Abstract:
An image processing method includes receiving a two-dimensional (2D) input image; detecting an image of a block in the 2D image to generate depth information for the block; and determining a depth of a sub-block image within the block according to the depth information, accurately estimating block-based depth information according to image characteristics of the block and obtaining a depth of a given block/pixel according to the depth information to generate improved stereoscopic images.

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This patent application is based on Taiwan, R.O.C. patent application No. 100121439 filed on Jun. 20, 2011. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to an image processing mechanism, and more particularly, to an image processing apparatus and method thereof capable of determining a corresponding depth of a two-dimensional (2D) image in a small range according to depth information estimated via a 2D image in a large range. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the conventional 2D to three-dimensional (3D) stereoscopic image conversion technology, a depth of each pixel of a 2D image is estimated and calculated one by one, i.e., in the prior art, different independent estimation and calculation procedures are performed on different pixels, resulting in high calculation resources (e.g., time and circuit areas) in order to accurately estimate the depth of each pixel, and the entire circuit system becomes relatively complicated and costly. Accordingly, for current image processing applications, complicated circuit systems, using many calculation resources, is rather lacking in flexibility. In addition, the conventional technology fails to accurately estimate depth information of image content corresponding to a 2D image, and the conventional 2D image to 3D stereoscopic image conversion technology also creates serious distortion when the 2D image is converted to a 3D stereoscopic image. These are some of the problems faced in the prior art in this field which the current invention serves to address. 
       SUMMARY OF THE INVENTION 
       [0004]    One object of the present invention is to provide an image processing apparatus and method thereof capable of accurately estimating block-based depth information according to image characteristics of a block and obtaining a depth of a pixel according to the depth information to generate a stereoscopic image so as to solve the foregoing problems. 
         [0005]    According to an embodiment of the present invention, an image processing method comprises receiving a 2D input image; and detecting an image of a block in the 2D input image to generate depth information for the block, wherein the depth information indicates a depth of the image of the block when the image is stereoscopically displayed. 
         [0006]    According to an embodiment of the present invention, an image processing apparatus comprises a detecting circuit, for receiving a 2D input image and detecting an image of a block in the 2D input image to generate depth information for the block; and a determining circuit, coupled to the detecting circuit, for determining a depth of a sub-block image within the block according to the depth information. 
         [0007]    According to an embodiment of the present invention, a detecting circuit applied to image processing receives a 2D input image, and detects an image of a block in the 2D input image to generate depth information for the block, wherein the depth information indicates a depth of the image of the block when the image is stereoscopically displayed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic diagram of an image processing apparatus in accordance with an embodiment of the present invention. 
           [0009]      FIG. 2  is a schematic diagram of depth variations of a preliminary depth D 1 , pixel-based depth variations, and depth variations of a target depth in accordance with an embodiment of the present invention. 
           [0010]      FIG. 3   a  is a schematic diagram of a target depth D 1 ′, a variation range D_R of the target depth D 1 ′, a horizontal shift V_shift, a 2D image IMG — 2D and a 3D image IMG — 3D perceived by human eyes in accordance with an embodiment of the present invention. 
           [0011]      FIG. 3   b  is a schematic diagram of a target depth D 1 ′, a variation range D_R of the target depth D 1 ′, a horizontal shift V_shift, a 2D image IMG — 2D and a 3D image IMG — 3D perceived by human eyes in accordance with an embodiment of the present invention. 
           [0012]      FIG. 4   a  is a schematic diagram of image sequence distortion created by a horizontal shift V_shift being larger than 1 when a preliminary depth D 1  is adopted to perform depth calculation. 
           [0013]      FIG. 4   b  is a schematic diagram of an image conversion weight method for a generating unit illustrated in  FIG. 1 . 
           [0014]      FIG. 4   c  is a schematic diagram of operations for selecting a weight average point via the image conversion weight method illustrated in  FIG. 4   b.    
           [0015]      FIG. 5  is a flow chart of operations of an image processing apparatus illustrated in  FIG. 1  in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0016]      FIG. 1  is a schematic diagram of an image processing apparatus  100  in accordance with an embodiment of the present invention. The image processing apparatus  100  comprises a detecting circuit  105 , a storage circuit  110 , and a processing circuit  115 . The processing circuit  115  comprises a determining unit  120  and a generating unit  125 . The detecting circuit  105  receives a 2D input image S — 2D and detects an image of a block MB in a 2D image S — 2D to generate depth information INFO of the block MB. The 2D input image S — 2D is a plane image not carrying 3D stereoscopic depth information, and the block MB is an image region having M×N pixels in the 2D input image S — 2D, where M and N are positive integer numbers; M may or may not be equal to N, for this example, M and N are 16. The depth information INFO comprises parameters for indicating a depth of the block MB. In this embodiment, the parameters contain a luminance contrast, a color, a spatial position, edge image information, motion information of the image in the block MB, and the like. The parameters of the depth information INFO are outputted by the detecting circuit  105 , and are temporarily stored in the storage circuit  110 , which may be realized by a digital storage medium, such as dynamic random access memory (DRAM) or a buffer. The processing circuit  115  reads the parameters contained in the depth information INFO from the storage circuit  110 , determines a depth of each sub-block image in the block MB, and generates a stereoscopic image according to the generated depths. In this embodiment, a sub-block image, e.g., the image of a single pixel, has a depth equal to that of the image of the single pixel being stereoscopically displayed. In other words, the processing circuit  115  determines the depth of each single pixel according to the depth information INFO of the block MB. In this embodiment, operations for determining the depth of each pixel in the block MB are described below. Since preliminary depths D 1  of pixels in the block MB are determined via the determining unit  120  of the processing circuit  115  according to the parameters contained in the depth information INFO of the block MB, they have identical values, so that the preliminary depth D 1  is regarded as a block-based depth of all pixels in the block MB. When the determining unit  120  generates the preliminary depth D 1  of the pixels in the block MB, the preliminary depth D 1  is outputted to and is temporarily stored in the storage circuit  110 . Before a stereoscopic image is generated, the subsequent generating unit  125  first reads from the storage unit  110  the preliminary depth D 1  and image characteristics of each pixel to generate a target depth D 1 ′ (not shown in  FIG. 1 ) of the pixel in the block MB. Since the target depth D 1 ′ is qualified to represent a depth degree of the pixel of the stereoscopic image, the generating unit  125  generates the stereoscopic image displayed on the pixel with reference to the target depth D 1 ′. In addition, the generating unit  125  generates the stereoscopic image on the pixel (e.g., a left-eye image or a right-eye image) according to an input reference motion vector MV (i.e., motion information generated via motion estimation). 
         [0017]    Operations of the detecting circuit  105 , the determining unit  120 , and the generating unit  125  are described below. The depth information INFO detected and generated by the detecting circuit  105  contains parameters, such as a luminance contrast, a color, a spatial position, edge image information, motion information of the image in the block MB, and the like. Taking the luminance contrast of the image as an example, the detecting circuit  105  detects a maximum gray-scale value and a minimum gray-scale value of the image in the block MB, calculates a difference between the maximum gray-scale value and the minimum gray-scale value, determines the luminance contrast of the image according to the difference, and stores the determined luminance contrast of the image into the storage circuit  110 . The difference represents a degree of the luminance contrast of the image. For example, when the difference is equal to a first difference value, the detecting circuit  105  determines the luminance contrast of the image in the block MB as a first reference value, and also determines that the depth information for the block MB indicates a first depth; when the difference is a second difference that is larger than the first difference value (i.e., the luminance contrast is relatively higher), the detecting circuit  105  determines the luminance contrast of the image in the block MB as a second reference value that is larger than the first reference value, and determines that the depth information for the block MB indicates a second depth that is smaller than the first depth. In other words, the detecting circuit  105  adjusts the depth indicated by the depth information INFO by determining the luminance contrast degree of the image in the block MB. When the luminance contrast gets larger, the detecting circuit  105  determines that the image in the block MB becomes closer to human eyes, i.e., the depth is smaller, and therefore the parameters contained in the depth information INFO are adjusted accordingly to indicate an appropriate depth. 
         [0018]    Taking the color of the image as an example, the detecting circuit  105  generates the depth information INFO with reference to the color of the image in the block MB so as to detect whether the image in the block MB shows identifiable portions, for example, a part of the sky. For example, since the color of the sky is approximate to blue, when an image of a block is determined as showing a part of the sky, the block is farther from human eyes when it is stereoscopically displayed, i.e., the block has a greater or greatest relative depth. In practice, since the color of the sky contains a predetermined color range that is approximate to blue, in the event that the color of the image in the block MB is within or corresponds to the predetermined color range, meaning that the image in the block MB shows a part of the sky, the detecting circuit  105  determines that the depth information INFO indicates the first depth (i.e., representing the great or greatest depth). When the color of the image in the block MB is not within or does not correspond to the predetermined color range, meaning that the image in the block MB does not show any part of the sky, the detecting circuit  105  determines that the depth information indicates the second depth that is smaller than the first depth. The color of the image is an average color of images in one block or a color of majority images. In addition, the color of the sky may also not be blue, and is gray or other colors, so that the color range of the sky contains a predetermined color range approximate to gray or a certain predetermined color, i.e., the predetermined color range is not limited to being approximate to a certain predetermined color, and may also be composed of a plurality of color ranges. In addition, the color of the sky shall not be construed as limiting the present invention, and colors of other images at a remote distance which may also be detected according to the present invention are likewise within scope. Therefore, the foregoing embodiments are described for illustration purposes, and shall not be construed as limitations of the present invention. 
         [0019]    Taking the spatial position of the image as an example, the detecting circuit  105  detects a spatial position of the image in the block MB, and generates the depth information INFO according to the detected spatial position of the image in the block MB. The spatial position of the image in the block MB is detected by determining a position of the block MB within the 2D image. When the image in the block MB is at an upper position of the 2D image, the block MB has a greater depth; otherwise, the block has a smaller depth. For example, an image of an office floor (at a higher spatial position) is farther from observing human eyes, and an image of an office desk (at a lower spatial position) is closer to observing human eyes. In practice, when the image in the block MB is at a first spatial position of the 2D input image S — 2D, the detecting circuit  105  determines that the depth information INFO indicates a first depth; when the image in the block MB is at a second spatial position that is higher than the first spatial position of the 2D input image S — 2D, the detecting circuit  105  determines that the depth information INFO indicates a second depth that is greater than the first depth. 
         [0020]    Taking an edge image as an example, the detecting circuit  105  generates the depth information INFO according to edge image information of the image in the block MB. In this embodiment, when it is detected that the block MB comprises numerous edge images, the detecting circuit  105  determines that the image in the block MB has a small depth. Therefore, in practice, when the detected edge image information indicates that the block MB has a first number of edge images, the detecting circuit  105  determines that the block MB has the first depth. When the detected edge image information indicates that the block MB has a second number of edge images and the second number is larger than the first number, the detecting circuit  105  determines that block MB has a second depth that is smaller than the first depth. 
         [0021]    Taking motion information as an example, the detecting circuit  105  generates the depth information INFO according to motion information of the image in the block MB. In this embodiment, when the estimated motion information indicates a large motion vector, meaning a detectable image is deemed to be moving quickly, typically in a scene close to human eyes. Therefore, the detecting circuit  105  determines that the image has a small depth. In practice, when the motion information indicates a first motion vector, the detecting circuit  105  determines that the depth information INFO of the block MB indicates a first depth; when the motion information indicates a second motion vector that is larger than the first motion vector, the detecting circuit  105  determines that the depth information INFO of the block MB indicates a second depth that is smaller than the first depth. 
         [0022]    It is to be noted that, in order to accurately generate a depth of each pixel in subsequent operations, the depth information INFO generated by the detecting circuit  105  comprises the foregoing types of parameters for indicating depths. However, when circuit calculation cost reduction is taken into consideration, the depth information INFO may comprise a few types of parameters but not all parameters, or may only comprise one type of parameters. In addition, the detecting circuit  105  can also generate the depth information INFO according to luminance contrasts, colors, spatial positions and edge image information, and motion information of images within a plurality of adjacent blocks in the block MB, and modifications thereof shall be within the spirit and scope of the present invention. 
         [0023]    When the detecting circuit  105  generates and stores the parameters of the depth information INFO into the storage circuit  110 , the determining unit  120  reads from the storage circuit  110  the stored parameters, and determines a preliminary depth D 1  (i.e., a block-based depth) of the block MB according to the parameters of the depth information INFO. The preliminary depth D 1  is regarded as preliminary depths of all pixels in the block MB. When the preliminary depth D 1  of each pixel in the block MB is determined, the determining unit  120  temporarily stores the preliminary depth D 1  into the storage circuit  110 , and reads from the storage circuit  110  via the generating unit  125 . In another embodiment, the detecting circuit  105  and the determining unit  120  comprise independent storage circuits, the depth information INFO is outputted from the detecting circuit  105  and is transmitted to the determining unit  120 , and the preliminary depth D 1  is outputted from the determining unit  120  and is transmitted to the generating unit  125 , wherein both the depth information INFO and the preliminary depth D 1  are transmitted via the storage circuit  110  during the transmission process. Therefore, the generating unit  125  determines a target depth D 1 ′ of a pixel according to the preliminary depth D 1  and a 2D image of the pixel. In practice, the generating unit  125  fine-tunes the preliminary depth D 1  according to a gray-scale value of the 2D image of the pixel to generate the target depth D 1 ′ in association with image content of the pixel. When the gray-scale value of the pixel is large (i.e., the luminance value is large), the generating unit  125  reduces the preliminary depth D 1  of the pixel according to the large gray-scale value to generate the target depth D 1 ′. When the gray-scale value of the pixel is small (i.e., the luminance value is small), the generating unit  125  increases the preliminary depth D 1  of the pixel according to the small gray-scale value to generate the target depth D 1 ′. 
         [0024]    Therefore, although human eyes cannot obtain a stereoscopic visual lay-perception of the image in the block MB since the preliminary depths D 1  of all pixels are identical to each other, the generating unit  125  fine-tunes the preliminary depth D 1  of each pixel according to the gray-scale value of each pixel to generate a target depth of each pixel, so as to achieve a depth compensation effect of different pixels according to different pixel gray-scale values. For example, supposing that the image displayed in the block MB shows a leaf of a tree, when the foregoing preliminary depth D 1  is regarded as the target depth of each pixel, the target depths D 1 ′ of leaves are the same, human eyes cannot obtain a stereoscopic depth perception between leaves from a subsequently-generated stereoscopic image. However, when the target depth D 1 ′ of each pixel is generated by fine-tuning/compensating the preliminary depth D 1  of each pixel, the target depths of leaves are different from each other, and thus human eyes can easily obtain the stereoscopic depth perception from the subsequently-generated stereoscopic image. 
         [0025]    It is to be noted that, a preferred stereoscopic depth perception is obtained by fine-tuning the preliminary depth D 1  to generate the target depth D 1 ′, and it shall not be constructed as limiting the present invention. In other embodiments, the generating unit  125  directly adopts the preliminary depth D 1  of the block MB as the target depth D 1 ′ of each pixel in the block MB to meet a basic requirement of stereoscopic image display as well as reducing the circuit calculation cost. For example, supposing that the image displayed in the block MB is a part of the sky, the generating unit  125  determines that the image in the block MB shows the farthest scene according to the temporarily stored preliminary depth D 1 . Since human eyes are not sensitive to depth variations of the image showing the farthest scene, the generating unit  125  directly defines the preliminary depth D 1  of the block MB as the target depth D 1 ′ of each pixel in the block MB but not adopt the foregoing step of fine-tuning the preliminary depth D 1 . Accordingly, the basic requirement of stereoscopic image display (while human eyes cannot perceive the depth variations of the image showing the farthest scene) is met and the software/hardware calculation cost is also reduced. 
         [0026]    Accordingly, in this embodiment, the generating unit  125  adaptively determines whether to fine-tune the preliminary depth D 1  according to characteristics of the image in the block MB. In addition, since the preliminary depth D 1  of the block MB may be selected as a target depth of one pixel, the generating unit  125  is regarded as determining a depth of a pixel in the block MB according to the depth information INFO. Since the determining unit  120  and the generating unit  125  are contained in the processing circuit  115 , operations of the determining unit  120  and the generating unit  125  are also considered operations of the processing circuit  115 . In order to illustrate a difference between the preliminary depth D 1  and the target depth D 1 ′,  FIG. 2  shows a schematic diagram of depth variations of the preliminary depth D 1  of the image frame, pixel-based depth variations, and depth variations of the target depth D 1 ′. Referring to  FIG. 2 , a curve S_B representing variations of the preliminary depth D 1  of a plurality of blocks changes slowly and smoothly, meaning that the preliminary depths D 1  of all pixels in the plurality of blocks of an image frame are identical to each other. A curve S_P representing pixel-based depth variations changes more dramatically and randomly than the curve S_B, meaning that the pixel-based depth variations of all pixels in the plurality of blocks of the image frame are different, so that the pixel-based depth variations are represented by the curve S_P. A curve S_B′ generated by modifying the curve S_B via the curve S_P represents variations of the target depth D 1 ′. Therefore, the operations of generating the preliminary depth D 1  and generating the target depth D 1 ′ by fine-tuning the preliminary depth D 1  are capable of effectively and accurately generating a stereoscopic depth corresponding to an image of each pixel of an image frame. 
         [0027]    In addition, when the target depth D 1 ′ of a pixel in the block MB is generated, the generating unit  125  determines a horizontal shift V_shift between a first visual-angle image (e.g., a left-eye image) corresponding to the image (e.g., a sub-block image) of the pixel and a second visual-angle image (e.g., a right-eye image) according to the generated target depth D 1 ′, and generates the first visual-angle image and the second visual-angle image according to the determined horizontal shift V_shift.  FIG. 3   a  shows a schematic diagram of a target depth D 1 ′, a horizontal shift V_shift, a 2D image IMG — 2D, and a 3D image IMG — 3D perceived by human eyes in accordance with an embodiment of the present invention. A left eye L represents a left eye of a person, a right eye R represents a right eye of the person, a horizontal line P represents a display panel, and an image IMG — 2D represents a 2D plane image displayed on a pixel. When the target depth D 1 ′ is generated, the generating unit  125  respectively generates a left-eye image IMG_L and a right-eye image IMG_R at a horizontal shift V_shift from the left side and the right side of the 2D image according to principles of stereoscopic imaging and the target depth D 1 ′ (D_R represents a variation range from a smallest depth to a greatest depth of the target depth. Accordingly, the left eye L observes the left-eye image IMG_L at an accurate position point of the frame and the right eye R observes the right-eye image IMG_R at another accurate position point of the frame, so that the human eyes perceive imaging of the stereoscopic image IMG — 3D. It is to be noted that, the generating unit  125  generates another horizontal shift V_shift&#39; corresponding to the image (i.e., a sub-block image) of the pixel according to the generated target depth D 1 ′, and generates multi-visual-angle images according to the horizontal shift V_shift . In other words, the generating unit  125  generates multi-visual-angle images according to a target depth of an image of a single pixel. 
         [0028]    In addition, the generating unit  125  determines the horizontal shift V_shift according to the generated target depth D 1 ′, a foreground/background adjustment value to provide diversified design variations of imaging of the stereoscopic image. Refer to  FIG. 3   b  showing a schematic diagram of the target depth D 1 ′, the variation range D_R of the target depth D 1 ′, the horizontal shift V_shift, the 2D image IMG — 2D, and the 3D image IMG — 3D perceived by human eyes in accordance with an embodiment of the present invention. A left eye L represents a left eye of a person, a right eye R represents a right eye of the person, a horizontal line P represents a display panel, and an image IMG — 2D represents a 2D panel image displayed on a pixel. When the target depth D 1 ′ is generated, the generating unit  125  defines a variation range D_R from a smallest depth to a greatest depth of the target depth according to the foreground/background adjustment value. Referring to  FIG. 3   b,  the range D_R indicates that the stereoscopic image perceived by human eyes is designed as being at the foreground of the display panel. The generating unit  125  generates a left-eye image IMG_L at a horizontal shift V_shift from the right side of the 2D image IMG — 2D, and generates a right-eye image at the horizontal shift V_shift from the left side of the 2D image IMG — 2D according to the principles of stereoscopic imaging, the target depth D 1 ′ and the variation range D_R of the target depth D 1 ′ defined via the foreground/background adjustment value, so that the left eye L observes the left-eye image IMG_L at an accurate position point of a frame and the right eye R observes the right eye image IMG_R at another accurate position point, and thus human eyes perceive that the stereoscopic image IMG — 3D is imaged at the foreground of the display panel P. In addition, the generating unit  125  generates the foregoing horizontal shift V_shift according to the target depth D 1 ′ and a gain value, which is for reducing or increasing the horizontal shift V_shift, so that generation of the horizontal shift V_shift gets more flexibility. In addition, when a horizontal shift V_shift corresponding to each pixel is generated, the horizontal shift V_shift is designed as being smaller than 1, so as to avoid sequence disorder of the left-eye and right-eye images corresponding to the current pixel and left-eye and right-eye images corresponding to an adjacent pixel. Therefore, disadvantages that are created by the application of the 2D image for generating the stereoscopic image are avoided. 
         [0029]    In order to understand the sequence disorder of the images, refer to  FIG. 4   a  showing a schematic diagram of image sequence disorder created by the horizontal shift V_shift being larger than 1 when the preliminary depth D 1  is adopted to perform depth calculation. At this point, the preliminary depth D 1  is applied to a plurality of pixel points within a block range. In order to smooth depths of the plurality of pixel points, a depth linear interpolation is performed on a plurality of pixel points within two blocks to provide smooth depth variations to the pixel points. Referring to  FIG. 4   a,  pixel points  0  to  64  on a 2D image plane are projected at 32 pixel points on a 3D image plane, and the horizontal shift V_shift is 2. In such situations, the pixel point  2  on the 2D image plane is projected at the position- 1  on the 3D image plane, and the pixel point  4  is projected at the position- 2  on the 3D image plane, thus creating left and right sequence disorder. Obviously, such a sequence disorder generates an error (the image of the 3D image plane is a mirror image of the image of the 2D image plane), such that the displayed result is not the desired output. In order to solve such a problem, the pixel points  0  to  64  on the 2D image plane need to be arranged within the 32 pixel points on the 3D image plane, i.e., a horizontal shift between every two pixel points on the 2D image plane needs to be 0.5 so as to linearly interpolate the numbers of the 2D image plane into the 3D image plane while sequence disorder is avoided. It is to be noted that, the operation of designing the horizontal shift V_shift as being smaller than 1 is explained from example, and it shall not construed as a specific limitation of the present invention. In other embodiments, the horizontal shift V_shift may also be designed as being smaller than a predetermined value (e.g., the predetermined value of 1), so as to overcome the disadvantages created by the application of the 2D image for generating the stereoscopic image. 
         [0030]    When the target depth D 1 ′ comprises depth details of each pixel, taking an image having a certain visual-angle (e.g., a right-eye image) as an example, during a process of converting a 2D image to a 3D right-eye image, in the event that a plurality of 3D right-eye images corresponding to each pixel of the 2D image are generated according to the respective corresponding horizontal shift V_shift, the right-eye images may not be necessarily displayed on pixel display points of the display panel. In other words, the conventional approach of converting the 2D image to the 3D stereoscopic image creates the problem that an accurate shift of the current pixel cannot be accurately displayed or even cannot be displayed. In order to solve this problem, in this embodiment, the generating unit  125  by weight generates a horizontal shift corresponding to a target depth of the right-eye image of the current pixel according to two target depths of two right-eye images around the current pixel and two horizontal shifts corresponding to the target depths of the two right-eye images. Likewise, the generating unit  125  by weight generates a horizontal shift corresponding to a target depth of the left-eye image of the current pixel according to two target depths of two left-eye images around the current pixel and two horizontal shifts corresponding to the target depths of the two left-eye images. In other words, according to the depth information INFO, the generating unit  125  first determines a first horizontal shift of a plurality images with different visual angles corresponding to a first sub-block image and a second horizontal shift of a plurality of images with different visual angles corresponding to a second sub-block image, and then generates a horizontal shift (corresponding to the target depth of the image of the current pixel) of a plurality of images with different visual angles within a sub-block image between the first and second sub-block images according to the first horizontal shift of the plurality of images with different visual angles corresponding to the first sub-block image and the second horizontal shift of the plurality of images with different visual angles corresponding to the second sub-block image, so as to generate the target depth of the current pixel via weight calculation approach to effectively overcome the disadvantages of stereoscopic image display. 
         [0031]    In order to illustrate the foregoing weight calculation process, refer to  FIG. 4   b  showing a schematic diagram of an image converting weight method in accordance with an embodiment of the present invention. There are a plurality of pixel display points (comprising but not limited to point A and point B) on an original 2D image plane, the pixel display points carry different horizontal shifts after having been converted and are rearranged on a 3D image plane illustrated in  FIG. 4   b.  As mentioned above, the problem is that the pixel display point may not be redisplayed on the 3D image plane since the horizontal shifts of the pixel display points may not be integers. In order to solve this problem, a pixel display point Q on the 3D image plane is first defined as a center point, and a search range of pixel display points on the 2D image plane is defined as being within a certain integer value range before and after the point Q. After that, points on the 3D image plane that are generated from converting the pixel points on the 2D image plane are one by one checked within the search range to select two converted points closest to both sides of the point Q on the 3D image plane, so as to perform weight calculation according to horizontal shifts of the pixel point A and the pixel point B on the 2D image plane corresponding to the two converted points. In this embodiment, linear interpolation is performed on the horizontal shifts of the point A and the point B to calculate a horizontal shift of the point Q; however, these particulars shall not be construed as a specific limitation of the present invention. The horizontal shift of the point A on the 3D image plane is represented by L_shift, and the horizontal shift of the point B on the 3D image plane is represented by R_shift. A mathematic relationship is represented by: 
         [0000]    
       
         
           
             Q 
             = 
             
               
                 
                   L_shift 
                   
                     L_shift 
                     + 
                     R_shift 
                   
                 
                  
                 B 
               
               + 
               
                 
                   R_shift 
                   
                     L_shift 
                     + 
                     R_shift 
                   
                 
                  
                 A 
               
             
           
         
       
     
         [0032]    More specifically, when the weight calculation is performed to generate the horizontal shift of the current pixel, the foregoing image sequence disorder problem needs to be taken into consideration. In order to solve this type of problems, when the target depth D 1 ′ is adopted to perform calculation, e.g., when the horizontal shifts of the points A and B on both sides of and closest to the point Q are selected for weight calculation, points closest to a user (i.e., points having the smallest depths) are selected for weight calculation to display a phenomena that a pixel point having a greater depth is shielded by a pixel point having a smaller depth on the 3D image plane that is further horizontally shifted. Referring to the right side of  FIG. 4   c,  compared to the point A, a projected point of a point C on the 3D image plane is farther from the point Q, and the point C has a depth smaller than that of the point A, so that the point C is also selected as a weight average point for calculating the horizontal shift of the point Q even if the projected point of the point A on the 3D image plane is closer to the point Q. In addition, referring to the left side of  FIG. 4   c,  the projected point of the point C on the 3D image plane is farther from the point Q, and the projected point of the point A on the 3D image plane is closer to the point Q. At this point, since the depth of the point A is smaller than that of the point C, the point A is selected as the weight average point for calculating the horizontal shift of the point Q. 
         [0033]    In order to understand the scope and the spirit of the present invention,  FIG. 5  shows a flow chart of operations of the image processing apparatus  100  in accordance with an embodiment of the present invention.  FIG. 5  need not be performed exclusively according to this original sequence, nor the step of the flow need be consecutively performed, provided that a substantially same result is obtained, i.e., other steps may be added to the flow. 
         [0034]    The flow begins with Step  502 . In Step  504 , the detecting circuit  105  receives a 2D input image S — 2D. In Step  506 , the detecting circuit  105  detects an image of a block MB in the 2D image S — 2D to generate depth information INFO of the block MB, wherein the depth information comprises parameters, such as a luminance contrast, a color, a spatial position, edge image information, motion information of the image, and the like. In Step  508 , the determining unit  120  generates a preliminary depth D 1  of pixels in the block MB according to the depth information INFO of the block MB. In Step  510 , the generating unit  125  refers to the preliminary depth D 1  and determines whether to fine-tune the preliminary depth D 1  to generate a target depth D 1 ′ of each pixel, wherein the preliminary depth D 1  is a block-based depth, and the target depths D 1 ′ is a pixel-based depth. In Step  512 , the generating unit  125  generates a horizontal shift V_shift corresponding to a multi-visual-angle image of the pixel according to the target depth D 1 ′. In Step  514 , the generating unit  125  generates the multi-visual-angle image of the pixel according to the horizontal shift V_shift, so that human eyes can perceive imaging of a stereoscopic image when an image frame is observed. The flow ends in Step  516 . 
         [0035]    While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not to be limited to the above embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.