KR102520697B1 - Display device using subpixel rendering and image processing method thereof - Google Patents

Abstract

The present invention relates to a subpixel rendering display device and an image processing method capable of improving color drawing expression and text readability. Consisting of 2-color subpixels or 2-color subpixels among 3 colors, each pixel including a panel having a subpixel arrangement structure different from those of adjacent pixels in the vertical and horizontal directions, primary subpixel rendering The input data is firstly converted to fit the subpixel arrangement structure of the panel, and if a color edge in at least one direction is detected for the firstly converted data, the second subpixel rendering is performed according to the detected edge direction and pixel structure. Image processing of correcting data of a subpixel of a different color so that at least one subpixel of a different color is turned on among a pixel to which a subpixel constituting a color edge belongs and pixels adjacent to the pixel in an edge direction through It includes an image processing unit that performs

Description

Subpixel rendering display device and image processing method thereof

The present invention relates to a sub-pixel rendering display device and an image processing method capable of improving color grill expressiveness and text readability.

A display device usually displays a full color image using three color (RGB) subpixels including red (R), green (G), and blue (B), or uses white (W) to enhance luminance. A full color image may be displayed using WRGB subpixels to which subpixels are added.

In order to improve luminance and reduce power consumption, in a 4-color (WRGB) display, each pixel is composed of 3-color (WRG, BWR, GBW, RGB) subpixels in a different color arrangement order from adjacent pixels among the 4 colors (WRGB). An M+ WRGB structure is known which consists of or consists of two-color (WR, GB) subpixels. In a three-color (RGB) display, an RG-BG pentile structure in which two-color (RG, BG) subpixels constituting each pixel are arranged in a diamond shape is known.

The M+ WRGB structure display and the RG-BG pentile structure display are subpixels that distribute the source image to adjacent pixels by color according to the subpixel arrangement structure of the panel in order to utilize the color of the surrounding pixel for the color not present in each pixel. Since it uses a rendering algorithm, it can be expressed as a sub-pixel rendering display.

However, since subpixels of different colors are located in the subpixel rendering display in the horizontal and vertical directions, the subpixels of the same color are spaced apart from each other with subpixels of different colors interposed therebetween.

Due to this, when displaying each color grille of R, G, and B or displaying thin color text, the subpixel rendering display displays discontinuously or unclearly the color line or color text. There is a problem in that color drawing expressiveness and text readability are poor.

SUMMARY OF THE INVENTION The present invention provides a subpixel rendering display device and an image processing method thereof capable of improving color grill expressiveness and text readability.

In the sub-pixel rendering display device according to an embodiment of the present invention, each pixel is composed of 3-color sub-pixels or 2-color sub-pixels among 4 colors, or 2-color sub-pixels among 3 colors, and each pixel is configured in a vertical direction and a horizontal direction. The input data is firstly converted to fit the subpixel arrangement structure of the panel through a panel having a subpixel arrangement structure different from each other of adjacent pixels, a panel driving unit, and primary subpixel rendering, and converts the firstly converted data into If a color edge in at least one direction is detected, a pixel to which the subpixel constituting the color edge belongs and pixels adjacent to the pixel in the edge direction are rendered through secondary subpixel rendering according to the detected edge direction and pixel structure. and an image processing unit which performs image processing to correct data of at least one sub-pixel of a different color so that at least one sub-pixel of a different color is turned on, and outputs the image-processed data to the panel driving unit.

The image processing unit applies a first edge detection mask for each color channel to the primary conversion data, and if only one color channel satisfies the edge detection condition, detects a color edge in the first direction among the vertical and horizontal directions, and Correct the data of other color sub-pixels adjacent to the color edge of . The image processing unit applies a second edge detection mask for each color channel to the primary conversion data, and if only one color channel satisfies the edge detection condition, detects a color edge in the second direction among the vertical and horizontal directions, and Correct the data of other color sub-pixels adjacent to the color edge of . The image processing unit outputs the primary conversion data without data correction when no color edge is detected.

The panel includes white, red, green, and blue subpixels, and has a first pixel structure in which each pixel is composed of 3-color subpixels out of 4 colors, or a second pixel structure in which each pixel is composed of 2-color subpixels out of 4 colors. It has a 2-pixel structure.

When the color edge of any one of the red, green, and blue channels displayed on the panel is in the vertical direction, between the subpixels of the corresponding color constituting the color edge in the vertical direction and the subpixels of the corresponding color in the vertical direction Among the positioned pixels, white subpixels are turned on. When a color edge of one channel is in the horizontal direction, subpixels of the corresponding color constituting the color edge in the horizontal direction and white subpixels positioned between the subpixels of the corresponding color in the horizontal direction are turned on.

When the red or blue color edge displayed on the panel is in the vertical direction, the subpixels of the corresponding color belonging to the color edge in the vertical direction and the subpixel of the corresponding color in the pixel row between the subpixels of the corresponding color and the diagonal direction adjacent white subpixels are turned on. When a green color edge displayed on the panel is in the vertical direction, green subpixels belonging to the green color edge and white subpixels positioned between the green subpixels in the vertical direction are turned on.

Luminance of white subpixels is determined to be proportional to luminance of subpixels of a corresponding color belonging to a color edge.

The panel has a structure in which first pixels composed of green and red subpixels and second pixels composed of green and blue subpixels are alternately arranged in the horizontal and vertical directions, and the image processing unit displays red or blue color. Only edges are detected as color edges, and green color edges are not detected as color edges.

When a red or blue color edge displayed on the panel is in the vertical direction, both first pixels to which the color edge in the vertical direction belongs and second pixels positioned in the vertical direction between the first pixels are turned on. When the red or blue color edge is in the horizontal direction, the third pixels to which the color edge in the horizontal direction belongs and the fourth pixels located between the third pixels in the horizontal direction are all turned on.

An image processing method of a subpixel display device according to an embodiment includes the steps of firstly converting input data according to a subpixel arrangement structure of a panel through first subpixel rendering, and performing first conversion on each color channel on the firstly converted data. Detecting a color edge in a first direction among vertical and horizontal directions by applying an edge detection mask, and if a color edge in the first direction is detected, secondary subpixel rendering according to the first direction and the pixel structure of the panel Correcting data of other color subpixels adjacent to the color edge in the first direction, and applying a second edge detection mask for each color channel to the first-order converted data to obtain a color in a second direction among vertical and horizontal directions. detecting an edge; if a color edge in a second direction is detected, data of another color subpixel adjacent to the color edge in the second direction is obtained through secondary subpixel rendering in the second direction and according to the pixel structure of the panel; The step of correcting, and if no color edge is detected, the primary converted data is output without data correction.

In the subpixel rendering display device and its image processing method according to an embodiment of the present invention, when an input image is determined as a color edge corresponding to a color grill or color text using an edge detection method, the M+ WRGB structured display displays the color edge By utilizing the luminance of the white sub-pixels adjacent to the RG-BG pentile structure, the display of the RG-BG pentile structure utilizes the luminance of the other two-color sub-pixels adjacent to the color edge, thereby increasing the expressiveness of the color grille and color text. Color text can improve readability.

The sub-pixel rendering display device and its image processing method according to an embodiment of the present invention can not only improve the expressiveness of the color grill recognized by the naked eye, but also use the SSIM index, which quantifies the morphological similarity between the original image and the comparison image, in three colors. Since it can be increased to the level of (RGB) stripes, it is possible to prevent the resolution from being evaluated low even when the resolution is evaluated using the color grill image and the SSIM index.

1 is a diagram illustrating various pixel arrangement structures applied to a subpixel rendering display according to an embodiment of the present invention.
2 is a block diagram illustrating a subpixel rendering display device according to an embodiment of the present invention.
3 is a flowchart illustrating an image processing method of a subpixel rendering display device according to an embodiment of the present invention.
4 is a diagram illustrating a red grill in a vertical direction displayed on a display having an M+3-subpixel structure according to an embodiment of the present invention.
5 is a diagram illustrating a red grill in a horizontal direction displayed on a display having an M+3-subpixel structure according to an embodiment of the present invention.
6 is a diagram illustrating a green grill in a vertical direction displayed on a display having an M+3-subpixel structure according to an embodiment of the present invention.
7 is a diagram illustrating a green grill in a horizontal direction displayed on a display having an M+3-subpixel structure according to an embodiment of the present invention.
8 is a diagram illustrating a blue grill in a vertical direction displayed on a display having an M+3-subpixel structure according to an embodiment of the present invention.
9 is a diagram illustrating a blue grille in a horizontal direction displayed on a display having an M+3-subpixel structure according to an embodiment of the present invention.
10 is a diagram illustrating a red grill in a vertical direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.
11 is a diagram illustrating a red grill in a horizontal direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.
12 is a diagram illustrating a green grill in a vertical direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.
13 is a diagram illustrating a green grill in a horizontal direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.
14 is a diagram illustrating a blue grill in a vertical direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.
15 is a diagram illustrating a blue grille in a horizontal direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.
16 is a diagram illustrating a red and blue grill in a vertical direction displayed on a pentile-structured display according to an embodiment of the present invention.
17 is a diagram illustrating a red and blue grill in a horizontal direction displayed on a pentile-structured display according to an embodiment of the present invention.
18 is a diagram illustrating a comparison between the expressiveness of each color grill displayed on a display having an M+3-subpixel structure according to an exemplary embodiment of the present invention and a prior art.
19 is a graph showing a comparison of SSIM indices for each color grille image displayed on a display having an M+3-subpixel structure according to the prior art and an embodiment of the present invention.
FIG. 20 is a diagram illustrating a comparison between the expressiveness of each color grille displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention and the prior art.
21 is a graph showing a comparison of SSIM indices for each color grill image displayed on a display having an M+2-subpixel structure according to the prior art and an embodiment of the present invention.
22 is a diagram showing the expressiveness of each color grill displayed on a display having a pentile structure according to the prior art and an embodiment of the present invention.
23 is a graph showing a comparison of SSIM indices for each color grill image displayed on a display having a pentile structure according to the prior art and an embodiment of the present invention.
24 is a diagram showing a comparison between red, green and blue texts displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention and the prior art.

1 is a diagram illustrating various pixel arrangement structures applied to a subpixel rendering display according to an embodiment of the present invention.

As shown in FIGS. 1(a) and 1(b), each pixel is a sub-pixel rendering display of 3 colors (WRG, BWR, GBW, RGB) or 2 colors (WR, GB) out of 4 colors (WRGB). An M+ pixel structure composed of pixels may be used. As shown in FIG. 1(c), the subpixel rendering display may use a pentile pixel structure in which each pixel is composed of subpixels of two colors (RG, BG). Such a sub-pixel rendering display has an advantage of reducing power consumption and manufacturing cost while being advantageous in realizing high luminance and high resolution as an aperture ratio (emission area) is increased compared to an RGB stripe structure.

Figure 1 (a) shows the 3-subpixel structure of M+ WRGB, each pixel is composed of 3 color (WRG, BWR, GBW, RGB) subpixels among 4 colors (WRGB), 2 * 4 pixels The pixel group 110 consisting of is repeated in the horizontal and vertical directions to form a pixel array. Each pixel group 110 includes WRG pixels (first pixels), BWR pixels (second pixels), GBW pixels (third pixels), RGB pixels (fourth pixels) sequentially disposed in the first row, and GBW pixels (fifth pixels), RGB pixels (sixth pixels), WRG pixels (seventh pixels), and BWR pixels (eighth pixels) are arranged in the second row in a different order from the rows.

1(b) shows a 2-subpixel structure of M+ WRGB, each pixel is composed of 2-color (WR, GB) sub-pixels among 4 colors (WRGB), and a pixel composed of 2*2 pixels Groups 120 are repeated horizontally and vertically to form a pixel array. Each pixel group 120 includes WR pixels (first pixels) and GB pixels (second pixels) sequentially arranged in the first row, and GB pixels (third row) arranged in the second row in the opposite order to the first row. pixel) and a WR pixel (fourth pixel).

1(c) shows a pentile structure, each pixel is composed of subpixels of two colors (GR, GB) among three colors (RGB), and a pixel group 130 composed of 2*2 pixels is It is repeated in the horizontal and vertical directions to form a pixel array. Each pixel group 130 includes GR pixels (first pixels) and GB pixels (second pixels) sequentially disposed in the first row, and GB pixels (second pixels) disposed in the second row in the opposite order to the first row. pixel) and a GR pixel (fourth pixel).

In the M+ WRGB pixel structure shown in FIGS. 1(a) and (b), it can be seen that subpixels of different colors are located in the horizontal and vertical directions. When displaying a color grill in which one of red (R), green (G), and blue (B) color lines alternates with a black line on a line-by-line basis in such a pixel structure, a line shape occurs due to the spacing of subpixels of the same color. Since is not clear, the expressiveness of the color grill may deteriorate.

In order to solve this problem, the subpixel rendering display device according to an embodiment utilizes the luminance of a white subpixel adjacent to a subpixel of a corresponding color through subpixel rendering along an edge direction, thereby clearly displaying a color grille, thereby increasing color grille expressiveness. can improve In addition, even when text of each color is displayed, text readability can be improved by clearly displaying text by further utilizing surrounding white subpixels through subpixel rendering. A detailed subpixel rendering method according to an embodiment for this purpose will be described later.

In the pentile structure shown in FIG. 1(c), it can be seen that red (R) and blue (B) subpixels excluding the green (G) subpixel are alternately positioned in the horizontal and vertical directions. When a color grille is expressed in such a pixel structure, red and blue subpixels excluding green are spaced apart from subpixels of the same color, and thus the expressiveness of the red or blue color grille or the readability of text may deteriorate.

In order to solve this problem, a subpixel rendering display device according to an embodiment utilizes the low grayscale luminance of subpixels of a different color adjacent to a subpixel of a corresponding color through subpixel rendering along an edge direction, thereby improving color grill expressiveness and text readability. can improve A detailed subpixel rendering method according to an embodiment for this purpose will be described later.

2 is a block diagram showing the configuration of a subpixel rendering display device according to an embodiment of the present invention.

Referring to FIG. 2 , the display device includes a panel 100 , a gate driver 200 , a data driver 300 , a timing controller 400 , a gamma voltage generator 500 , and the like.

The panel 100 displays an image through a pixel array. The panel 100 may use any one of various pixel structures shown in FIG. 1 . The panel 100 may use all types of display panels including a liquid crystal display (LCD) panel, an organic light emitting diode (OLED) display panel, and an LED display panel.

The gate driver 200 and the data driver 300 shown in FIG. 2 may be expressed as a panel driver that drives the panel 100 .

The gate driver 200 receives a plurality of gate control signals from the timing controller 400 and performs a shift operation to individually drive the gate lines of the panel 100 . The gate driver 200 supplies a gate-on voltage scan signal to the corresponding gate line during the driving period of each gate line, and supplies a gate-off voltage to the corresponding gate line during the non-driving period of each gate line.

The gate driver 200 according to an embodiment is composed of one or a plurality of gate ICs (Integrated Circuits), and the gate ICs are individually mounted on a circuit film such as COF (Chip On Film) to form a TAB (TAB) on the panel 100. It may be bonded and connected in a Tape Automatic Bonding (Tape Automatic Bonding) method or mounted on the panel 100 in a COG (Chip On Glass) method. Meanwhile, the gate driver 200 according to an exemplary embodiment is formed on a substrate together with a thin film transistor array constituting a pixel array of the panel 100 and is provided in a non-display area of both sides or one side of the panel 100 (GIP). In Panel) type can be embedded.

The gamma voltage generator 500 generates a reference gamma voltage set including a plurality of reference gamma voltages having different voltage levels and supplies it to the data driver 300 . The gamma voltage generator 500 may adjust the reference gamma voltage level according to the control of the timing controller 400 .

The data driver 300 is controlled according to the data control signal supplied from the timing controller 400, converts the digital data supplied from the timing controller 400 into an analog data signal, and supplies it to the data lines of the panel 100. . At this time, the data driver 300 converts digital data into an analog data signal using grayscale voltages in which a plurality of reference gamma voltages supplied from the gamma voltage generator 500 are subdivided, and converts the analog data signal into a data signal of the panel 100. supply to the lines.

The data driver 300 is composed of a plurality of data ICs, and the data ICs are individually mounted on a circuit film such as COF (Chip On Film) and bonded to the panel 100 by a TAB (Tape Automatic Bonding) method, or COG ( Chip On Glass) method may be mounted on the panel 100.

The timing controller 400 receives three color (RGB) source image signals and timing control signals from the host system. The host system may be any one of a system of a portable terminal such as a computer, a TV system, a set-top box, a tablet or a mobile phone. The timing control signals may include a dot clock, a data enable signal, a vertical sync signal, a horizontal sync signal, and the like.

The timing controller 400 generates a plurality of data control signals for controlling driving timing of the data driver 300 by using the supplied timing control signals and timing setting information stored therein, and supplies them to the data driver 300. , A plurality of gate control signals for controlling driving timing of the gate driver 200 are generated and supplied to the gate driver 400 .

The timing controller 400 includes an image processing unit 600 that performs various image processing including subpixel rendering on the supplied source image and outputs the image to the data driver 300 . Meanwhile, the image processing unit 600 may be separated from the timing controller 400 and positioned to be connected to an input terminal of the timing controller 400. In this case, the output of the image processing unit 600 is a data driver through the timing controller 400. (300).

The image processing unit 600 performs primary subpixel rendering on the input image to firstly convert 3-color source data into WRGB data or RGBG data corresponding to the pixel structure shown in FIG. 1 . The image processing unit 600 performs edge detection for each color channel on the primary converted data to obtain a 1*k pixel size corresponding to a color grill or color text of any one of red, green, and blue (where k is greater than 2). integer) or k*1 pixel-sized color edges. The image processing unit 600 corrects data to utilize the luminance of other adjacent subpixels by performing secondary subpixel rendering according to the edge direction when it is determined to be a color edge, and renders secondary subpixels when it is not determined to be a color edge , that is, no data correction is performed.

When the panel 100 has an M+ pixel structure, the image processing unit 600 corrects the luminance of a white subpixel adjacent to a subpixel of a corresponding color, that is, white (W) data, through secondary subpixel rendering. When the panel 100 has a pentile structure, the image processing unit 600 controls the luminance of other color subpixels adjacent to any one of red and blue subpixels other than green, that is, data of one of the two colors (RB). and green (G) data are calibrated.

As a result, the discontinuity or unclear boundary of the color edge is compensated by the surrounding sub-pixels of different colors, so that the expressive power of the color grill and color text can be improved.

The image processing unit 600 performs edge determination in the first direction and subpixel rendering in the first direction among the horizontal and vertical directions on the image of one frame, and then determines the edge in the second direction and sub-pixel rendering in the second direction. You can do pixel rendering. The image processor 600 outputs image-processed data to the data driver 300 .

Meanwhile, the image processing method of the image processing unit 600 may further include other compensation processes such as degradation compensation, which are performed after primary subpixel rendering and before secondary subpixel rendering. That is, it is preferable to improve the expressive power of a color grill or color text that the secondary subpixel rendering process is performed after other compensation processes are completed.

3 is a flowchart illustrating an image processing method of a subpixel rendering display device according to an embodiment of the present invention, and is performed by the image processing unit 600 shown in FIG. 2 .

The image processing method of the image processing unit 600 shown in FIG. 3 includes a degamma correction step (S310), a first sub-pixel rendering step (S320), color edge determination to improve the expressiveness of color grills or color text, and second sub-pixels. A pixel rendering step (S330, S340) and a gamma correction step (S350) are included.

The image processor 600 performs de-gamma correction on the supplied input image (S310). The image processing unit 600 converts 3-color gradation data, which is a non-linear color value of the input image, into 3-color luminance data (hereinafter, abbreviated as 3-color data), which is a linear color value, using a predetermined de-gamma lookup table (LUT) do.

The image processing unit 600 performs primary subpixel rendering on the linear three-color data and first converts it into four-color data or three-color data corresponding to the pixel structure of the panel 100 (S320). The image processing unit 600 performs primary subpixel rendering on linear three-color data using a first rendering filter predetermined according to the pixel structure of the panel 100, thereby generating the M+3-subpixels shown in FIG. 1. WRGB data corresponding to the structure or M+2-subpixel structure, or firstly converted to RGBG data corresponding to the pentile subpixel structure.

The image processing unit 600 performs color edge determination and secondary sub-pixel rendering steps (S330 and S340) on the primary transformed data. The color edge determination and secondary subpixel rendering steps (S330 and S340) include a vertical color edge determination and subpixel rendering step (S330) and a horizontal color edge determination and subpixel rendering step (S340). Here, the order of determining the color edge in the vertical direction and rendering the subpixel (S330) and determining the color edge in the horizontal direction and rendering the subpixel (S340) may be interchanged.

The image processing unit 600 horizontally shifts the first edge detection mask for each channel to data of a 3-color (RGB) channel or 2-color (RB) channel among the first-order converted data, and applies the 3-color (RGB) or 2-color (RB) channel data. It is determined whether it is a color edge in the vertical direction corresponding to a vertical grill or text of any one color among the colors (RB) (S332), and if it is determined as a color edge in the vertical direction (Y), subpixel rendering is performed in the vertical direction It is performed (S334). When the panel 100 has an M+ pixel structure, the image processing unit 600 applies a first edge detection mask to each of the three color (RGB) channels, and when the panel 100 has a pentile structure, the image processing unit 600 A first edge detection mask is applied to each of the two-color (RB) channels except green.

For example, as shown in Table 1 below, the image processing unit 600 applies a first edge detection mask having a size of 1*2 pixels to each color data while shifting it in a pixel unit in a horizontal direction. As a result of applying the first mask, the image processing unit 600 calculates the current pixel data P(i, j) and the previous pixel data P(i, j-1) that are horizontally adjacent to each other in the horizontal direction as shown in Equation 1 below only for any one color channel as a result of applying the first mask. If the absolute value (|α|) of the luminance difference (α) of is greater than or equal to the preset threshold value (TH), the current pixel is determined as a color edge in the vertical direction, and in other cases, it is not determined as a color edge. . In addition to the first edge detection mask of Table 1 below, the image processing unit 600 may use edge detection masks of various sizes or various edge detection methods to determine whether there is a color edge. In Table 1, i and j represent pixel locations, and c represents color (R, G, and B) channels.

P(i, j-1, c) P(i, j, c)

<Equation 1>

α = P(i, j, c) - P(i, j-1, c)

When the image processing unit 600 determines that the color edge is in the vertical direction (S332, Y), by performing secondary subpixel rendering in the vertical direction, the luminance of another color subpixel of a pixel vertically adjacent to the current pixel is corrected. Do (S334).

When the panel 100 has an M+ pixel structure, the image processor 600 performs secondary subpixel rendering in a vertical direction, corrects the luminance of a white subpixel among pixels adjacent to the current pixel, and turns on the white subpixel. The luminance of the white subpixel is determined in consideration of the luminance of the subpixel determined as the color edge. The luminance of the white subpixel may be determined by applying a luminance deviation α between two adjacent pixels of the corresponding color and a first compensation gain in proportion to the luminance of the subpixel determined as the color edge.

When the panel 100 has a pentile structure, the image processing unit 600 corrects the luminance of subpixels of other colors adjacent to the current subpixel to display a low grayscale by performing secondary subpixel rendering in a vertical direction. At this time, the luminance of the other color sub-pixel is determined low enough that the color difference between before and after correction cannot be recognized. The luminance of another color subpixel may be determined by applying a luminance deviation (α) between two adjacent pixels of a corresponding color determined as a color edge and a second compensation gain.

Meanwhile, if the image processing unit 600 does not determine the color edge in the vertical direction (S332, N), the image processing unit 600 does not perform the above-described vertical secondary subpixel rendering, that is, the next step (S340) without data correction of neighboring subpixels. ) to proceed.

The image processing unit 600 performs edge determination in the vertical direction and the subpixel rendering step (S320) on the image of one frame, and then determines the edge in the horizontal direction and performs the subpixel rendering step (S340).

The image processing unit 600 applies the second edge detection mask while shifting it in the vertical direction to data of a 3-color (RGB) channel or 2-color (RB) channel among the first-order converted data to obtain 3-color (RGB) or 2-color ( RB), it is determined whether it is a color edge in the horizontal direction corresponding to a horizontal grill or text of any one color (S342), and if it is determined as a color edge in the horizontal direction (Y), subpixel rendering is performed in the horizontal direction (S342). S344).

For example, as shown in Table 2 below, the image processing unit 600 applies a second edge detection mask having a size of 2*1 pixels to each color data while shifting it in a pixel unit in a vertical direction. As a result of applying the second edge detection mask, the image processing unit 600 calculates the current pixel data P(i, j) and the previous pixel data P(i-1, If the absolute value (|β|) of the luminance difference (β) of j) is greater than or equal to the preset threshold value (TH), the current pixel is determined as a color edge in the vertical direction, and judged as a color edge in other cases. I never do that. In addition to the second edge detection mask of Table 1 below, the image processing unit 600 may use edge detection masks of various sizes or various edge detection methods to determine whether there is a color edge.

P(i-1, j, c) P(i, j, c)

<Equation 2>

β = P(i, j, c) - P(i-1, j, c)

If it is determined that the color edge is in the horizontal direction (S342, Y), the image processing unit 600 corrects the luminance of another color sub-pixel horizontally adjacent to the current pixel by performing secondary sub-pixel rendering in the horizontal direction (S342, Y). S344).

When the panel 100 has an M+ pixel structure, the image processing unit 600 corrects the luminance of a white subpixel horizontally adjacent to the current subpixel by performing secondary subpixel rendering in a horizontal direction.

When the panel 100 has a pentile structure, the image processing unit 600 corrects luminance of subpixels of different colors adjacent to the current subpixel by performing secondary subpixel rendering in a horizontal direction.

Meanwhile, if the image processing unit 600 does not determine the color edge in the horizontal direction (S342, Y), the image processor 600 does not perform the aforementioned horizontal secondary subpixel rendering, that is, does not correct the data of the surrounding subpixels, and proceeds to the next step (S350). ) to proceed.

The image processing unit 600 performs the horizontal direction edge determination and the subpixel rendering step (S320) on the image of one frame, and then performs the gamma correction step (S350).

The image processor 600 performs gamma correction on the data output from the previous step (S340) and outputs the data (S350). The image processing unit 600 converts linear color values of 4-color or 3-color data into non-linear color values using gamma LUT and outputs the converted color values.

4 is a diagram illustrating a red grill in a vertical direction displayed on a display having an M+3-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 4(a) , when displaying a red grille in odd rows, the W subpixels of GBW pixels vertically adjacent to the WRG pixels are turned on together with the R subpixels of WRG pixels in odd rows, so that the odd rows are displayed. The expressiveness of the red grill is improved.

In other words, when displaying an odd-numbered row red grille, odd-numbered rows (mod(i, 2) = 1) and W subpixels belonging to the GBW pixels of the 4M-1 column (mod (j, 4) = 3), and even rows (mod (i, 2) = 0) and the 4M-3 column (mod (j , 4) = 1), the W subpixel belonging to the GBW pixel is turned on, and the remaining subpixels are turned off.

Referring to FIG. 4(b), when displaying a red grill in even rows, the W subpixel of the BWR pixel adjacent to the RGB pixel in the vertical direction is turned on together with the R subpixel of the RGB pixel in the even row, so that the even row is displayed. The expressiveness of the red grill is improved.

In other words, when displaying the even-numbered row red grille, the odd-numbered row and the 4M-2th column (mod (j, 4) = 2 ) and W subpixels of BWR pixels belonging to even rows and 4M columns (mod(j, 4) = 0) are turned on, and the remaining subpixels are turned off.

The luminance W' of the turned-on W subpixel is determined to be proportional to the luminance of the turned-on R subpixel. For example, the data (W') of the turned-on W subpixel is the first R proportional to the R data difference value (α) between two horizontally adjacent pixels and the luminance of the R subpixel as shown in Equation 3 below. It is determined by the multiplication result of the compensation gain (Gain_R). As the R data difference value (α) between two adjacent pixels increases, the luminance (W') of the W sub-pixel increases, thereby improving the expressiveness of the red drawing.

<Equation 3>

W' = α*Gain_R

5 is a diagram illustrating a red grill in a horizontal direction displayed on a display having an M+3-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 5(a) , when a red grille for odd rows is displayed, along with R subpixels in odd rows, W subpixels horizontally adjacent to the R subpixels are turned on, thereby turning on the red color displayed in odd rows. The expressive power of drawing is improved.

In other words, when displaying the odd-numbered row red grille, together with the R subpixels belonging to the WRG, BWR, and RGB pixels of the 4M-3, 4M-2, and 4M columns of the odd-numbered row, WRG of column 4M-3 (mod (j, 4) = 1), column 4M-2 (mod (j, 4) = 2), column 4M-1 (mod (j, 4) = 3), W subpixels belonging to the BWR and GBW pixels are turned on, and the remaining subpixels are turned off.

Referring to FIG. 5( b ), when displaying a red grille in an even row, the R subpixels of the even row and the W subpixel horizontally adjacent to the R subpixel are turned on, thereby turning on the red color displayed in the even row. The expressive power of drawing is improved.

In other words, when displaying an even-numbered row red grill, together with the R subpixels belonging to the RGB, WRG, and BWR pixels of the 4M-2 column, 4M-1 column, and 4M column of the even-numbered row, GBW, WRG of column 4M-3 (mod (j, 4) = 1), column 4M-1 (mod (j, 4) = 3), column 4M (mod (j, 4) = 0), The W subpixel belonging to the BWR pixel is turned on, and the remaining subpixels are turned off.

The luminance W' of the turned-on W subpixel is determined to be proportional to the luminance of the turned-on R subpixel. For example, the data (W') of the turned-on W subpixel is proportional to the difference value (β) of R data between two vertically adjacent pixels and the luminance of the R subpixel as shown in Equation 4 below. It is determined by the multiplication result of the R compensation gain (Gain_R).

<Equation 4>

W' = β*Gain_R

6 is a diagram illustrating a green grill in a vertical direction displayed on a display having an M+3-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 6(a) , when displaying a green grill in odd rows, the W subpixel of the GBW pixel and the WRG pixel vertically adjacent to the GBW pixel are turned on together with the G subpixel of the GBW pixel in the odd row, so that the odd row is displayed. The expressiveness of the green grille is improved.

In other words, when displaying an odd-numbered row green grille, odd-numbered rows (mod(i, 2)=1) and 4M-th, together with G subpixels belonging to GBW pixels in columns 4M-3 and 4M-1 W subpixels belonging to the WRG pixels in the -3 column (mod (j, 4) = 1), even rows (mod (i, 2) = 0) and the 4M-1 column (mod (j, 4) = 3 ) is turned on, and the other subpixels are turned off.

Referring to FIG. 6(b), when displaying a green grill in even rows, the W subpixel of the BWR pixel adjacent to the RGB pixel in the vertical direction is turned on together with the G subpixel of the RGB pixels in the even row, so that the even rows are displayed. The expressiveness of the green grille is improved.

In other words, when displaying the even-numbered row green grille, the odd-numbered row and the 4M-2th column (mod(j, 4) = 2 ) and W subpixels of BWR pixels belonging to even rows and 4M columns (mod(j, 4) = 0) are turned on, and the remaining subpixels are turned off.

The luminance of the turned-on W subpixel is determined to be proportional to the luminance of the turned-on G subpixel. For example, the data (W') of the turned-on W subpixel is proportional to the difference value (α) of G data between two horizontally adjacent pixels and the luminance of the G subpixel as shown in Equation 5 below. The G compensation gain (Gain_G) is determined by the multiplication result.

<Equation 5>

W' = α*Gain_G

7 is a diagram illustrating a green grill in a horizontal direction displayed on a display having an M+3-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 7(a) , when displaying a green grill in odd rows, the W subpixels horizontally adjacent to the G subpixels along with the G subpixels in the odd rows are turned on, so that the red color displayed in the odd rows is turned on. The expressive power of drawing is improved.

In other words, when displaying an odd-numbered row green grille, together with the G subpixels belonging to the WRG, GBW, and RGB pixels of the 4M-3, 4M-1, and 4M columns of the odd-numbered row, WRG of column 4M-3 (mod (j, 4) = 1), column 4M-2 (mod (j, 4) = 2), column 4M-1 (mod (j, 4) = 3), W subpixels belonging to the BWR and GBW pixels are turned on, and the remaining subpixels are turned off.

Referring to FIG. 7( b ), when a green grille in even rows is displayed, along with G subpixels in even rows, W subpixels horizontally adjacent to the G subpixels are turned on, so that green is displayed in even rows. The expressive power of drawing is improved.

In other words, when displaying an even-numbered row green grille, together with the G subpixels belonging to the GBW, RGB, and WRG pixels of the 4M-3, 4M-1, and 4M columns of the even-numbered rows, GBW, WRG of column 4M-3 (mod (j, 4) = 1), column 4M-1 (mod (j, 4) = 3), column 4M (mod (j, 4) = 0), W subpixels belonging to the BWR pixel are turned on, and the remaining subpixels are turned off.

The luminance of the turned-on W subpixel is determined to be proportional to the luminance of the turned-on G subpixel. For example, the data (W') of the turned-on W subpixel is proportional to the difference value (β) of G data between two vertically adjacent pixels and the luminance of the G subpixel as shown in Equation 6 below. It is determined by the result value multiplied by the G compensation gain (Gain_G).

<Equation 6>

W' = β*Gain_G

8 is a diagram illustrating a blue grill in a vertical direction displayed on a display having an M+ 3-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 8(a), when displaying a blue grille in odd rows, the W subpixel of the WRG pixel adjacent to the GBW pixel in the vertical direction is turned on together with the B subpixel of the GBW pixel in the odd row, so that the odd rows are displayed. The expressive power of the blue grille is improved.

In other words, when displaying the odd-numbered row blue grille, odd-numbered rows (mod(i, 2)=1) and 4M-th rows together with B subpixels belonging to GBW pixels in columns 4M-3 and 4M-1 W subpixels belonging to the WRG pixels in the -3 column (mod (j, 4) = 1), even rows (mod (i, 2) = 0) and the 4M-1 column (mod (j, 4) = 3 ) is turned on, and the other subpixels are turned off.

Referring to FIG. 8(b), when displaying a blue grille in even rows, the B subpixel of the RGB pixels in the even rows and the W subpixel of the BWR pixels vertically adjacent to the RGB pixels are turned on, so that the even rows are displayed. The expressive power of the blue grille is improved.

In other words, when displaying an even-numbered row blue grille, odd rows and 4M-2 columns (mod (j, 4) = 2 ) and W subpixels of BWR pixels belonging to even rows and 4M columns (mod(j, 4) = 0) are turned on, and the remaining subpixels are turned off.

The luminance of the turned-on W subpixel is determined to be proportional to the luminance of the turned-on B subpixel. For example, the data (W') of the turned-on W subpixel is proportional to the difference value (α) of B data between two horizontally adjacent pixels and the luminance of the B subpixel as shown in Equation 7 below. It is determined by the result value multiplied by the B compensation gain (Gain_B).

<Equation 7>

W' = α*Gain_B

9 is a diagram illustrating a blue grille in a horizontal direction displayed on a display having an M+ 3-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 9(a) , when a green grille is displayed on odd rows, the B subpixels of odd rows and the W subpixels horizontally adjacent to the B subpixels are turned on, so that the blue color displayed on odd rows is turned on. The expressive power of drawing is improved.

In other words, when displaying an odd-numbered row blue grille, together with the B subpixels belonging to the BWR, GBW, and RGB pixels of the 4M-2 column, 4M-1 column, and 4M column of the odd-numbered row, WRG of column 4M-3 (mod (j, 4) = 1), column 4M-2 (mod (j, 4) = 2), column 4M-1 (mod (j, 4) = 3), W subpixels belonging to the BWR and GBW pixels are turned on, and the remaining subpixels are turned off.

Referring to FIG. 9(b) , when a blue grille is displayed in an even row, the B subpixels of the even row and the W subpixel horizontally adjacent to the B subpixel are turned on, so that the green color displayed in the even row is turned on. The expressive power of drawing is improved.

In other words, when displaying an even-numbered row blue grill, together with the B subpixels belonging to the GBW, RGB, and BWR pixels of the 4M-3, 4M-2, and 4M columns of the even-numbered row, GBW, WRG of column 4M-3 (mod (j, 4) = 1), column 4M-1 (mod (j, 4) = 3), column 4M (mod (j, 4) = 0), W subpixels belonging to the BWR pixel are turned on, and the remaining subpixels are turned off.

The luminance of the turned-on W subpixel is determined to be proportional to the luminance of the turned-on B subpixel. For example, the data (W') of the turned-on W subpixel is proportional to the difference value (β) of B data between two vertically adjacent pixels and the luminance of the B subpixel as shown in Equation 8 below. It is determined by the result value multiplied by the B compensation gain (Gain_B).

<Equation 8>

W' = β*Gain_B

10 is a diagram illustrating a red grill in a vertical direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 10( a ), when displaying a red grille in odd rows, the W subpixels of WR pixels in even rows diagonally adjacent to the WR pixels in the diagonal direction are turned on together with the R subpixels of WR pixels in odd rows, thereby The expressiveness of the red grill displayed in the column is improved. In other words, when displaying an odd row red grill, even rows (mod(i, 2)=0) and even rows (mod(j, 2)=0) together with R subpixels belonging to odd row pixels W subpixels belonging to the pixel of are turned on, and the remaining subpixels are turned off.

Referring to FIG. 10(b), when a red grille in even rows is displayed, the W subpixels of WR pixels in odd rows diagonally adjacent to the WR pixels are turned on together with the R subpixels of WR pixels in even rows, so that the even number The expressiveness of the red grill displayed in the column is improved. In other words, when displaying the even-numbered row red grill, together with the R subpixels of the pixels belonging to the even-numbered columns, the W subpixels of the odd-numbered rows and the pixels belonging to the odd-numbered rows (mod(j, 2) = 1) are turned on , the remaining subpixels are off.

The luminance of the turned-on W subpixel is determined in proportion to the luminance of the turned-on R subpixel as in FIG. 4 .

11 is a diagram illustrating a red grill in a horizontal direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 11(a), when displaying an odd row red grille, W subpixels together with R subpixels belonging to odd rows and odd rows improve the expressiveness of the odd row red grille, and the remaining subpixels are turned off. .

Referring to FIG. 11(b), when even-numbered row red grille is displayed, even-numbered row red grille expressiveness is improved by turning on W subpixels together with R subpixels of even-numbered row and even-numbered row, and the remaining subpixels are turned off. do.

The luminance of the turned-on W subpixel is determined in proportion to the luminance of the turned-on R subpixel as in FIG. 5 .

12 is a diagram illustrating a green grill in a vertical direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 12(a), when the odd-numbered row green grille is displayed, the G subpixel of the odd-numbered row GB pixel and the W subpixel of the WR pixel vertically adjacent to the GB pixel are turned on, thereby increasing the expression power of the odd-numbered row green grille. is enhanced, and the remaining subpixels are turned off.

Referring to FIG. 12(b), when an even-numbered row green grille is displayed, the G subpixel of the even-numbered row GB pixel and the W subpixel of the WR pixel vertically adjacent to the GB pixel are turned on, thereby increasing the expression power of the even-numbered row green grille. is enhanced, and the remaining subpixels are turned off.

The luminance of the turned-on W subpixel is determined in proportion to the luminance of the turned-on G subpixel as shown in FIG. 6 .

13 is a diagram illustrating a green grill in a horizontal direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 13(a), when a green grill in odd rows is displayed, the G subpixels in odd rows and the W subpixels in odd rows and even columns horizontally adjacent to the G subpixels are turned on, thereby turning on the green grill in odd rows. Expressive power is improved, and the remaining subpixels are turned off.

Referring to FIG. 13(b), when a green grille in even rows is displayed, W subpixels in even rows and even columns horizontally adjacent to the G subpixels along with the G subpixels in even rows are turned on so that even rows are green. Expressive power to draw is improved, and the remaining subpixels are turned off.

The luminance of the turned-on W subpixel is determined to be proportional to the luminance of the turned-on G subpixel as in FIG. 7 .

14 is a diagram illustrating a blue grill in a vertical direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 14(a) , when a blue grille in odd rows is displayed, along with B subpixels of GB pixels in odd rows, W subpixels of WR pixels in odd rows and odd columns vertically adjacent to the GB pixels are turned on. As a result, the expressive power of the odd-numbered row blue grille is improved, and the remaining subpixels are turned off.

Referring to FIG. 14(b), when a blue grille in even rows is displayed, along with the B subpixels of GB pixels in even rows, the W subpixels of WR pixels in even rows and even columns vertically adjacent to the GB pixels are turned on. As a result, even-numbered row blue grill expression is improved, and the remaining subpixels are turned off.

The luminance of the turned-on W subpixel is determined in proportion to the luminance of the turned-on B subpixel as shown in FIG. 8 .

15 is a diagram illustrating a blue grill in a horizontal direction displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention.

Referring to FIG. 15(a) , when a blue grille in an odd row is displayed, the B subpixels in the odd row and the W subpixel in the odd row horizontally adjacent to the B subpixel are turned on, thereby turning on the blue grille in the odd row. Expressive power to draw is improved, and the remaining subpixels are turned off.

Referring to FIG. 15(b) , when a blue grille in an even row is displayed, the W subpixel in an even row adjacent to the B subpixel in the horizontal direction is turned on together with the B subpixels in the even row, so that the even row is green. Expressive power to draw is improved, and the remaining subpixels are turned off.

The luminance of the turned-on W subpixel is determined to be proportional to the luminance of the turned-on B subpixel as in FIG. 9 .

16 is a view showing a red and blue grill in a vertical direction displayed on a pentile-structured display according to an embodiment of the present invention.

Referring to FIG. 16(a) , when displaying a red grill in the vertical direction, the G and B subpixels of the pixel column to which the turned-on R subpixel belongs are also turned on, thereby improving the expressive power of the red grille, and the remaining subpixels are turned off. . The luminances (G', B') of the turned-on G and B subpixels are determined to have a minimum color difference enough that the color difference (Δu'v') before and after correction is not perceived. For example, the color difference (Δu'v') between the color coordinates before compensation in which only the R subpixel is turned on and the color coordinates after compensation in which the G and B subpixels are turned on in addition to the R subpixel is set to be less than the perceptual minimum color difference (0.004). . The minimum perceptible color difference (0.004) is 1mpcd (Minimum Perceptible Color Difference), which means the minimum color difference at which a person perceives that two colors are different. As shown in Equation 9 below, it is determined as a result value obtained by multiplying the difference value (α) of R data between two horizontally adjacent pixels by the second G compensation gain (Gain_G) and the second B compensation gain (Gain_B), respectively.

<Equation 9>

G' = α*Gain_G

B' = α *Gain_B

Referring to FIG. 16(b), when displaying a blue grille in the vertical direction, the expressiveness of the blue grille is improved by turning on the G and R subpixels in the pixel column where the B subpixel is turned on, and the remaining subpixels are turned off. . The luminances (R', G') of the turned-on G and R subpixels are the difference value (α) of B data between two horizontally adjacent pixels, the R compensation gain (Gain_G) and the B compensation as shown in Equation 10 below. It is determined by the result value obtained by multiplying each gain (Gain_G).

<Equation 10>

R' = α *Gain_R

G' = α*Gain_G

17 is a diagram illustrating a horizontally directed red and blue grill displayed on a pentile structure display according to an embodiment of the present invention.

Referring to FIG. 17(a), when displaying a red grill in the horizontal direction, G and B subpixels are also turned on in a pixel row in which the red subpixel is turned on, thereby improving the expressive power of the red grille in the horizontal direction, and the remaining subpixels are turned off. The luminances (G', B') of the turned-on G and B subpixels are the difference value (β) of R data between two vertically adjacent pixels as shown in Equation 11 below, the second G compensation gain (Gain_G) and It is determined as a result value obtained by multiplying each of the second B compensation gains (Gain_B).

<Equation 11>

G' = β*Gain_G

B' = β*Gain_B

Referring to FIG. 17( b ), when displaying a blue grill in a horizontal direction, G and R subpixels are turned on in a pixel row in which a blue subpixel is turned on, thereby improving expressive power of the blue grille, and the remaining subpixels are turned off. The luminances (G', R') of the turned-on G and R subpixels are the difference value (β) of B data between two vertically adjacent pixels, the second R compensation gain (Gain_G) and It is determined as a result value obtained by multiplying each of the second G compensation gains (Gain_G).

<Equation 12>

R' = β*Gain_R

G' = β*Gain_G

18 is a diagram illustrating a comparison of color grill expressiveness of an M+ 3-subpixel structure display according to the prior art and an embodiment of the present invention, and FIG. 19 is a view showing an M+ 3-subpixel structure display according to the prior art and an embodiment It is a graph showing the comparison of the SSIM index for each color drawing image.

Referring to FIG. 18, the red grill image, the green grill image, and the blue grill image before improvement displayed on a display having an M+ 3-subpixel structure according to the prior art are discontinuously displayed, and the color grill expressiveness visually perceived is poor. For example, each color grill image after improvement displayed on an M+ 3-subpixel structured display according to an embodiment is recognized by turning on W subpixels around R, G, and B subpixels to compensate for the discontinuity of each color grille. It can be seen that the color grill expression is improved.

SSIM (Structural SIMilarity) index is a method of evaluating the degree of similarity between two images by quantifying morphological similarities such as luminance, contrast, and structure between the original image and the comparison image. The higher the SSIM index, the closer the comparison image is to the original image, and the SSIM index When is smaller, the comparison image is different from the original image.

Referring to FIG. 19, the SSIM index for each of red, green, and blue grill images before enhancement displayed on a display having an M+ 3-subpixel structure according to the prior art is as low as 60%, whereas according to an embodiment of the present invention The SSIM index for each of the red, green, and blue grill images after improvement displayed on the M+ 3-subpixel structure display is 90%, which is similar to the RGB stripe structure, and it can be seen that the color grill expressive power has increased. Accordingly, when the resolution of the display is evaluated using the SSIM index for the color grille image, the resolution may be highly evaluated.

20 is a view showing a comparison of color grill expressiveness of an M+ 2-subpixel structure display according to the prior art and an embodiment of the present invention, and FIG. It is a graph showing the comparison of the SSIM index for each color drawing image.

Referring to FIG. 20, each color image before improvement displayed on a display having an M+ 2-subpixel structure according to the prior art is discontinuous and displayed in an unclear line shape, so that the color grill expressiveness visually recognized is further deteriorated. After improvement displayed on the M+ 3-subpixel structure display according to the embodiment, each color grill image is recognized by turning on the W subpixels around the R, G, and B subpixels to compensate for the discontinuity and line shape of each color grille. It can be seen that the color grill expression is improved.

Referring to FIG. 21, while the SSIM index for each of the red, green, and blue grill images before enhancement displayed on a display having an M+ 2-subpixel structure according to the prior art is low enough to be close to 0%, an embodiment of the present invention After improvement displayed on the display of the M+ 2-subpixel structure according to the above, the SSIM index for each of the red and blue grill images increased to 70%, and the SSIM index for the green grill image increased to a level close to 90%, resulting in color grill expressiveness. It can be seen that this has risen. Accordingly, when the resolution of the display is evaluated using the SSIM index for the color grille image, the resolution may be highly evaluated.

22 is a diagram illustrating a comparison of color grill expression powers of a pentile structure display according to the prior art and an embodiment of the present invention, and FIG. It is a graph showing the comparison of the SSIM index.

Referring to FIG. 22, the red and blue grill images before improvement displayed on the display having a pentile structure according to the prior art are discontinuous and displayed in an unclear line shape, so that the visually perceived color grill expression is poor. After the improvement displayed on the pentile structure display according to the embodiment, each color grill image utilizes all of the R, G, and B subpixels of the corresponding pixel row to compensate for the discontinuity and line shape of the red or blue grill, thereby recognizing color grill expression. It can be seen that this improvement

Referring to FIG. 23, the SSIM index for each of the red and blue grill images before improvement displayed on the display of the pentile structure according to the prior art is low enough to be close to 0%, whereas the pentile structure according to an embodiment of the present invention After the improvement displayed on the display of , the SSIM index for each of the red and blue grill images increased to the level of 80%, indicating that the color grill expressiveness increased. Accordingly, when the resolution of the display is evaluated using the SSIM index for the color grille image, the resolution may be highly evaluated.

24 is a diagram showing a comparison between red, green and blue texts displayed on a display having an M+2-subpixel structure according to an embodiment of the present invention and the prior art.

Referring to FIG. 24, before improvement displayed on a display having an M+ 2-subpixel structure according to the prior art, each of the red, green, and blue texts is discontinuously displayed in a line shape, resulting in poor text readability. After the improvement displayed on the display of the M+ 2-subpixel structure according to , it can be seen that the text readability is improved because the discontinuity of each of the red, green, and blue texts is clearly displayed by complementing the discontinuity by the surrounding white subpixels.

Through the above description, those skilled in the art will understand that various changes and modifications are possible without departing from the spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims.

100: panel 200: gate driver
300: data driver 400: timing controller
500: gamma voltage generator 600: image processor

Claims (14)

Each pixel is composed of 3-color sub-pixels or 2-color sub-pixels among 4 colors, or 2-color sub-pixels among 3 colors, and each pixel has a subpixel arrangement structure different from those of adjacent pixels in the vertical and horizontal directions. A panel having
a panel driver for driving the panel;
Through primary subpixel rendering, input data is firstly converted to conform to the subpixel arrangement structure of the panel, and when a color edge in at least one direction is detected for the firstly converted data, the detected edge direction and pixel structure According to the secondary subpixel rendering, at least one subpixel of a different color among the pixel to which the subpixel constituting the color edge belongs and the pixels adjacent to the pixel in the edge direction is turned on, so that the subpixel of the different color is turned on. An image processing unit that performs image processing to correct data of and outputs the image-processed data to the panel driving unit;
the panel
It includes white, red, green, and blue subpixels corresponding to the four colors,
Each of the pixels has a first pixel structure composed of subpixels of three colors among the four colors;
When the color edge of any one of the red, green, and blue channels displayed on the panel is in the vertical direction, sub-pixels of the corresponding color constituting the color edge in the vertical direction and the sub-pixels of the corresponding color in the vertical direction Among the pixels located between the pixels, white subpixels are turned on,
When the color edge of any one channel is in the horizontal direction, subpixels of the corresponding color constituting the color edge in the horizontal direction and white subpixels located between the subpixels of the corresponding color in the horizontal direction are turned on. subpixel rendering display device. The method of claim 1,
The image processing unit
When a first edge detection mask is applied to each color channel to the primary conversion data and an edge detection condition is satisfied in only one color channel, a color edge in a first direction among the vertical and horizontal directions is detected, and Correct the data of other color subpixels adjacent to the color edge of
When a second edge detection mask is applied to each color channel to the primary conversion data and an edge detection condition is satisfied in only one color channel, a color edge in a second direction among the vertical and horizontal directions is detected, and the second edge correcting the data of other color subpixels adjacent to the color edge of
and outputting the primary conversion data without data correction when the color edge is not detected. delete delete Each pixel is composed of 3-color sub-pixels or 2-color sub-pixels among 4 colors, or 2-color sub-pixels among 3 colors, and each pixel has a subpixel arrangement structure different from those of adjacent pixels in the vertical and horizontal directions. A panel having
a panel driver for driving the panel;
Through primary subpixel rendering, input data is firstly converted to conform to the subpixel arrangement structure of the panel, and when a color edge in at least one direction is detected for the firstly converted data, the detected edge direction and pixel structure According to the secondary subpixel rendering, at least one subpixel of a different color among the pixel to which the subpixel constituting the color edge belongs and the pixels adjacent to the pixel in the edge direction is turned on, so that the subpixel of the different color is turned on. An image processing unit that performs image processing to correct data of and outputs the image-processed data to the panel driving unit;
the panel
It includes white, red, green, and blue subpixels corresponding to the four colors,
Each of the pixels has a second pixel structure composed of subpixels of two colors among the four colors;
When the red or blue color edge displayed on the panel is in the vertical direction, subpixels of the corresponding color belonging to the color edge in the vertical direction and the corresponding color in the pixel row between the subpixels of the corresponding color White subpixels diagonally adjacent to the subpixel are turned on;
When the green color edge displayed on the panel is in the vertical direction, rendering of a subpixel in which green subpixels belonging to the green color edge and white subpixels located between the green subpixels in the vertical direction are turned on display device. According to claim 1 or claim 5,
The luminance of the white subpixels is determined to be proportional to the luminance of subpixels of a corresponding color belonging to the color edge. According to claim 1 or claim 5,
the panel
A first pixel composed of green and red subpixels and a second pixel composed of green and blue subpixels are alternately arranged in the horizontal and vertical directions,
The image processing unit
A subpixel rendering display device that detects only a red or blue color edge as the color edge and does not detect a green color edge as the color edge. The method of claim 7,
When the red or blue color edge displayed on the panel is in the vertical direction, first pixels to which the color edge in the vertical direction belongs and second pixels located in the vertical direction between the first pixels are both being warmed up,
When the red or blue color edge is in the horizontal direction, subpixel rendering in which third pixels to which the color edge in the horizontal direction belongs and fourth pixels positioned in the horizontal direction between the third pixels are all turned on display device. The method of claim 8,
When the red color edge is displayed on the panel,
Red subpixels belonging to the first pixels or the third pixels display a first luminance;
The green sub-pixels belonging to the first pixels or the third pixels and the green and blue sub-pixels belonging to the second pixels or the fourth pixels have a second luminance so low that the change in red color is not perceived. A sub-pixel rendering display device that displays. The method of claim 8,
When the blue color edge is displayed on the panel,
Blue subpixels belonging to the first pixels or the third pixels display a first luminance;
The green subpixels belonging to the first pixels or the third pixels and the green and red subpixels belonging to the second pixels or the fourth pixels have a second luminance so low that the change in blue color is not perceived. A sub-pixel rendering display device that displays. Each pixel is composed of 3-color sub-pixels or 2-color sub-pixels among 4 colors, or 2-color sub-pixels among 3 colors, and each pixel has a subpixel arrangement structure different from those of adjacent pixels in the vertical and horizontal directions. In the image processing method of a display device including a panel having,
firstly transforming input data according to the subpixel arrangement structure of the panel through first subpixel rendering;
detecting a color edge in a first direction among vertical and horizontal directions by applying a first edge detection mask for each color channel to the primary converted data;
If a color edge in the first direction is detected, correcting data of another color subpixel adjacent to the color edge in the first direction through secondary subpixel rendering according to the first direction and the pixel structure of the panel. and,
detecting a color edge in a second direction among the vertical and horizontal directions by applying a second edge detection mask for each color channel to the primary converted data;
If the color edge in the second direction is detected, correcting data of another color subpixel adjacent to the color edge in the second direction through secondary subpixel rendering according to the second direction and the pixel structure of the panel. and,
if the color edge is not detected, outputting the primary conversion data without data correction;
the panel
It includes white, red, green, and blue subpixels corresponding to the four colors,
Each of the pixels has a first pixel structure composed of subpixels of three colors out of the four colors, or each pixel has a second pixel structure composed of subpixels of two colors out of the four colors;
When the color edge of any one of the red, green, and blue channels displayed on the panel is in the vertical direction, sub-pixels of the corresponding color constituting the color edge in the vertical direction and the sub-pixels of the corresponding color in the vertical direction Among the pixels located between the pixels, white subpixels are turned on,
When the color edge of any one channel is in the horizontal direction, subpixels of the corresponding color constituting the color edge in the horizontal direction and white subpixels located between the subpixels of the corresponding color in the horizontal direction are turned on. An image processing method of a subpixel rendering display device. The method of claim 11,
The image processing method of the subpixel rendering display device in which the luminance of the turned-on white subpixels is proportional to the luminance of the subpixels constituting the corresponding color edge. The method of claim 11,
The panel has a structure in which a first pixel composed of green and red subpixels and a second pixel composed of green and blue subpixels are alternately arranged in the horizontal and vertical directions;
An image processing method of a subpixel rendering display device that detects only a red or blue color edge as the color edge and does not detect a green color edge as the color edge. The method of claim 13,
When the red or blue color edge displayed on the panel is in the vertical direction, first pixels to which the color edge in the vertical direction belongs and second pixels located in the vertical direction between the first pixels are both being warmed up,
When the red or blue color edge is in the horizontal direction, third pixels to which the color edge in the horizontal direction belongs and fourth pixels positioned in the horizontal direction between the third pixels are all turned on;
The green subpixels belonging to the first pixels or the third pixels and the green and other color subpixels belonging to the second pixels or the fourth pixels are such that the color change of the corresponding color edge is not recognized. An image processing method of a subpixel rendering display device displaying low luminance.

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