Patent Publication Number: US-11381757-B2

Title: Imaging system and method

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to imaging systems and methods, and more specifically to imaging systems and methods for vehicles. 
     BACKGROUND 
     Vehicles may include one or more cameras and one or more displays to display areas that are not generally visible to a driver, for example, areas to the rear of the vehicle or in a blindspot. An image captured by a camera may include additional information for alerting the driver. Such information is often overlaid on the image after the image has been processed and generated by an image processor. One common disadvantage of overlaying an image is an increase in additional processing. This additional processing for overlaying information on the image may increase processing time and computing requirements. 
     SUMMARY 
     In one aspect, the present disclosure provides an imaging system for a vehicle. The imaging system includes an image sensor, an image signal processor (ISP) and a display device. The image sensor is disposed on the vehicle. The image sensor is configured to generate image data. The image data includes a set of pixel values. The ISP is communicably coupled to the image sensor. The ISP is configured to receive the image data from the image sensor. The ISP is further configured to define a first subset of pixel values from the set of pixel values. The first subset of pixel values corresponds to at least one region of interest in the image data. The ISP is further configured to define a second subset of pixel values from the set of pixel values. The second subset of pixel values is complementary to the first subset of pixel values. The ISP is further configured to generate a first sub-image based on the second subset of pixel values. The ISP is further configured to process the first subset of pixel values to generate a second sub-image. Processing the first subset of pixel values includes at least one of: (i) changing a color of one or more pixel values from the first subset of pixel values; and (ii) scaling the first subset of pixel values. The ISP is further configured to merge the first and second sub-images to generate an output image. The display device is configured to display the output image received from the ISP. 
     In an example, the at least one region of interest may correspond to one or more distance lines with respect to the vehicle. 
     In an example, the at least one region of interest may include at least one of an object or an icon. 
     In an example, the processing of the first subset of pixel values may include changing a color of each pixel value of the first subset of pixel values. 
     In an example, the processing of the first subset of pixel values may further include filtering out at least one of red, green and blue colors from each pixel value of the first subset of pixel values. 
     In an example, the processing of the first subset of pixel values may include magnifying the first subset of pixel values. 
     In an example, the ISP may be further configured to perform high dynamic range (HDR) processing of the first subset of pixel values. 
     In an example, the ISP may be further configured to perform high dynamic range (HDR) processing of the second subset of pixel values. 
     In another aspect, the present disclosure provides an imaging method for a vehicle. The method includes receiving image data from an image sensor disposed on the vehicle. The image data includes a set of pixel values. The method further includes defining a first subset of pixel values from the set of pixel values. The first subset of pixel values corresponds to at least one region of interest in the image data. The method further includes defining a second subset of pixel values from the set of pixel values. The second subset of pixel values is complementary to the first subset of pixel values. The method further includes generating a first sub-image based on the second subset of pixel values. The method further includes processing the first subset of pixel values to generate a second sub-image. Processing the first subset of pixel values includes at least one of: (i) changing a color of one or more pixel values from the first subset of pixel values; and (ii) scaling the first subset of pixel values. The method further includes merging the first and second sub-images to generate an output image. The method further includes displaying the output by a display device disposed on the vehicle. 
     In an example, the at least one region of interest may correspond to one or more distance lines with respect to the vehicle. 
     In an example, the at least one region of interest may include at least one of an object or an icon. 
     In an example, the processing of the first subset of pixel values may include changing a color of each pixel value of the first subset of pixel values. 
     In an example, the processing of the first subset of pixel values may include magnifying the first subset of pixel values. 
     In an example, the imaging method may further include performing high dynamic range (HDR) processing of the first subset of pixel values. 
     In an example, the imaging method may further include performing high dynamic range (HDR) processing of the second subset of pixel values. 
     In one aspect, the present disclosure provides an imaging system for a vehicle. The imaging system includes an image sensor, and an image signal processor (ISP) and a display device. The image sensor is disposed on the vehicle. The image sensor is configured to generate image data. The image data includes a set of pixel values. The ISP is communicably coupled to the image sensor. The ISP is configured to receive the image data from the image sensor. The ISP is further configured to define a first subset of pixel values from the set of pixel values. The first subset of pixel values corresponds to a plurality of distance lines with respect to the vehicle. The ISP is further configured to define a second subset of pixel values from the set of pixel values. The second subset of pixel values is complementary to the first subset of pixel values. The ISP is further configured to generate a first sub-image based on the second subset of pixel values. The ISP is further configured to process the first subset of pixel values to generate a second sub-image. Processing the first subset of pixel values includes at least one of: (i) changing a color of one or more pixel values from the first subset of pixel values; and (ii) scaling the first subset of pixel values. The ISP is further configured to merge the first and second sub-images to generate an output image. The display device is configured to display the output image received from the ISP. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description, will be better understood when read in conjunction with the appended drawings. For the purpose of illustration, certain examples of the present description are shown in the drawings. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities shown. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of system, apparatuses, and methods consistent with the present description and, together with the description, serve to explain advantages and principles consistent with the disclosure. The figures are not necessarily drawn to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number. 
         FIG. 1  is a schematic side view of an example of a vehicle; 
         FIG. 2  is a block diagram of an example of an imaging system for a vehicle; 
         FIG. 3  is flow diagram of an example process for image processing; 
         FIGS. 4A, 4B, 4C, 4D, and 4E  illustrate an example of processing of image data; 
         FIGS. 5A and 5B  illustrate an example of magnifying a region of interest in image data; 
         FIGS. 6A and 6B  illustrate examples of changing a color of a region of interest in image data; 
         FIGS. 7 and 8  illustrate an example of output images with regions of interest; 
         FIG. 9  illustrates an example of an image without any region of interest; 
         FIGS. 10, 11, and 12  illustrate an example of output images with regions of interest; 
         FIGS. 13A and 13B  illustrate an example of a change in color of a region of interest; and 
         FIG. 14  is a flow chart illustrating an example of an imaging method for a vehicle. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the systems, apparatuses and/or methods described herein will be suggested to those of ordinary skill in the art. Also, descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness. 
     It is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. For example, the use of a singular term, such as, “a” is not intended as limiting of the number of items. Also the use of relational terms, such as but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” are used in the description for clarity and are not intended to limit the scope of the disclosure or the appended claims. Further, it should be understood that any one of the features can be used separately or in combination with other features. Other systems, methods, features, and advantages of the disclosure will be or become apparent to one with skill in the art upon examination of the detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. 
     Referring now to the Figures,  FIG. 1  illustrates an example of a vehicle  100 . A camera  102  is disposed on the vehicle  100 . The camera  102  may provide images from all angles around the vehicle  100  depending on the requirements of a driver or an occupant of the vehicle  100 . For example, the camera  102  may help the driver to view areas rear of the vehicle  100 . Further, the camera  102  may also be used to view areas to the side of the vehicle  100 . The camera  102  may also enable the driver to view areas in a blindspot. The camera  102  may be provided at any location on the vehicle  100 , for example, a rear of the vehicle  100 , a side of the vehicle  100 , and so forth. The camera  102  may be fixedly or adjustably mounted on the vehicle  100 . The camera  102  may be configured to acquire both still images and moving images (e.g., video). Further, the camera  102  may be a digital camera. Though one camera  102  is shown in  FIG. 1 , multiple cameras may be disposed at different locations on the vehicle  100 . Although the vehicle  100  is illustrated as a passenger car in  FIG. 1 , the camera  102  may be used with other types of vehicles, for example, buses, trucks, off-road vehicles, motorcycles, aircrafts, bicycles, trams, locomotives, heavy-duty vehicles used in construction and earthworking, and so forth. 
       FIG. 2  illustrates an imaging system  200  for a vehicle such as the vehicle  100  described in  FIG. 1 . Referring to  FIGS. 1 and 2 , the imaging system  200  includes the camera  102  and a display device  202 . The camera  102  includes an image sensor  204  and an image signal processor (ISP)  206 . Though one image sensor  204  is illustrated in  FIG. 2 , the camera  102  may include multiple image sensors. The camera  102  may further include a lens (not shown). The image sensor  204  is disposed on the vehicle  100  and configured to generate image data. The ISP  206  is communicably coupled to the image sensor  204 . The ISP  206  may be connected to the image sensor  204  by wired connections, wireless connections, or a combination thereof. The display device  202  may be disposed on the vehicle  100  such as in a rear view device and is communicably coupled to the ISP  206 . The display device  202  may be connected to the ISP  206  by wired connections, wireless connections, or a combination thereof. Though in the illustrated example of  FIG. 2  the ISP  206  is shown to be part of the camera  102 , in alternative examples, the ISP  206  may be part of a separate processing device which is communicably coupled to one or more image sensors. The imaging system  200 , as shown in  FIG. 2 , is exemplary in nature. In other embodiments, the imaging system  200  may include multiple cameras and/or multiple display devices. In some cases, the display device  202  may simultaneously or selectively display multiple images from multiple cameras. 
     The image sensor  204  may be configured to capture and convert light into electrical signals. For example, the image sensor  204  may include a CMOS image sensor (e.g., a CMOS active-pixel sensor (APS)) or a CCD (charge-coupled device) sensor. Generally, the image sensor  204  of the camera  102  includes an integrated circuit having an array of pixels, where each pixel includes a photodetector for sensing light. The image sensor  204  may further include a color filter array (CFA) that may overlay or be disposed over the pixel array of the image sensor to capture color information. The color filter array may include a Bayer color filter array. The color filter array may include an array of small color filters, each of which may overlap a respective pixel of the image sensor and filter the captured light by wavelength. When used in conjunction, the color filter array and the photodetectors may provide both wavelength and intensity information with regard to light captured through the camera  102 , which may be representative of a captured image. 
     The ISP  206  may provide for various image processing steps, such as defective pixel detection/correction, lens shading correction, demosaicing, high dynamic range (HDR) processing, image sharpening, noise reduction, gamma correction, image enhancement, color-space conversion, image compression, chroma sub-sampling, color shifting, edge enhancement, image scaling operations, other types of pixel manipulation, and so forth. In some examples, the ISP  206  may include various subcomponents and/or discrete units of logic that collectively form an image processing pipeline for performing each of the various image processing steps. These subcomponents may be implemented using hardware (e.g., one or more processors) or software, or via a combination of hardware and software components. The processor(s) of the ISP  206  may include one or more microprocessors, such as one or more general-purpose microprocessors, one or more special-purpose microprocessors and/or application-specific microprocessors (ASICs), or a combination of such processing components. The instructions or data to be processed by the processor(s) may be stored in a computer-readable medium, such as a memory device. The memory device may be provided as a volatile memory, such as random access memory (RAM) or as a non-volatile memory, such as read-only memory (ROM), or as a combination of one or more RAM and ROM devices. The memory may store a variety of information and may be used for various purposes. For example, the memory may store firmware for the ISP  206  and the camera  102 , such as a basic input/output system (BIOS), an operating system, various programs, applications, or any other routines that may be executed on the camera  102 , including user interface functions, processor functions, and so forth. In addition, the memory may be used for buffering or caching during operation of the ISP  206  and the camera  102 . In an example, the ISP  206  may be implemented in an integrated circuit, such as a system on chip (SoC). 
     The display device  202  may be configured to display an output image received from the ISP  206 . The display device  202  may include any type of device including a display, for example, but not limited to, a display in an instrument panel of the vehicle  100 , a head-up display (HUD), a smartphone, a tablet computer, a rearview or a sideview mirror including a display, and so forth. The display device  202  may include a liquid crystal display (LCD), a light-emitting diode (LED) display, a cathode ray tube (CRT) display, a plasma display panel (PDP), an electrolumiscent display (ELD), and so forth. Further, the display device  202  may be touch-enabled. The display device  202  may be fixedly or adjustably mounted on the vehicle  100 . The display device  202  may be located such that the driver can view the output image displayed on the display device  202 . The display device  202  may be disposed internally or externally with respect to the vehicle  100 . Though one display device  202  is shown in  FIG. 2 , in other examples, the ISP  206  may be coupled with multiple display devices. 
     The imaging system  200  may allow the driver to view an object  104  located behind and/or to a side of the vehicle  100 . The imaging system  200  may also process the output image to highlight one or more regions of interest in the output image. For example, the imaging system  200  may indicate one or more distance lines with respect to the vehicle  100 . A distance line is a virtual line that indicates a distance from the vehicle  100 . A distance line may be disposed to a rear, a front or a side of the vehicle  100 . The distance may be measured from any reference point of the vehicle  100 , for example, a rear end of the vehicle  100 . Referring to  FIG. 1 , the imaging system  200  may indicate distance lines DL 1 , DL 2 , DL 3  with respect to the vehicle  100  in the output image displayed on the display device  202 . In the illustrated example, the distance lines DL 1 , DL 2 , DL 3  are located to the rear of the vehicle  100 . The distance lines DL 1 , DL 2 , DL 3  may be located at distances m 1 , m 2 , m 3 , respectively, with respect to the vehicle  100 . In the illustrated embodiment, m 1 &lt;m 2 &lt;m 3 . In an example, m 1  may be about 3 meters (m), m 2  may be about 10 m and m 3  may be about 25 m. The distance lines DL 1 , DL 2 , DL 3  may allow the driver to estimate a distance between the vehicle  100  and the object  104 . 
       FIG. 3  shows a flow diagram  300  for an example of a process for image processing implemented by the imaging system  200 . Referring to  FIGS. 1-3 , at step  302 , an image sensor  204  of the camera  102  generates image data  304 . At step  305 , the image data  304  is transmitted to the ISP  206  for processing. The image data  304  may include a set of pixel values corresponding to the array of pixels of the image sensor  204 . The image data  304  may include a raw or unprocessed data bit stream of the pixel values. In some cases, the pixel values may include RGB (red, green, blue) data.  FIG. 4A  illustrates the image data  304  including a set of pixel values ST. In this example, the set of pixel values ST include one or more pixel values  402 . In the illustrated example of  FIG. 4A , the pixel values  402  are arranged in a 12×16 array. However, a number of rows and columns of the pixel values  402  may vary based on the configuration of the image sensor  204 . Each pixel value  402  may include color data (e.g., RGB data) and intensity data. The image data  304  may dynamically change based on movement of the vehicle  100  and change in the surroundings of the vehicle  100 . 
     Referring back to  FIG. 3 , at step  306 , the ISP  206  receives the image data  304  from the image sensor  204  and processes the image data  304 . In an example, the ISP  206  may define a first subset of pixel values S 1  from the set of pixel values ST. The first subset of pixel values S 1  may correspond to at least one region of interest (ROI) in the image data  304 . For example, the at least one region of interest may correspond to one or more distance lines DL 1 , DL 2 , DL 3  with respect to the vehicle  100 . In another example, the at least one region of interest includes at least one of an object and an icon. As shown in  FIG. 4B , the first subset of pixel values S 1  may correspond to three regions of interest  406  in the image data  304 . Each region of interest  406  may have any suitable shape, for example, rectangular, linear, circular, polygonal, elliptical, or any irregular shape. The ISP  206  may identify the regions of interest  406  based on instructions stored in the associated memory. The regions of interest  406  may be user-defined or defined by a manufacturer. The regions of interest  406  may also dynamically change based on various parameters, such as level of ambient light (day/night), proximity to an object, speed of the vehicle  100 , among other factors. A number and shapes of the regions of interest  406  may therefore vary as per application requirements. In some examples, each region of interest  406  may correspond to a distance line relative to the vehicle  100 . For example, the first subset of pixel values S 1  may correspond to a plurality of distance lines DL 1 , DL 2 , DL 3  relative to the vehicle  100 . In other examples, each region of interest  406  may include at least one of an object (e.g., image of the object  104 ) and an icon. 
     The one or more regions of interest  406  may correspond to certain ranges of pixel values  402  that represent the distance lines DL 1 , DL 2 , DL 3  in the image data  304 . For example, the pixel values  402  in the range from C 11  to N 11  may represent the distance line DL 1  in the array of pixels. Further, the pixel values  402  in the range from C 7  to N 7  may represent the distance line DL 2  in the array of pixels. Moreover, the pixel values  402  in the range from C 2  to N 2  may represent the distance line DL 3  in the array of pixels. The first subset of pixel values S 1  may therefore include the pixel values  402  from C 11  to N 11 , from C 7  to N 7  and from C 2  to N 2 . 
     The ISP  206  may further define a second subset of pixel values S 2  from the set of pixel values ST. The second subset of pixel values S 2  may be complementary to the first subset of pixel values S 1 . In other words, the second subset of pixel values S 2  may include the pixel values  402  of the set of pixel values ST that do not belong to the first subset of pixel values S 1 , i.e., S 2 =ST−S 1 .  FIG. 4C  illustrates the first subset of pixels S 1  and the second subset of pixels S 2  separated from each other. 
     In an example, the ISP  206  may process the first subset of pixel values S 1  and the second subset of pixel values S 2  separately. The processing of the first subset of pixel values S 1  may be different from the processing of the second subset of pixel values S 2 . Referring back to  FIG. 3  together with  FIG. 4D , at step  308 , the ISP  206  may generate a first sub-image IM 1  using the second subset of pixel values S 2 . The first sub-image IMI may be a colored image or a greyscale image. The ISP  206  may perform various image processing steps on the second subset of pixel values S 2 , such as defective pixel detection/correction, lens shading correction, demosaicing, image sharpening, noise reduction, gamma correction, image enhancement, color-space conversion, image compression, chroma sub-sampling, among other processing steps. The ISP  206  may be further configured to perform high dynamic range (HDR) processing of the second subset of pixel values S 2 . HDR processing may provide a greater dynamic range of luminosity that can be perceived by a human eye. In some cases, HDR processing may include tone mapping. The ISP  206  may therefore partially generate an image, i.e., the first sub-image IMI, by processing the second subset of pixel values S 2 . 
     Still referring to  FIG. 3  together with  FIG. 4D , at step  310 , the ISP  206  may generate a second sub-image IM 2  using the first subset of pixel values S 1 . The second sub-image IM 2  may be a colored image or a greyscale image. The ISP  206  may perform various image processing steps on the first subset of pixel values S 1 , such as defective pixel detection/correction, lens shading correction, demosaicing, image sharpening, noise reduction, gamma correction, image enhancement, color-space conversion, image compression, chroma sub-sampling, among other processing steps. The processing of the first subset of pixel values S 1  may further include at least one of changing a color of one or more pixel values  402  from the first subset of pixel values S 1  and scaling the first subset of pixel values S 1 . Processing the first subset of pixel values S 1  may include pixel manipulation in addition to the processing carried out on the second subset of pixel values S 2 . Pixel manipulation may include color shifting and/or scaling. 
     In some examples, processing the first subset of pixel values S 1  may further include changing a color of each pixel value  402  of the first subset of pixel values S 1 . In further examples, processing the first subset of pixel values S 1  may also include filtering out at least one of red, green and blue colors from each pixel value  402  of the first subset of pixel values S 1 . Filtering of red, green and/or blue colors may be achieved by applying a color filter on the first subset of pixel values S 1 . Removal of red, green and/or blue colors may highlight the regions of interest  406  with respect to the adjacent areas in the image data  304 . The ISP  206  may dynamically change the color of each region of interest  406  based on various parameters, such as ambient light conditions, color of the adjacent areas in the image data  304 , speed of the vehicle  100 , proximity of each region of interest  406  to the vehicle  100 , among other parameters. For example, the ISP  206  may apply a first predefined color shift or change during the day and a second predefined color shift during the night. In another example, the ISP  206  may determine a color of each pixel value  402  surrounding each region interest of interest  406 . The ISP  206  may have chosen a predefined filtering process to provide an intended color to each region of interest  406 . If an intended color of the region of interest  406  is substantially close to that of the surrounding pixel values  402 , the ISP  206  may adjust the color of each region of interest  406  so that the driver can recognize each region of interest  406 . For example, the color of each region of interest  406 , may be adjusted to a color belonging to the same color family in order to distinguish each region of interest  406  from surrounding portions. In some embodiments, the regions of interest  406  may have different colors. 
     The first subset of pixel values S 1  may be selectively or additionally scaled. Scaling the first subset of pixel values S 1  may be achieved by various interpolation techniques, such as nearest-neighbor interpolation, bilinear interpolation, among other interpolation techniques. The first subset of pixel values S 1  may be interpolated outwards or inwards. The second subset of pixel values S 2  may not be scaled similarly. In some examples, processing the first subset of pixel values S 1  may further include magnifying the first subset of pixel values S 1 . The magnified regions of interest  406  when merged with the rest of the image may result in breaks or discontinuities at corresponding interfaces. The scaling ratio or amount of magnification may depend on various factors and can dynamically change as the factors change. The factors may include ambient light conditions, speed of the vehicle  100 , proximity of each region of interest  406  to the vehicle  100 , and so forth. For example, magnification may be increased during low ambient light conditions (e.g., during the night) as compared to good ambient light conditions (e.g., during the day). In another example, the magnification of each region of interest  406  may change based on a change in distance between each region of interest  406  and the vehicle  100 . An increase in magnification may easily attract the attention of a driver. In other words, greater magnification may provide a more distinct warning to a driver. A region of interest may also be dynamically identified and magnified during an emergency. For example, an object may suddenly appear near the vehicle  100 , and the corresponding region of interest in the image data  304  may be identified and magnified to attract the attention of the driver. 
     The ISP  206  may be further configured to perform high dynamic range (HDR) processing of the first subset of pixel values S 1 . HDR processing may provide a greater dynamic range of luminosity that can be perceived by a human eye. In some cases, HDR processing may include tone mapping. The ISP  206  may therefore partially generate an image, i.e., the second sub-image IM 2 , by processing the first subset of pixel values S 1 . In some examples, HDR processing of the first subset of pixel values S 1  may be performed first and then pixel manipulation (scaling and/or color shifting) may be subsequently performed on the HDR processed first subset of pixel values S 1 . 
     In some examples, the ISP  206  may generate the second sub-image IM 2  corresponding to all the regions of interest  406 . In other examples, the ISP  206  may generate separate sub-images for the respective regions of interest  406 . The processing of the regions of interest  406  may also vary from each other. For example, the color shifting and/or scaling may vary across the regions of interest  406 . 
     Referring to  FIG. 4E , the ISP  206  may be further configured to merge the first and second sub-images IM 1 , IM 2  to generate an output image IMO. In this example, the ISP  206  transmits the output image IMO to the display device  202 . Referring back to  FIG. 3 , at step  312 , the display device  202  displays the output image IMO received from the ISP  206 . The merging of the first and second sub-images IM 1 , IM 2  may be achieved based on locations of the pixel values  402  in the pixel array. For example, an image portion at B 2 , as shown in  FIG. 4B , may be disposed adjacent to an image portion at C 2 . In case the regions of interest  406  are magnified, portions of the second sub-image IM 2  may be overlaid on portions of the first sub-image IM 1 . Due to magnification, certain portions of the second sub-image IM 2  may overlap with certain portion of the first sub-image IM 1 . In such cases, the portions of the second sub-image IM 2  may be overlaid on the corresponding portions of the first sub-image IM 1 . For example, an image portion corresponding to B 2  in the second sub-image IM 2  may be overlaid on a corresponding image portion of the first sub-image IM 1 . Processed pixel values of the second sub-image IM 2  may overwrite processed pixel values of the first sub-image IM 1 . 
     Portions of the output image IMO corresponding to the regions of interest  406  may have undergone pixel manipulation that has not been implemented in the rest of the output image IMO. The output image IMO may dynamically change based on the movement of the vehicle  100  and change in surroundings. In some examples, the ISP  206  may further generate a video output for display at the display device  202 . 
     In the illustrated example of  FIG. 3 , all the processing of the image data  304  may be done by the ISP  206  in a pre-processing stage, i.e., at steps  306 ,  308  and  310 . Pre-processing may include any activity that occurs before an image is generated from raw data. In some examples, no post-processing may be required on the output image IMO. Post-processing may include any activity that occurs after the image is generated from raw data. For example, no overlay may have to be applied on top of the output image IMO by post-processing. 
       FIGS. 5A and 5B  illustrate an example of a pixel manipulation method for magnifying a region of interest  502  in image data  500 . In this example, image data  500  includes an array of pixel values  504  arranged in a 12×16 array. The region of interest  502  is a rectangular region with C 3 , C 5 , N 3  and N 5  as its corners. One or more of the pixel values  504  in the region of interest  502  may be interpolated outwards for magnifying the region of interest  502 . The ISP  206  (shown in  FIG. 3 ) may perform the magnification. The pixel value  504  at C 3  may be interpolated to adjoining pixels, namely, B 2 , B 3  and C 2 . Similarly, the pixel value  504  at C 4  may be interpolated to B 4 . Other pixel values  504  may be similarly interpolated and an example of the resulting magnified region  506  is shown in  FIG. 5B . The interpolated pixel values  504  may be overlaid on the surrounding pixel values  504 . The interpolated pixel values  504  of the magnified region  506  may overwrite the surrounding pixel values  504 . Since only the region of interest  502  is magnified and not the other parts of the image data  500 , discontinuities or breaks may be present at one or more interfaces between the magnified region  506  and surrounding portions of the image. For example, a break may be present between rows  1  and  2 . 
       FIGS. 6A and 6B  illustrate an exemplary color shifting method of a region of interest  602  in image data  600 . The image data  600  includes an array of pixel values  604  arranged in a 12×16 array. The region of interest  602  is a rectangular region with D 3 , D 5 , O 3  and O 5  as its corners. Color of one or more pixel values  604  in the region of interest  602  may be changed by the ISP  206 . In the illustrated embodiment of  FIG. 6B , a color of each pixel value  604  in the region of interest  602  is changed. The color may be changed by filtering out at least one of red, green and blue colors from each pixel value  604  in the region of interest  602 . Color shifting may result in a color shifted region  606  shown in  FIG. 6B . 
       FIG. 7  illustrates an example of an output image  700  displayed on the display device  202 , as previously illustrated in  FIG. 2 . The output image  700  may include one or more regions of interest  702 ,  704 , and  706  which correspond to one or more respective distance lines. For example, the one or more regions of interest  702 ,  704 , and  706  may correspond to distance lines DL 1 , DL 2  and DL 3 , respectively, as described in reference with  FIG. 1 . In this example, the regions of interest  702 ,  704  and  706  are magnified with respect to other regions of the output image  700 . Due to magnification, breaks  708 ,  710 ,  712  may be disposed between the respective regions of interest  702 ,  704 ,  706  and the adjoining portions of the output image  700  that are not similarly magnified. In an example, the breaks  708 ,  710 ,  712  may be easily noticeable by the driver. Using the breaks  708 ,  710 ,  712 , the driver may be able to estimate distances between the vehicle  100  and different objects such as object  104  described in reference to  FIG. 1 . 
       FIG. 8  illustrates another example of an output image  800  that is similar to the output image  700 . In this example, the three regions of interest  702 ,  704  and  706  in the output image  800  are colored. The pixel values in the three regions of interest  702 ,  704  and  706  have been color shifted so that three regions of interest  702 ,  704  and  706  have different colors with respect to the surrounding portions of the output image  800 . Further, in an example, the three regions of interest  702 ,  704  and  706  may have colors that are different from each other. The colors in the three regions of interest  702 ,  704 ,  706  may be changed by filtering out red, green and/or blue colors in the corresponding pixel values. The color-coded regions of interest  702 ,  704  and  706  may provide additional information to the driver. 
       FIG. 9  illustrates an example of an image  900  without any region of interest.  FIG. 10  illustrates an example of an output image  1000  with three regions of interest  1002 ,  1004 ,  1006 . Each region of interest  1002 ,  1004 ,  1006  in this example is a rectangular region corresponding to a respective distance line. For example, the regions of interest  1002 ,  1004 ,  1006  may correspond to the distance lines DL 1 , DL 2 , DL 3 , respectively, as described in reference with  FIG. 1 . A color of each region of interest  1002 ,  1004 ,  1006  may be changed in order to attract the attention of the driver. The colors of the regions of interest  1002 ,  1004 ,  1006  may be different from each other.  FIG. 11  illustrates an output image  1100  including a region of interest  1102 . The region of interest  1102  is an icon with a substantially triangular shape. The region of interest  1102  may be generated by changing the color of the corresponding pixel values. The icon may provide a warning to the driver.  FIG. 12  illustrates an example of an output image  1200  with a region of interest  1202 . The region of interest  1202  may be an object, such as an obstruction on a road. A color of the region of interest  1202  may be changed to alert the driver. 
       FIGS. 13A and 13B  illustrate an example of a change in color of one or more regions of interest  1302 . The region of interest  1302  may be any one of the regions of interest  1002 ,  1004 ,  1004  shown in  FIG. 10 . The color of the region of interest  1302  has been changed in the example of  FIG. 13B . In some examples, the color of the region of interest  1302  may be changed in response to an intended or present color of the region of interest  1302  being similar to surrounding portions of the image. The color of the region of interest  1302  may be adjusted to a similar color (for example, a different shade of red) or a different color that can be recognized by the driver. 
       FIG. 14  is a flowchart illustrating an example of an imaging method  1400  (hereinafter referred to as “the method  1400 ”) for a vehicle. The method  1400  may be implemented using an imaging system, such as the imaging system  200  described above in reference with  FIG. 2 , for a vehicle, such as the vehicle  100  described above in reference with  FIG. 1 . Referring to  FIGS. 1-14 , at step  1402 , the method  1400  includes receiving the image data  304  from the image sensor  204  disposed on the vehicle  100 . The image data  304  includes the set of pixel values ST. The ISP  206  receives the image data  304  from the image sensor  204 . 
     At step  1404 , the ISP  206  defines a first subset of pixel values S 1  from the set of pixel values ST. The first subset of pixel values S 1  may correspond to at least one region of interest in the image data  304 . In an example, the at least one region of interest may correspond to one or more distance lines DL 1 , DL 2 , DL 3  with respect to the vehicle  100 , as described above in reference with  FIG. 1 . In another example, the at least one region of interest includes at least one of an object and an icon. 
     At step  1406 , the ISP  206  may define a second subset of pixel values S 2  from the set of pixel values ST. The second subset of pixel values S 2  may be complementary to the first subset of pixel values S 1 . 
     At step  1408 , the ISP  206  may generate a first sub-image IM 1  based on the second subset of pixel values S 2 . 
     At step  1410 , the ISP  206  may process the first subset of pixel values S 1  to generate the second sub-image IM 2 . Processing the first subset of pixel values S 1  may include at least one of changing a color of one or more pixel values  402  from the first subset of pixel values S 1  and scaling the first subset of pixel values S 1 . In an example, the processing of the first subset of pixel values S 1  may include changing a color of each pixel value  402  of the first subset of pixel values. In another example, the processing of the first subset of pixel values S 1  may include magnifying the first subset of pixel values S 1 . In some examples, the method  1400  may further include performing high dynamic range (HDR) processing of the first subset of pixel values S 1 . In additional examples, the method  1400  may further include performing high dynamic range (HDR) processing of the second subset of pixel values S 2 . 
     At step  1412 , the ISP  206  may merge the first and second sub-images IM 1 , IM 2  to generate an output image IMO. In an example, portions of the first sub-image IM 1  may be overlaid or superimposed on corresponding portions of the second sub-image IM 2 . 
     At step  1414 , the method  1400  may further include displaying the output image IMO by the display device  202  disposed on the vehicle  100 , as described above in reference with  FIGS. 1 and 2 . In this example, the ISP  206  may transmit the output image IMO to the display device  202 , and the display device  202  may display the output image IMO. 
     In certain aspects, the imaging system  200  and the method  1400  enable processing of one or more regions of interest in image data during the pre-processing stage, i.e., before an output image is generated. In an example, post-processing of the output image may not be required. For example, there is no requirement for applying an overlay on top of the output image by post-processing. As a result, processing time and computing requirements may be reduced. 
     Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. 
     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof. 
     Furthermore, the features of the disclosure disclosed in this specification, the claims and the drawings may be employed both individually and in any possible combination for practicing the disclosure in its various exemplary embodiments. In particular, all claim feature combinations, irrespective of the claim dependencies, are covered with this application. 
     LIST OF NUMBERS 
     
         
         
           
               100  Vehicle 
               102  Camera 
               104  Object 
               200  Imaging System 
               202  Display Device 
               204  Image Sensor 
               206  Image Signal Processor (ISP) 
             DL 1  Distance Line 
             DL 2  Distance Line 
             DL 3  Distance Line 
             m 1  Distance 
             m 2  Distance 
             m 3  Distance 
               300  Process Flow 
               302  Block 
               304  Image Data 
               305  Block 
               306  Block 
               308  Block 
               310  Block 
               312  Block 
               402  Pixel Values 
               406  Regions Of Interest 
             ST Set Of Pixel Values 
             S 1  First Subset Of Pixel Values 
             S 2  Second Subset Of Pixel Values 
             IM 1  First Sub-Image 
             IM 2  Second Sub-Image 
             IMO Output Image 
               500  Image Data 
               502  Region Of Interest 
               504  Pixel Values 
               506  Magnified Region 
               600  Image Data 
               602  Region Of Interest 
               604  Pixel Values 
               606  Color Shifted Region 
               700  Output Image 
               702  Region of Interest 
               704  Region of Interest 
               706  Region Of Interest 
               708  Break 
               710  Break 
               712  Break 
               800  Output Image 
               900  Image 
               1000  Output Image 
               1002  Region Of Interest 
               1004  Region Of Interest 
               1006  Region Of Interest 
               1100  Output Image 
               1102  Region Of Interest 
               1200  Output Image 
               1202  Region Of Interest 
               1302  Region Of Interest 
               1400  Imaging Method 
               1402  Step 
               1404  Step 
               1406  Step 
               1408  Step 
               1410  Step 
               1412  Step 
               1414  Step