Patent Publication Number: US-9898953-B2

Title: Offset method and equipment of RGBW panel subpixel

Description:
BACKGROUND 
     1. Technical Field 
     The invention relates to the field of display technology, and more particularly to an offset method of a RGBW panel subpixel and an equipment of the RGBW panel subpixel. 
     2. Description of the Related Art 
     LG Display creatively adds white (W) subpixels based on RGB to form RGBW 4K. Light transmittance of a RGBW 4K panel increases due to the addition of white subpixels, lightness of a panel is also 1.5 times as bright as a conventional RGB 4K panel. 
     With further study in a RGBW panel, simply extending the arrangement of RGB panel subpixels to achieve a stripe-RGBW arrangement gets the most of study and attention. Each pixel of a stripe-RGBW panel consists of four horizontally arranged subpixels, dimension of each subpixel is same as that of subpixels of a RGB panel with the same size. With the arrangement, number and size of subpixels maintain the same, however, number of pixels is cut to be three fourths of that of the original RGB panel, so that the real resolution of the entire screen is fallen by a quarter compared with a RGB panel with the same size. A subsampling algorithm needs to be programmed to compress four subpixels of RGBW in order to correctly display a RGBW four-channel image converted from a RGB three-channel image on a panel with the same number of subpixels. Conventional subsampling methods include a simple ¾ entire pixel level interpolation subsampling method and a simple ¾ subpixel offset method that only horizontally adjacent pixels are considered. 
     An image can be displayed on a RGBW panel according to the previous method, but without considering the color relationship among adjacent pixels, jagged edges and image details loss appear during display. 
     SUMMARY 
     The invention mainly provides an offset method of a RGBW panel subpixel and an equipment of the RGBW panel subpixel, which can solve resolution loss and jagged edges when the whole pixel is subsampled. 
     The proposal according to the invention to overcome the previous problem is: an offset method of a RGBW subpixel panel, including: inputting data of a pixel based on RGB color space in an image; determining the most similar pixel of each of the pixels in the image according to the data of the pixels based on RGB color space; converting the data of the pixels based on RGB color space to data of the pixels based on RGBW color space under the circumstances that resolution of pixels is the same to determination the data based on RGBW color space corresponding to the most similar pixels of the pixels; three fourths subsampling pixels in the image according to the data of the pixels based on RGBW color space, the data based on RGBW color space corresponding to the most similar pixels of each of the pixels; outputting data of pixels in the image after being sampled; the sequence of determining the most similar pixels of each of the pixels in the image according to the data of pixels based on RGB color space including: converting the data of pixels based on RGB color space to data of the pixels based on HSI color space; calculating similarity of each of the pixels and adjacent pixels according to the data of pixels based on HSI color space to achieve the most similar pixels of each of the pixels; the sequence of three fourths subsampling pixels in the image according to the data of pixels based on RGBW color space, the data based on RGBW color space corresponding to the most similar pixels of the pixels including: dividing pixels in the image in an order of each group consisting of four pixels; adjusting arrangement of 16 subpixels in each of the group, arrangement of the 16 pixels in each of the groups after adjustment is: RGBW, WRGB, BWRG, GBWR; three fourths subsampling the 16 subpixels of each of the groups according to the arrangement of the 16 subpixels of each of the group after adjustment, achieving arrangement of 4 three-channel subpixels of each of the group: RGB, WRG, BWR, GBW, when the pixel i is RGBW, a strategy for sampling is: 
                 R   d     ⁡     (   i   )       =       P   r     ⁡     (   i   )                       G   d     ⁡     (   i   )       =       G   o     ⁡     (   i   )                         B   d     ⁡     (   i   )       =       B   o     ⁡     (   i   )         ,         
when the pixel i is WRGB, a strategy for sampling is:
 
                 W   d     ⁡     (   i   )       =       P   w     ⁡     (   i   )                       R   d     ⁡     (   i   )       =       R   o     ⁡     (   i   )                         G   d     ⁡     (   i   )       =       G   o     ⁡     (   i   )         ,         
when the pixel i is BWRG, a strategy for sampling is:
 
                 B   d     ⁡     (   i   )       =       P   b     ⁡     (   i   )                       W   d     ⁡     (   i   )       =       W   o     ⁡     (   i   )                         R   d     ⁡     (   i   )       =       R   o     ⁡     (   i   )         ,         
when the pixel i is GBWR, a strategy for sampling is:
 
                 G   d     ⁡     (   i   )       =       P   g     ⁡     (   i   )                       B   d     ⁡     (   i   )       =       B   o     ⁡     (   i   )                         W   d     ⁡     (   i   )       =       W   o     ⁡     (   i   )         ,         
R d (i), G d (i), B d (i) and W d (i) are respectively grey levels of the pixel i based on RGBW four channels on RGBW color space after being sampled, R o (i), G o (i), B o (i) and W o (i) are respectively grey levels of the pixel i based on RGBW four channels on RGBW color space before being sampled, P r (i) is achieved according to R s (i), R o (i) and R o (i−1), P w (i) is achieved according to W s (i), W o (i) and W o (i−1), P b (i) is achieved according to B s (i), B o (i) and B o (i−1), P g (i) is achieved according to G s (i), G o (i) and G o (i−1), R s (i), G s (i), B s (i) and W s (i) are grey levels of the RGBW four channels on RGBW color space corresponding to the most similar pixel of the pixel i, R o (i−1), G o (i−1), B o (i−1) and W o (i−1) are grey levels of the RGBW four channels on the RGBW color space based on the pixel i−1 before being sampled.
 
     The P r (i), P w (i), P b (i) and P g (i) are determined by a formula 1, the formula 1 is:
 
 P   r ( i )=max( R   s ( i ), R   o ( i ), R   o ( i− 1))
 
 P   w ( i )=max( W   s ( i ), W   o ( i ), W   o ( i− 1))
 
 P   b ( i )=max( B   s ( i ), B   o ( i ), B   o ( i− 1))
 
 P   g ( i )=max( G   s ( i ), G   o ( i ), G   o ( i− 1))
 
     max(R s (i), R o (i), R o (i−1)) is the maximum value in R s (i), R o (i) and R o (i−1), max(W s (i), W o (i), W o (i−1)) is the maximum value in W s (i), W o (i) and W o (i−1), max(B s (i), B o (i), B o (i−1)) is the maximum value in B s (i), B o (i) and B o (i−1), max(G s (i), G o (i), G o (i−1)) is the maximum value in G s (i), G o (i) and G o (i−1). 
     When the resolution of pixels is the same, the sequence that converting the data of the pixels based on data of RGB color space to the data of the pixels based on RGBW color space to determination data of the most similar pixels of the pixels corresponding to RGBW color space includes: determining a grey level W o (i) of the pixels based on white channels on RGBW color space, where W o (i)=D min (i), i is a position of the pixel, D min (i) is the minimum value of grey levels of the pixel i based on RGB three channels on RGB color space; calculating a yield value M of RGB three channels on the pixel, where 
               M   =       (         W   o     ⁡     (   i   )       +       D   max     ⁡     (   i   )         )         D   max     ⁡     (   i   )           ,         
D max (i) is the maximum value of grey levels of the pixel i based on RGB three channels on RGB color space; determining grey levels R o (i), G o (i) and B o (i) of the pixel based on RGB three channels on RGBW color space respectively by the yield value, where
 
 R   o ( i )= R ( i )× M−W   o ( i )
 
 G   o ( i )= G ( i )× M−W   o ( i )
 
 B   o ( i )= B ( i )× M−W   o ( i )
 
     R(i), G(i) and B(i) are grey levels of the pixel based on RGB three channels on RGB color space; determining data R s (i), G s (i), B s (i) and W s (i) based on RGBW color space corresponding to the most similar pixel of the pixel according to the most similar pixel of the pixel in the image. 
     To solve the technical obstacle above, another proposal according to the invention is: providing an offset method of a RGBW panel subpixel, including: inputting data of pixels based on RGB color space in an image; determining the most similar pixels of each of the pixels in the image according to the data of the pixels based on RGB color space; when the resolution of pixels is the same, converting the data of the pixels based on RGB color space to the data of the pixels based on RGBW color space to determination the data based on RGBW color space corresponding to the most similar pixels of the pixels; three fourths subsampling the pixels in the image according to the data of the pixels based on RGBW color space, the data based on RGBW color space corresponding to the most similar pixels of each of the pixels; outputting data of pixels in the image after being sampled. 
     The sequence of determining the most similar pixels of each of the pixels in the image according to the data of pixels based on RGB color space includes: converting the data of pixels based on RGB color space to data of the pixels based on HSI color space; calculating similarity of each of the pixels and adjacent pixels according to the data of the pixels based on HSI color space to achieve the most similar pixels of the each of the pixels. 
     The sequence of three fourths subsampling pixels in the image according to the data of pixels based on RGBW color space, the data based on RGBW color space corresponding to the most similar pixels of the pixels includes: dividing pixels in the image in an order of each group consisting of four pixels; adjusting arrangement of 16 subpixels in each of the groups, an arrangement of the 16 subpixels in each of the group after adjustment is: RGBW, WRGB, BWRG, GBWR; three fourths subsampling the 16 subpixels of each of the groups according to the arrangement of the 16 subpixels of each of the groups after adjustment, achieving arrangement of 4 three-channel subpixels of each of the groups: RGB, WRG, BWR, GBW, when the pixel i is RGBW, a strategy for sampling is: 
                 R   d     ⁡     (   i   )       =       P   r     ⁡     (   i   )                       G   d     ⁡     (   i   )       =       G   o     ⁡     (   i   )                         B   d     ⁡     (   i   )       =       B   o     ⁡     (   i   )         ,         
when the pixel i is WRGB, a strategy for sampling is:
 
                 W   d     ⁡     (   i   )       =       P   w     ⁡     (   i   )                       R   d     ⁡     (   i   )       =       R   o     ⁡     (   i   )                         G   d     ⁡     (   i   )       =       G   o     ⁡     (   i   )         ,         
when the pixel i is BWRG, a strategy for sampling is:
 
                 B   d     ⁡     (   i   )       =       P   b     ⁡     (   i   )                       W   d     ⁡     (   i   )       =       W   o     ⁡     (   i   )                         R   d     ⁡     (   i   )       =       R   o     ⁡     (   i   )         ,         
when the pixel i is GBWR, a strategy for sampling is:
 
                 G   d     ⁡     (   i   )       =       P   g     ⁡     (   i   )                       B   d     ⁡     (   i   )       =       B   o     ⁡     (   i   )                         W   d     ⁡     (   i   )       =       W   o     ⁡     (   i   )         ,         
R d (i), G d (i), B d (i) and W d (i) are respectively grey levels of the pixel i based on RGBW four channels on RGBW color space after being sampled, R o (i), G o (i), B o (i) and W o (i) are respectively grey levels of the pixel i based on RGBW four channels on RGBW color space before being sampled, P r (i) is achieved according to R s (i), R o (i) and R o (i−1), P w (i) is achieved according to W s (i), W o (i) and W o (i−1), P b (i) is achieved according to B s (i), B o (i) and B o (i−1), P g (i) is achieved according to G s (i), G o (i) and G o (i−1), R s (i), G s (i), B s (i) and W s (i) are gray levels based on RGBW four channels on RGBW color space corresponding to the most similar pixel of the pixel i, R o (i−1), G o (i−1), B o (i−1) and W o (i−1) are grey levels of RGBW four channels on the RGBW color space based on the pixel i−1 before being sampled.
 
     The P r (i), P w (i), P b (i) and P g (i) are determined by a formula 1, the formula 1 is:
 
 P   r ( i )=max( R   s ( i ), R   o ( i ), R   o ( i− 1))
 
 P   w ( i )=max( W   s ( i ), W   o ( i ), W   o ( i− 1)),
 
 P   b ( i )=max( B   s ( i ), B   o ( i ), B   o ( i− 1))
 
 P   g ( i )=max( G   s ( i ), G   o ( i ), G   o ( i− 1))
 
     max(R s (i), R o (i), R o (i−1)) is the maximum value in R s (i), R o (i) and R o (i−1), max(W s (i), W o (i), W o (i−1)) is the maximum value in W s (i), W o (i) and W o (i−1), max(B s (i), B o (i), B o (i−1)) is the maximum value in B s (i), B o (i) and B o (i−1), max(G s (i), G o (i), G o (i−1)) is the maximum value in G s (i), G o (i) and G o (i−1). 
     When the resolution of pixels is the same, the sequence that converting the data of the pixels based on RGB color space to the data of the pixels based on RGBW color space, and determining the data of the most similar pixels of the pixels corresponding to RGBW color space includes: determining a grey level W o (i) of the pixels based on white channels on RGBW color space, wherein W o (i)=D min (i), i is a position of the pixel, D min (i) is the minimum value of gray levels of the pixel i based on RGB three channels on RGB color space; calculating a yield value M of three channels RGB on the pixels, 
               M   =       (         W   o     ⁡     (   i   )       +       D   max     ⁡     (   i   )         )         D   max     ⁡     (   i   )           ,         
D max (i) is the maximum value of gray levels of the pixel i based on three channels RGB on RGB color space; determining grey levels R o (i), G o (i) and B o (i) of the pixel based on three channels RGB on RGBW color space respectively by the yield value, where
 
 R   o ( i )= R ( i )× M−W   o ( i )
 
 G   o ( i )= G ( i )× M−W   o ( i )
 
 B   o ( i )= B ( i )× M−W   o ( i )
 
     R(i), G(i) and B(i) are respectively grey levels of the pixel based on three channels RGB on RGB color space; determining data R s (i), G s (i), B s (i) and W s (i) based on RGBW color space corresponding to the most similar pixel of the pixel according to the most similar pixel of the pixel in the image. 
     To solve the technology problems above, another proposal according to the invention is: providing an offset equipment of a RGBW panel subpixel, the equipment including: an input module, applied to input data of pixels in an image based on RGB color space; a determination module, applied to determine the most similar pixels of each of the pixels in the image according to data of the pixels based on RGB color space; a conversion module, applied to convert data of the pixels based on RGB color space to data of the pixels based on RGBW color space when the resolution of pixels, so as to determine data based on RGBW color space corresponding to the most similar pixels of the pixels; a sample module, applied to three fourths subsample pixels in the image according to data of the pixels based on RGBW color space, data based on RGBW color space corresponding to the most similar pixels of each of the pixels; an output module, applied to output data of pixels in the image after being sampled. 
     The determination module includes: a conversion unit, applied to convert data of the pixels based on RGB color space to data of the pixels based on HSI color space; a first calculation unit, applied to calculate similarity of each of the pixels and adjacent pixels according to data of the pixels based on HSI color space to achieve the most similar pixels of the each of the pixels. 
     The sample module includes: a grouping unit, applied to divide pixels in the image in an order of each group consisting of four pixels in the RGBW color space; an adjustment unit, applied to adjust arrangement of 16 subpixels in each of the groups, an arrangement of the 16 pixels in each of the groups after adjustment is: RGBW, WRGB, BWRG, GBWR; a sample unit, applied to three fourths subsampling the 16 subpixels of each of the groups according to the arrangement of the 16 subpixels of each of the groups after adjustment, achieving arrangement of 4 three-channel subpixels of each of the groups: RGB, WRG, BWR, GBW, when the pixel i is RGBW, a strategy for sampling is: 
                 R   d     ⁡     (   i   )       =       P   r     ⁡     (   i   )                       G   d     ⁡     (   i   )       =       G   o     ⁡     (   i   )                         B   d     ⁡     (   i   )       =       B   o     ⁡     (   i   )         ,         
when the pixel i is WRGB, a strategy for sampling is:
 
                 W   d     ⁡     (   i   )       =       P   w     ⁡     (   i   )                       R   d     ⁡     (   i   )       =       R   o     ⁡     (   i   )                         G   d     ⁡     (   i   )       =       G   o     ⁡     (   i   )         ,         
when the pixel i is BWRG, a strategy for sampling is:
 
                 B   d     ⁡     (   i   )       =       P   b     ⁡     (   i   )                       W   d     ⁡     (   i   )       =       W   o     ⁡     (   i   )                         R   d     ⁡     (   i   )       =       R   o     ⁡     (   i   )         ,         
when the pixel i is GBWR, a strategy for sampling is:
 
                 G   d     ⁡     (   i   )       =       P   g     ⁡     (   i   )                       B   d     ⁡     (   i   )       =       B   o     ⁡     (   i   )                         W   d     ⁡     (   i   )       =       W   o     ⁡     (   i   )         ,         
R d (i), G d (i), B d (i) and W d (i) are respectively gray levels of the pixel i based on four channels RGBW on RGBW color space after being sampled, R o (i), G o (i), B o (i) and W o (i) are respectively gray levels of the pixel i based on four channels RGBW on RGBW color space before being sampled, P r (i) is achieved according to R s (i), R o (i) and R o (i−1), P w (i) is achieved according to W s (i), W o (i) and W o (i−1), P b (i) is achieved according to B s (i), B o (i) and B o (i−1), P g (i) is achieved according to G s (i), G o (i) and G o (i−1), R s (i), G s (i), B s (i) and W s (i) are grey levels based on RGBW four channels on RGBW color space corresponding to the most similar pixel of the pixel i, R o (i−1), G o (i−1), B o (i−1) and W o (i−1) are grey levels of RGBW four channels on the RGBW color space based on the pixel i−1 before being sampled.
 
     The P r (i), P w (i), P b (i) and P g (i) are determined by a formula 1, the formula 1 is:
 
 P   r ( i )=max( R   s ( i ), R   o ( i ), R   o ( i− 1))
 
 P   w ( i )=max( W   s ( i ), W   o ( i ), W   o ( i− 1))
 
 P   b ( i )=max( B   s ( i ), B   o ( i ), B   o ( i− 1))
 
 P   g ( i )=max( G   s ( i ), G   o ( i ), G   o ( i− 1))
 
     max(R s (i), R o (i), R o (i−1)) is the maximum value in R s (i), R o (i) and R o (i−1) max(W s (i), W o (i), W o (i−1)) is the maximum value in W s (i), W o (i) and W o (i−1) max(B s (i), B o (i), B o (i−1)) is the maximum value in B s (i), B o (i) and B o (i−1), max(G s (i), G o (i), G o (i−1)) is the maximum value in G s (i), G o (i) and G o (i−1). 
     The conversion module includes: a first determination unit, applied to determine a grey level W o (i) of the pixel based on white channels on RGBW color space, where W o (i)=D min (i), i is a position of the pixel, D min (i) is the minimum value of grey levels of the pixel i based on three channels RGB on RGB color space; a second calculation unit, applied to calculate a yield value M of three channels RGB on the pixels, where 
               M   =       (         W   o     ⁡     (   i   )       +       D   max     ⁡     (   i   )         )         D   max     ⁡     (   i   )           ,         
D max (i) is the maximum value of grey levels of the pixel i based on three channels RGB on RGB color space; a second determination unit, applied to determine grey levels R o (i), G o (i) and B o (i) of the pixel based on three channels RGB on RGBW color space respectively by the yield value, where
 
 R   o ( i )= R ( i )× M−W   o ( i )
 
 G   o ( i )= G ( i )× M−W   o ( i )
 
 B   o ( i )= B ( i )× M−W   o ( i )
 
     R(i), G(i) and B(i) are grey levels of the pixel based on three channels RGB on RGB color space respectively; a third determination unit, applied to determine data R s (i), G s (i), B s (i) and W s (i) based on RGBW color space corresponding to the most similar pixel of the pixel according to the most similar pixel of the pixel in the image. 
     Advantages of the invention are: distinguishing from the conventional technique, the most similar pixels of each of the pixels in an image are pre-determined according to the invention, when pixels in an image are three fourths subsampled, influence factors include the data of pixels based on RGBW color space as well as the data based on RGBW color space corresponding to the most similar pixels of each of pixels, therefore, resolution loss and jagged edges can be fixed accordingly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flow chart of an offset method of a RGBW panel subpixel according to a first exemplary embodiment of the invention; 
         FIG. 2  is a flow chart of an offset method of a RGBW panel subpixel according to a second exemplary embodiment of the invention; 
         FIG. 3  is a flow chart of an offset method of a RGBW panel subpixel according to a third exemplary embodiment of the invention; 
         FIG. 4  is a schematic view of pixels after being grouped and subpixels after arrangement in the method of offsetting a RGBW panel subpixel according to the invention; 
         FIG. 5  is a schematic view of subsampling process in the method of offsetting a RGBW panel subpixel according to the invention; 
         FIG. 6  is a schematic view of an offset method of a RGBW panel subpixel according to a second exemplary embodiment of the invention; 
         FIG. 7  is a schematic view of an image from a first comparative test of the offset method of a RGBW panel subpixel according to the invention,  FIG. 7 a    is an image shown RGB original blue vertical stripes,  FIG. 7 b    is a RGBW image achieved by interpolation according to the method in the reference,  FIG. 7 c    is a RGBW image achieved by interpolation according to the present method; 
         FIG. 8  is a schematic view of an image from a second comparative test of the offset method of a RGBW panel subpixel according to the invention,  FIG. 8 a    is an image shown RGB original blue oblique stripes,  FIG. 8 b    is a RGBW image achieved by interpolation according to the method in the reference,  FIG. 8 c    is a RGBW image achieved by interpolation according to the present method; 
         FIG. 9  is a schematic view of an image from a third comparative test of the offset method of a RGBW panel subpixel according to the invention,  FIG. 9 a    is a RGB original colored image,  FIG. 9 b    is a RGBW image achieved by interpolation according to the method in the reference,  FIG. 9 c    is a RGBW image achieved by interpolation according to the present method; 
         FIG. 10  is a schematic structural view of an offset equipment of a RGBW panel subpixel according to a first exemplary embodiment of the invention; 
         FIG. 11  is a schematic structural view of an offset method of a RGBW panel subpixel according to a second exemplary embodiment of the invention; 
         FIG. 12  is a schematic structural view of an offset method of a RGBW panel subpixel according to a third exemplary embodiment of the invention; 
         FIG. 13  is a schematic structural view of an offset method of a RGBW panel subpixel according to a fourth exemplary embodiment of the invention; 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. 
     Referring to  FIG. 1 , which is a flow chart of an offset method of a RGBW panel subpixel according to an exemplary embodiment of the invention, including: 
     Step S 101 : inputting data of pixels based on RGB color space in an image. 
     Step S 102 : determining the most similar pixels of each of the pixels in the image according to the data of the pixels based on RGB color space. 
     There are numerous methods to determination the similarity among pixels in an image according to conventional technology, for example: a conventional method to calculate the similarity of pixels, a method to calculate the similarity of pixels of spectrum cluster image segmentation, etc., the similarity of central pixels and surrounding pixels can be calculated according to the methods, the most similar pixel compared with central pixels can be determined by comparing the similarity, the pixel with the most similarity is the most similar pixel of the central pixels, the most similar pixel of each pixel in an image can be determined correspondingly. 
     Step S 103 : under a circumstance that resolution of pixels is the same, converting the data of the pixels based on RGB color space to data of the pixels based on RGBW color space, for determining the data based on RGBW color space corresponding to the most similar pixels of the pixels. 
     Same resolution of pixels means the number, size and dimension of each subpixel are all the same in RGB color space and RGBW color space. 
     In conventional technique, a number of methods can convert data of pixels based on RGB color space to data of pixels based on RGBW color space, for example: methods to extract red-green-blue-white signals from red-green-blue signals in conventional technique. 
     When resolution of pixels is the same, data of pixels based on RGB color space is converted to data of pixels based on RGBW color space by a conventional method, as the most similar pixel of pixels is pre-determined, data based on RGBW color space corresponding to the most similar pixel of pixels can be discovered accordingly. 
     For example, the most similar pixel of a pixel  11  is a pixel  21 , data of the pixel  21  based on RGBW color space can be discovered. Without uncertainty, during operation, data of RGBW color space based on the most similar pixel  21  of the pixel  11  can be re-converted to data of the pixel  21  based on RGBW color space, details in completing the process have no barriers. 
     Step S 104 : sub sampling three fourths of the pixels in the image according to the data of the pixels based on RGBW color space, the data based on RGBW color space corresponding to the most similar pixels of each of the pixels. 
     Subsample points to sample in a certain interval, a new sample achieved is a subsample of the original sample. 
     Some method for three fourths subsampling pixels in an image according to conventional technique merely employs ¾ interpolation of the entire pixels, which means only data of pixels based on RGBW color space is referred; besides considering data of pixels based on RGBW color space, influence of adjacent pixels is the only factor to be included, however, influence of horizontally adjacent cannot represent the real influence in application. In exemplary embodiments of the invention, data of pixels based on RGBW color space and data based on RGBW color space corresponding to the most similar pixel of each pixel are both in reference during three fourths subsampling pixels in an image, which means influence of the most similar pixel of each pixel on the pixel, in conventional technique, only considering data of pixels based on RGBW color space and data based on RGBW color space corresponding to the most similar pixel of each pixel is enough to three fourths subsample pixels in an image. More details group no limits. 
     Since the most similar pixel of the pixel and the pixel are alike, influence of the most similar pixel of the pixel on the pixel approaches to the influence in reality, therefore, resolution loss and jagged edges when subsampling the entire pixels can be mostly conquered. 
     Step S 105 : outputting data of pixels in the image after being sampled. 
     As the most similar pixel of each of the pixels in an image is pre-determined according to exemplary embodiments of the invention, when pixels in an image are three fourths subsampled, influence of data of pixels based on RGBW color space and data based on RGBW color space corresponding to the most similar pixel of each pixel should be considered, therefore, resolution loss and jagged edges when subsampling the entire pixels can be mostly conquered. 
     Referring to  FIG. 2 , the step S 102  can include: a sub step S 1021  and a sub step S 1022 . 
     Sub step S 1021 : converting the data of pixels based on RGB color space to data of the pixels based on HSI color space. 
     Sub step S 1022 : calculating similarity of each of the pixels and adjacent pixels according to the data of the pixels based on HIS color space, and achieving the most similar pixels of the each of the pixels. 
     Hue Saturation Intensity (HSI) color space or color model is characterized by H, S and I as color, where H defines wavelength of the color and is named hue; S represents saturation of the color and is named saturation; I is intensity or lightness. A color of an object is described in hue, saturation and intensity when observed. Hue describes property of a pure color, saturation measures the extent of a pure color diluted by a white light, intensity is a subjective description, actually which is not able to be measured, and gives conception of colorless intensity, intensity is a vital parameter to describe a color, intensity is the most useful factor in description of a monochromatic image, which is measurable and easily explained. The module can remove intensity from colored information in a color image, making the HSI model to become a useful tool to develop a method of analyzing images based on color description, the color description is apparent to people. 
     Data of pixels based on RGB color space is converted to data of pixels based on HSI color space, then the similarity of each pixel in HSI color space and 8 surrounding pixels is calculated, the pixel with the most similarity compared with the pixel is the most similar pixel of the pixel. 
     The similarity among pixels is measured by the HSI color space, as the color description with help of the HSI color model is apparent to people, therefore, the calculation of the most similar pixels of pixels approach to the reality, color distortion of pixels caused by subsample can be decreased. 
     Referring to  FIG. 3 , step S 104  can include: a sub step S 1041 , a sub step S 1042  and a sub step S 1043 . 
     Sub step S 1041 : In RGBW color space, grouping pixels in the image in an order of each group consisting of four pixels. 
     Sub step S 1042 : adjusting arrangement of 16 subpixels in the each group, the arrangement of the 16 pixels in the each group after being adjusted is: RGBW, WRGB, BWRG, GBWR. 
     Grouping and arrangement after being adjusted in step S 1041  and step S 1042  refer to  FIG. 4 . Four pixels grouped in one group are i,i+1, i+2 and i+3 respectively, before adjustment, a sequence of 16 subpixels in the four pixels i,i+1, i+2 and i+3 is RGBW, RGBW, RGBW, RGBW, a sequence of the 16 subpixels after adjustment is: RGBW, WRGB, BWRG, GBWR. 
     Sub step S 1043 : sub sampling three fourths of the 16 subpixels of the each group according to the arrangement of the 16 subpixels of the each group after being adjusted, achieving arrangement of 4 three-channel subpixels of the each group: RGB, WRG, BWR, GBW, 
     when the pixel i is RGBW, a strategy for sampling is: 
                 R   d     ⁡     (   i   )       =       P   r     ⁡     (   i   )                       G   d     ⁡     (   i   )       =       G   o     ⁡     (   i   )                         B   d     ⁡     (   i   )       =       B   o     ⁡     (   i   )         ,         
when the pixel i is WRGB, a strategy for sampling is:
 
                 W   d     ⁡     (   i   )       =       P   w     ⁡     (   i   )                       R   d     ⁡     (   i   )       =       R   o     ⁡     (   i   )                         G   d     ⁡     (   i   )       =       G   o     ⁡     (   i   )         ,         
when the pixel i is BWRG, a strategy for sampling is:
 
                 B   d     ⁡     (   i   )       =       P   b     ⁡     (   i   )                       W   d     ⁡     (   i   )       =       W   o     ⁡     (   i   )                         R   d     ⁡     (   i   )       =       R   o     ⁡     (   i   )         ,         
when the pixel i is GBWR, a strategy for sampling is:
 
                 G   d     ⁡     (   i   )       =       P   g     ⁡     (   i   )                       B   d     ⁡     (   i   )       =       B   o     ⁡     (   i   )                         W   d     ⁡     (   i   )       =       W   o     ⁡     (   i   )         ,         
R d (i), G d (i), B d (i) and W d (i) are respectively grey values of the pixel i based on four channels RGBW on RGBW color space after being sampled, R o (i), G o (i), B o (i) and W o (i) are respectively grey values of the pixel i based on four channels RGBW on RGBW color space before being sampled, P r (i) is achieved according to R s (i), R o (i) and R o (i−1), P w (i) is achieved according to W s (i), W o (i) and W o (i−1), P b (i) is achieved according to B s (i), B o (i) and B o (i−1), P g (i) is achieved according to G s (i), G o (i) and G o (i−1), R s (i), G s (i), B s (i) and W s (i) are grey levels of the RGBW four channels on the RGBW color space corresponding to the most similar pixel of the pixel i, R o (i−1), G o (i−1), B o (i−1) and W o (i−1) are grey levels of the RGBW four channels on the RGBW color space based on the pixel i−1 before being sampled.
 
     For example, P r (i) is an average value of a sum of R s (i), R o (i) and R o (i−1), or an average value of a sum after being weighted etc., P w (i) is an average value of a sum of W s (i), W o (i) and W o (i−1), or an average value of a sum after being weighted etc., P b (i) is an average value of a sum of B s (i), B o (i) and B o (i−1), or an average value of a sum after being weighted etc., P g (i) is an average value of a sum of G s (i), G o (i) and G o (i−1), or an average value of a sum after being weighted etc. 
     A process of the sub step S 1043  can refer to  FIG. 5 , four pixels grouped in one group are i, i+1, i+2 and i+3 respectively, the 16 subpixels are three fourths subsampled after adjustment, sequences of 4 three-channel subpixels in each group are: RGB, WRG, BWR and GBW, P r (i) derives from R s (i), R o (i) and R o (i−1), P w (i+1) derives from W s (i+1), W o (i+1) and W o (i), P b (i+2) derives from B s (i+2), B o (i+2) and B o (i+1), P g (i+3) derives from G s (i+3), G o (i+3) and G o (i+2). 
     P r (i), P w (i), P b (i) and P g (i) are determined by a formula 1, the formula 1 is:
 
 P   r ( i )=max( R   s ( i ), R   o ( i ), R   o ( i− 1))
 
 P   w ( i )=max( W   s ( i ), W   o ( i ), W   o ( i− 1)),
 
 P   b ( i )=max( B   s ( i ), B   o ( i ), B   o ( i− 1))
 
 P   g ( i )=max( G   s ( i ), G   o ( i ), G   o ( i− 1))
 
     max(R s (i), R o (i), R o (i−1)) is the maximum value in R s (i), R o (i) and R o (i−1), max(W s (i), W o (i), W o (i−1)) is the maximum value in W s (i), W o (i) and W o (i−1) max(B s (i), B o (i), B o (i−1)) is the maximum value in B s (i), B o (i) and B o (i−1), max(G s (i), G o (i), G o (i−1)) is the maximum value in G s (i), G o (i) and G o (i−1). 
     In other words, in the exemplary embodiment, P r (i) is the maximum grey level among R s (i), R o (i) and R o (i−1), P w (i) is the maximum grey level among W s (i), W o (i) and W o (i−1), P b (i) is the maximum grey level among B s (i), B o (i) and B o (i−1), P g (i) is the maximum grey level among G s (i), G o (i) and G o (i−1). 
     P r (i), P b (i), P b (i) and P g (i) are maximum values respectively, therefore, difference of edge pixels and other pixels can be preserved ultimately to increase resolution and decrease loss of image details. 
     Referring to  FIG. 6 , step S 103  can include: a sub step S 1031 , a sub step S 1032 , a sub step S 1033  and a sub step S 1034 . 
     Sub step S 1031 : determining a grey level W o (i) of the pixels based on white channels on RGBW color space, where W o (i)=D min (i), i is a position of the pixel, D min (i) is the minimum value of grey levels of the pixel i based on three channels RGB on RGB color space. 
     Sub step S 1032 : calculating a yield value M of three channels RGB on the pixels, where 
               M   =       (         W   o     ⁡     (   i   )       +       D   max     ⁡     (   i   )         )         D   max     ⁡     (   i   )           ,         
D max (i) is the maximum value of grey levels of the pixel i based on three channels RGB on RGB color space.
 
     Sub step S 1033 : determining grey levels R o (i), G o (i) and B o (i) of the pixel based on three channels RGB on RGBW color space respectively by the yield value, where
 
 R   o ( i )= R ( i )× M−W   o ( i )
 
 G   o ( i )= G ( i )× M−W   o ( i ),
 
 B   o ( i )= B ( i )× M−W   o ( i )
 
     R(i), G(i) and B(i) are grey levels of the pixel based on three channels RGB on RGB color space. 
     Sub step S 1034 : determining data R s (i), G s (i), B s (i) and W s (i) based on RGBW color space corresponding to the most similar pixel of the pixel according to the most similar pixel of the pixel in the image. 
     The invention can overcome loss of color gradation and fine strips of a strip RGBW panel caused by interpolation in a method referred to the paper (Kwon K J, Kim Y H. Scene-adaptive RGB-to-RGBW conversion using retinex theory-based color preservation [J]. Display Technology, Journal of, 2012, 8(12): 684-694.). To test the effectiveness of the invention, three groups of comparison images is employed to illustrate, the results are shown in  FIG. 7 a   ,  FIG. 7 b   ,  FIG. 7 c   ,  FIG. 8 a   ,  FIG. 8 b   ,  FIG. 8 c   ,  FIG. 9 a   ,  FIG. 9 b    and  FIG. 9 c    (note: the image is originally colored and processed to be hoary). 
       FIG. 7 a    is a RGB original blue vertical stripe image, the resolution is 256*256;  FIG. 7 b    is a RGBW image interpolated from the method in the reference, the resolution is 256*256 (strips in the figure is lost);  FIG. 7 c    is a RGBW image interpolated from the invention, the resolution is 256*256 (strips in the figure shift one pixel without loss).  FIG. 8 a    is a RGB original blue oblique strip image, the resolution is 256*256;  FIG. 8 b    is a RGBW image interpolated from the method in the reference, the resolution is 256*256 (strips in the figure is broken);  FIG. 8 c    is a RGBW image interpolated from the invention, the resolution is 256*256.  FIG. 9 a    is a RGB original colored image, the resolution is 256*256,  FIG. 9 b    is a RGBW image interpolated from the method in the reference, the resolution is 256*256 (strips in the figure are lost or broken);  FIG. 9 c    is a RGBW image interpolated from the invention, the resolution is 256*256. 
     The RGBW images interpolated from the method in the reference as shown in  FIG. 7 b   ,  FIG. 8 b    and  FIG. 9 b    can be distortion and broken, or even lost when display monochromatic strips; the RGBW images interpolated from the invention as shown in  FIG. 7 c   ,  FIG. 8 c    and  FIG. 9 c    can avoid the previous problems and reserve more information. 
     Referring to  FIG. 10 ,  FIG. 10  is a schematic structural view of an offset equipment of a RGBW panel subpixel according to a first exemplary embodiment of the invention, the equipment can execute the sequence of the method above, which can refer to the description above. 
     The equipment includes: an input module  101 , a determination module  102 , a conversion module  103 , a sample module  104  and an output module  105 . 
     The input module  101  is applied to input data of pixels in an image based on RGB color space. 
     The determination module  102  is applied to determination the most similar pixels of each of the pixels in the image according to data of the pixels based on RGB color space. 
     The conversion module  103  is applied to transform data of the pixels based on RGB color space to data of pixel based on RGBW color space, and determining data based on RGBW color space corresponding to the most similar pixels of the pixels. 
     The sample module  104  is applied to three fourths subsample pixels in the image according to data of the pixels based on RGBW color space, data based on RGBW color space corresponding to the most similar pixels of each of the pixels. 
     The output module  105  is applied to output data of pixels in the image after being sampled. 
     The most similar pixels of each of the pixels in an image are pre-determined according to the invention, when pixels in an image are three fourths subsampled, influence factors include data of pixels based on RGBW color space as well as data based on RGBW color space corresponding to the most similar pixels of each of pixels are both considered, therefore, resolution loss and jagged edges can be fixed accordingly. 
     Referring to  FIG. 11 , the determination module  102  includes: a conversion unit  1021  and a first calculation unit  1022 . 
     The conversion unit  1021  is applied to transform data of the pixels based on RGB color space to data of the pixels based on HSI color space. 
     The first calculation unit is applied to calculate similarity of each of the pixels and adjacent pixels according to the data of the pixels based on HSI color space, and achieving the most similar pixels of the each of the pixels. 
     Referring to  FIG. 12 , the sample module  104  includes: a grouping unit  1041 , an adjustment unit  1042  and a sample unit  1043 . 
     The grouping unit  1041  is applied to group pixels in the image in an order of each group consisting of four pixels in the RGBW color space. 
     The adjustment unit is applied to adjust arrangement of 16 subpixels in the each group, the arrangement of the 16 pixels in the each group after being adjusted is: RGBW, WRGB, BWRG, GBWR. 
     The sample unit, applied to three fourths subsample the 16 subpixels of the each group according to the arrangement of the 16 subpixels of the each group after being adjusted, achieving arrangement of 4 three-channel subpixels of the each group: RGB, WRG, BWR, GBW, 
     when the pixel i is RGBW, a strategy for sampling is: 
                 R   d     ⁡     (   i   )       =       P   r     ⁡     (   i   )                       G   d     ⁡     (   i   )       =       G     o   ⁢               ⁡     (   i   )                         B   d     ⁡     (   i   )       =       B   o     ⁡     (   i   )         ,         
when the pixel i is WRGB, a strategy for sampling is:
 
                 W   d     ⁡     (   i   )       =       P   w     ⁡     (   i   )                       R   d     ⁡     (   i   )       =       R     o   ⁢               ⁡     (   i   )                         G   d     ⁡     (   i   )       =       G   o     ⁡     (   i   )         ,         
when the pixel i is BWRG, a strategy for sampling is:
 
                 B   d     ⁡     (   i   )       =       P   b     ⁡     (   i   )                       W   d     ⁡     (   i   )       =       W     o   ⁢               ⁡     (   i   )                         R   d     ⁡     (   i   )       =       R   o     ⁡     (   i   )         ,         
when the pixel i is GBWR, a strategy for sampling is:
 
                 G   d     ⁡     (   i   )       =       P   g     ⁡     (   i   )                       B   d     ⁡     (   i   )       =       B     o   ⁢               ⁡     (   i   )                         W   d     ⁡     (   i   )       =       W   o     ⁡     (   i   )         ,         
R d (i), G d (i), B d (i) and W d (i) are respectively grey values of the pixel i based on four channels RGBW on RGBW color space after being sampled, R o (i), G o (i), B o (i) and W o (i) are respectively grey values of the pixel i based on four channels RGBW on RGBW color space before being sampled, P r (i) is achieved according to R s (i), R o (i) and R o (i−1), P w (i) is achieved according to W s (i), W o (i) and W o (i−1), P b (i) is achieved according to B s (i), B o (i) and B o (i−1), P g (i) is achieved according to G s (i), G o (i) and G o (i−1), R s (i), G s (i), B s (i) and W s (i) are grey levels of the RGBW four channels on the RGBW color space corresponding to the most similar pixel of the pixel i, R o (i−1), G o (i−1), B o (i−1) and W o (i−1) are grey levels of the RGBW four channels on the RGBW color space based on the pixel i−1 before being sampled.
 
     P r (i), P w (i), P b (i) and P g (i) are determined by a formula 1, the formula 1 is:
 
 P   r ( i )=max( R   s ( i ), R   o ( i ), R   o ( i− 1))
 
 P   w ( i )=max( W   s ( i ), W   o ( i ), W   o ( i− 1))
 
 P   b ( i )=max( B   s ( i ), B   o ( i ), B   o ( i− 1))
 
 P   g ( i )=max( G   s ( i ), G   o ( i ), G   o ( i− 1))
 
     max(R s (i), R o (i), R o (i−1)) is the maximum value in R s (i), R o (i) and R o (i−1), max(W s (i), W o (i), W o (i−1)) is the maximum value in W s (i), W o (i) and W o (i−1), max(B s (i), B o (i), B o (i−1)) is the maximum value in B s (i), B o (i) and B o (i−1), max(G s (i), G o (i), G o (i−1)) is the maximum value in G s (i), G o (i) and G o (i−1). 
     Referring to  FIG. 13 , the conversion module  103  includes: a determination unit  1031 , a second calculation unit  1032 , a second determination unit  1033  and a third determination unit  1034 . 
     The first determination unit is applied to determination a grey level W o (i) of the pixels based on white channels on RGBW color space, where W o (i)=D min (i), i is a position of the pixel, D min (i) is the minimum value of grey levels of the pixel i based on three channels RGB on RGB color space. 
     The second calculation unit, applied to calculate a yield value M of three channels RGB on the pixels, where 
               M   =       (         W   o     ⁡     (   i   )       +       D   max     ⁡     (   i   )         )         D   max     ⁡     (   i   )           ,         
D max (i) is the maximum value of grey levels of the pixel i based on three channels RGB on RGB color space.
 
     The second determination unit, applied to determination grey levels R o (i), G o (i) and B o (i) of the pixel based on three channels RGB on RGBW color space respectively by the yield value, where
 
 R   o ( i )= R ( i )× M−W   o ( i )
 
 G   o ( i )= G ( i )× M−W   o ( i )
 
 B   o ( i )= B ( i )× M−W   o ( i )
 
     R(i), G(i) and B(i) are grey levels of the pixel based on three channels RGB on RGB color space. 
     The third determination unit, applied to determination data R s (i), G s (i), B s (i) and W si ) based on RGBW color space corresponding to the most similar pixel of the pixel according to the most similar pixel of the pixel in the image. 
     The embodiments are preferred chosen and described in order to best explain the present invention. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. It is intended that the scope of the invention is defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated.