  FIG.  4   ) in a minimal repeating unit in implementations of the disclosure. The minimal repeating unit has 64 photosensitive pixels  110  in 8 rows and 8 columns, and each subunit has 4 photosensitive pixels  110  in 2 rows and 2 columns. The 64 pixels are arranged as follows: 
                                                    W B W B W A W A               B W B W A W A W               W B W B W A W A               B W B W A W A W               W A W A W C W C               A W A W C W C W               W A W A W C W C               A W A W C W C W                        
where W represents a panchromatic photosensitive pixel, A represents a first-color photosensitive pixel in multiple color photosensitive pixels, B represents a second-color photosensitive pixel in the multiple photosensitive color pixels, and C represents a third-color photosensitive pixel in the multiple color photosensitive pixels.
 
     For example, as illustrated in  FIG.  10   , the panchromatic pixels W are arranged in a first diagonal direction D 1  (that is, a direction connecting the upper left corner and the lower right corner in  FIG.  10   ). The color pixels are arranged in a second diagonal direction D 2  (such as a direction connecting the lower left corner and the upper right corner in  FIG.  10   ). The first diagonal direction D 1  is different from the second diagonal direction D 2 . 
     For example,  FIG.  11    illustrates an arrangement of photosensitive pixels  110  (illustrated in  FIG.  4   ) in a minimal repeating unit in implementations of the disclosure. The minimal repeating unit has 64 photosensitive pixels  110  in 8 rows and 8 columns, and each subunit has 4 photosensitive  110  pixels in 2 rows and 2 columns. The 64 pixels are arranged as follows: 
                                                    B W B W A W A W                W B W B W A W A               B W B W A W A W               W B W B W A W A               A W A W C W C W                W A W A W C W C               A W A W C W C W               W A W A W C W C                        
where W represents a panchromatic photosensitive pixel, A represents a first-color photosensitive pixel in multiple color photosensitive pixels, B represents a second-color photosensitive pixel in the multiple photosensitive color pixels, and C represents a third-color photosensitive pixel in the multiple color photosensitive pixels.
 
     For example, as illustrated in  FIG.  11   , the panchromatic pixels W are arranged in a second diagonal direction D 2  (that is, a direction connecting the upper right corner and the lower left corner in  FIG.  11   ). The color pixels are arranged in a first diagonal direction D 1  (such as a direction connecting the lower right corner and the upper left corner in  FIG.  11   ). For example, the first diagonal direction is perpendicular to the second diagonal direction. 
     In some implementations, in the minimal repeating units illustrated in  FIG.  6    to  FIG.  11   , the first-color photosensitive pixel A may be a green pixel G, the second-color photosensitive pixel B may be a red pixel R, and the third-color photosensitive pixel C may be a blue pixel Bu. 
     In some implementations, in the minimal repeating units illustrated in  FIG.  6    to  FIG.  11   , the first-color photosensitive pixel A may be a yellow pixel Y, the second-color photosensitive pixel B may be a red pixel R, and the third-color photosensitive pixel C may be a blue pixel Bu. 
     In some implementations, in the minimal repeating units illustrated in  FIG.  6    to  FIG.  11   , the first-color photosensitive pixel A may be a cyan pixel Cy, the second-color photosensitive pixel B may be a magenta pixel M, and the third-color photosensitive pixel C may be a yellow pixel Y. 
     It should be noted that, in some implementations, a response waveband of the panchromatic photosensitive pixel W may be a visible band (e.g., 400 nm-760 nm). For example, an infrared filter may be disposed on the panchromatic photosensitive pixel W to filter out infrared lights. In some implementations, the response waveband of the panchromatic photosensitive pixel may be a visible band and a near infrared band (e.g., 400 nm-1000 nm), and is matched with a response waveband of the photoelectric conversion element  1111  (illustrated in  FIG.  5   ) in the image sensor  10  (illustrated in  FIG.  2   ). For example, the panchromatic photosensitive pixel W may not be provided with a filter or may be provided with a filter that can pass lights of full wavebands, and the response waveband of the panchromatic photosensitive pixel W is determined by the response waveband of the photoelectric conversion element  1111 , that is, the response waveband of the panchromatic photosensitive pixel W matches the response waveband of the photoelectric conversion element  1111 . The implementations of the disclosure include but are not limited to the above wavebands. 
     For easy of description, in the following implementations, the first-color photosensitive pixel A is a green pixel G, the second-color photosensitive pixel B is a red pixel R, and the third-color photosensitive pixel C is a blue pixel Bu. 
     Referring to  FIG.  17   , in some implementations, the control unit  13  (illustrated in  FIG.  3   ) control exposure of the pixel array  11  (illustrated in  FIG.  3   ) to obtain a first image. The first image contains panchromatic image pixels W generated by the panchromatic photosensitive pixels W, a first-color image pixel A generated by the first-color photosensitive pixel A, a second-color image pixel B generated by the second-color photosensitive pixel B, and a third-color image pixel C generated by the third-color photosensitive pixel C. After exposure of the pixel array  11 , the processor obtains the first image and then processes the panchromatic image pixels W, the first-color image pixel A, the second-color image pixel B, and the third-color image pixel C to obtain the target image. 
     Specifically, referring to  FIG.  12   , operations at block  02  where the second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels includes the following. 
     At block  0201 , whether a panchromatic image pixel to-be-converted in is a flat region is determined. 
     At block  0202 , when the panchromatic image pixel is in the flat region, a first calculating window centered on the panchromatic image pixel to-be-converted is preset. 
     At block  0203 , pixel values of all pixels in the first calculating window are obtained. 
     At block  0204 , a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted is obtained according to the pixel values of all pixels in the first calculating window, a pixel value of the panchromatic image pixel to-be-converted, a preset first weighting matrix, and a preset second weighting matrix. 
     In conjunction with  FIG.  2    and  FIG.  12   , operations at blocks  0201 ,  0202 ,  0203 , and  0204  may be performed by the processor  20 . That is, the processor  20  is further configured to: determine whether a panchromatic image pixel W 0  to-be-converted in is a flat region; when the panchromatic image pixel W 0  is in the flat region, preset a first calculating window C 1  centered on the panchromatic image pixel W 0  to-be-converted; obtain pixel values of all pixels in the first calculating window C 1 ; and obtain a pixel value of a first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted, according to the pixel values of all pixels in the first calculating window C 1 , a pixel value of the panchromatic image pixel W 0  to-be-converted, a preset first weighting matrix N 1 , and a preset second weighting matrix N 2 . 
     In some implementations, a detection window centered on the panchromatic image pixel W to-be-detected may be preset. A standard deviation of pixel values of multiple image pixels within the detection window is calculated. If the standard deviation is greater than a preset value, the panchromatic image pixel W 0  to-be-converted is determined not to be in the flat region, that is, the panchromatic image pixel W 0  to-be-converted is determined to be in the non-flat region. If the standard deviation is less than the preset value, the panchromatic image pixel W 0  to-be-converted is determined to be in the flat region. In some implementations, whether the panchromatic image pixel W 0  to-be-converted is in the flat region may also be determined according to a variance of the pixel values of the multiple image pixels within the detection window. If the variance is greater than a preset value, the panchromatic image pixel W 0  to-be-converted is determined not to be in the flat region, that is, the panchromatic image pixel W 0  to-be-converted is determined to be in the non-flat region. If the variance is less than the preset value, the panchromatic image pixel W 0  to-be-converted is determined to be in the flat region. Whether the panchromatic image pixel W 0  to-be-converted is in the flat region may also be determined with other methods, which will not be exhausted herein. 
     Referring to  FIG.  2   ,  FIG.  13   , and  FIG.  14   , when the panchromatic image pixel W 0  to-be-converted is in the flat region, the first calculating window C 1  is preset, which is centered on the panchromatic image pixel W 0  to-be-converted. Pixels values of all pixels in the first calculating window C 1  are obtained. For example, assume that the first calculating window C 1  has a size of 7×7. The panchromatic image pixel W 0  to-be-converted is at the center of the first calculating window C 1 , that is, the panchromatic image pixel W 0  to-be-converted is in row 3, column 3 of the first calculating window C 1 . Pixel values of all pixels in the calculating window C 1  are obtained. It should be noted that the first calculating window C 1  is a virtual window for calculating, rather than an actual structure. In addition, the size of the first calculating window C 1  may be adjusted according to actual needs. The same is true for all calculating windows mentioned below, which will not repeated herein. 
     After presetting the first calculating window C 1  and obtaining the pixel values within the first calculating window C 1 , the processor  20  can obtain a first converting value M 1  and a second converting value M 2  according to all pixel values within the first calculating window C 1 , a preset first weighting matrix N 1 , and a preset second weighting matrix N 2 . Specifically, the first converting value M 1  may be obtained according to formula M 1 =sum(sum(I×N 1 )×sum(N 2 )), where I represents a pixel value of each image pixel in the first calculating window C 1 . That is, multiple new pixel values are first obtained by multiplying the pixel value of each image pixel in the first calculating window C 1  by a value at a corresponding location in the preset first weighting matrix N 1 , and then a summation of the new pixel values is multiplied by a summation of all values in the preset second weighting matrix N 2  to obtain the first converting value M 1 . The second converting value M 2  may be obtained according to formula M 2 =sum(sum(I×N 2 )×sum(N 1 )), where I represents the pixel value of each image pixel in the first calculating window C 1 . That is, multiple new pixel values are first obtained by multiplying the pixel value of each image pixel in the first calculating window C 1  with a value at a corresponding location in the preset second weighting matrix N 2 , and then a summation of the new pixel values is multiplied by a summation of all values in the preset first weighting matrix N 1  to obtain the second converting value M 2 . 
     The processor  20  obtains the pixel value of the first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted, according to the pixel value of the panchromatic image pixel W 0  to-be-converted, the first converting value M 1 , and the second converting value M 2 . Specifically, the pixel value of the first-color image pixel A 0  converted may be obtained according to formula A 0 ′=W 0 ′×(M 2 /M 1 ), where A 0 ′ represents the pixel value of the first-color image pixel A 0  converted, and W 0 ′ represents the pixel value of the panchromatic image pixel W 0  to-be-converted. That is, a first converting coefficient is obtained by dividing the second converting value M 2  by the first converting value M 1 , and then the first converting coefficient is multiplied by the pixel value of the panchromatic image pixel W 0  to-be-converted to obtain the pixel value of the first-color image pixel A 0  converted. 
     It should be noted that in some implementations, the processor  20  obtains the preset first weighting matrix N 1  and the preset second weighting matrix N 2  according to position information of a first-color image pixel A 1  closest to the panchromatic image pixel W 0  to-be-converted, where the preset first weighting matrix N 1  and the preset second weighting matrix N 2  are matrixes corresponding to the first calculating window C 1 . The preset first weighting matrix N 1  as well as the preset second weighting matrix N 2  varies with the position of the first-color image pixel A 1  closest to the panchromatic image pixel W 0  to-be-converted. 
     In some implementations, the processor  20  obtains the preset first weighting matrix N 1  and the preset second weighting matrix N 2  according to a column coordinate of the first-color image pixel A 1  which is in a same row as and closest to the panchromatic image pixel W 0  to-be-converted. For example, the column coordinate of the first-color image pixel A 1  may be less than a column coordinate of the panchromatic image pixel W 0  to-be-converted. As illustrated in  FIG.  13   , the panchromatic image pixel W 0  to-be-converted is in row 3, column 3 of the first calculating window, and the first-color image pixel A 1  closest to the panchromatic image pixel W 0  to-be-converted is in row 3, column 2 of the first calculating window C 1 . That is, the closest first-color image pixel A 1  is on the left of the panchromatic image pixel W 0  to-be-converted. In this case, the preset first weighting matrix 
     
       
         
           
             
               
                 N 
                 ⁢ 
                 1 
               
               = 
               
                 [ 
                 
                   
                     
                       1010101 
                     
                   
                   
                     
                       0202020 
                     
                   
                   
                     
                       1040401 
                     
                   
                   
                     
                       0208020 
                     
                   
                   
                     
                       1040401 
                     
                   
                   
                     
                       0202020 
                     
                   
                   
                     
                       1010101 
                     
                   
                 
                 ] 
               
             
             , 
           
         
       
     
     and the preset second weighting matrix 
     
       
         
           
             
               N 
               ⁢ 
               2 
             
             = 
             
               
                 [ 
                 
                   
                     
                       0100010 
                     
                   
                   
                     
                       1000200 
                     
                   
                   
                     
                       0004000 
                     
                   
                   
                     
                       0040001 
                     
                   
                   
                     
                       0200020 
                     
                   
                   
                     
                       1000200 
                     
                   
                   
                     
                       0001000 
                     
                   
                 
                 ] 
               
               . 
             
           
         
       
     
     For another example, the column coordinate of the first-color image pixel A 1  may be greater than the column coordinate of the panchromatic image pixel W 0  to-be-converted. As illustrated in  FIG.  14   , the panchromatic image pixel W 0  to-be-converted is in row 3, column 3 of the first calculating window, and the first-color image pixel A 1  closest to the panchromatic image pixel W 0  to-be-converted is in row 3, column 4 of the first calculating window C 1 . That is, the closest first-color image pixel A 1  is on the right of the panchromatic image pixel W 0  to-be-converted. In this case, the preset first weighting matrix 
     
       
         
           
             
               
                 N 
                 ⁢ 
                 1 
               
               = 
               
                 [ 
                 
                   
                     
                       1010101 
                     
                   
                   
                     
                       0202020 
                     
                   
                   
                     
                       1040401 
                     
                   
                   
                     
                       0208020 
                     
                   
                   
                     
                       1040401 
                     
                   
                   
                     
                       0202020 
                     
                   
                   
                     
                       1010101 
                     
                   
                 
                 ] 
               
             
             , 
           
         
       
     
     and the preset second weighting matrix 
     
       
         
           
             
               N 
               ⁢ 
               2 
             
             = 
             
               
                 [ 
                 
                   
                     
                       0100010 
                     
                   
                   
                     
                       1000200 
                     
                   
                   
                     
                       0004000 
                     
                   
                   
                     
                       0040001 
                     
                   
                   
                     
                       0200020 
                     
                   
                   
                     
                       1000200 
                     
                   
                   
                     
                       0001000 
                     
                   
                 
                 ] 
               
               . 
             
           
         
       
     
     In some implementations, the processor  20  may also obtain the first weighting matrix N 1  and the second weighting matrix N 2  according to a row coordinate of the first-color image pixel A 1  which is in a same column as and closest to the panchromatic image pixel W 0  to-be-converted, which is not limited herein. 
     Referring to  FIG.  15   , operations at block  02  where the second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels includes the following. 
     At block  0201 , whether a panchromatic image pixel to-be-converted in is a flat region is determined. 
     At block  0205 , when the panchromatic image pixel is in a non-flat region, a feature direction of the panchromatic image pixel to-be-converted is obtained. 
     At block  0206 , when the feature direction is a first direction and a first-color image pixel closest to the panchromatic image pixel to-be-converted in the feature direction is at a first side of the panchromatic image pixel to-be-converted, a first offset is obtained according to a pixel value of the panchromatic image pixel to-be-converted and a pixel value of a panchromatic image pixel adjacent to the panchromatic image pixel to-be-converted at the first side, and a second offset is obtained according to the pixel value of the panchromatic image pixel to-be-converted and pixel values of two panchromatic image pixels adjacent to the panchromatic image pixel to-be-converted at a second side opposite to the first side. 
     At block  0207 , a first weight is obtained according to the first offset and a preset weighting function, and a second weight is obtained according to the second offset and the weighting function. 
     At block  0208 , a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted is obtained according to the first weight, the second weight, the pixel value of the first-color image pixel closest to the panchromatic image pixel to-be-converted at the first side, and a pixel value of a first-color image pixel adjacent to the panchromatic image pixel to-be-converted at the second side. 
     In conjunction with  FIG.  2    and  FIG.  15   , operations at blocks  0205 ,  0206 ,  0207 , and  0208  may be performed by the processor  20 . That is, the processor  20  is further configured to: when the panchromatic image pixel W 0  is in a non-flat region, obtain a feature direction of the panchromatic image pixel W 0  to-be-converted; when the feature direction is a first direction H and a first-color image pixel A 1  closest to the panchromatic image pixel W 0  to-be-converted in the feature direction is at a first side of the panchromatic image pixel to-be-converted W 0 , obtain a first offset L 1  according to a pixel value of the panchromatic image pixel W 0  to-be-converted and a pixel value of a panchromatic image pixel W adjacent to the panchromatic image pixel W 0  to-be-converted at the first side, and obtain a second offset L 2  according to the pixel value of the panchromatic image pixel W 0  to-be-converted and pixel values of two panchromatic image pixels W adjacent to the panchromatic image pixel W 0  to-be-converted at a second side opposite to the first side; obtain a first weight F(L 1 ) according to the first offset L 1  and a preset weighting function F(x), and obtain a second weight F(L 2 ) according to the second offset L 2  and the weighting function F(x); and obtain a pixel value of a first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted, according to the first weight F(L 1 ), the second weight F(L 2 ), the pixel value of the first-color image pixel A closest to the panchromatic image pixel W 0  to-be-converted at the first side, and a pixel value of a first-color image pixel A adjacent to the panchromatic image pixel W 0  to-be-converted at the second side. 
     The manner of determining whether the panchromatic image pixel W 0  to-be-converted is in the flat region may be the same as that illustrated in  FIG.  12   , which will not be repeated herein. It should be noted that if the panchromatic image pixel W 0  to-be-converted is not in the flat region, it indicates that the panchromatic image pixel W 0  to-be-converted is in the non-flat region. 
     If the panchromatic image pixel W 0  to-be-converted is in the non-flat region, the feature direction of the panchromatic image pixel W 0  to-be-converted is obtained. Specifically, referring to  FIG.  16   , operations at block  0205  further include the following. 
     At block  02051 , gradient values in multiple directions at the panchromatic image pixel to-be-converted are obtained, and a direction corresponding to a smallest gradient value is selected as the feature direction of the panchromatic image pixel. 
     In conjunction with  FIG.  2    and  FIG.  16   , operations at block  02051  may be performed by the processor  20 . That is, the processor  20  is further configured to obtain gradient values in multiple directions at the panchromatic image pixel W 0  to-be-converted, and select a direction corresponding to a smallest gradient value as the feature direction of the panchromatic image pixel W 0 . 
     Specifically, referring to  FIG.  17   , the processor  20  obtains gradient values at the panchromatic image pixel W 0  to-be-converted along a first direction H, a second direction V, and a third direction E respectively, and selects a direction corresponding to a smallest gradient value as the feature direction of the panchromatic image pixel. The first direction H includes a row direction H 1  and a column direction H 2 . The second direction V and the first direction H intersect, and the second direction V extends from an upper left corner of the first image to the lower right corner of the first image. The third direction E is perpendicular to the second direction V and extends from an upper right corner of the first image to a lower left corner of the first image. For example, assume that after calculation, the processor  20  obtains a first gradient value g 1  along the row direction H 1 , a second gradient value g 2  along the column direction H 2 , a third gradient value g 3  along the second direction V, and a fourth gradient value g 4  along the third direction E, where g 1 &gt;g 2 &gt;g 3 &gt;g 4 , that is, the fourth gradient value g 4  along the third direction E is the smallest. In this case, the third direction E is selected as the feature direction of the panchromatic image pixel. 
     Referring to  FIG.  2   ,  FIG.  17   ,  FIG.  18   , and  FIG.  19   , when the feature direction is the first direction H and a first-color image pixel A 2  closest to the panchromatic image pixel W 0  to-be-converted in the feature direction H is at the first side of the panchromatic image pixel W 0  to-be-converted, a pixel value of a first panchromatic image pixel W 1  adjacent to the panchromatic image pixel W 0  to-be-converted at the first side, and pixel values of a second panchromatic image pixel W 2  and a third panchromatic image pixel W 3  adjacent to the panchromatic image pixel W 0  to-be-converted at the second side are obtained. The first offset L 1  and the second offset L 2  are obtained according to the pixel value of the panchromatic image pixel W 0  to-be-converted, the pixel value of the first panchromatic image pixel W 1 , the pixel value of the second panchromatic image pixel W 2 , the pixel value of the third panchromatic image pixel W 3 . Specifically, the first offset L 1  may be obtained according to formula L 1 =abs(W 0 ′−(W 0 ′+W 1 ′)/2), where W 0 ′ represents the pixel value of the panchromatic image pixel W 0  to-be-converted, and W 1 ′ represents the pixel value of the first panchromatic image pixel W 1 . That is, a mean of the pixel value of the panchromatic image pixel WO to-be-converted and the pixel value of the first panchromatic image pixel W 1  is first calculated, then the mean is subtracted from the pixel value of the panchromatic image pixel W 0  to-be-converted to obtain a difference, and finally the first offset L 1  is obtained by calculating an absolute value of the difference. The second offset L 2  may be obtained according to formula L 2 =abs(W 0 ′−(W 2 ′+W 3 ′)/2), where W 0 ′ represents the pixel value of the panchromatic image pixel W 0  to-be-converted, W 2 ′ represents the pixel value of the second panchromatic image pixel W 2 , and W 3 ′ represents the pixel value of the third panchromatic image pixel W 3 . That is, a mean of the pixel value of the second panchromatic image pixel W 2  and the pixel value of the third panchromatic image pixel W 3  is first calculated, then the mean is subtracted from the pixel value of the panchromatic image pixel W 0  to-be-converted to obtain a difference, and finally the second offset L 2  is obtained by calculating an absolute value of the difference. 
     After obtaining the first offset L 1  and the second offset L 2 , the processor  20  obtains the first weight F(L 1 ) according to the first offset L 1  and the preset weighting function F(x), and obtains the second weight F(L 2 ) according to the second offset L 2  and the preset weighting function F(x). It should be noted that the preset weighting function F(x) may be an exponential function, a logarithmic function, or a power function, as long as the smaller the input value, the greater the output weight. The same is true for the weight function F(x) mentioned below, which will not be repeated herein. For example, if the first offset L 1  is greater than the second offset L 2 , then the first weight F(L 1 ) is smaller than the second weight F(L 2 ). 
     After obtaining the first weight F(L 1 ) and the second weight F(L 2 ), the processor  20  obtains the pixel value of the first-color image pixel A 2  closest to the panchromatic image pixel W 0  to-be-converted at the first side, and the pixel value of the first-color image pixel A 3  adjacent to the panchromatic image pixel W 0  to-be-converted at the second side. According to the first weight F(L 1 ), the second weight F(L 2 ), the pixel value of the first-color image pixel A 2  closest to the panchromatic image pixel W 0  to-be-converted at the first side, and the pixel value of the first-color image pixel A 3  adjacent to the panchromatic image pixel W 0  to-be-converted at the second side, the processor  20  obtains the pixel value of the first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted. Specifically, the pixel value of the first-color image pixel A 0  converted may be obtained according to a formula A 0 ′=(k×A 2 ′×F(L 1 )+A 3 ′×F((L 2 ))/(k×F(L 1 )+F(L 2 )), where A 0 ′ represents the pixel value of the first-color image pixel A 0  converted, and k represents a preset coefficient. The preset coefficient k may be adjusted as needed. In this implementation, the preset coefficient k is 4. 
     It should be noted that since the first direction H includes the row direction H 1  and the column direction H 2 , when the feature direction is the row direction H 1  in the first direction H, referring to  FIG.  18   , the first side of the panchromatic image pixel W 0  to-be-converted represents the left side of the panchromatic image pixel W 0  to-be-converted, and the second side of the panchromatic image pixel W 0  to-be-converted represents the right side of the panchromatic image pixel W 0  to-be-converted. When the feature direction is the column direction H 2  in the first direction H, referring to  FIG.  19   , the first side of the panchromatic image pixel W 0  to-be-converted represents the lower side of the panchromatic image pixel W 0  to-be-converted, and the second side of the panchromatic image pixel W 0  to-be-converted represents the upper side of the panchromatic image pixel W 0  to-be-converted. 
     Referring to  FIG.  20   , operations at block  02  where the second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels includes the following. 
     At block  0201 , whether a panchromatic image pixel to-be-converted in is a flat region is determined. 
     At block  0205 , when the panchromatic image pixel is in a non-flat region, a feature direction of the panchromatic image pixel to-be-converted is obtained. 
     At block  0209 , when the feature direction is a first direction and a first-color image pixel closest to the panchromatic image pixel to-be-converted in the feature direction is at a second side of the panchromatic image pixel to-be-converted, a third offset is obtained according to a pixel value of the panchromatic image pixel to-be-converted and a pixel value of a panchromatic image pixel adjacent to the panchromatic image pixel to-be-converted at the second side, and a fourth offset is obtained according to the pixel value of the panchromatic image pixel to-be-converted and pixel values of two panchromatic image pixels adjacent to the panchromatic image pixel to-be-converted at a first side opposite to the second side. 
     At block  0210 , a third weight is obtained according to the third offset and a preset weighting function, and a fourth weight is obtained according to the fourth offset and the weighting function 
     At block  0211 , a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted is obtained according to the third weight, the fourth weight, a pixel value of a first-color image pixel adjacent to the panchromatic image pixel to-be-converted at the first side, and the pixel value of the first-color image pixel closest to the panchromatic image pixel to-be-converted at the second side. 
     In conjunction with  FIG.  2    and  FIG.  20   , operations at blocks  0209 ,  0210 , and  0211  may be performed by the processor  20 . That is, the processor  20  is further configured to: when the feature direction is a first direction H and a first-color image pixel A 4  closest to the panchromatic image pixel W 0  to-be-converted in the feature direction is at a second side of the panchromatic image pixel W 0  to-be-converted, obtain a third offset L 3  according to a pixel value of the panchromatic image pixel W 0  to-be-converted and a pixel value of a panchromatic image pixel W adjacent to the panchromatic image pixel W 0  to-be-converted at the second side, and obtain a fourth offset L 4  according to the pixel value of the panchromatic image pixel W 0  to-be-converted and pixel values of two panchromatic image pixels W adjacent to the panchromatic image pixel to-be-converted at a first side opposite to the second side; obtain a third weight F(L 3 ) according to the third offset L 3  and a preset weighting function F(x), and obtain a fourth weight F(L 4 ) according to the fourth offset L 4  and the weighting function F(x); and obtain a pixel value of a first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted, according to the third weight F(L 3 ), the fourth weight F(L 4 ), a pixel value of a first-color image pixel A adjacent to the panchromatic image pixel to-be-converted at the first side, and the pixel value of the first-color image pixel A closest to the panchromatic image pixel to-be-converted at the second side. 
     The manner of determining whether the panchromatic image pixel W 0  to-be-converted is in the flat region, as well as the manner of obtaining the feature direction of the panchromatic image pixel W 0  to-be-converted, are the same as those described above, which will not be repeated herein. 
     Referring to  FIG.  2   ,  FIG.  21   , and  FIG.  22   , when the feature direction is the first direction H and the first-color image pixel A 4  closest to the panchromatic image pixel W 0  to-be-converted in the feature direction is at the second side of the panchromatic image pixel W 0  to-be-converted, a pixel value of a second panchromatic image pixel W 2  adjacent to the panchromatic image pixel W 0  to-be-converted at second first side, and pixel values of a first panchromatic image pixel W 1  and a fourth panchromatic image pixel W 4  adjacent to the panchromatic image pixel W 0  to-be-converted at the first side are obtained. The third offset L 3  and the fourth offset L 4  are obtained according to the pixel value of the panchromatic image pixel W 0  to-be-converted, the pixel value of the first panchromatic image pixel W 1 , the pixel value of the second panchromatic image pixel W 2 , the pixel value of the fourth panchromatic image pixel W 4 . Specifically, the third offset L 3  may be obtained according to a formula L 3 =abs(W 0 ′−(W 1 ′+W 4 ′)/2), where W 0 ′ represents the pixel value of the panchromatic image pixel W 0  to-be-converted, and W 1 ′ represents the pixel value of the first panchromatic image pixel W 1 , and W 4 ′ represents the pixel value of the fourth panchromatic image pixel W 4 . That is, a mean of the pixel value of the first panchromatic image pixel W 1  and the pixel value of the fourth panchromatic image pixel W 4  is first calculated, then the mean is subtracted from the pixel value of the panchromatic image pixel W 0  to-be-converted to obtain a difference, and finally the third offset L 3  is obtained by finding an absolute value of the difference. The fourth offset L 4  may be obtained according to a formula L 4 =abs(W 0 ′−(W 0 ′+W 2 ′)/2), where W 0 ′ represents the pixel value of the panchromatic image pixel W 0  to-be-converted, and W 2 ′ represents the pixel value of the second panchromatic image pixel W 2 . That is, a mean of the pixel value of the panchromatic image pixel W 0  to-be-converted and the pixel value of the second panchromatic image pixel W 2  is first calculated, then the mean is subtracted from the pixel value of the panchromatic image pixel W 0  to-be-converted to obtain a difference, and finally the fourth offset L 4  is obtained by finding an absolute value of the difference. 
     After obtaining the third offset L 3  and the fourth offset L 4 , the processor  20  obtains the third weight F(L 3 ) according to the third offset L 3  and the preset weighting function F(x), and obtains the fourth weight F(L 4 ) according to the fourth offset L 4  and the preset weighting function F(x). After obtaining the third weight F(L 3 ) and the fourth weight F(L 4 ), the processor  20  obtains the pixel value of the first-color image pixel A 4  closest to the panchromatic image pixel W 0  to-be-converted at the second side, and the pixel value of the first-color image pixel A 5  adjacent to the panchromatic image pixel W 0  to-be-converted at the first side. According to the third weight F(L 3 ), the fourth weight F(L 4 ), the pixel value of the first-color image pixel A 4  closest to the panchromatic image pixel W 0  to-be-converted at the second side, and the pixel value of the first-color image pixel A 5  adjacent to the panchromatic image pixel W 0  to-be-converted at the first side, the processor  20  obtains the pixel value of the first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted. Specifically, the pixel value of the first-color image pixel A 0  converted may be obtained according to a formula A 0 ′=(A 5 ′×F(L 3 )+k×A 5 ′×F(L 4 ))/(F(L 3 )+k×F(L 4 )), where A 0 ′ represents the pixel value of the first-color image pixel A 0  converted, and k represents a preset coefficient. The preset coefficient k may be adjusted as needed. In this implementation, the preset coefficient k is 4. 
     It should be noted that since the first direction H includes the row direction H 1  and the column direction H 2 , when the feature direction is the row direction H 1  in the first direction H, referring to  FIG.  21   , the first side of the panchromatic image pixel W 0  to-be-converted represents the left side of the panchromatic image pixel W 0  to-be-converted, and the second side of the panchromatic image pixel W 0  to-be-converted represents the right side of the panchromatic image pixel W 0  to-be-converted. When the feature direction is the column direction H 2  in the first direction H, referring to  FIG.  22   , the first side of the panchromatic image pixel W 0  to-be-converted represents the lower side of the panchromatic image pixel W 0  to-be-converted, and the second side of the panchromatic image pixel W 0  to-be-converted represents the upper side of the panchromatic image pixel W 0  to-be-converted. 
     Referring to  FIG.  23   , operations at block  02  where the second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels includes the following. 
     At block  0201 , whether a panchromatic image pixel to-be-converted in is a flat region is determined. 
     At block  0205 , when the panchromatic image pixel is in a non-flat region, a feature direction of the panchromatic image pixel to-be-converted is obtained. 
     At block  0212 , when the feature direction is a second direction, a second calculating window centered on the panchromatic image pixel to-be-converted is preset. 
     At block  0213 , pixel values of all pixels in the second calculating window are obtained. 
     At block  0214 , a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted is obtained according to the pixel values of all pixels in the second calculating window, a pixel value of the panchromatic image pixel to-be-converted, a preset third weighting matrix, and a preset fourth weighting matrix. 
     In conjunction with  FIG.  2    and  FIG.  23   , operations at blocks  0212 ,  0213 , and  0214  may be performed by the processor  20 . That is, the processor  20  is further configured to: when the feature direction is a second direction V, preset a second calculating window C 2  centered on the panchromatic image pixel W 0  to-be-converted, where the second direction V intersects with the first direction H of the first image; obtain pixel values of all pixels in the second calculating window C 2 ; and obtain a pixel value of a first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted, according to the pixel values of all pixels in the second calculating window C 2 , a pixel value of the panchromatic image pixel W 0  to-be-converted, a preset third weighting matrix N 3 , and a preset fourth weighting matrix N 4 . 
     The manner of determining whether the panchromatic image pixel W 0  to-be-converted is in the flat region, as well as the manner of obtaining the feature direction of the panchromatic image pixel W 0  to-be-converted, may be the same as those described above, which will not be repeated herein. 
     Referring to  FIG.  2   ,  FIG.  24    and  FIG.  25   , when the feature direction is the second direction V, the second calculating window C 2  is preset, which is centered on the panchromatic image pixel W 0  to-be-converted. The manner of presetting the second calculating window C 2  is the same as that of presetting the first calculating window C 1 , which will not be repeated herein. 
     After the processor  20  presets the second calculating window C 2  and obtains all pixel values in the second calculating window C 2 , the processor  20  may obtain the third converting value M 3  and the fourth converting value M 4  according to all pixel values in the second calculating window C 2 , the third weighting matrix N 3 , and the fourth weighting matrix N 4 . Specifically, the third converting value M 3  may be obtained according to a formula M 3 =sum(sum(I×N 3 ))/sum(sum(N 3 )), where I represents a pixel value of each image pixel in the second calculating window C 2 . That is, new pixel values are first obtained by multiplying the pixel value of each image pixel in the second calculating window C 2  by a value at a corresponding location in the preset third weighting matrix N 3 , and then a summation of the new pixel values is divided by a summation of all values in the preset third weighting matrix N 3  to obtain the third converting value M 3 . The fourth converting value M 4  may be obtained according to the formula M 4 =sum(sum(I×N 4 ))/sum(sum(N 4 )), where I represents the pixel value of each image pixel in the second calculating window C 2 . That is, new pixel values are first obtained by multiplying the pixel value of each image pixel in the second calculating window C 2  by a value at a corresponding location in the preset fourth weighting matrix N 4 , and then a summation of the new pixel values is divided by a summation of all values in the preset fourth weighting matrix N 4  to obtain the fourth converting value M 4 . 
     The processor  20  obtains the pixel value of the first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted, according to the pixel value of the panchromatic image pixel W 0  to-be-converted, the third converting value M 3 , and the fourth converting value M 4 . Specifically, the pixel value of the first-color image pixel A 0  converted may be obtained according to a formula A 0 ′=W 0 ′×(M 4 /M 3 ), where A 0 ′ represents the pixel value of the first-color image pixel A 0  converted, and W 0 ′ represents the pixel value of the panchromatic image pixel W 0  to-be-converted. 
     It should be noted that in some implementations, the processor  20  obtains the preset third weighting matrix N 3  and the preset fourth weighting matrix N 4  according to position information of a first-color image pixel A 1  closest to the panchromatic image pixel W 0  to-be-converted, where the preset third weighting matrix N 3  and the preset fourth weighting matrix N 4  are matrixes corresponding to the second calculating window C 2 . The preset third weighting matrix N 3  as well as the preset fourth weighting matrix N 4  varies with position of the first-color image pixel A 1  closest to the panchromatic image pixel W 0  to-be-converted. 
     In some implementations, the processor  20  obtains the preset third weighting matrix N 3  and the preset fourth weighting matrix N 4  according to a column coordinate of the first-color image pixel A 1  which is in a same row as and closest to the panchromatic image pixel W 0  to-be-converted. For example, the column coordinate of the first-color image pixel A 1  may be less than a column coordinate of the panchromatic image pixel W 0  to-be-converted. As illustrated in  FIG.  24   , the panchromatic image pixel W 0  to-be-converted is in row 3, column 3 of the second calculating window, and the first-color image pixel A 1  closest to the panchromatic image pixel W 0  to-be-converted is in row 3, column 2 of the second calculating window C 1 . That is, the closest first-color image pixel A 1  is on the left of the panchromatic image pixel W 0  to-be-converted. In this case, the preset third weighting matrix 
     
       
         
           
             
               
                 N 
                 ⁢ 
                 3 
               
               = 
               
                 [ 
                 
                   
                     
                       0000000 
                     
                   
                   
                     
                       0202010 
                     
                   
                   
                     
                       0040400 
                     
                   
                   
                     
                       0208020 
                     
                   
                   
                     
                       0040400 
                     
                   
                   
                     
                       0102020 
                     
                   
                   
                     
                       0000000 
                     
                   
                 
                 ] 
               
             
             , 
           
         
       
     
     and the preset fourth weighting matrix 
     
       
         
           
             
               N 
               ⁢ 
               4 
             
             = 
             
               
                 [ 
                 
                   
                     
                       0000000 
                     
                   
                   
                     
                       0000100 
                     
                   
                   
                     
                       0005000 
                     
                   
                   
                     
                       0050000 
                     
                   
                   
                     
                       0100020 
                     
                   
                   
                     
                       0000200 
                     
                   
                   
                     
                       0000000 
                     
                   
                 
                 ] 
               
               . 
             
           
         
       
     
     For another example, the column coordinate of the first-color image pixel A 1  may be greater than a column coordinate of the panchromatic image pixel W 0  to-be-converted. As illustrated in  FIG.  25   , the panchromatic image pixel W 0  to-be-converted is in row 3, column 3 of the second calculating window, and the first-color image pixel A 1  closest to the panchromatic image pixel W 0  to-be-converted is in row 3, column 4 of the second calculating window C 1 . That is, the closest first-color image pixel A 1  is on the right of the panchromatic image pixel W 0  to-be-converted. In this case, the preset third weighting matrix 
     
       
         
           
             
               
                 N 
                 ⁢ 
                 3 
               
               = 
               
                 [ 
                 
                   
                     
                       0000000 
                     
                   
                   
                     
                       0202010 
                     
                   
                   
                     
                       0040400 
                     
                   
                   
                     
                       0208020 
                     
                   
                   
                     
                       0040400 
                     
                   
                   
                     
                       0102020 
                     
                   
                   
                     
                       0000000 
                     
                   
                 
                 ] 
               
             
             , 
           
         
       
     
     and the preset fourth weighting matrix 
     
       
         
           
             
               N 
               ⁢ 
               4 
             
             = 
             
               
                 [ 
                 
                   
                     
                       0000000 
                     
                   
                   
                     
                       0000100 
                     
                   
                   
                     
                       0005000 
                     
                   
                   
                     
                       0050000 
                     
                   
                   
                     
                       0100020 
                     
                   
                   
                     
                       0000200 
                     
                   
                   
                     
                       0000000 
                     
                   
                 
                 ] 
               
               . 
             
           
         
       
     
     In some implementations, the processor  20  may also obtain the third weighting matrix N 3  and the fourth weighting matrix N 4  according to a row coordinate of the first-color image pixel A 1  which is in a same column as and closest to the panchromatic image pixel W 0  to-be-converted, which is not limited herein. 
     Referring to  FIG.  26   , operations at block  02  where the second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels includes the following. 
     At block  0201 , whether a panchromatic image pixel to-be-converted in is a flat region is determined. 
     At block  0205 , when the panchromatic image pixel is in a non-flat region, a feature direction of the panchromatic image pixel to-be-converted is obtained. 
     At block  0215 , when the feature direction is a third direction, a third calculating window centered on the panchromatic image pixel to-be-converted is preset. 
     At block  0216 , pixel values of all pixels in the third calculating window are obtained, and a transformed pixel value of each first-color image pixel in the third calculating window is obtained according to pixel values of multiple panchromatic image pixels around the first-color image pixel. 
     At block  0217 , a fifth weighting matrix is obtained according to the transformed pixel value of each first-color image pixel, a pixel value of the panchromatic image pixel to-be-converted, and a preset weighting function. 
     At block  0218 , a pixel value of a first-color image pixel converted from the panchromatic image pixel to-be-converted is obtained according to the transformed pixel value of each first-color image pixels, the fifth weighting matrix, and a distance weight. 
     In conjunction with  FIG.  2    and  FIG.  26   , operations at blocks  0215 ,  0216 ,  0217 , and  0218  may be performed by the processor  20 . That is, the processor  20  is further configured to: when the feature direction is a third direction E, preset a third calculating window C 3  centered on the panchromatic image pixel W 0  to-be-converted, where the third direction E is perpendicular to the second direction V of the first image; obtain pixel values of all pixels in the third calculating window C 3 , and obtain a transformed pixel value of each first-color image pixel A in the third calculating window C 3  according to pixel values of multiple panchromatic image pixels W around the first-color image pixel A; obtain a fifth weighting matrix N 5  according to the transformed pixel value of each first-color image pixel A, a pixel value of the panchromatic image pixel W 0  to-be-converted, and a preset weighting function F(x); and obtain a pixel value of a first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted, according to the transformed pixel value of each first-color image pixels A, the fifth weighting matrix N 5 , and a distance weight. 
     The manner of determining whether the panchromatic image pixel W 0  to-be-converted is in the flat region, as well as the manner of obtaining the feature direction of the panchromatic image pixel W 0  to-be-converted, may be the same as those described above, which will not be repeated herein. 
     Referring  FIG.  2    and  FIG.  27   , when the feature direction is the third direction E, the third calculating window C 3  is preset, which is centered on the panchromatic image pixel W to-be-converted. The manner of presetting the third calculating window C 3  is the same as that of presetting the first calculating window C 1 , which will not be repeated herein. 
     After obtaining the pixel values of all pixels in the third calculating window C 3 , the processor  20  obtains the transformed pixel value of each first-color image pixel A in the third calculating window C 3  according to pixel values of multiple panchromatic image pixels W around the first-color image pixel A. In some implementations, the processor  20  obtains the transformed pixel value of the first-color image pixel A by calculating a mean of multiple panchromatic image pixels W around the first-color image pixel A. The following illustrates exemplarily calculation of the transformed pixel value of the first-color image pixel A in row 2, column 1 in the third window C 3 , and transformed pixel values of other first-color image pixels A may be calculated in the same manner. The transformed pixel value of the first-color image pixel A in row 2, column 1 in the third window C 3  is equal to a mean of pixel values of four panchromatic image pixels W adjacent to the first-color image pixel A, that is, a mean of the panchromatic image pixel W in row 2, column 0 of the third window C 3 , the panchromatic image pixel W in row 2, column 2 of the third window C 3 , the panchromatic image pixel W in row 1, column 1 of the third window C 3 , and the panchromatic image pixel W in row 1, column 3 of the third window C 3 . 
     After obtaining the transformed pixel values of multiple first-color image pixels A in the third window C 3 , the processor  20  obtains the fifth weighting matrix N 5  according to the transformed pixel values of multiple first-color image pixels A, the panchromatic image pixel W to-be-converted, and the preset weighting function F(x). Specifically, referring to  FIG.  28   , assuming that the third window C 3  is a 7×7 window, then the fifth weighting matrix N 5  is also a 7×7 matrix. The processor  20  selects any image pixel in the third window C 3 . If the selected image pixel is a first-color image pixel A, the pixel value of the panchromatic image pixel W 0  to-be-converted is subtracted from the transformed value of the first-color image pixel A to obtain a fifth offset L 5 . According to the fifth offset L 5  and the preset weighting function F(x), a fifth weight F(L 5 ) is obtained and then filled at a position in the fifth weighting matrix N 5  corresponding to the selected first-color image pixel A 3 . For example, if the processor  20  selects the first-color image pixel A 3  in row 2, column 1 of the third calculating window C 3 , the pixel value of the panchromatic image pixel W 0  to-be-converted is subtracted from the transformed value of the first-color image pixel A 3  to obtain a corresponding fifth offset L (2,1)   5 . According to the fifth offset L 5  and the preset weighting function F(x), a fifth weight F(L (2,1)   5 ) is obtained and then filled in row 2, column 1 of the fifth weighting matrix N 5 , that is, X21=F(L (2,1)   5 ). If the selected image pixel is not a first-color image pixel A, the position in the fifth weighting matrix N 5  corresponding to the selected image pixel is filled with 0. For example, if the processor  20  selects a second-color image pixel B 1  in row 0, column 1 of the third calculating window C 3 , then 0 is filled in row 0, column 1 of the fifth weighting matrix N 5 , that is, X01=0. After filling data at one position, another image pixel will be selected and processed with the above operations, until all image pixels in the third calculating window C 3  are selected. Finally, the fifth weighting matrix N 5  is obtained. 
     After obtaining the fifth weighting matrix N 5 , the processor  20  obtains the fifth converting value M 5  and the sixth converting M 6  according to the transformed value of the first-color image pixel A, the fifth weighting matrix N 5 , and a preset distance weight R. Specifically, the fifth converting value M 5  may be obtained according to a formula M 5 =sum(sum(J×N 5 )×R)/sum(sum(N 5 ×R)), where J represents the transformed value of each first-color image pixel A in the third calculating window C 3 , and R represents the distance weight such that the closer the image pixel to the center of the third window C 3 , the greater the weight of the image pixel. That is, multiple new pixel values are first obtained by multiplying the transformed value of each first-color image pixel A in the third calculating window C 3  by a value at the corresponding position in the fifth weighting matrix N 5 , and then a summation of the new pixel values is multiplied by the distance weight R to obtain a first calculating value. A summation of values in the fifth weighting matrix N 5  is multiplied by the distance weight R to obtain a second calculating value. The first calculating value is then divided by the second calculating value to obtain the fifth converting value M 5 . The sixth converting value M 6  may be obtained according to a formula M 6 =sum(sum(I×N 5 )×R)/sum(sum(N 5 ×R)), where I represents a transformed value of each image pixel in the third calculating window C 3 . That is, multiple new pixel values are first obtained by multiplying a pixel value of each image pixel in the third calculating window C 3  by a value at the corresponding position in the fifth weighting matrix N 5 , and then a summation of the new pixel values is multiplied by the distance weight R to obtain a third calculating value. A summation of values in the fifth weighting matrix N 5  is multiplied by the distance weight R to obtain a fourth calculating value. The third calculating value is then divided by the fourth calculating value to obtain the sixth converting value M 6 . 
     The processor  20  obtains the pixel value of the first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted, according to the pixel value of the panchromatic image pixel W 0  to-be-converted, the fifth converting value M 5 , and the sixth converting value M 6 . Specifically, the pixel value of the first-color image pixel A 0  converted may be obtained according to a formula A 0 ′=W 0 ′×(M 5 /M 6 ), where A 0 ′ represents the pixel value of the first-color image pixel A 0  converted, and W 0 ′ represents the pixel value of the panchromatic image pixel W 0  to-be-converted. 
     In some implementations, after obtaining the first image, the processor  20  randomly selects an image pixel in the first image, and identify whether the selected image pixel is a panchromatic image pixel W. If the selected image pixel is a panchromatic image pixel W, the processor  20  obtains the pixel value of the first-color image pixel A 0  converted from the panchromatic image pixel W 0  to-be-converted, by performing operations illustrated in  FIG.  12    to  FIG.  28   . If the selected image pixel is not a panchromatic image pixel W, another image pixel will be selected. The operations above will be repeated until all image pixels in the first image are selected. In this way, all panchromatic image pixels W in the first image can be converted into first-color image pixels. In some implementations, the processor  20  selects the image pixels in a certain order. For example, the first image pixel in the upper left corner of the first image may be first selected and processed, then an image pixel to the right of the first image pixel, and so on. Image pixels in the next row will not be selected until all image pixels in the first row are selected. The operations above will be repeated until all image pixels in the first image are selected. 
     Referring to  FIG.  2    and  FIG.  29   , the processor  20  obtains a second image by converting all panchromatic image pixels W in the first image into first-color image pixels A. The second image contains only first-color image pixels A, second-color image pixels B, and third-color image pixels C. The processor  20  obtains the third image by converting the second-color image pixels B and the third-color image pixels C in the second image into first-color image pixels A. The third image contains only multiple first-color image pixels A. 
     Specifically, referring to  FIG.  30   , operations at block  03  where the third image is obtained by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels include the following. 
     At block  031 , whether the second-color image pixel to-be-converted is in a flat-region is determined. 
     At block  032 , when the second-color image pixel is in the flat region, a pixel value of a first-color image pixel converted from the second-color image pixel to-be-converted is obtained according to pixel values of first-color image pixels adjacent to the second-color image pixel to-be-converted in multiple directions. 
     In conjunction with  FIG.  2    and  FIG.  30   , operations at blocks  031  and  032  may be performed by the processor  20 . That is, the processor  20  is further configured to determine whether the second-color image pixel B 0  to-be-converted is in the flat-region, and when the second-color image pixel B 0  is in the flat region, obtain a pixel value of a first-color image pixel A 0  converted from the second-color image pixel B 0  to-be-converted, according to pixel values of first-color image pixels A adjacent to the second-color image pixel B 0  to-be-converted in multiple directions. 
     The manner of determining whether the second-color image pixel B 0  to-be-converted is in the flat region may be the same as that of determining whether the panchromatic image pixel W 0  to-be-converted is in the flat region described above, which will not be repeated herein. 
     Referring to  FIG.  31   , when the second-color image pixel B 0  to-be-converted is in the flat region, the processor  20  obtains pixel values of first-color image pixels A around the second-color image pixel B 0  to-be-converted, calculate a mean of the obtained pixel values of the first-color image pixels A as the pixel value of the first-color image pixel A 0  converted from the second-color image pixel B 0  to-be-converted. For example, assume that the second image has image pixels arranged in 5 rows and 5 columns, and the second-color image pixel B 0  to-be-converted is in row 3, column 1 of the second image. The processor  20  calculates a mean of a pixel value of a first-color image pixel A in row 2, column 1 of the second image, a pixel value of a first-color image pixel A in row 4, column 1 of the second image, a pixel value of a first-color image pixel A in row 3, column 0 of the second image, and a pixel value of a first-color image pixel A in row 3, column 2 of the second image, and then takes the mean as the pixel value of the converted first-color image pixel A 0 . 
     Referring to  FIG.  32   , operations at block  03  where the third image is obtained by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels include the following. 
     At block  031 , whether the second-color image pixel to-be-converted is in a flat-region is determined. 
     At block  033 , when the second-color image pixel is in a non-flat region, a feature direction of the second-color image pixel to-be-converted is obtained. 
     At block  034 , a pixel value of a first-color image pixel converted from the second-color image pixel to-be-converted is obtained according to pixel values of two first-color image pixels adjacent to the second-color image pixel to-be-converted in the feature direction. 
     Referring to  FIG.  2    and  FIG.  32   , operations at blocks  033  and  034  may be performed by the processor  20 . That is, the processor  20  is further configured to: determine whether the second-color image pixel B 0  to-be-converted is in the flat-region; when the second-color image pixel B 0  is in the non-flat region, obtain a feature direction of the second-color image pixel B 0  to-be-converted; and obtain a pixel value of a first-color image pixel A 0  converted from the second-color image pixel B 0  to-be-converted, according to pixel values of two first-color image pixels A adjacent to the second-color image pixel B 0  to-be-converted in the feature direction. 
     The manner of determining whether the second-color image pixel B 0  to-be-converted is in the flat region may be the same as that of determining whether the panchromatic image pixel W 0  to-be-converted is in the flat region, and the manner of obtaining the feature direction of the second-color image pixel B 0  to-be-converted may be the same as that of obtaining the feature direction of the panchromatic image pixel W 0  to-be-converted described above, which will not be repeated herein. 
     Referring to  FIG.  2    and  FIG.  31   , when the second-color image pixel B 0  to-be-converted is in the flat region, after obtaining the feature direction of the second-color image pixel B 0  to-be-converted, the processor  20  obtains pixel values of two first-color image pixels A adjacent to the second-color image pixel B 0  to-be-converted in the feature direction, and calculates a mean of the obtained pixel values of the two first-color image pixels A as the pixel value of the first-color image pixel A 0  converted from the second-color image pixel B 0  to-be-converted. For example, assume that the second image contains image pixels arranged in 5 rows and 5 columns, and the second-color image pixel B 0  to-be-converted is in row 3, column 1 of the second image. If the feature direction is the row direction H 2  (illustrated in  FIG.  17   ), the processor  20  calculates a mean of a pixel value of a first-color image pixel A in row 3, column 0 of the second image and a pixel value of a first-color image pixel A in row 3, column 2 of the second image, and takes the mean as the pixel value of the first-color image pixel A 0  converted. If the feature direction is the column direction H 1  (as illustrated in  FIG.  17   , the processor  20  calculates a mean of a pixel value of a first-color image pixel A in row 2, column 1 of the second image and a pixel value of a first-color image pixel A in row 4, column 1 of the second image, and takes the mean as the pixel value of the first-color image pixel A 0  converted. 
     Referring to  FIG.  33   , operations at block  03  where the third image is obtained by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels include the following. 
     At block  035 , whether the third-color image pixel to-be-converted is in a flat-region is determined. 
     At block  036 , when the third-color image pixel is in the flat region, a pixel value of a first-color image pixel converted from the third-color image pixel to-be-converted is obtained according to pixel values of first-color image pixels adjacent to the third-color image pixel to-be-converted in multiple directions. 
     In conjunction with  FIG.  2    and  FIG.  33   , operations at blocks  035  and  036  may be performed by the processor  20 . That is, the processor  20  is further configured to determine whether the third-color image pixel C 0  to-be-converted is in the flat-region, and when the third-color image pixel C 0  is in the flat region, obtain a pixel value of a first-color image pixel A 0  converted from the third-color image pixel C 0  to-be-converted, according to pixel values of first-color image pixels A adjacent to the third-color image pixel C 0  to-be-converted in multiple directions. 
     Referring to  FIG.  34   , operations at block  03  where the third image is obtained by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels include the following. 
     At block  035 , whether the third-color image pixel to-be-converted is in a flat-region is determined. 
     At block  037 , when the third-color image pixel is in a non-flat region, a feature direction of the third-color image pixel to-be-converted is obtained. 
     At block  038 , a pixel value of a first-color image pixel converted from the third-color image pixel to-be-converted is obtained according to pixel values of two first-color image pixels adjacent to the third-color image pixel to-be-converted in the feature direction. 
     In conjunction with  FIG.  2    and  FIG.  34   , operations at blocks  035 ,  037 , and  038  may be performed by the processor  20 . That is, the processor  20  is further configured to: determine whether the third-color image pixel C 0  to-be-converted is in the flat-region; when third-color image pixel C 0  is in the non-flat region, obtain a feature direction of the third-color image pixel C 0  to-be-converted; and obtain a pixel value of a first-color image pixel A 0  converted from the third-color image pixel C 0  to-be-converted, according to pixel values of two first-color image pixels A adjacent to the third-color image pixel C 0  to-be-converted in the feature direction. 
     The manner of obtaining the pixel value of the first-color image pixel A 0  converted from the third-color image pixel C 0  to-be-converted may be the same as the manner of obtaining the pixel value of the first-color image pixel A 0  converted from the second-color image pixel B 0  to-be-converted described above, which will not be repeated herein. 
     In some implementations, after obtaining the second image, the processor  20  randomly select an image pixel in the second image, and identify whether the selected image pixel is a second-color image pixel B or a third-color image pixel C. If the selected image pixel is a second-color image pixel B or a third-color image pixel C, the processor  20  obtains the pixel value of the first-color image pixel A 0  converted from the second-color image pixel B 0  or the third-color image pixel C 0  to-be-converted, by performing operations illustrated in  FIG.  30    to  FIG.  34   . If the selected image pixel is not a second-color image pixel B or a third-color image pixel C, another image pixel will be selected. The operations above will be repeated, until all image pixels in the second image are selected. In this way, all second-color image pixels B and third-color image pixels C in the second image can be converted into first-color image pixels. In some implementations, the processor  20  selects the image pixels in a certain order. For example, the first image pixel in the upper left corner of the first image may be first selected and processed, then an image pixel to the right of the first image pixel, and so on. Image pixels in the next row will not be selected until all image pixels in the first row are selected. The operations above will be repeated, until all image pixels in the second image are selected. 
     Referring to  FIG.  2    and  FIG.  35   , after obtaining the third image containing only the fist-color image pixels A, the processor  20  processes the third image according to the first image to obtain a second-color intermediate image and a third-color intermediate image. The second-color intermediate image contains only second-color image pixels B and the third-color intermediate image contains only third-color image pixels C. 
     Specifically, referring to  FIG.  36   , in some implementations, operations at block  04  where the second-color intermediate image and the third-color intermediate image are obtained by processing the third image according to the first image include the following. 
     At block  041 , the second-color intermediate image and the third-color intermediate image are obtained by performing bilateral filtering on the first image and the third image. 
     In conjunction with  FIG.  2    and  FIG.  36   , operations at block  041  may be performed by the processor  20 . That is, the processor  20  is further configured to obtain the second-color intermediate image and the third-color intermediate image by performing bilateral filtering on the third image according to the first image. 
     Specifically, referring  FIG.  37   , the first image includes multiple second-color image pixels B and multiple third-color image pixels C. The multiple second-color image pixels B form a second-color original image and the multiple third-color image pixels C form a third-color original image. The second-color intermediate image is obtained by performing bilateral filtering on the second-color original image and the third image. The third-color intermediate image is obtained by performing bilateral filtering on the third-color original image and the third image. 
     For example, the following describes obtaining the second-color intermediate image by performing bilateral filtering on the second-color original image and the third image. In some implementations, referring to  FIG.  38   , a joint bilateral filtering algorithm may be represented as 
     
       
         
           
             
               
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     where k p =Σ q∈Ω f(∥p−q∥)g(∥I p ′−I q ′), J p  represents an output pixel value, k p  represents a summation of weights, Ω represents a filtering window, p represents a coordinate of a pixel to-be-filtered in the second-color original image, q represents a coordinate of a pixel within the filtering window in the second-color original image, I q  represents a pixel value of pixel q, I p ′ represents a pixel value corresponding to the pixel to-be-filtered in the third image, I q ′ represents a pixel value corresponding to pixel q in the third image, and f and g each represent a weighting distribution function, where the weighting distribution function includes a Gaussian function. 
     Specifically, in the joint bilateral filtering algorithm, a first distance weight f (∥p−q∥) is determined according to a difference between the coordinate of the pixel p to-be-filtered and the coordinate of the pixel q within the filtering window. As illustrated in  FIG.  38   , the difference between coordinates of pixels p and q may be 2. A second distance weight g(∥I p ′−I q ′∥) is determined according to a difference between the pixel value I p ′ corresponding to the pixel p and the pixel value I q ′ corresponding to the pixel q in the third image. The output pixel value J p  is determined according to the first distance weight and the second distance weight of each pixel in the filtering window, the pixel value I q  corresponding to pixel q in the second-color original image, and the summation of weights k p . 
     It should be noted that in the second-color original image, a position without a second-color image pixel has a pixel value of 0. The output pixel value J p  fills at the position corresponding to the pixel p to-be-filtered in the second-color intermediate image. After one output, the filtering window moves to a position of the next image pixel, until all image pixels in the second-color original image are filtered. As such, the second-color intermediate image that contains only the second-color image pixels can be obtained. The third-color intermediate image can be obtained by performing bilateral filtering on the third-color original image and the third image in the same manner as that of obtaining the second-color intermediate image, which will not be repeated herein. 
     Referring to  FIG.  39   , after obtaining the third image, the second-color intermediate image and the third-color intermediate image, the processor  20  merges the third image, the second-color intermediate image and the third-color intermediate image to obtain the target image. Specifically, information of positions without image pixels in neither the second-color intermediate image nor the third-color intermediate image are obtained, and first-color image pixels A at the corresponding positions in the third image are extracted. The multiple extracted first-color image pixels A, the multiple second-color image pixels B in the second-color intermediate image, and the multiple third-color image pixels C in the third-color intermediate image are arranged to obtain the target image in a Bayer array. 
     In the method for image processing in implementations of the disclosure, by adding panchromatic photosensitive pixels W in the pixel array  11 , the panchromatic image pixels W are interpolated into color image pixels with wide spectral response to obtain the second image, and then the second image is processed to obtain the target image arranged in a Bayer array. In this way, the problem that the image processor cannot directly process the images with image pixels arranged in a non-Bayer array is solved. In addition, since the panchromatic photosensitive pixels W are introduced to the pixel array  11 , the resolution ability and signal-to-noise ratio of the finally obtained image can be improved, thus improving the photographing effect at night. 
     Referring to  FIG.  40   , the disclosure further provides an electronic device  1000 . The electronic device  1000  in implementations of the disclosure includes a lens  300 , a housing  200 , and the system for image processing  100  in any of implementations above. The lens  300 , the system for image processing  100  are integrated in the housing  200 . The lens  300  and the image sensor  10  of the system for image processing  100  cooperate for imaging. 
     The electronic device  1000  may be a mobile phone, tablet computer, laptop, intelligent wearable device (such as smart watch, smart bracelet, smart glasses, smart helmet), UAV, head display device, etc., which is not limited herein. 
     In implementations of the disclosure, by introducing panchromatic photosensitive pixels W in the pixel array  11 , the electronic device  1000  interpolates the panchromatic image pixels W into color image pixels with wide spectral response to obtain the second image, and then processes the second image to obtain the target image arranged in a Bayer array. In this way, the problem that the image processor cannot directly process the images with image pixels arranged in a non-Bayer array is solved. In addition, since the panchromatic photosensitive pixels W are introduced to the pixel array  11 , the resolution and signal-to-noise ratio of the finally obtained image can be improved, thus improving the photographing effect at night. 
     Referring to  FIG.  41   , the disclosure further provides a non-transitory computer-readable storage medium  400  that includes a computer program. When executed by a processor  60 , the computer program causes the processor  60  to execute the method for image processing in any implementation described above. 
     For example, referring to  FIG.  1    and  FIG.  41   , when executed by the processor  60 , the computer program causes the processor  60  to perform the operations below. 
     At block  01 , a first image is obtained by exposing the pixel array  11 , where the first image contains panchromatic image pixels generated by the panchromatic photosensitive pixels, a first-color image pixel generated by the first-color photosensitive pixel, a second-color image pixel generated by the second-color photosensitive pixel, and a third-color image pixel generated by the third-color photosensitive pixel. 
     At block  02 , a second image is obtained by converting the panchromatic image pixels in the first image into first-color image pixels. 
     At block  03 , a third image is obtained by converting the second-color image pixel and the third-color image pixel in the second image into first-color image pixels. 
     At block  04 , a second-color intermediate image and a third-color intermediate image are obtained by processing the third image according to the first image, where the second-color intermediate image contains second-color image pixels, the third-color intermediate image contains third-color image pixels. 
     At block  05 , a target image is obtained by merging the third image, the second-color intermediate image, and the third-color intermediate image, where the target image contains multiple color image pixels arranged in a Bayer array. 
     It should be noted that the processor  60  can be the same processor as the processor  20  disposed in the image processor  100 , and the processor  60  can also be disposed in the device  1000 . That is, the processor  60  may also be different from the processor  20  disposed in the image processor  100 , which will not be limited herein. 
     In the description of this specification, reference to the description of the terms “one implementation”, “some implementations”, “schematic implementations”, “examples”, “specific examples” or “some examples” means that the specific features, structures, materials or features described in combination with the implementations or examples are included in at least one implementation or example of this disclosure. In this specification, the schematic expressions of the above terms do not necessarily refer to the same implementations or examples. Moreover, the specific features, structures, materials or features described may be combined in an appropriate manner in any one or more implementations or examples. In addition, those skilled in the art can combine different implementations or examples described in this specification and the characteristics of different implementations or examples without contradiction. 
     Any process or method description in the flowchart or otherwise described herein can be understood as representing a module, segment or part of code including one or more executable instructions for implementing the steps of a specific logic function or process, and the scope of the preferred implementation method of the present disclosure includes other implementations, which may not be in the order shown or discussed. It shall be understood by those skilled in the art of the implementations of the present disclosure that functions are performed in a substantially simultaneous manner or in reverse order according to the functions involved. 
     Although the implementations of the disclosure have been shown and described above, it can be understood that the above implementations are exemplary and cannot be understood as restrictions on the disclosure. Those skilled in the art can change, modify, replace and transform the above implementations within the scope of the disclosure.