Patent Publication Number: US-11049471-B2

Title: Display control circuit

Description:
TECHNICAL FIELD 
     The disclosure relates in general to a display control circuit and a display device, and more particularly to a display control circuit and a display device capable of improving the display quality of the display panels with various subpixel layout. 
     BACKGROUND 
     Nowadays, many display devices such as laptops or mobiles are equipped with display panels. The display panels are used together with display control circuits, for transforming input images IMGin into controlling signals suitable for the display panels. 
       FIG. 1  is a schematic diagram illustrating an input image IMGin to be displayed on a display panel. The input image IMGin can be considered as a matrix of input points (inPT). The input points (inPT) in the input image IMGin are arranged in Min columns and Nin rows, and each colored input point (inPT) includes multiple colored input points (inPT_c 1 , inPT_c 2 , inPT_c 3 ). 
     In display systems, R-G-B representation is widely used. Usually, the input image IMGin can be separated into three color-planes, a red color-plane (IMGin_c 1 ), a green color-plane (IMGin_c 2 ), and a blue color-plane (IMGin_c 3 ). In the specification, the color red (c 1 ) is represented by horizontal screentone, the color green (c 2 ) is represented by vertical screentone, and the color blue (c 3 ) is represented by grid screentone. Although the illustrations are based on the R-G-B representation, the application of the present disclosure is not limited to the R-G-B representation. 
       FIG. 2  is a schematic diagram illustrating subpixels being mounted on a conventional display panel. Pixels PX mounted on a conventional display panel  12  are arranged in Mdp columns and Ndp rows, and each pixel PX includes a red subpixel (SPX_c 1 ), a green subpixel (SPX_c 2 ), and a blue subpixel (SPX_c 3 ). 
     Because the resolution of the input image (IMGin) is usually different from the resolution of various display panels, a subpixel rendering circuit is used by the display control circuit. The subpixel rendering circuit adjusts the apparent resolution of the display panel by rendering pixels to take into account the physical properties of the display panel. As the display panels may have various pixel layout, the subpixel rendering circuit needs to consider the physical layout of the pixels. 
     SUMMARY 
     The disclosure is directed to a display control circuit and a display device. The display control circuit is used together with a display panel in the display device. 
     According to another embodiment, a display control circuit for controlling a display panel is provided. The display panel includes a plurality of first colored subpixels in a target region. The display control circuit includes a subpixel rendering circuit. The subpixel rendering circuit converts a plurality of first colored input points in a first selected region to a plurality of first rendered subpixel data corresponding to the plurality of first colored subpixels. The first selected region includes a first core area and a first boundary area. Layout of the plurality of first colored input points in the first core area and layout of the first colored subpixel are inconsistent. 
     According to an alternative embodiment, a display device including a display panel and a display control circuit is provided. The display panel includes a plurality of first colored subpixels in a target region. The display control circuit controls the display panel. The display control circuit includes a subpixel rendering circuit. The subpixel rendering circuit converts a plurality of first colored input points in a first selected region to a plurality of first rendered subpixel data corresponding to the plurality of first colored subpixels. The first selected region includes a first core area and a first boundary area. Layout of the plurality of first colored input points in the first core area and layout of the first colored subpixel are inconsistent. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  (prior art) is a schematic diagram illustrating an input image IMGin to be displayed on a display panel. 
         FIG. 2  (prior art) is a schematic diagram illustrating subpixels being mounted on a conventional display panel. 
         FIG. 3  is a block diagram of a display device equipped with a display control circuit and a display panel. 
         FIGS. 4A, 4B and 4C  are schematic diagrams illustrating various ways of implementing the timing controller, the SPR circuit, and the source driver. 
         FIG. 5  is a schematic diagram illustrating the coordinate mapping between an input point (inPT(x, y)) in the input image (IMGin) and a target pixel tgPX[a, b] on the display panel. 
         FIG. 6  is a schematic diagram illustrating the transformation from the input image IMGin to the display panel suitable for direct mapping. 
         FIG. 7  is a schematic diagram illustrating generation of the rendered subpixel data. 
         FIG. 8  is a schematic diagram illustrating an exemplary selected region SR acquired from the input image IMGin in  FIG. 6 . 
         FIG. 9  is a schematic diagram illustrating an exemplary target region TR displaying the white vertical stripe. 
         FIG. 10  is a schematic diagram illustrating the target region of a display panel having staggered subpixel layout. 
         FIG. 11A  is a schematic diagram illustrating a scenario that the red filter kernel FMx_c 1 , the green filter kernel FMx_c 2 , and the blue filter kernel FMx_c 3  have identical rendering filter coefficients. 
         FIG. 11B  is a schematic diagram illustrating that the target subpixels tgSPX in  FIG. 10  displaying the rendered subpixel data being generated based on the direct mapping approach. 
         FIG. 12A  is a schematic diagram illustrating generation of the red rendered subpixel data sprD{x, y}_c 1  to be respectively provided to the red target subpixels tgSPX[a, b]_c 1  based on the coordinate shift mapping according to the embodiment of the present disclosure. 
         FIG. 12B  is a schematic diagram illustrating generation of the green rendered subpixel data sprD{x, y}_c 2  to be respectively provided to the green target subpixels tgSPX[a, b]_c 2  based on the coordinate shift mapping according to the embodiment of the present disclosure. 
         FIG. 12C  is a schematic diagram illustrating generation of the blue rendered subpixel data sprD{x, y}_c 3  to be respectively provided to the blue target subpixels tgSPX[a, b]_c 3  based on the coordinate shift mapping according to the embodiment of the present disclosure. 
         FIG. 13 , a schematic diagram illustrating layout of rendered subpixel data of the target pixels based on the coordinate shift mapping according to the embodiment of the present disclosure. 
         FIG. 14  is a schematic diagram showing the visual effect of the target pixels shown in  FIG. 13  in an intuitive way. 
         FIG. 15  is a block diagram illustrating components of the SPR circuit. 
         FIG. 16  is a schematic diagram illustrating an example of the pixels having three subpixels. 
         FIG. 17  is a schematic diagram illustrating an example of the OLED pixels having two subpixels. 
         FIG. 18  is a top view diagram illustrating an exemplary pixel layout of an OLED display panel. 
         FIGS. 19A, 19B, and 19C  are schematic diagrams illustrating three types of pixels in  FIG. 18 . 
         FIG. 20  is a schematic diagram illustrating pixel definitions of the display shown in  FIG. 18 . 
         FIG. 21  is a schematic diagram illustrating the subpixels located in the vertical stripe display zone but not displaying. 
         FIGS. 22A, 22B, and 22C  are schematic diagrams illustrating the selected region in different color-planes based on the coordinate shifting approach according to the embodiment of the present disclosure. 
         FIGS. 23A, 23B, and 23C  are schematic diagrams illustrating the generation of the red rendered subpixel data set sprDSET_c 1  and mapping the red rendered subpixel data to the red target subpixels tgSPX[a, b]_c 1  according to the embodiment of the present disclosure. 
         FIGS. 24A, 24B, and 24C  are schematic diagrams illustrating the generation of the green rendered subpixel data set sprDSET_c 2  and mapping the green rendered subpixel data to the green target subpixels tgSPX[a, b]_c 2  according to the embodiment of the present disclosure. 
         FIGS. 25A, 25B, and 25C  are schematic diagrams illustrating the generation of the blue rendered subpixel data set sprDSET_c 3  and mapping the blue rendered subpixel data to the blue target subpixels tgSPX[a, b]_c 3  according to the embodiment of the present disclosure. 
         FIGS. 26A and 26B  are schematic diagrams illustrating the mapping between the rendered subpixel data and the subpixels of the target pixels. 
         FIG. 27  is a top view diagram illustrating another exemplary pixel layout of an OLED display panel. 
         FIG. 28  is a schematic diagram showing a white horizontal stripe. 
         FIG. 29  is a schematic diagram illustrating the display effects of the display showing the white horizontal stripe according to the direct mapping. 
         FIG. 30  is a schematic diagram illustrating the display effects of the display showing the horizontal stripe based on the coordinate shifting method according to the embodiment of the present disclosure. 
     
    
    
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
     DETAILED DESCRIPTION 
       FIG. 3  is a block diagram of a display device equipped with a display control circuit and a display panel. The display device  20  includes an image/video processing circuit  21  (for example, a video decoder), an image buffer  23  (for example, a memory), a display control circuit  25 , and a display panel  27 . The image buffer  23  is electrically connected to the image/video processing circuit  21  and the display control circuit  25 , and the display panel  27  is electrically connected to the display control circuit  25 . 
     Pixels mounted on the display panel  27  are arranged in Mdp columns and Ndp rows, and each pixel PX includes a red subpixel (SPX_c 1 ), a green subpixel (SPX_c 2 ), and a blue subpixel (SPX_c 3 ). For the sake of illustration, sizes of the different colored subpixels are assumed to be equivalent in the specification. Whereas, the SPR circuit  253  can also be applied to the display panels whose subpixels may have different sizes. 
     The display control circuit  25  further includes a timing controller  251 , a subpixel rendering circuit (hereinafter, SPR)  253 , a source driver  255 , and a gate driver  257 . The timing controller  251  is electrically connected to the image buffer  23 , the SPR circuit  253 , and the gate driver  257 , and the source driver  255  is electrically connected to the SPR circuit  253  and the display panel  27 . 
     The image/video processing circuit  21  generates an input image IMGin, which can be temporarily stored at the image buffer  23  or directly transmitted to the timing controller  251 . Then, the timing controller  251  decomposes input image IMGin into sequences of colored input points (inPT_c 1 , inPT_c 2 , inPT_c 3 ) and transmits color values CV of the colored input points (inPT_c 1 , inPT_c 2 , inPT_c 3 ) to the SPR circuit  253  in sequence (R-G-B-R-G-B . . . and so forth). The color values CV can be ranged from 0 to 255. 
     Then, the SPR circuit  253  transforms color values CV of the colored input points (inPT_c 1 , inPT_c 2 , inPT_c 3 ) to three rendered subpixel data sets sprDSET_c 1 , sprDSET_c 2 , sprDSET_c 3 . Later, the source driver  255  generates and transmits data signals Sdat based on the rendered subpixel data sets sprDSET_c 1 , sprDSET_c 2 , sprDSET_c 3  to the display panel  27 . The brightness of the subpixels in the display panel is determined by the data signals Sdat. The data signals Sdat representing the rendered subpixel data sets sprDSET_c 1 , sprDSET_c 2 , sprDSET_c 3  are transmitted to the display panel in a row-by-row manner. Besides, the timing controller  251  generates timing related signals to the gate driver  257  so that the gate driver  257  can generate gate control signals Sgc accordingly. The gate control signals Sgc are further transmitted to the display panel  27 . 
     In the display control circuit  25 , the timing controller  251 , the SPR circuit  253 , and the source driver  255  are related to the generation of data signals Sdat. According to the embodiment of the present disclosure, the implementations of the timing controller  251 , the SPR circuit  253 , and the source driver  255  are not limited. 
       FIGS. 4A, 4B and 4C  are schematic diagrams illustrating various exemplary implementations of the timing controller, the SPR circuit, and the source driver. In  FIG. 4A , the timing controller  251   a , the SPR circuit  253   a , and the source driver  255   a  are jointly integrated into one circuitry  25   a . In  FIG. 4B , the timing controller  251   b  includes the SPR circuit  253   b , and the source driver  255   b  is a separate circuit. In  FIG. 4C , the timing controller  251   c  is a separate circuit, and the SPR circuit  253   c  and the source driving circuit  255   c  are integrated into the source driver  252   c.    
     As illustrated above, the SPR circuit  253  transforms color values CV of the colored input points (inPT_c 1 , inPT_c 2 , inPT_c 3 ) to the rendered subpixel data sets sprDSET_c 1 , sprDSET_c 2 , sprDSET_c 3 . Such transformation involves positions of the input points (inPT) in the input image IMGin and positions and arrangement of the subpixels on the display panel. 
     For the sake of illustration, positions of the input points (inPT) are represented by x-y coordinates in parentheses, for example, (x, y). Thus, a colored input point (inPT(x, y)_c) represents that a red input point is located at the x-th column and the y-th row of the red color-plane of the input image. Representations of the green input points and the blue input points are similar. On the other hand, positions of the subpixels SPX are represented by a-b coordinates in square brackets, for example, [a, b]. Thus, a pixel PX[a, b] including a red subpixel SPX[a, b]_c 1 , a green subpixel SPX[a, b]_c 2 , and a blue subpixel SPX[a, b]_c 3  is located at the a-th column and the b-th row of the display panel. 
     The subpixel rendering operation is repetitively performed in units of a selected region SR being alternatively selected from the input image IMGin and a target region TR being alternatively selected from the display area of the display panel. Alternatively speaking, the SPR circuit  253  transforms input points (inPT) in the selected region SR to the pixels located at the target region TR. For the sake of illustration, the pixels in the target region TR are defined as target pixels tgPX, and subpixels of the target pixels tgPX are defined as target subpixels tgSPX. Moreover, the exemplary target region TR is assumed to include 3×3 target pixels tgPX. 
     To generate the rendered data essential for the target pixels tgPX in a specific target region TR, a selected region SR including multiple colored input points should be defined in the input image IMGin. The number of colored input points in the core area crSR is equivalent to the number of the target pixels tgPX in the target region tgRX. As the exemplary target region TR is assumed to include 3×3 target pixels tgPX, the core area thus includes 3×3 input points. Each of the 3×3 input points include 3 colored input points inPT_c 1 , inPT_c 2 , inPT_c 3 . 
     The relative positions (layout) of the colored input points in the core areas of different color-planes crSR_c 1 , crSR_c 2 , and crSR_c 3  can be identical to or different from the relative positions (layout) of the target subpixels in the target region TR. In addition, the relative positions (layout) of the colored input points in the boundary areas of different color-planes bdrySR_c 1 , bdrySR_c 2 , bdrySR_c 3  can be identical to or different from each other. 
     In the specification, a direct mapping approach, a coordinate mapping approach or both are provided for determining the colored input points in the core areas crSR_c 1 , crSR_c 2 , crSR_c 3 , that is, the colored input points being considered/defined as the ones actually corresponding to the target subpixels tgSPX. Once the core areas crSR_c 1 , crSR_c 2 , crSR_c 3  are determined, the colored inputs inPT_c 1 , inPT_c 2 , inPT_c 3  in the boundary area bdrySR_c 1 , bdrySR_c 2 , bdrySR_c 3  can determined accordingly. 
     Basically, when the subpixel layout of the display panel is similar to the one shown in  FIG. 2 , the SPR circuit performs a direct mapping between the selected region SR and the target region TR, and the direct mapping results in that the relative positions of the colored input points (inPT_c 1 , inPT_c 2 , and inPT_c 3 ) in the core areas (crSR_c 1 , crSR_c 2 , and crSR_c 3 ) are identical to each other, and the relative positions of the colored input points (inPT_c 1  inPT_c 2 , inPT_c 3 ) in the boundary area (bdrySR_c 1 , bdrySR_c 2 , bdrySR_c 3 ) are identical to each other. 
     Due to the manufacturing process or some other considerations, the subpixel layout of the display panel  27  is highly unlikely to be similar to the one shown in  FIG. 2 . In some cases, a subpixel having a certain color is not aligned with the subpixels having the same color. In some other cases, not each of the target pixels tgPX includes the three types of target subpixels tgSPX_c 1 , tgSPX_c 2 , tgSPX_c 3 . Therefore, the subpixel rendering method performed by the SPR circuit should change with these arrangement variations and the direct mapping might not be applicable. More details about how the input points in the core areas crSR_c 1 , crSR_c 2 , crSR_c 3 , and the boundary areas bdrySR_c 1 , bdrySR_c 2 , bdrySR_c 3  are selected from different color-planes of the input image IMGin_c 1 , IMGin_c 2 , IMGin_c 3  will be illustrated below. 
       FIG. 5  is a schematic diagram illustrating the coordinate mapping between an input point (inPT(x, y)) in the input image IMGin and a target pixel tgPX[a, b] on the display panel. In the specification, the coordinate mapping between the input point (inPT(x, y)) and the target pixel tgP[a, b] is performed based on a per-color-plane basis. That is, the mapping from the red input point (inPT(x, y)_c 1 ) to the red target subpixel tgSPX[a, b]_c 1 , the mapping from the green input point (inPT(x, y)_c 2 ) to the green target subpixel tgSPX[a, b]c 2 , and the mapping from the blue input point (inPT(x, y)_c 3 ) to the blue target subpixel tgSPX[a, b]_c 3  are separate and independent. 
     When the SPR circuit  253  performs the subpixel rendering to the subpixels of the target point tgPX[a, b], the rendered subpixel data sprD_c 1 , sprD_c 2 , sprD_c 3  to be displayed by the target pixel tgPX[a, b] is generated based on the color values of the colored input points (inPT(x, y)_c 1 , inPT(x, y)_c 2 , inPT(x, y)_c 3 ) and color values of the colored input points which are respectively surrounding the colored input points (inPT(x, y)_c 1 , inPT(x, y)_c 2 , inPT(x, y)_c 3 ) to proceed a convolution operation. 
     Usually, all of the three subpixels SPX_c 1 , SPX_c 2 , SPX_c 3  of the same pixel PX receive the greatest values of rendered subpixel data (for example, sprD_c 1 =sprD_c 2 =sprD_c 3 =255) to emit the highest luminance when a white color is displayed by the pixel PX. On the other hand, all of the three subpixels SPX_c 1 , SPX_c 2 , SPX_c 3  of the same pixel PX receive the smallest values of rendered subpixel data (for example, sprD_c 1 =sprD_c 2 =sprD_c 3 =0) to emit the lowest luminance when black color is displayed by the pixel PX. For the sake of illustration, the rendered data for displaying the white color and the black color are simplified to “1” and “0”, respectively. 
     The convolution operation is an important and useful operation in image processing. In each convolution operation, a convolution sum representing a rendered subpixel datum sprD is computed. According to the embodiment of the present disclosure, filter coefficients used in the convolution operation are known in advance. 
       FIG. 6  is a schematic diagram illustrating the transformation from the input image IMGin to the display panel suitable for direct mapping. The input image IMGin is assumed to be a white vertical stripe and color values of the colored input points (inPT_c 1 , inPT_c 2 , inPT_c 3 ) in the three color-planes which are corresponding to the white vertical stripe are shown. 
     In  FIG. 6 , the color values of the colored input points (inPT_c 1 , inPT_c 2 , inPT_c 3 ) representing the white vertical stripe are assumed to be “1,” and color values of the color input points (inPT_c 1 , inPT_c 2 , inPT_c 3 ) not showing the white vertical stripe are assumed to be “0”. The white vertical stripe is an exemplary pattern, and the input image IMGin may show different patterns in practical application. 
     The red input points (inPT_c 1 ) in the red color-plane of the input image IMGin_c 1  are arranged in Min_c 1  columns and Nin_c 1  rows. The green input points (inPT_c 2 ) in the green color-plane of the input image IMGin_c 2  are arranged in Min_c 2  columns and Nin_c 2  rows. The blue input points (inPT_c 3 ) in the blue color-plane of the input image IMGin_c 3  are arranged in Min_c 3  columns and Nin_c 3  rows. In the specification, it is assumed that the column number of input points in the red color-plane, the green color-plane, and the blue color-plane are equivalent (Min_c 1 =Min_c 2 =Min_c 3 =Min), and the row number of input points in the red color-plane, the green color-plane, and the blue color-plane are equivalent (Nin_c 1 =Nin_c 2 =Nin_c 3 =Nin). 
     In the specification, the display panel 37 is defined as having an RGB-stripe subpixel layout if the following conditions are satisfied. These conditions include that each pixel has a red subpixel SPX_c 1 , a green subpixel SPX_c 2 , and a blue subpixel SPX_c 3 , and the colored subpixels having the same color are aligned with each other in columns and rows. 
     In a case that the display panel has the RGB-stripe subpixel layout, the SPR circuit performs the direct mapping between the three colored input points (inPT(x, y)_c 1 , inPT(x, y)_c 2 , inPT(x, y)_c 3 ) and the three target subpixels (tgPX[a, b]_c 1 , tgPX[a, b]_c 2 , tgPX[a, b]_c 3 ). In a case that the display panel does not have the RGB-stripe subpixel layout, the SPR circuit adopts a coordinate shift mapping between the three colored input points (inPT(x, y)_c 1 , inPT(x, y)_c 2 , inPT(x, y)_c 3 ) and the three target subpixels (tgPX[a, b]_c 1 , tgPX[a, b]_c 2 , tgPX[a, b]_c 3 ). 
     To generate the rendered subpixel datum sprD_c 1  for the red target subpixel tgSPX[a, b]_c 1 , the red color values of the red input point (inPT(x, y)_c 1 ) and its 8 adjacent red input points are used together to calculate with a red filter kernel FMx_c 1 . To generate the rendered subpixel datum sprD_c 2  for the green target subpixel tgSPX[a, b]_c 2 , the green color values of the green input points (inPT(x, y)_c 1 ) and its 8 adjacent green input points are used together to calculate with a green filter kernel (FMx_c 2 ). To generate the rendered subpixel datum sprD_c 3  for the blue target subpixel tgSPX[a, b]c 3 , the blue color values of the blue input point (inPT(x, y)_c 3 ) and its 8 adjacent blue input points are used together to calculate with a blue filter kernel (FMx_c 3 ). 
     In the specification, the symbols used together with braces “{x, y}” represent the data related to the input point (inPT(x, y)). For example, the symbol CV{x, y}c 1  represents the red color value CV of the red input point (inPT(x, y)_c 1 ). 
       FIG. 7  is a schematic diagram illustrating generation of the rendered subpixel data. The upper part, the middle part, and the bottom part of  FIG. 7  are corresponding to generation of the rendered subpixel data sprD {x, y}_c 1 , sprD{x, y}_c 2 , sprD{x, y}_c 3 , respectively. 
     The red color values CV{x−1, y−1}c 1 ˜CV{x+1, y+1}_c 1  jointly form a red sampling matrix inDS{x, y}_c 1 . The green color values CV{x−1, y−1}_c 2 ˜CV{x+1, y+1}c 2  jointly form a green sampling matrix inDS{x, y}_c 2 . The blue color values CV{x−1, y−1}_c 3 ˜CV{x+1, y+1}_c 3  jointly form a blue sampling matrix inDS{x, y}_c 3 . The red input point (inPT(x, y)_c 1 ) is defined as a red core element of the red sampling matrix inDS{x, y}c 1  in one convolution operation, and the red input points (inPT(x−1, y−1)_c 1 , inPT(x, y−1)_c 1 , inPT(x+1, y−1)_c 1 , inPT(x+1, y)_c 1 , inPT(x+1, y+1)_c 1 , inPT(x, y+1)_c 1 , inPT(x−1, y+1)_c 1 , inPT(x−1, y)_c 1 ) are defined as boundary elements of the red sampling matrix (inDS{x, y}_c 1 ) in one convolution operation. Similar definitions can be applied to the green input points (inPT(x−1, y−1)_c 2 ˜inPT(x+1, y+1)_c 2 ) and the blue input points (inPT(x−1, y−1)_c 3 ˜inPT(x+1, y+1)_c 3 ) as well. 
     In the specification, it is assumed that the red filter kernel (FMx_c 1 ) is a rendering convolution matrix includes rendering filter coefficients CFMx_c 1 ( 1 )˜CFMx_c 1 ( 9 ), the green filter kernel (FMx_c 2 ) is another rendering convolution matrix includes rendering filter coefficients CFMx_c 2 ( 1 )˜CFMx_c 2 ( 9 ), and the blue filter kernel (FMx_c 3 ) is still another rendering convolution includes rendering filter coefficients CFMx_c 3 ( 1 )˜CFMx_c 3 ( 9 ). Values of the rendering filter coefficients are related to characteristics of the subpixel rendering function to be provided by the SPR circuit. 
     The red sampling matrix inDS{x, y}_c 1  and the red filter kernel FMx_c 1  are utilized together to generate the red rendered subpixel datum sprD{x, y}_c 1 , which is utilized to determine the luminance of the target subpixel tgSPX[a, b]_c 1 . The green sampling matrix inDS{x, y}_c 2  and the green filter kernel FMx_c 2  are utilized together to generate the green rendered subpixel datum sprD{x, y}_c 2 , which is utilized to determine the luminance of the target subpixel tgSPX[a, b]_c 2 . The blue sampling matrix inDS{x, y}_c 3  and the blue filter kernel FMx_c 3  are utilized together to generate the blue rendered subpixel datum sprD{x, y}_c 3 , which is utilized to determine the luminance of the target subpixel tgSPX[a, b]_c 3 . 
     The red filter kernel FMx_c 1 , the green filter kernel FMx_c 2 , and the blue filter kernel FMx_c 3  are essential for digital image processing, and providing storage space for the rendering filter coefficients CFMx_c 1 ( 1 )˜CFMx_c 1 ( 9 ), CFMx_c 2 ( 1 )˜CFMx_c 2 ( 9 ), CFMx_c 3 ( 1 )˜CFMx_c 3 ( 9 ) for convolution operation is essential. However, the storage space in the display control circuit is limited, and it is preferred to reduce the amount of the rendering filter coefficients to be stored. In other words, the storage space can be decreased if the rendering filter coefficients in the filter kernels can be commonly reused for different color-planes IMGin_c 1 , IMGin_c 2 , IMGin_c 3 . 
       FIG. 8  is a schematic diagram illustrating an exemplary selected region SR acquired from the input image IMGin in  FIG. 6 . The exemplary selected region SR showing part of the white vertical stripe includes a core area crSR and a boundary area bdrySR. The input points (inPT_c 1 , inPT_c 2 , inPT_c 3 ) in the core area crSR_c 1 , crSR_c 2 , crSR_c 3  are the ones being utilized as the core elements. The input points (inPT) being used for calculating the rendered subpixel data but not located in the core area crSR_c 1 , crSR_c 2 , crSR_c 3  are defined as the input points located at the boundary area bdrySR_c 1 , bdrySR_c 2 , bdrySR_c 3 . Alternative speaking, the input points (inPT) forming the boundary area bdrySR are the ones being utilized as the boundary elements only. Relatively, some of the input points in the core area crSR might also be utilized as the boundary elements while other input points are utilized as the core elements in different convolution operations. 
     The core area crSR in the red color-plane, the green color-plane, and the blue color-plane of the input image (IMGin_c 1 , IMGin_c 2 , IMGin_c 3 ) are represented as crSR_c 1 , crSR_c 2 , and crSR_c 3 , respectively. The boundary area in the red color-plane, the green color-plane, and the blue color-plane of the input image (IMGin_c 1 , IMGin_c 2 , IMGin_c 3 ) are represented as bdrySR_c 1 , bdrySR_c 2 , and bdrySR_c 3 , respectively. 
     According to the embodiment of the present disclosure, each of the core areas crSR_c 1 , crSR_c 2 , and crSR_c 3  has the same quantities of core elements, for example, 3×3=9 core elements. Despite this, the relative positions of the core elements in the core areas crSR_c 1 , crSR_c 2 , and crSR_c 3  might be different. On the other hand, numbers of the boundary elements in the boundary area bdrySR_c 1 , bdrySR_c 2 , bdrySR_c 3  may or may not be equivalent but related to the relative positions of the core elements. Accordingly, sizes of the selected regions SR_c 1 , SR_c 2 , SR_c 3  may or may not be the same. When the relative positions of the core elements in the selected regions SR_c 1 , SR_c 2 , SR_c 3  are different, sizes of the selected regions SR_c 1 , SR_c 2 , SR_c 3  are different. 
       FIG. 9  is a schematic diagram illustrating an exemplary target region TR displaying the white vertical stripe. In  FIG. 9 , each target pixel tgPX[a, b](a=1˜3, b=1˜3) includes three target subpixels tgSPX, that is, a red target subpixel tgSPX[a, b]_c 1 , a green target subpixel tgSPX[a, b]_c 2 , and a blue target subpixel tgSPX[a, b]_c 3 . Due to the limited space, only the target subpixels located at the first row are notified in  FIG. 9 . 
     When the direct mapping is applied to the display panel having the RGB-stripe subpixel layout, the relative positions between the target subpixels tgSPX in the target region TR and the relative positions between the core elements in the core area crSR are consistent. Alternatively speaking, the mappings between the colored input points (inPT(x,y)_c 1 , inPT(x, y)_c 2 , inPT(x, y)_c 3 ) and the target subpixels (tgSPX[a, b]_c 1 , tgSPX[a, b]_c 3 , tgSPX[a, b]_c 3 ) are satisfied with the conditions that x=a and y=b (x=1˜3, y=1˜3, a=1˜3, b=1˜3). 
     Under such circumstance, the luminance of the target subpixel tgSPX[1, 1]_c 1  is determined by the rendered subpixel data sprD{1, 1}_c 1  which is generated by the convolution operation based on the red filter kernel FMx_c 1  and the red sampling matrix inDS{1, 1}_c 1 , in which the red input point (inPT(1, 1)_c 1 ) is selected as the red core element. Similarly, the luminance of the target subpixel tgSPX[1, 1]_c 2  is determined by the rendered subpixel data sprD{1, 1}_c 2  which is generated by the convolution operation based on the green filter kernel FMx_c 2  and the green sampling matrix inDS{1, 1}_c 2 , in which the green input point (inPT(1, 1)_c 2 ) is selected as the green core element, and the luminance of the target subpixel tgSPX[1, 1]_c 3  is determined by the rendered subpixel data sprD{1, 1}_c 3  which is generated by the convolution operation based on the blue filter kernel FMx_c 3  and the blue sampling matrix inDS{1, 1}c 3 , in which the blue input point (inPT(1, 1)_c 3 ) is selected as the blue core element. The relationships between the other colored input points, rendered subpixel data, and target subpixels are similar so that details are not further described. 
     It is obtained that the target subpixels at the first column (tgPX[a, b]_c 1 , tgPX[a, b]_c 2 , tgPX[a, b]_c 3 , where a=1 and b=1˜3) and the target subpixels at the third column (tgPX[a, b]_c 1 , tgPX[a, b]_c 2 , tgPX[a, b]_c 3 , where a=3 and b=1˜3) display the rendered subpixel data equivalent to “0”. On the other hand, the target subpixels at the second column (tgPX[a, b]_c 1 , tgPX[a, b]_c 2 , tgPX[a, b]_c 3 , where a=2 and b=1˜3) display the rendered subpixel data being equivalent to “1”. Thus, the white vertical stripe can be displayed appropriately. 
     In some applications, the subpixel layout of the display panel is not RGB-stripe. The SPR circuit, according to the embodiment of the present disclosure, provides the coordinate shift mapping to the display panel having a non-RGB-stripe subpixel layout. The display panel having the non-RGB-stripe subpixel layout implies that the subpixel configurations of the pixels on the display panel are not all the same. The non-RGB-stripe subpixel layout can be, for example, 2D pattern subpixel layout, RGBW subpixel layout, RGB-stripe subpixel layout, multi-primary subpixel layout, and so forth.  FIG. 10  is an example showing that not all the three target subpixels tgSPX of the same target pixel tgPX are aligned in a unified manner. FIGS.  18  and  27  are examples showing that the target pixels tgPX may include only two target subpixels tgSPX. 
       FIG. 10  is a schematic diagram illustrating the target region of a display panel having staggered subpixel layout. A target region TR including 3×3 target pixels tgPX is shown. Each of the target pixels tgPX[a, b] (a=1˜3, and b=1˜3) includes a red target subpixel tgSPX[a, b]_c 1 , a green target subpixel tgSPX[a, b]_c 2 , and a blue target subpixel tgSPX[a, b]_c 3 . 
     As shown in  FIG. 10 , the target subpixels having the same color are not aligned in all rows. In short, the target subpixels tgSPX at the second row (b=2) are relatively right shifted for a width of a subpixel. For example, the red target subpixel tgSPX[1, 2]_c 1  is not aligned with the red target subpixel tgSPX[1, 1]_c 2 . Instead, the red target subpixel tgSPX[1, 2]_c 1  is aligned with the green target subpixel tgSPX[1, 1]_c 2 . Similarly, instead of being aligned with the green target subpixel tgSPX[1, 1]_c 2 , the green target subpixel tgSPX[1, 2]_c 2  is aligned with the blue target subpixel tgSPX[1, 1]_c 3 . 
     As the storage space in the display control circuit is limited, it is desired that the same set of rendering filter coefficients in the rendering convolution matrixes can be repetitively reused for different color-planes IMGin_c 1 , IMGin_c 2 , IMG_c 3 .  FIG. 11A  is a schematic diagram illustrating a scenario that the red filter kernel FMx_c 1 , the green filter kernel FMx_c 2 , and the blue filter kernel FMx_c 3  having identical values of rendering filter coefficients. When the display panel has the subpixel layout shown in  FIG. 10 , and the direct mapping is utilized with the filter kernels shown in  FIG. 11A , the display panel will have the visual result shown in  FIG. 11B . 
       FIG. 11B  is a schematic diagram illustrating the target subpixels tgSPX in  FIG. 10  displaying the rendered subpixel data generated based on the direct mapping approach. As shown in  FIG. 11B , the second row of the white vertical stripe is right shifted with a width of one subpixel. Instead of showing the white vertical stripe, the display panel shows a skewed white stripe. 
     To prevent the displayed image from having the skewed phenomena, the coordinate shift mapping is provided to the occasions when the subpixel layout of the display panel is not RGB-stripe. In short, the subpixel layout of the display panel is taken into consideration by the coordinate shift mapping. By doing so, the areas and positions of the selected regions SR in different color-planes IMGin_c 1 , IMGin_c 2 , IMGin_c 3  may not be consistent.  FIGS. 12A, 12B, 12C  are respectively corresponding to generation of the rendered subpixel data sprD_c 1 , sprD_c 2 , sprD_c 3 , which are further transmitted to the target subpixels tgSPX_c 1 , tgSPX_c 2 , tgSPX_c 3  to determine their luminances. 
       FIG. 12A  is a schematic diagram illustrating generation of the red rendered subpixel data sprD{x, y}_c 1  to be respectively provided to the red target subpixels tgSPX[a, b]_c 1  based on the coordinate shift mapping according to the embodiment of the present disclosure. The dotted frame at the left part of  FIG. 12A  shows the red selected region SR_c 1  and the red filter kernel FMx_c 1 . In the red selected region SR_c 1 , each grid represents the red color value of a red input point (inPT_c 1 ) in the red selected region SR_c 1 . The area circulated by a thick line represents the core area crSR_c 1 . The area between the thick dotted line and the thick line represents the boundary area bdrySR_c 1 . 
     According to  FIG. 12A , the core area crSR_c 1  includes 9 red input points (inPT(1, 1)_c 1 ˜inPT(3, 3)_c 1 ), and the boundary area bdrySR_c 1  includes 16 red input points (inPT_c 1 ). By repetitively performing the convolution operation to the red sampling matrixes inDS{x, y}_c 1  having the red input points (inPT_c 1 ) in the core area crSR_c 1  as their corresponding red core elements with the red filter kernel FMx_c 1 , the red rendered subpixel data sprD{1, 1}_c 1 ˜sprD{3, 3}_c 1  are generated. Then, the red rendered subpixel data sprD{1, 1}_c 1 ˜sprD{3, 3}_c 1  are respectively transmitted to and utilized by the red target subpixels tgSPX[1, 1]_c 1 ˜tgPX[3, 3]_c 1 . The red rendered subpixel data sprD{1, 1}_c 1 ˜sprD{3, 3}_c 1  collectively form the red rendered subpixel data set sprDSET_c 1 . 
     The corresponding relationships between the red target subpixels tgSPX[a, b]_c 1 , the red rendered subpixel data sprD{x, y}_c 1 , and the horizontal/vertical coordinate shift parameters of color red are summarized in Table 1. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                   
                 horizontal 
                 vertical 
               
            
           
           
               
               
               
               
            
               
                 coordinate of 
                   
                 coordinate shift 
                 coordinate shift 
               
               
                 red rendered 
                 coordinate of red 
                 parameter 
                 parameter 
               
               
                 subpixel data 
                 target subpixel 
                 Δx_c1 
                 Δy_c1 
               
               
                 sprD{x, y}_c1 
                 tgSPX[a, b]_c1 
                 (a-x) 
                 (b-y) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 x = 1 
                 y = 1 
                 a = 1 
                 b = 1 
                 0 
                 0 
               
               
                 x = 2 
                   
                 a = 2 
                   
                 0 
                 0 
               
               
                 x = 3 
                   
                 a = 3 
                   
                 0 
                 0 
               
               
                 x = 1 
                 y = 2 
                 a = 1 
                 b = 2 
                 0 
                 0 
               
               
                 x = 2 
                   
                 a = 2 
                   
                 0 
                 0 
               
               
                 x = 3 
                   
                 a = 3 
                   
                 0 
                 0 
               
               
                 x = 1 
                 y = 3 
                 a = 1 
                 b = 3 
                 0 
                 0 
               
               
                 x = 2 
                   
                 a = 2 
                   
                 0 
                 0 
               
               
                 x = 3 
                   
                 a = 3 
                   
                 0 
                 0 
               
               
                   
               
            
           
         
       
     
     In  FIG. 12A , the relative positions between the red target subpixels tgSPX[a, b]_c 1  and the relative positions between the red core elements in the core area crSR_c 1  are consistent. Thus, coordinates (x, y) of the red input points inPT(x, y)_c 1  in the core area crSR_c 1  of the red color-plane IMGin_c 1  can be directly mapped to the coordinates [a, b] of the red target subpixels tgSPX[a, b]_c 1  in the target region TR_c 1 . In other words, the direct mapping can be applied to the red color-plane IMGin_c 1 , and the mapping between the red input points inPT(x, y)_c 1  and the red target subpixels tgSPX[a, b]_c 1  is satisfied with a=x and b=y. 
       FIG. 12B  is a schematic diagram illustrating generation of the green rendered subpixel data sprD{x, y}c 2  to be respectively provided to the green target subpixels tgSPX[a, b]_c 2  based on the coordinate shift mapping according to the embodiment of the present disclosure. The dotted frame at the left part of  FIG. 12B  shows the green selected region SR_c 2  and the green filter kernel FMx_c 2 . In the green selected region (SR_c 2 ), each grid represents the green color value of a green input point (inPT_c 2  in) the green selected region (SR_c 2 ). The area circulated by a thick line represents the core area crSR_c 2 . The area between the thick dotted line and the thick line represents the boundary area bdrySR_c 2 . 
     According to  FIG. 12B , the core area crSR_c 2  includes 9 green input points (inPT(1, 1)_c 2 ˜inPT(3, 3)_c 2 ), and the boundary area bdrySR_c 2  includes 16 green input points (inPT_c 2 ). By repetitively performing the convolution operation to the green sampling matrixes inDS{x, y}_c 2  having the green input points (inPT_c 2 ) in the core area crSR_c 2  as their corresponding green core elements with the green filter kernel FMx_c 2 , the green rendered subpixel data sprD{1, 1}c 2 ˜sprD{3, 3}_c 2  are generated. Then, the green rendered subpixel data sprD{1, 1}_c 2 ˜sprD{3, 3}_c 2  are respectively transmitted to and utilized by the green target subpixels tgSPX[1, 1]_c 2 ˜tgPX[3, 3]_c 2 . The green rendered subpixel data sprD{1, 1}_c 2 ˜sprD{3, 3}c 2  collectively form the green rendered subpixel data set sprDSET_c 2 . 
     The corresponding relationships between the green target subpixels tgSPX[a, b]_c 2 , the green rendered subpixel data sprD{x, y}_c 2 , and the horizontal/vertical coordinate shift parameters of color green are summarized in Table 2. 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                   
                 horizontal 
                 vertical 
               
            
           
           
               
               
               
               
            
               
                 coordinate of 
                   
                 coordinate shift 
                 coordinate shift 
               
               
                 green rendered 
                 coordinate of green 
                 parameter 
                 parameter 
               
               
                 subpixel data 
                 target subpixel 
                 Δx_c2 
                 Δy_c2 
               
               
                 sprD{x, y}_c2 
                 tgSPX[a, b]_c2 
                 (a-x) 
                 (b-y) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 x = 1 
                 y = 1 
                 a = 1 
                 b = 1 
                 0 
                 0 
               
               
                 x = 2 
                   
                 a = 2 
                   
                 0 
                 0 
               
               
                 x = 3 
                   
                 a = 3 
                   
                 0 
                 0 
               
               
                 x = 1 
                 y = 2 
                 a = 1 
                 b = 2 
                 0 
                 0 
               
               
                 x = 2 
                   
                 a = 2 
                   
                 0 
                 0 
               
               
                 x = 3 
                   
                 a = 3 
                   
                 0 
                 0 
               
               
                 x = 1 
                 y = 3 
                 a = 1 
                 b = 3 
                 0 
                 0 
               
               
                 x = 2 
                   
                 a = 2 
                   
                 0 
                 0 
               
               
                 x = 3 
                   
                 a = 3 
                   
                 0 
                 0 
               
               
                   
               
            
           
         
       
     
     In  FIG. 12B , the relative positions between the green target subpixels tgSPX[a, b]_c 2  and the relative positions between the green core elements in the core area crSR_c 2  are consistent. Thus, coordinates (x, y) of the green input points inPT(x, y)_c 2  in the core area crSR_c 2  of the green color-plane IMGin_c 2  can be directly mapped to the coordinates [a, b] of the green target subpixels tgSPX[a, b]_c 2  in the target region TR_c 2 . In other words, the direct mapping can be applied to the green color-plane IMGin_c 2  and the mapping between the green input points inPT(x, y)_c 2  and the green target subpixels tgSPX[a, b]_c 2  is satisfied with a=x and b=y. 
       FIG. 12C  is a schematic diagram illustrating generation of the blue rendered subpixel data sprD{x, y}_c 3  to be respectively provided to the blue target subpixels tgSPX[a, b]_c 3  based on the coordinate shift mapping according to the embodiment of the present disclosure. The dotted frame at the left part of  FIG. 12C  shows the blue selected region SR_c 3  and the blue filter kernel (FMx_c 3 ). In the blue selected region (SR_c 3 ), each grid represents the blue color value of a blue input point (inPT_c 3 ) in the blue selected region (SR_c 3 ). The area circulated by the thick line represents the core area (crSR_c 3 ). The area between the thick dotted line and the thick line represents the boundary area (bdrySR_c 3 ). 
     According to  FIG. 12C , the core area crSR_c 3  includes 9 blue input points (inPT(1, 1)_c 3 ˜inPT(3, 1)_c 3 , inPT(2, 2)_c 3 ˜inPT(4, 2)_c 3 , inPT(1, 3)_c 3 ˜inPT(3, 3)_c 3 ), and the boundary area bdrySR_c 3  includes 19 blue input points (inPT_c 3 ). By repetitively performing the convolution operation to the green sampling matrixes inDS{x, y}_c 3  having the blue input points (inPT_c 3 ) in the core area crSR_c 3  as their corresponding blue core elements with the blue filter kernel FMx_c 3 , the blue rendered subpixel data sprD{1, 1}_c 3 ˜sprD{3, 1}_c 3 , sprD{2, 2}_c 3 ˜sprD{4, 2}_c 3 , sprD{1, 3}_c 3 ˜sprD{3, 3}_c 3  are generated. Then, the blue rendered subpixel data sprD{1, 1}_c 3 ˜sprD{3, 1}_c 3 , sprD{2, 2}_c 3 ˜sprD{4, 2}_c 3 , sprD{1, 3}_c 3 ˜sprD{3, 3}_c 3  are respectively transmitted to and utilized by the blue target subpixels tgSPX[1, 1]_c 3 ˜tgPX[3, 3]_c 3 . The blue rendered subpixel data sprD{1, 1}_c 3 ˜sprD{3, 1}_c 3 , sprD{2, 2}_c 3 ˜sprD{4, 2}_c 3 , sprD{1, 3}_c 3 ˜sprD{3, 3}_c 3  collectively form the blue rendered subpixel data set sprDSET_c 3 . 
     In  FIG. 12C , the relative positions between the blue target subpixels tgSPX[a, b]_c 3  and the relative positions between the blue core elements in the core area crSR_c 3  are not completely consistent. Thus, coordinates (x, y) of the blue input points inPT(x, y)_c 3  in the core area crSR_c 3  of the blue color-plane IMGin_c 3  needs to be shifted before being mapped to the coordinates [a, b] of the blue target subpixels tgSPX[a, b]_c 3  in the target region TR_c 3 . Among the 3×3 blue input points inPT_c 3 , the coordinate shift mapping should be adapted to the mapping between the blue input points at the second row of the core area crSR_c 3  (that is, blue input points inPT(x, y)_c 3 , wherein x=1˜3 and y=2) and the blue target subpixels at the second row of the blue target region TR_c 3  (that is, blue target pixels tgSPX[a, b]_c 3 , wherein a=1˜3 and b=2). 
     The corresponding relationships between the blue target subpixels tgSPX[a, b]_c 3 , the blue rendered subpixel data sprD{x, y}_c 3 , and the horizontal/vertical coordinate shift parameters of color blue are summarized in Table 3. 
     
       
         
           
               
               
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                   
                 horizontal 
                 vertical 
               
            
           
           
               
               
               
               
            
               
                 coordinate of 
                   
                 coordinate shift 
                 coordinate shift 
               
               
                 blue rendered 
                 coordinate of blue 
                 parameter 
                 parameter 
               
               
                 subpixel data 
                 target subpixel 
                 Δx_c3 
                 Δy_c3 
               
               
                 sprD{x, y}_c3 
                 tgSPX[a, b]_c3 
                 (a-x) 
                 (b-y) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 x = 1 
                 y = 1 
                 a = 1 
                 b = 1 
                 0 
                 0 
               
               
                 x = 2 
                   
                 a = 2 
                   
                 0 
                 0 
               
               
                 x = 3 
                   
                 a = 3 
                   
                 0 
                 0 
               
               
                 x = 2 
                 y = 2 
                 a = 1 
                 b = 2 
                 −1 
                 0 
               
               
                 x = 3 
                   
                 a = 2 
                   
                 −1 
                 0 
               
               
                 x = 4 
                   
                 a = 3 
                   
                 −1 
                 0 
               
               
                 x = 1 
                 y = 3 
                 a = 1 
                 b = 3 
                 0 
                 0 
               
               
                 x = 2 
                   
                 a = 2 
                   
                 0 
                 0 
               
               
                 x = 3 
                   
                 a = 3 
                   
                 0 
                 0 
               
               
                   
               
            
           
         
       
     
     In  FIG. 12C , coordinate of the blue input point (inPT(x, y)_c 3 , y=2) is not directly mapped to coordinate of the blue target subpixel (tgSPX[a, b]_c 3 , b=2). Thus, x=a is not satisfied. Instead, a=(x−1) is satisfied. Alternatively speaking, the blue rendered subpixel datum sprD{1, 2}_c 3  is generated for and utilized by the blue target pixel tgSPX[1, 2]_c 3 ; the blue rendered subpixel datum sprD{3, 2}_c 3  is generated for and utilized by the blue target pixel tgSPX[2, 2]_c 3 ; and the blue rendered subpixel datum sprD{4, 2}_c 3  is generated for and utilized by the blue target pixel tgSPX[3, 2]_c 3 . 
     In other words, for the mapping between the blue input points inPT(x, y)_c 3  at the second row (y=2) and the blue target subpixels tgSPX[a, b]_c 3  at the second row (b=2), the equation a=(x+1) is satisfied. That is, the coordinate shift mapping should be applied to the blue color-plane IMGin_c 3 . 
     In the specification, a difference between the horizontal coordinate of the target subpixel “a” and that of the input point “x” is defined as a horizontal coordinate difference (Δx=a−x), and/or a difference between the vertical coordinate of the target subpixel “b” and that of the input point “y” is defined as a vertical coordinate difference (Δy=b−y). The horizontal coordinate difference and the vertical coordinate difference are considered as horizontal/vertical coordinate shift parameters, which are utilized to modify the mapping between the core elements and the target subpixels. 
     According to the above illustrations, it is possible that direct mapping and the coordinate shift mapping are applied to different color-planes. Or, for the core elements with the same color, it is possible that to apply the direct mapping to some of which and apply the coordinate shift mapping to the other of which. In practical application, the appliances of the direct mapping and the coordinate shift mapping should be determined in response to the physical layout of the target subpixels. 
     Please compare  FIGS. 12A, 12B, and 12C  together. The layout of the red input points inPT(x, y)_c 1  in the core area csSR_c 1  and the layout of the green input points inPT(x, y)_c 2  in the core area csSR_c 2  are the same. However, the layout of the blue input points inPT(x, y)_c 3  in the core area crSR_c 3  is different from the others. Whereas, number of the red, green, blue input points inPT(x, y)_c 1 , inPT(x, y)_c 2 , inPT(x, y)_c 3  respectively in the core area csSR_c 1 , csSR_c 2 , csSR_c 3  are all equivalent to number of the target pixels tgPX[a, b] (that is, 9). The rendering filter coefficients defined in the red filter kernel FMx_c 1 , the green filter kernel FMx_c 2  and the blue filter kernel FMx_c 3  are identical. In other words, the same rendering filter coefficients can be repetitively used for generation of the rendered subpixel data of the three color-planes IMGin_c 1 , IMGin_c 2 , IMGin_c 3  and the storage space required for subpixel rendering can be reduced. The results of  FIGS. 12A, 12B, 12C  can be utilized to generate  FIG. 13 , a schematic diagram illustrating the layout of rendered subpixel data of the target pixels tgPx[1, 1]˜tgPX[3, 3] based on the combination of the direct mapping and the coordinate shift mapping according to the embodiment of the present disclosure.  FIG. 14  shows the display effect of  FIG. 13  intuitively, and the white vertical stripe  50  can be correctly displayed. 
       FIG. 15  is a block diagram illustrating components of the SPR circuit. According to the embodiment of the present disclosure, the SPR circuit  33  is used together with a memory  35 . The memory  35  is electrically connected to the SPR circuit  33 . In addition to the SPR circuit  33 , the memory  35  can be used by other function circuits in the display device. 
     The SPR circuit  33  includes a sampling circuit  333  and a convolution circuit  335 . Optionally, the SPR circuit  33  may have a pre-processing circuit  331 , a post-processing circuit  337  or both. The post-processing circuit  337  can be, for example, a low pass filter (hereinafter, LPF), a high pass filter, an edge detector, and so forth. The uses and functions of the pre-processing circuit  331  and the post-processing circuit  337  are not described here. The memory  35  includes a coordinate portion  351  and a filter portion  355 . 
     The coordinate portion  351  stores coordinate shift parameters representing the mapping between the core elements in the selected region SR and the target subpixels in the target region TR based on the coordinate shift mapping. With the coordinate shift parameters, the sampling circuit  333  acquires suitable input points in different color-planes for all the following image processing related operations. 
     Based on the coordinate shift parameters, the sampling circuit  333  samples the input points to be utilized as the red/green/blue sampling matrixes inDS{x, y}_c 1 , inDS{x, y}_c 2 , inDS{x, y}_c 3 . Then, color values of the input points in the red/green/blue sampling matrixes inDS{x, y}_c 1 , inDS{x, y}_c 2 , inDS{x, y}_c 3  are transmitted to the convolution circuit  335 . 
     The filter portion  355  stores the rendering filter coefficients of the red/green/blue filter kernels. Based on the color values of the input points in the red/green/blue sampling matrixes inDS{x, y}_c 1 , inDS{x, y}_c 2 , inDS{x, y}_c 3  and the red/green/blue filter kernels, the convolution circuit  355  performs the convolution operation to generate the rendered subpixel data sets sprDSET_c 1 , sprDSET_c 2 , sprDSET_c 3 . In the specification, the rendering filter coefficients of the red/green/blue filter kernels are entirely identical. Alternatively speaking, only one copy of the rendering filter coefficients needs to be saved, and the storage space required for the filter kernels can be dramatically reduced. 
     In short, variations of the subpixel layout of the non-RGB-stripe display panel have been pre-transformed by the sampling circuit  333 , with reference of the coordinate shift parameters. Thus, the input points acquired by the sampling circuit  333  are different in the red, the green, and the blue color-planes. Inconsequence, the pre-processing circuit  311 , the convolution circuit  335 , and the post-processing circuit  337  can equally perform their image processing operations to these acquired input points, regardless of their colors. Therefore, use of the coordinate shift parameter(s) can reduce the storage spaces required by the pre-processing circuit  311 , the convolution circuit  335 , and the post-processing circuit  337 . 
     Technology development drives new types of display panels. For example, organic light-emitting diodes (hereinafter, OLED) offer many advantages over both thin-film-transistor liquid-crystal display (hereinafter, LCD) and light-emitting diode (hereinafter, LED). Due to the manufacturer limitation, subpixels of the OLED display panel require a bigger area. 
       FIG. 16  is a schematic diagram illustrating an example of the pixels having three subpixels. In  FIG. 16 , each of the pixels has substantially the same size and the same subpixel layout. Each of the conventional pixels PX 1 , PX 2 , PX 3  includes a red subpixel SPX_c 1 , a green subpixel SPX_c 2 , and a blue subpixel SPX_c 3 . 
       FIG. 17  is a schematic diagram illustrating an example of the OLED pixels having two subpixels. Unlike the pixels are shown in  FIG. 16 , each of the OLED pixels PL 1 ′, PL 2 ′, PL 3 ′ includes only two subpixels. The OLED pixel PX 1 ′ includes a red OLED subpixel SPX_c 1  and a green OLED subpixel SPX_c 2 , the OLED pixel PX 2 ′ includes a blue OLED subpixel SPX_c 3  and a red OLED subpixel SPX_c 1 , and the OLED pixel PX 3 ′ includes a green OLED subpixel SPX_c 2  and a blue OLED subpixel SPX_c 3 . That is, the OLED pixels PX 1 ′, PX 2 ′, PX 3 ′ alternatively miss one type of colored OLED subpixels. 
     Comparing with the pixel PX 1 , the OLED pixel PX 1 ′ does not include a blue OLED subpixel SPX_c 3 . Comparing with the pixel PX 2 , the OLED pixel PX 2 ′ does not include a green OLED subpixel SPX_c 2 . Comparing with the pixel PX 3 , the OLED pixel PX 3 ′ does not include a red OLED subpixel SPX_c 1 . Therefore, the sizes of the OLED subpixels in  FIG. 17  can be bigger than the sizes of the subpixels in  FIG. 16 . 
     To reduce the side effects of decreasing the number of subpixels, the subpixels corresponding to different colors are alternatively dismissed in  FIG. 17 . Consequentially, the column numbers of the red/green/blue OLED subpixels of the OLED display panel can be equivalent to or less than the column number of the OLED pixels (Mdp_c 1 ≤Mdp, Mdp_c 2 ≤Mdp, Mdp_c 3 ≤Mdp), and the row number of the red/green/blue OLED subpixels can be equivalent to or less than the row number of the OLED pixels (Ndp_c 1 ≤Ndp, Ndp_c 2 ≤Ndp, Ndp_c 3 ≤Ndp). Thus, designing the SPR circuit specific to the OLED display panel should consider the subpixel layout. 
       FIG. 18  is a top view diagram illustrating an exemplary non-RGB-stripe pixel layout. In  FIG. 18 , the subpixels  60  are aligned in a column (vertical) direction but not aligned in a row (horizontal) direction. The subpixels  60  can be, for example, OLED subpixels. 
       FIGS. 19A, 19B, and 19C  are schematic diagrams illustrating three types of pixels in  FIG. 18 . The pixels in the display panel shown in  FIG. 18  can be classified as having three types of subpixel layout.  FIG. 19A  shows that the first type of subpixel layout includes two horizontally side-by-side subpixels, a red subpixel SPX[a, b]_c 1  and a green subpixel SPX[a, b]_c 2 . The second and the third types of subpixel layout include two subpixels and part of which are vertically side-by-side. A red subpixel SPX[a, b]_c 1  and a blue subpixel SPX[a, b]_c 3  are shown in  FIG. 19B , and a blue subpixel SP[a, b]_c 3  and a green subpixel SP[a, b]_c 2  are shown in  FIG. 19C . 
       FIG. 20  is a schematic diagram showing the subpixel layout of the target region TR shown in  FIG. 18 . Based on the three types of pixels defined in  FIG. 19A, 19B, 19C , the pixels shown in  FIG. 18  can be considered as a target region TR including 3×3 target pixels. In practical application, the display panel having the subpixel layout shown in  FIG. 20  may be used to display the selected region SR shown in  FIG. 8 . 
       FIG. 21  is a schematic diagram illustrating the display effect when the direct mapping is applied to the subpixel layout in  FIG. 20 . Details about generating the rendered subpixel data based on the selected regions SR_c 1 , SR_c 2 , SR_c 3  and the selection of the core areas crSR_c 1 , crSR_c 2 , crSR_c 3 , and mapping between the rendered subpixel data to the target subpixels tgSPX[1,1]-tgSPX[3, 3] are omitted to avoid redundancy. As each of the pixels has one subpixel missing, not all the input points (inPT_c 1 , inPT_c 2 , inPT_c 3 ) in the selected region SR_c 1 , SR_c 2 , SR_c 3  are used as core elements in  FIG. 21 . 
     For the red color-plane IMGin_c 1 , none of the input points (inPT(3, 1)_c 1 , inPT(2,2)_c 1 , and inPT(3, 3)_c 1 ) is selected as a red core element for the convolution operation because none of the target pixels tgPX[3, 1], tgPX[2, 2], and tgPX[3, 3] includes a red target subpixel tgSPX[a, b]_c 1 . Therefore, the core area (crSR_c 1 ) includes 6 red input points (inPT_c 1 ), and the boundary area bdrySR_c 1  includes 19 red input points (inPT_c 1 ). The red target subpixels tgSPX[1,1]_c 1 , tgPX[2, 1]_c 1 , tgPX[1, 2]_c 1 , tgPX[3, 2], tgPX[1,3]_c 1 , and tgPX[2, 3]_c 1  receive the rendered subpixel data sprD{1,1}_c 1 , sprD{2,1}_c 1 , sprD{1,2}_c 1 , sprD{3, 2}, sprD{1, 3}_c 1 , and spr{2, 3}_c 1 , respectively. In  FIG. 21 , 6 red target subpixels (tgSPX[a, b] _c 1 ) respectively receive their corresponding red rendered subpixel data (sprD{x, y}_c 1 ) and two of the red target subpixels (tgSPX[a, b] _c 1 ) are located at the vertical stripe display zone  61 . 
     For the green color-plane IMGin_c 2 , none of the input points (inPT(2, 1)_c 2 , inPT(1,2)_c 2 , and inPT(2, 3)_c 2 ) is selected as a green core element for the convolution operation because none of the target pixels tgPX[2, 1], tgPX[1, 2], and tgPX[2, 3] includes a green subpixel SPX_c 2 . Therefore, the core area (SR_c 1 ) includes 6 green input points (inPT_c 2 ), and the boundary area bdrySR_c 2  includes 19 green input points (inPT_c 2 ). The green target subpixels tgSPX[1,1]_c 2 , tgSPX[3, 1]_c 2 , tgSPX[2, 2]_c 2 , tgSPX[3,2]_c 2 , tgSPX[1, 3] and tgSPX[3, 3]_c 2  receive the rendered subpixel data sprD{1,1}c 2 , sprD{3,1}_c 2 , sprD {2,2}c 2 , sprD{3, 2}c 2 , sprD{3, 1}_c 2  and sprD{3, 3}_c 2 , respectively. In  FIG. 21 , 6 green target subpixels (tgSPX[a, b]_c 2 ) receive the green rendered subpixel data (sprD{x, y}c 2 ) and one of which is located at the vertical stripe display zone  61 . 
     For the blue color-plane IMGin_c 3 , none of the input points (inPT(1, 1)_c 3 , inPT(3, 2)_c 3 , and inPT(1, 3)_c 3 ) is selected as a blue core element for the convolution operation because none of the target pixels tgSPX[1, 1], tgSPX[3, 2], and tgSPX[1, 3] includes a blue target subpixel tgSPX[a, b]_c 3 . Therefore, the core area crSR_c 3  includes 6 blue input points (inPT_c 3 ), and the boundary area bdrySR_c 1  includes 17 blue input points (inPT_c 3 ). The blue target subpixels tgSPX[2,1]_c 3 , tgSPX[1, 2]_c 3 , tgSPX[2, 2]_c 3  and tgSPX[2,3]_c 3  receive the rendered subpixel data sprD{2, 1}_c 3 , sprD{1, 2}_c 3 , sprD{2, 2}_c 3 , and sprD{2, 3}_c 3 , respectively. In  FIG. 21 , 6 blue target subpixels (tgSPX[a, b] _c 3 ) receive the blue rendered subpixel data (sprD{x, y}c 3 ), and three of which are located at the vertical stripe display zone  61 . 
     Based on the above illustration, the vertical stripe display zone includes two red target subpixels tgSPX[a, b]_c 1 , one green target subpixel tgSPX[a, b]_c 2 , and three blue target subpixels tgSPX[a, b]_c 3 . In other words, the number of the blue target subpixels tgSPX[a, b]_c 3  whose rendered subpixel data sprD_c 3  have non-zero values is greater than the number of the red target subpixels tgSPX[a, b]_c 1  whose rendered subpixel data sprD_c 1  have non-zero values, and the number of the red target subpixels tgSPX[a, b]_c 1  whose rendered subpixel data sprD_c 1  have non-zero values is higher than the number of the green target subpixels tgSPX[a, b]_c 2  whose rendered subpixel data sprD_c 2  have non-zero values. Because the number of the red target subpixels tgSPX[a, b]_c 1 , the target green subpixels tgSPX[a, b]_c 2 , and the blue target subpixels tgSPX[a, b]_c 3  located in the vertical stripe display zone  61  are not equivalent, the white-color vertical stripe cannot be accurately displayed. 
     Alternative speaking, the white vertical stripe cannot be appropriately displayed because some of the target subpixels tgSPX located in the vertical stripe display zone  61  do not receive the rendered subpixel data sprD. As shown in  FIG. 21 , the target subpixels tgSPX located in the vertical stripe display zone  61  but not displaying include the green target subpixel (tgSPX [3, 1]_c 2 ), the red target subpixel (tgSPX[2, 2]_c 2 ), and the green target subpixel (tgSPX [3, 3]_c 2 ). 
       FIGS. 22A, 22B, and 22C  are schematic diagrams illustrating the selected region in different color-planes based on the coordinate shifting approach according to the embodiment of the present disclosure. 
     Comparing to the core area crSR_c 1  in  FIG. 21 , the core area crSR_c 1  in  FIG. 22A  excludes the red input point (inPT(1, 2)_c 1 ) as the core element, but further includes the red input point (inPT(2, 2)_c 1 ) as the core element. The core area crSR_c 1  includes 6 red input points (inPT(1, 1)_c 1 , inPT(2, 1)_c 1 , inPT(2, 2)_c 1 , inPT(3, 2)_c 1 , inPT(1, 3)_c 1 , inPT(2, 3)_c 1 ), and the boundary area bdrySR_c 1  includes 17 red input points (inPT_c 1 ). The convolution operations of the red sampling matrixes (inDS_c 1 ) centered at different red input points inPT_c 1  within the core area crSR_c 1  and the green filter kernel FMx_c 1  are respectively calculated to generate the red rendered subpixel data sprD{1, 1}_c 1 , sprD{2, 1}_c 1 , sprD{2, 2}_c 1 , sprD{3, 2}_c 1 , sprD{1, 3}_c 1 , sprD{2, 3}_c 1 . 
     Comparing to the core area (crSR_c 2 ) in  FIG. 21 , the core area (crSR_c 2 ) in  FIG. 22B  excludes the green input points (inPT(3,1)_c 2 , inPT(3, 3)_c 2 ) as the core element, but further includes the green input points (inPT(2,1)_c 2 , inPT(2, 3)_c 2 ) as the core elements. The core area (crSR_c 2 ) includes 6 green input points (inPT(1, 1)_c 2 , inPT(2, 1)_c 2 , inPT(2, 2)_c 2 , inPT(3, 2)_c 2 , inPT(1, 3)_c 2 , inPT(2, 3)_c 2 ), and the boundary area (bdrySR_c 2 ) includes 17 green input points. The convolution operations of the green sampling matrixes (inDS_c 2 ) centered at different green input points inPT_c 2  within the core area crSR_c 2  and the green filter kernel FMx_c 2  are respectively calculated to generate the green rendered subpixel data sprD{1, 1}_c 2 , sprD{2, 1}_c 2 , sprD{2, 2}_c 2 , sprD{3, 2}_c 2 , sprD{1, 3}_c 3 , sprD{2, 3}_c 2 . 
     The core areas (crSR_c 3 ) in  FIGS. 21 and 22C  are identical. Therefore, the core elements acquired in the blue color-plane IMGin_c 3  remain unchanged. The core area crSR_c 3  includes 6 blue input points (inPT(2, 1)_c 3 , inPT(3, 1)_c 3 , inPT(1, 2)_c 3 , inPT(2, 2)_c 3 , inPT(2, 3)_c 3 , inPT(3, 3)_c 3 ), and the boundary area bdrySR_c 3  includes 17 blue input points. The convolution operations of the blue sampling matrixes (inDS_c 3 ) centered at different blue input points inPT_c 3  within the core area crSR_c 3  and the blue filter kernel FMx_c 3  are respectively calculated to generate the blue rendered subpixel data sprD{2, 1}_c 3 , sprD{3, 1}_c 3 , sprD{1, 2}_c 3 , sprD{2, 2}_c 3 , sprD{2, 3}_c 3 , sprD{3, 3}_c 3 . 
     Please compare  FIGS. 22A, 22B, and 22C  together. The layout of the red input points inPT(x, y)_c 1  in the core area csSR_c 1  and the layout of the green input points inPT(x, y)_c 2  in the core area csSR_c 2  are the same. However, the layout of the blue input points inPT(x, y)_c 3  in the core area crSR_c 3  is different from the others. Moreover, number of the red, green, blue input points inPT(x, y)_c 1 , inPT(x, y)_c 2 , inPT(x, y)_c 3  respectively in the core area csSR_c 1 , csSR_c 2 , csSR_c 3  are equivalent to each other (that is, 6, as shown in  FIGS. 22A, 22B, 22C ) but different from the number of the target pixels tgPX[a, b] (that is, 9, as shown in  FIG. 20 ). 
       FIGS. 23A, 23B, and 23C  are schematic diagrams illustrating the generation of the red rendered subpixel data set sprDSET_c 1  and mapping the red rendered subpixel data to the red target subpixels tgSPX[a, b]_c 1  according to the embodiment of the present disclosure. The matrixes circulated by the dotted line at the left side of  FIG. 23A  are the red sampling matrixes (inDS{1, 1}_c 1 , inDS{2, 1}_c 1 , inDS{2, 2}_c 1 , inDS{3, 2}_c 1 , inDS{1, 3}_c 1 , inDS{2, 3}c 1 ), which can be obtained by selecting the core elements (inPT(1, 1)_c 1 , inPT(2, 1)_c 1 , inPT(2, 2)_c 1 , inPT(3, 2)_c 1 , inPT(1, 3)_c 1 , inPT(2, 3)_c 1 ) in  FIG. 22A , and the matrixes circulated by the dotted line at the right side of  FIG. 23A  are the red filter kernels (FMx{1, 1}_c 1 , FMx{2,1}_c 1 , FMx{2,2}c 1 , FMx{3, 2}c 1 , FMx{1, 3}_c 1 , FMx{2,3}_c 1 ). The red sampling matrixes inDS{x, y}_c 1  and the red filter kernels FMx{x, y}c 1  are listed in accordance with the relative positions of the core elements inPT(x, y)_c 1  in the core area crSR_c 1 . 
     By respectively performing the convolution operation to the red sampling matrixes (inDS{1, 1}_c 1 , inDS{2, 1}_c 1 , inDS{(2, 2)_c 1 , inDS{3, 2}_c 1 , inDS{1, 3}_c 1 , inDS{2, 3}c 1 ) with the red filter kernel FMx_c 1 , the red rendered subpixel data set sprDSET_c 1  (as shown in  FIG. 23B ) including red rendered subpixel data sprD{1, 1}_c 1 , sprD(2, 1)_c 1 , sprD{2, 2}_c 1 , sprD{3, 2}_c 1 , sprD{1, 3}_c 1 , sprD{2, 3}_c 1  can be obtained. As the red rendered subpixel data set sprDSET_c 1  is generated by performing the convolution operation being centered with each of the red core elements, the number and layout of the red rendered subpixel data (sprD{1, 1}_c 1 , sprD{2, 1}_c 1 , sprD{2, 2}_c 1 , sprD(3, 2)_c 1 , sprD{1, 3}_c 1 , sprD{2, 3}_c 1 ) are to the same as those of the red core elements. The relationships and comparisons between the rendered subpixel data (sprD{1, 1}_c 1 , sprD{2, 1}_c 1 , sprD{2, 2}_c 1 , sprD{3, 2}_c 1 , sprD{1, 3}_c 1 , sprD{2, 3}_c 1 ) and red target subpixels (tgSPX[1, 1]_c 1 , tgSPX[2, 1]_c 1 , tgSPX[1, 2]_c 1 , tgSPX[3, 2]_c 1 , tgSPX[1, 3]_c 1 , tgSPX[2, 3]_c 1 ) are shown in  FIG. 23C  and summarized in Table 4. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                   
                 coordinate 
                   
                   
                   
               
               
                   
                 of red 
                   
                   
                   
               
               
                 coordinate 
                 rendered 
                 coordinate 
                 horizontal 
                 vertical 
               
               
                 of red 
                 subpixel 
                 of red target 
                 coordinate 
                 coordinate 
               
               
                 input point 
                 data 
                 subpixel 
                 shift 
                 shift 
               
               
                 inPT(x, 
                 sprD{x, 
                 tgSPX[a, 
                 parameter 
                 parameter 
               
               
                 y)_c1 
                 y}_c1 
                 b]_c1 
                 Δx_c1 
                 Δy_c1 
               
               
                   
               
             
            
               
                 (1, 1) 
                 {1, 1} 
                 [1, 1] 
                 0 
                 0 
               
               
                 (2, 1) 
                 {2, 1} 
                 [2, 1] 
                 0 
                 0 
               
               
                 (3, 1) 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 (1, 2) 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 (2, 2) 
                 {2, 2} 
                 [1, 2] 
                 −1  
                 0 
               
               
                 (3, 2) 
                 {3, 2} 
                 [3, 2] 
                 0 
                 0 
               
               
                 (1, 3) 
                 {1, 3} 
                 [1, 3] 
                 0 
                 0 
               
               
                 (2, 3) 
                 {2, 3} 
                 [2, 3] 
                 0 
                 0 
               
               
                 (3, 3) 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                   
               
            
           
         
       
     
     As shown in  FIG. 20 , target pixels tgPX[3,1], tgPX[2,2], tgPX[3, 3] do not have red target subpixel). Therefore, not all the red input points inPT(x, y)_c 1  (x=1˜3, y=1˜3) in the core area crSR_c 1  are utilized as the red core elements. For the existing red target subpixels, coordinates of some but not all of the red target subpixels tgSPX[a, b]_c 1  and coordinates of their corresponding red rendered subpixel data spr{x, y}_c 1  are matched (that is, a=x, b=y). In contrast, coordinates of one of the existing red target subpixels tgSPX[a, b]_c 1  and coordinates of its corresponding red rendered subpixel data spr{x, y}_c 1  are inconsistent (that is, a=x−1, b=y). 
     For example, the red target subpixels tgSPX[1, 1]c, tgSPX[2, 1]_c 1 , tgSPX[3, 2]_c 1 , tgSPX[1, 3]_c 1 , tgSPX[2, 3]_c 1  respectively acquire the red rendered subpixel data sprD{1,1}_c 1 , sprD{2, 1}_c 1 , sprD{3, 2}_c 1 , sprD{1, 3}_c 2  sprD{2, 3}_c 2  to determine their luminances. Coordinates of the red target subpixels tgSPX[a, b] and coordinates of the rendered subpixel data sprD{x, y}_c 1  are matched. That is, a=x and b=y. On the other hand, the red target subpixel tgSPX[1, 2]_c 1  acquires the red rendered subpixel datum sprD{2, 2}_c 2  for determining its luminance, not the red rendered subpixel data sprD{1, 2}_c 1 . Alternatively speaking, a horizontal coordinate shift parameter of “Δx_c 1 =−1” should be applied to the horizontal coordinate of the red input point inPT(x, y)_c 1  when x=2 and y=2. 
       FIGS. 24A, 24B, and 24C  are schematic diagrams illustrating the generation of the green rendered subpixel data set sprDSET_c 2  and mapping the green rendered subpixel data to the green target subpixels tgSPX[a, b]_c 2  according to the embodiment of the present disclosure. The matrixes circulated by the dotted line at the left side of  FIG. 24A  are the green sampling matrixes (inDS{1, 1}c 2 , inDS{2, 1}_c 2 , inDS{2, 2}_c 2 , inDS{3, 2}_c 2 , inDS{1, 3}_c 2 , inDS{2, 3}_c 2 ), which can be obtained by selecting the core elements (inPT(1, 1)_c 2 , inPT(2, 1)_c 2 , inPT(2, 2)_c 2 , inPT(3, 2)_c 2 , inPT(1, 3)_c 2 , inPT(2, 3)_c 2 ) in  FIG. 22B , and the matrixes circulated by the dotted line at the right side of  FIG. 24A  are the green filter kernels (FMx{1, 1}_c 2 , FMx{2,1}_c 2 , FMx{2,2}_c 2 , FMx{3, 2}_c 2 , FMx{1, 3}_c 2 , FMx{2,3}_c 2 ). The green sampling matrixes inDS{x, y}_c 2  and the green filter kernels FMx{x, y}_c 2  are listed in accordance with the relative positions of the core elements inPT(x, y)_c 2  in the core area crSR_c 2 . 
     By respectively performing the convolution operation to the green sampling matrixes inDS{1, 1}_c 2 , inDS{2, 1}_c 2 , inDS{2, 2}_c 2 , inDS{3, 2}_c 2 , inDS{1, 3}_c 2 , inDS{2, 3}_c 2  with the green filter kernel FMx_c 2 , the green rendered subpixel data set sprDSET_c 2  (as shown in  FIG. 24B ) including green rendered subpixel data sprD{1, 1}_c 2 , sprD{2, 1}_c 2 , sprD{2, 2}_c 2 , sprD{3, 2}_c 2 , sprD{1, 3}_c 2 , sprD{2, 3}_c 2 ) can be obtained. As the green rendered subpixel data set sprDSET_c 2  is generated by performing the convolution operation being centered with the green core elements, the number and layout of the green rendered subpixel data (sprD{1, 1}_c 2 , sprD{2, 1}_c 2 , sprD{2, 2}_c 2 , sprD{3, 2}_c 2 , sprD{1, 3}_c 2 , sprD{2, 3}_c 2 ) are the same as those of the green core elements. The relationships and comparisons between the rendered subpixel data (sprD{1, 1}_c 2 , sprD{2, 1}_c 2 , sprD{2, 2}_c 2 , sprD{3, 2}_c 2 , sprD{1, 3}_c 2 , sprD{2, 3}_c 2 ) and the red target subpixels (tgSPX[1, 1]_c 2 , tgSPX[2, 1]_c 2 , tgSPX[1, 2]_c 2 , tgSPX[3, 2]_c 2 , tgSPX[1, 3]_c 2 , tgSPX[2, 3]_c 2 ) are shown in  FIG. 24C  and summarized in Table 5. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                   
                 coordinate 
                   
                   
                   
               
               
                   
                 of green 
                   
                   
                   
               
               
                 coordinate 
                 rendered 
                 coordinate 
                 horizontal 
                 vertical 
               
               
                 of green 
                 subpixel 
                 of green target 
                 coordinate 
                 coordinate 
               
               
                 input point 
                 data 
                 subpixel 
                 shift 
                 shift 
               
               
                 inPT(x, 
                 sprD{x, 
                 tgSPX[a, 
                 parameter 
                 parameter 
               
               
                 y)_c2 
                 y}_c2 
                 b]_c2 
                 Δx_c2 
                 Δy_c2 
               
               
                   
               
             
            
               
                 (1, 1) 
                 {1, 1} 
                 [1, 1] 
                 0 
                 0 
               
               
                 (2, 1) 
                 {2, 1} 
                 [3, 1] 
                 +1  
                 0 
               
               
                 (3, 1) 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 (1, 2) 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 (2, 2) 
                 {2, 2} 
                 [2, 2] 
                 0 
                 0 
               
               
                 (3, 2) 
                 {3, 2} 
                 [3, 2] 
                 0 
                 0 
               
               
                 (1, 3) 
                 {1, 3} 
                 [1, 3] 
                 0 
                 0 
               
               
                 (2, 3) 
                 {2, 3} 
                 [3, 3] 
                 +1  
                 0 
               
               
                 (3, 3) 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                   
               
            
           
         
       
     
     As shown in  FIG. 20 , target pixels tgPX[2,1], tgPX[1,2], tgPX[2, 3] do not have green target subpixels. Therefore, not all the green input points inPT(x, y)_c 2  (x=1˜3, y=1˜3) in the core area crSR_c 2  are utilized as the green core elements. For the existing green target subpixels, coordinates of some of the existing green target subpixels tgSPX[a, b]_c 2  are consistent with coordinates of their corresponding green rendered subpixel data spr{x, y}_c 2  (that is, a=x, b=y). In contrast, coordinates of two of the existing green target subpixels tgSPX[a, b]_c 2  and coordinates of their corresponding green rendered subpixel data spr{x, y}_c 2  are inconsistent (that is, a=x+1, b=y). 
     For example, the green target subpixels tgSPX[1, 1]_c 2 , tgSPX[2, 2]_c 2 , tgSPX[3, 2]_c 2 , tgSPX[1, 3]_c 2  respectively acquire the green rendered subpixel data sprD{1,1}_c 2 , sprD{2, 2}_c 2 , sprD{3, 2}_c 2  and sprD{1, 3}_c 2  to determine their luminances. Coordinates of the green target subpixels tgSPX[a, b]_c 2  and coordinates of the green rendered subpixel data sprD{x, y}_c 2  are matched. That is, a=x and b=y. On the other hand, the green target subpixel tgSPX[3, 1]_c 2 , tgSPX[3, 3]_c 2  respectively acquire the green rendered subpixel data sprD{2, 1}_c 2 , sprD{2, 3}_c 2  for determining their luminances, not the green rendered subpixel data sprD{3, 1}_c 2 , sprD{3, 3}_c 2 . Alternatively speaking, a horizontal coordinate shift parameter of “Δx_c 2 =+1” should be applied to the horizontal coordinate of the green input point inPT(x, y)_c 2  when x=2 and y=1, or when x=2 and y=3. 
       FIGS. 25A, 25B, and 25C  are schematic diagrams illustrating the generation of the blue rendered subpixel data set sprDSET_c 3  and mapping the blue rendered subpixel data to the blue target subpixels tgSPX[a, b]_c 3  according to the embodiment of the present disclosure. The matrixes circulated by the dotted line at the left side of  FIG. 25A  are the blue sampling matrixes (inDS{2, 1}_c 3 , inDS{3, 1}_c 3 , inDS{1, 2}_c 3 , inDS{2, 2}_c 3 , inDS{2, 3}_c 3 , inDS{3, 3}_c 3 ), which can be obtained by selecting the core elements (inPT(2, 1)_c 3 , inPT(3, 1)_c 3 , inPT(1, 2)_c 3 , inPT(2, 2)_c 3 , inPT(2, 3)_c 3 , inPT(3, 3)_c 3 ) in  FIG. 22C , and the matrixes circulated by the dotted line at the right side of  FIG. 25A  are the blue filter kernels (FMx{2, 1}_c 3 , FMx{3,1}_c 3 , FMx{1,2}_c 3 , FMx{2, 2}_c 3 , FMx{2, 3}_c 3 , FMx{3,3}_c 3 ). The blue sampling matrixes inDS{x, y}c 3  and the blue filter kernels FMx{x, y}_c 3  are listed in accordance with the relative positions of the core elements inPT(x, y)_c 3  in the core area crSR_c 3 . 
     By respectively performing the convolution operation to the blue sampling matrixes (inDS{2, 1}_c 3 , inDS{3, 1}_c 3 , inDS{1, 2}_c 3 , inDS{2, 2}_c 3 , inDS{2, 3}_c 3 , inDS{3, 3}_c 3 ) with the blue filter kernels FMx_c 3 , the blue rendered subpixel data set sprDSET_c 3  (as shown in  FIG. 25B ) including the blue rendered subpixel data (sprD{2, 1}_c 3 , sprD{3, 1}_c 3 , sprD{1, 2}_c 3 , sprD{2, 2}_c 3 , sprD{2, 3}_c 3 , sprD{3, 3}_c 3 ) can be obtained. As the blue rendered subpixel data set sprDSET_c 3  is generated by respectively performing the convolution operation being centered with each of the blue core elements, the number and layout of the blue rendered subpixel data (sprD{2, 1}_c 3 , sprD(3, 1)_c 3 , sprD{1, 2}_c 3 , sprD{2, 2}_c 3 , sprD{2, 3}_c 3 , sprD{3, 3}_c 3 ) are the same as those of the blue core elements. The relationships and comparisons between the rendered subpixel data (sprD{2, 1}_c 3 , sprD{3, 1}_c 3 , sprD{1, 2}_c 3 , sprD{2, 2}_c 3 , sprD{2, 3}_c 3 , sprD{3, 3}_c 3 ) and the blue target subpixels (tgSPX[2, 1]_c 3 , tgSPX[3, 1]_c 3 , tgSPX[1, 2]_c 3 , tgSPX[2, 2]_c 3 , tgSPX[2, 3]_c 3 , tgSPX[3, 3]_c 3 ) are shown in  FIG. 25C  and summarized in Table 6. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 6 
               
               
                   
               
               
                   
                 coordinate 
                   
                   
                   
               
               
                   
                 of blue 
                   
                   
                   
               
               
                 coordinate 
                 rendered 
                 coordinate 
                 horizontal 
                 vertical 
               
               
                 of blue 
                 subpixel 
                 of blue target 
                 coordinate 
                 coordinate 
               
               
                 input point 
                 data 
                 subpixel 
                 shift 
                 shift 
               
               
                 inPT(x, 
                 sprD{x, 
                 tgSPX[a, 
                 parameter 
                 parameter 
               
               
                 y)_c3 
                 y}_c3 
                 b]_c3 
                 Δx_c3 
                 Δy_c3 
               
               
                   
               
             
            
               
                 (1, 1) 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 (2, 1) 
                 {2, 1} 
                 [2, 1] 
                 0 
                 0 
               
               
                 (3, 1) 
                 {3, 1} 
                 [3, 1] 
                 0 
                 0 
               
               
                 (1, 2) 
                 {1, 2} 
                 [1, 2] 
                 0 
                 0 
               
               
                 (2, 2) 
                 {2, 2} 
                 [2, 2] 
                 0 
                 0 
               
               
                 (3, 2) 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 (1, 3) 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 (2, 3) 
                 {2, 3} 
                 [2, 3] 
                 0 
                 0 
               
               
                 (3, 3) 
                 {3, 3} 
                 [3, 3] 
                 0 
                 0 
               
               
                   
               
            
           
         
       
     
     As shown in  FIG. 20 , target pixels tgPX[1,1], tgPX[3,2], tgPX[3, 1] do not have blue target subpixels). Therefore, not all the blue input points inPT(x, y)_c 3  (x=1˜3, y=1˜3) in the core area crSR_c 3  are utilized as the blue core elements. For all the existing blue target subpixels, their coordinates are consistent with coordinates of their corresponding blue rendered subpixel data spr{x, y}c 3  (that is, a=x, b=y). Alternatively speaking, the coordinate shift parameter is not required for the blue color-plane IMGin_c 3 . 
     Please refer to  FIGS. 23A, 24A, and 25A  together. In  FIGS. 23A, 24A, and 25A , two types of rendering convolution matrixes are used, that is 
                 1   3     ·     [         0       0       0           1       2       0           0       0       0         ]       ⁢           ⁢   and   ⁢           ⁢       1   3     ·       [         0       0       0           0       2       1           0       0       0         ]     .             
The uses of the rendering convolution matrixes are summarized in Table 7.
 
     
       
         
           
               
               
               
               
             
               
                 TABLE 7 
               
               
                   
               
               
                 rendering 
                   
                   
                   
               
               
                 convolution 
                 red filter  
                 green filter  
                 blue filter  
               
               
                 matrix 
                 kernels 
                 kernels 
                 kernels 
               
               
                   
               
             
            
               
                 
                   
                     
                       
                         
                           1 
                           3 
                         
                         · 
                         
                           [ 
                           
                             
                               
                                 0 
                               
                               
                                 0 
                               
                               
                                 0 
                               
                             
                             
                               
                                 1 
                               
                               
                                 2 
                               
                               
                                 0 
                               
                             
                             
                               
                                 0 
                               
                               
                                 0 
                               
                               
                                 0 
                               
                             
                           
                           ] 
                         
                       
                     
                   
                 
                 FMx{1,1}_c1, FMx{2,2}_c1, FMx{1,3}_c1 
                 FMx{1,1}_c2, FMx{2,2}_c2, FMx{1,3}_c2 
                 FMx{2,1}_c3, FMx{1,2}_c3, FMx{2,3}_c3 
               
               
                   
               
               
                 
                   
                     
                       
                         
                           1 
                           3 
                         
                         · 
                         
                           [ 
                           
                             
                               
                                 0 
                               
                               
                                 0 
                               
                               
                                 0 
                               
                             
                             
                               
                                 0 
                               
                               
                                 2 
                               
                               
                                 1 
                               
                             
                             
                               
                                 0 
                               
                               
                                 0 
                               
                               
                                 0 
                               
                             
                           
                           ] 
                         
                       
                     
                   
                 
                 FMx{2,1}_c1, FMx{3,2}_c1, FMx{2,3}_c1 
                 FMx{2,1}_c2, FMx{3,2}_c2, FMx{2,3}_c2 
                 FMx{3,1}_c3, FMx{2,2}_c3, FMx{3,3}_c3 
               
               
                   
               
            
           
         
       
     
     As listed in Table 7, the two rendering convolution matrixes can be repetitively used in the convolution operations for the input points in different color-planes IMGin_c 1 , IMGin_c 2 , IMGin_c 3 . Therefore, the storage space required by the filter portion  355  in the memory  35  can be decreased dramatically. 
       FIG. 26A  is a schematic diagram illustrating mapping between the rendered subpixel data and the subpixels of the target pixels. The red, green, and blue target subpixels respectively shown in  FIGS. 23C, 24C, and 25C  are combined together in  FIG. 26A . 
     Please refer to  FIGS. 21 and 26A  together. In  FIG. 21 , the green target subpixel tgSPX[3, 1]_c 2  does not receives its rendered subpixel data, the red target subpixel tgSPX[1, 2]_c 1  does not receive its rendered subpixel data, nor the green target subpixel tgSPX[3, 3]_c 2  receives its rendered subpixel data, and the white vertical stripe cannot be displayed appropriately. Relatively, in  FIG. 26A , all the 9 target subpixels located at the vertical stripe display zone  62 , that is, target subpixels tgSPX[2, 1]_c 1 , tgSPX[2, 1]_c 3 , tgSPX[3, 1]_c 2 , tgSPX[1, 2]_c 1 , tgSPX[2, 2]_c 3 , tgSPX[2, 2]_c 2 , tgSPX[2, 3]_c 1 , tgSPX[2, 3]_c 3 , tgSPX[3, 3]_c 2 , can receive their corresponding rendered subpixel data, and the white vertical stripe can be displayed appropriately. 
     In  FIG. 26A , the green target subpixel tgSPX[3, 1]_c 2  (a=3 and b=1) displays the rendered subpixel datum sprD{x, y}c 2  (x=2 and y=1), not the green rendered subpixel datum sprD{3, 1}_c 2  (x=3 and y=1). A horizontal coordinate difference in the green color-plane (Δx_c 2 =a−x=1) exists between horizontal coordinates of the green target subpixel tgSPX[3, 1]_c 2  (a=3) and the green input point inPT(2, 1)_c 2  (x=2). 
     The red target subpixel tgSPX[1, 2]_c 1  (a=1 and b=2) displays the red rendered subpixel datum sprD{x, y}_c 1  (x=2 and y=2), no the red rendered subpixel datum sprD{1, 2}_c 1  (x=1 and y=2). A horizontal coordinate difference in the red color-plane (Δx_c 1 =a−x=−1) exists between horizontal coordinates of the red target subpixel tgSPX[1, 2]_c 1  (a=1 and b=2) and the red input point inPT(2, 2)_c 1  (x=2 and y=2). 
     The green target subpixel tgPX[3, 3]_c 2  (a=3 and b=3) displays the rendered subpixel datum sprD{2, 3}c 2  (x=2 and y=3), not the green rendered subpixel datum sprD{3, 3}_c 2  (x=3 and y=3). A horizontal coordinate difference in the green color-plane (Δx_c 1 =a−x=1) exists between horizontal coordinates of the green target subpixel tgSPX[3, 3]_c 2  (a=3 and b=3) and the green input point inPT(2, 3)_c 2  (x=2 and y=3). 
     According to the embodiment of the present disclosure, the horizontal coordinate differences (a−x) in different color-planes can truly reflect the physical layout of the subpixels, and the horizontal coordinate differences (a−x) in different color-planes are utilized as the coordinate shift parameter(s) and stored at the coordinate portion  351 . Consequentially, the image processing related operations used to consider separately for the three different color-planes IMGin_c 1 , IMGin_c 2 , IMGin_c 3  in the conventional approach, now only need to consider for one unified calculation, which can be applied to all the three different color-planes IMGin_c 1 , IMGin_c 2 , IMGin_c 3 . 
     Similarly, in a case that the vertical coordinate differences (b−y) exist, the image processing related operations can be simplified. The horizontal coordinate differences (a−x) and the vertical coordinate differences (b−y) are considered as the coordinate shift parameter(s). This is, use of the coordinate shift parameter(s) can make up (compensate) the layout inconsistency of the red, the green, and the blue target subpixels tgSPX[a, b]_c 1 , tgSPX[a, b]_c 2 , tgSPX[a, b]_c 3 . 
       FIG. 26B  shows the display results of  FIG. 26A  in an intuitive way. As shown in  FIG. 26B , all the target subpixels located at the vertical stripe display zone  62  receive their rendered subpixel data, and the white vertical stripe can be correctly displayed. 
       FIG. 27  is a top view diagram illustrating another exemplary pixel layout of an OLED display panel. In  FIG. 27 , the subpixels are aligned in row direction but not aligned in a column direction.  FIG. 28  is a schematic diagram showing a white horizontal stripe  703 . 
       FIG. 29  is a schematic diagram illustrating the display effects of the display showing the white horizontal stripe according to the direct mapping. When only the direct mapping is used, the horizontal stripe display zone  73  cannot display the white horizontal stripe  703  appropriately. 
       FIG. 30  is a schematic diagram illustrating the display effects of the display showing the horizontal stripe based on the coordinate shifting method according to the embodiment of the present disclosure. In a case that the coordinate shifting method is used, the horizontal stripe display zone  75  can display the white horizontal stripe appropriately. 
     In the specification, the SPR circuit considers the physical subpixel layout of the display panel while performing the subpixel rendering. The embodiments demonstrate that the content in the input image IMGin can be correctly displayed when the coordinate mapping function is adopted. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.