KR102490628B1 - Image processing method, image processing module and display device using the same - Google Patents

Abstract

The present invention relates to an image processing method and an image processing module capable of clearly expressing a line while using 3-color sub-pixels among 4-color sub-pixels, and a display device using the same, wherein 3-color data in pixel units is converted into primary 4-color sub-pixels. After conversion to color data, secondary 4-color data corresponding to the subpixel arrangement of the display panel is generated by rendering the primary 4-color data. According to the edge of the pixel using the primary white data among the primary 4-color data, secondary 3-color data of a first pixel without a white subpixel is applied to the primary white data of the first pixel to obtain 3 color data. Convert to difference 3-color data. In an embodiment, secondary white data among secondary 3-color data of a second pixel having a white subpixel is converted into tertiary white data by applying primary white data of the second pixel.

Description

Image processing method, image processing module and display device using the same

The present invention relates to an image processing method and an image processing module capable of clearly expressing a line while using three color subpixels among four color subpixels, and a display device using the same.

Examples of the image display device include a liquid crystal display (LCD) and an organic light emitting diode (OLED) display device.

Display devices have been developed in the direction of improving image quality while expressing high luminance by adding W (white) subpixels to R (red), G (green), and B (blue) subpixels constituting basic pixels.

In recent years, WRGB display devices have three subpixels (W/R) among W/R/G/B subpixels, as shown in FIG. /G, B/W/R, G/B/W, or R/G/B), and an M+ WRGB display device having a different subpixel arrangement order from adjacent pixels.

The M+ WRGB display device converts RGB data of an input image into WRGB data, renders the WRGB data, converts it into M+ WRGB data, and drives a display panel to display the M+ WRGB data.

However, in the rendering method of the M+ WRGB display device, when an RGB pixel without a W subpixel is included in a white area, white is expressed by utilizing the W subpixel of the left and right adjacent GBW pixels and WRG pixels instead of the RGB pixel. For this reason, even when the GBW and WRG pixels adjacent to the RGB pixels are to display black, there is a problem in that they are perceived as gray due to light emission of the W sub-pixels.

As a result, when a line such as a grill pattern in which white lines and black lines are repeated alternately is displayed, RGB pixels included in the white line display black, and GBW pixels and WRG pixels included in the black line. Since gray is displayed by light emission of the silver W subpixel, a white line and a black line may be expressed in an unclear or discontinuous dotted line in the M+ WRGB display device.

The present invention provides an image processing method, an image processing module, and a display device using the image processing module capable of clearly expressing a line while using three color subpixels among four color subpixels.

Any one of the image processing method and image processing module according to an embodiment of the present invention converts 3-color data in pixel units into primary 4-color data, and then renders the primary 4-color data to display the display panel. Secondary 4-color data corresponding to the subpixel arrangement is generated. According to the pixel edge using the primary white data among the primary 4-color data, secondary 3-color data of a first pixel without a white subpixel is applied to the primary white data of the first pixel to obtain 3 colors. Convert to difference 3-color data. In an embodiment, secondary white data among secondary 3-color data of a second pixel having a white subpixel is converted into tertiary white data by applying primary white data of the second pixel.

The image processing module includes a data conversion unit that converts 3-color data into primary 4-color data, and a first unit that generates secondary 4-color data by rendering the primary 4-color data supplied from the data converter. It includes a rendering unit. The image processing module includes an edge determination unit that determines whether each pixel has an edge by analyzing a pixel edge using primary white data of a plurality of pixels supplied from the data conversion unit. When the secondary 3-color data supplied from the first rendering unit corresponds to the first pixel, the image processing module determines the secondary 3-color data of the first pixel according to whether or not the first pixel supplied from the edge determination unit is an edge. and a second rendering unit that converts the data into tertiary 3-color data by applying the primary white data of the first pixel supplied from the edge determination unit. When the secondary 3-color data supplied from the first rendering unit corresponds to the second pixel, the second rendering unit outputs secondary white data of the second pixel according to whether or not the second pixel supplied from the edge determination unit is an edge. The primary white data of the second pixel supplied from the edge determiner is applied and converted into tertiary white data.

The edge determination unit applies a sharpen mask having a plurality of coefficients respectively corresponding to the plurality of pixels to the primary white data of the plurality of pixels, and obtains horizontal, vertical, and first diagonal directions for the corresponding pixel corresponding to the center cell of the sharpen mask. and an edge intensity detector detecting edge intensities in a plurality of directions including a second diagonal direction. The edge determination unit determines whether the corresponding pixel has an edge and the edge direction according to the edge strength in multiple directions supplied from the edge strength detection unit, determines whether the corresponding pixel has an edge and a gain value according to the edge direction, and determines the gain value of the corresponding pixel and the primary white and a gain determining unit supplying data to the second rendering unit.

The second rendering unit adds a result obtained by multiplying each of the secondary 3-color data of the first pixel by the primary white data of the first pixel and the gain value of the first pixel, and converts the secondary 3-color data of the first pixel to 3. Convert to difference 3-color data.

The second rendering unit multiplies the secondary white data by a value obtained by subtracting the gain value of the second pixel from 1 and adds a value obtained by multiplying the primary white data of the second pixel by the gain value of the second pixel, Secondary white data is converted into tertiary white data.

When the gain value of the corresponding pixel supplied from the gain determination unit indicates the horizontal direction, the image processing module is left adjacent to the first pixel among the tertiary 3-color data of each pixel supplied from the second rendering unit, and the color The tertiary color data of each of the plurality of subpixels having different colors and the rightwardly adjacent subpixels having different colors are obtained by combining the primary white data of the first pixel supplied from the gain determiner and the first pixel. It further includes a third rendering unit that applies a value multiplied by the gain value and converts it into 4th color data.

A display device according to an embodiment of the present invention includes the above-described image processing module, a display panel, and a panel driving unit that drives the display panel so that an image supplied from the image processing module is displayed on the display panel.

The display panel includes WRG pixels having a white/red/green subpixel arrangement, BWR pixels having a blue/white/red subpixel arrangement, GBW pixels having a green/blue/white subpixel arrangement, and red/white subpixel arrangements. It includes RGB pixels having a green/blue subpixel arrangement. The first pixel corresponds to an RGB pixel, and the second pixel corresponds to any one of the WRG pixel, BWR pixel, and GBW pixel.

When an image supplied from the image processing module includes a black line pattern and a white line pattern in units of pixel lines, the first pixels included in the first pixel lines displaying the white line patterns are their own red, green, and blue subpixels. White luminance is displayed using all of the pixels, and the second pixel included in the first pixel line displays white luminance using its own white sub-pixel. Both the first pixel and the second pixel included in the second pixel line displaying the black line pattern display black luminance.

When the white line pattern is in the horizontal direction, first and second pixels included in the first pixel line displaying the white line pattern display white luminance using all subpixels.

An image processing method and an image processing module according to an embodiment of the present invention and a display device using the same analyze pixel edges based on an input image and emit light of W subpixels of adjacent pixels even in pixels without white subpixels according to whether or not the edges are present. By displaying white using all three sub-pixels, the white line and the black line can be continuously and clearly displayed to improve image quality.

An image processing method and image processing module according to an embodiment of the present invention and a display device using the same display a white line continuously and clearly by using all sub-pixels of each pixel when displaying a white line in a horizontal direction, thereby improving image quality. can improve

As a result, when displaying a grill pattern for resolution authentication, the display device according to an embodiment of the present invention can satisfy both authentication conditions of contrast modulation obtained by measuring white line luminance and black line luminance, and can improve resolution expressiveness. can

1 is a diagram illustrating a subpixel arrangement of an M+ WRGB display device.
2 is a block diagram schematically illustrating the configuration of a WRGB display device according to an embodiment of the present invention.
FIG. 3 is an equivalent circuit diagram illustrating a configuration of an LCD subpixel applied to FIG. 2 .
FIG. 4 is an equivalent circuit diagram illustrating a configuration of an OLED sub-pixel applied to FIG. 2 .
5 is a block diagram showing the configuration of an image processing module according to an embodiment of the present invention.
6 is a flowchart illustrating an image processing method according to an embodiment of the present invention.
7 is a diagram for explaining a method of rendering RGB data into M+WRGB data according to an embodiment of the present invention.
8 is a diagram for explaining an edge analysis method using a sharpen mask according to an embodiment of the present invention.
9 is a diagram illustrating a comparison between an enlarged portion of a grill pattern displayed in the prior art and a display device according to an exemplary embodiment of the present invention.
10 is a diagram showing a comparison of grill patterns in a vertical direction displayed in a display device according to an embodiment of the present invention and a prior art.
11 is a diagram illustrating a comparison of grill patterns in a horizontal direction displayed in a display device according to an exemplary embodiment of the present invention and a prior art.
12 is a diagram illustrating a comparison between resolution authentication results for a vertical grill pattern displayed in a display device according to an embodiment of the present invention and a prior art.
13 is a diagram illustrating a comparison between resolution authentication results for a grill pattern in a horizontal direction displayed on a display device according to an embodiment of the present invention and a prior art.

2 is a block diagram schematically illustrating the configuration of a display device according to an exemplary embodiment of the present invention, FIG. 3 is a configuration of an LCD subpixel applied to the display panel of FIG. 2, and FIG. 4 is a configuration of the display panel of FIG. It is an equivalent circuit diagram illustrating the configuration of an applied OLED sub-pixel.

The display device shown in FIG. 2 includes a timing controller 10, a data driver 20 and a gate driver 30 as panel drivers, a display panel 40, and a gamma voltage generator 50.

The display panel 40 displays an image through a pixel array in which pixels are arranged in a matrix form. In the display panel 40 according to an exemplary embodiment, each pixel includes three subpixels (W/R/G, B/W/R, G/B/W or R/G/B), and an M+ WRGB panel in which the arrangement order of three subpixels is different from that of adjacent pixels is used.

That is, in the M+ WRGB display panel 40 according to an embodiment, each pixel line in the horizontal direction has a structure in which 4 subpixels W/R/G/B are regularly repeatedly arranged, but the basic pixel is W/R Among the /G/B subpixels, it is composed of three subpixels capable of implementing white with a color combination. Accordingly, in the M+WRGB display panel 40, each pixel is composed of 3 subpixels, compared to a panel in which each pixel is composed of 4 subpixels (W/R/G/B), so the pixel aperture ratio is increased. It is advantageous to implement high brightness and high resolution and has the advantage of reducing power consumption or manufacturing cost.

For example, as shown in FIG. 2, the M+ WRGB display panel 40 includes a WRG pixel (first pixel) having a combination of W/R/G subpixels and a BWR having a combination of B/W/R subpixels. (second pixel), a GBW pixel (third pixel) having a combination of G/B/W subpixels, and an RGB pixel (fourth pixel) having a combination of R/G/B subpixels. The first pixel group G1 arranged in the order of WRG pixels, BWR pixels, GBW pixels, and RGB pixels is repeated in the horizontal direction to form a first pixel line. The second pixel group G2 arranged in the order of GBW pixels, RGB pixels, WRG pixels, and BWR pixels is repeated in the horizontal direction to form a second pixel line. The first and second pixel lines are alternately arranged in the vertical direction to form a pixel array of the M+ WRGB display panel 40 . However, since the subpixel arrangement structure of the pixel array is various, it is not limited to the subpixel arrangement structure of FIG. 2 .

A liquid crystal display (LCD), an organic light emitting diode (OLED) display, or the like may be used as the display panel 40 .

For example, when the display panel 40 is an LCD panel, as shown in FIG. 3 , each subpixel SP includes a thin film transistor (TFT) connected to a gate line (GL) and a data line (DL), and a thin film. A liquid crystal capacitor Clc and a storage capacitor Cst are connected in parallel between the transistor TFT and the common electrode. The liquid crystal capacitor (Clc) charges the difference voltage between the data signal supplied to the pixel electrode and the common voltage (Vcom) supplied to the common electrode through the thin film transistor (TFT), and drives the liquid crystal according to the charged voltage to determine the amount of light transmittance. to control The storage capacitor Cst stably maintains the voltage charged in the liquid crystal capacitor Clc.

In contrast, when the display panel 40 is an OLED panel, as shown in FIG. 3 , each subpixel SP includes an OLED element connected between a high potential power supply (EVDD) line and a low potential power supply (EVSS) line. , a pixel circuit including first and second switching TFTs (ST1, ST2), a driving TFT (DT), and a storage capacitor (Cst) to independently drive the OLED element, and the pixel circuit configuration is diverse, so FIG. 3 is not limited to the structure of

The OLED element includes an anode connected to the driving TFT (DT), a cathode connected to the low potential voltage (EVSS), and a light emitting layer between the anode and the cathode, and emits light proportional to the amount of current supplied from the driving TFT (DT). Occurs.

The first switching TFT (ST1) is driven by the gate signal of one gate line (GLa) to supply the data voltage from the corresponding data line (DL) to the gate node of the driving TFT (DT), and the second switching TFT (ST2) ) is driven by a gate signal of another gate line GLb to supply a reference voltage from the reference line RL to the source node of the driving TFT DT. The second switching TFT (ST2) is further used as a path for outputting the current from the driving TFT (DT) to the reference line (R) in the sensing mode.

The storage capacitor Cst connected between the gate node and the source node of the driving TFT DT transmits the data voltage supplied to the gate node through the first switching TFT ST1 and the source node through the second switching TFT ST2. The differential voltage of the reference voltage supplied to is charged and supplied as the driving voltage of the driving TFT (DT).

The driving TFT DT controls the current supplied from the high-potential power supply EVDD according to the driving voltage supplied from the storage capacitor Cst, thereby supplying a current proportional to the driving voltage to the OLED element so that the OLED element emits light.

The data driver 20 receives a data control signal and 4-color data from the timing controller 10 . The data driver 20 is driven according to the data control signal, subdivides the reference gamma voltage set supplied from the gamma voltage generator 50 into grayscale voltages, and converts digital data into analog data using the divided grayscale voltages. signal, and the analog data signal is supplied to each data line of the display panel 10.

The data driver 20 is composed of a plurality of data drive ICs that divide and drive the data lines of the display panel 40, and each data drive IC is TCP (Tape Carrier Package), COF (Chip On Film), FPC (Flexible Print) It may be mounted on a circuit film such as a circuit film and attached to the display panel 40 using a Tape Automatic Bonding (TAB) method or mounted on the display panel 40 using a Chip On Glass (COG) method.

The gate driver 30 drives the plurality of gate lines of the display panel 40 respectively using the gate control signal supplied from the timing controller 10 . The gate driver 30 supplies a scan pulse of a gate-on voltage to each gate line in a corresponding scan period in response to a gate control signal, and supplies a gate-off voltage in the remaining period.

The gate driver 30 is composed of at least one gate IC, mounted on a circuit film such as TCP, COF, FPC, etc., and attached to the display panel 40 in a TAB method or mounted on the display panel 40 in a COG method. can Unlike this, the gate driver 30 is a GIP (Gate In Panel) type embedded in the non-display area of the display panel 40 by being formed on a thin film transistor substrate together with the thin film transistor array constituting the pixel array of the display panel 40 . can be provided with

The timing controller 10 receives image data and basic timing signals from an external host system. For example, the external host system may be any one of a computer, a TV system, a set-top box, a portable terminal system such as a tablet or mobile phone.

The timing controller 10 controls driving timings of the data driving unit 20 and the gate driving unit 30 respectively using the input basic timing signals. The input timing signal includes a dot clock, a data enable signal, a vertical sync signal, and a horizontal sync signal, but the vertical sync signal and the horizontal sync signal may be omitted. In this case, the timing controller 10 outputs data according to the dot clock. A vertical synchronization signal and a horizontal synchronization signal may be generated and used by counting the enable signal. Data control signals that control driving of the data driver 20 may include a source start pulse, a source sampling clock, a polarity control signal, a source output enable signal, and the like. Gate control signals for controlling driving of the gate driver 30 may include a gate start pulse, a gate shift clock, a gate output enable signal, and the like.

The timing controller 10 may include the image processing module 100, or the image processing module 100 may be separated from the timing controller 10 and provided as a separate IC at a previous stage of the timing controller 10. The image processing module 100 may mean hardware or an image processing module of software stored in a memory.

The image processing module 100 receives an input image and converts Ri, Gi, and Bi data, which are 3-color data of the input image, into W1, R1, G1, and B1 data, which are primary 4-color data. Next, the image processing module 100 first renders the W1, R1, G1, and B1 data according to the subpixel arrangement of the M+ display panel 40, and then performs the secondary 4-color data W2, R2, G2, and B2 data. generate Three or less color data among the W2, R2, G2, and B2 data is supplied to one pixel, and the remaining color data is supplied to other adjacent pixels.

The image processing module 100 analyzes the pixel edge and converts the secondary color data into tertiary color data by secondary rendering based on the W1 data of each pixel according to whether each pixel has an edge. Accordingly, R2, G2, B2 data, which are secondary 3-color data of an RGB pixel that corresponds to an edge and does not have a W sub-pixel, applies W1 data of the corresponding pixel to obtain tertiary 3-color data, R3, G3, B3 data. is converted to In addition, W2 data of pixels (WRG pixels, BWR pixels, GBW pixels) corresponding to edges and having W sub-pixels are converted into W3 data by applying W1 data, and the remaining secondary 2-color data is converted into tertiary 2-color data as it is. used for color data.

To this end, the image processing module 100 detects the edge strength and edge direction of each pixel through pixel edge analysis using the W1 data of each pixel, and determines whether there is a detected edge and a gain value according to the edge direction.

Next, the image processing module 100 uses different secondary rendering methods depending on whether each pixel has a W subpixel (WRG pixel, BWR pixel, GBW pixel) or does not have a W subpixel (RGB pixel). Secondary color data is converted into tertiary color data by applying W1 data and a gain value of a corresponding pixel.

Specifically, the image processing module 100 converts R2, G2, and B2 data of an RGB pixel without a W subpixel into R3, G3, and B3 data by applying W1 data and a gain value. For example, when an RGB pixel without a W subpixel corresponds to an edge and W1 data is a white grayscale, R3, G3, and B3 data represent a white grayscale corresponding to the W1 data.

The image processing module 100 converts only W2 data among secondary three-color data of each pixel (WRG pixel, BWR pixel, or GBW pixel) having W subpixels into W3 data by applying W1 data and a gain value, The remaining secondary 2-color data is used as tertiary 2-color data. For example, when a pixel having a W subpixel (WRG pixel, BWR pixel, or GBW pixel) corresponds to an edge and W1 data is a black gradation, W3 data of the corresponding pixel expresses a black gradation corresponding to the W1 data.

Accordingly, the RGB pixels corresponding to the white edge may display white, and each of the GBW and WRG pixels corresponding to the black edge while being horizontally adjacent to the white RGB pixel may display black corresponding to the W1 data.

In addition, the image processing module 100 additionally performs a tertiary rendering method for pixels having W subpixels (WRG pixels, BWR pixels, and GBW pixels) when the edge direction is in the horizontal direction, so that all subpixels included in the white line By causing the pixels to emit light, the continuity and sharpness of the white line can be reinforced. In other words, the image processing module 100 converts the W1 data corresponding to the RGB pixels included in the white line in the horizontal direction to the RGB pixels and their RGB pixels by secondary and tertiary rendering methods using gain values. By distributing R/G/B subpixels of adjacent pixels with , all subpixels can emit light.

For example, when the edge direction is horizontal, the image processing module 100 allocates some of the W1 data corresponding to the n-th RGB pixel to the RGB pixel by secondary rendering using the W1 data and the gain value to generate R3 , G3, B3 data (tertiary color data) is generated. Next, the image processing module 100 converts the rest of the W1 data to the R subpixel among the n-2th BWR pixels, the n-1th GBW pixel, and n+1 through tertiary rendering using the W1 data and gain values. 4th color data is generated by allocating to the B subpixel of the n+2 th BWR pixel of the th WRG pixel. Accordingly, since all subpixels included in the white line in the horizontal direction emit light, the white line can be continuously and more clearly displayed.

Additionally, the image processing module 100 may further perform necessary image processing such as power consumption reduction, image quality compensation, and degradation compensation, and then output the image to the data driver 20 . The image processing module 100 may linearize image data by performing inverse gamma correction before executing image processing, and perform non-linearization of image data by performing gamma correction after image processing to output the image data.

5 is a block diagram showing the configuration of an image processing module according to an embodiment of the present invention, and FIG. 6 is a flowchart showing an image processing method according to an embodiment of the present invention. The image processing module of FIG. 5 and the image processing method of FIG. 6 will be described in connection with each other.

Referring to FIG. 5 , an image processing module 100 according to an embodiment includes a data conversion unit 102, a first rendering unit 104, an edge intensity detection unit 106, and an edge determination unit including a gain determination unit 108 105, a second rendering unit 110, and a third rendering unit 112. “~unit” constituting the image processing module 100 is a block that processes at least one function or operation, and may mean hardware or a corresponding function processing module of software stored in a memory.

The data conversion unit 102 receives the input image (S2) and converts the 3-color data (Ri, Gi, Bi) of the input image to the primary 4-color data (W1, R1, G1, B1) (S4). As an RGB-to-WRGB conversion method, any one of various known methods may be used. For example, the data conversion unit 102 generates W1 data as a common value (minimum value) among the Ri, Gi, and Bi data of each pixel, and subtracts the W1 data from each of the Ri, Gi, and Bi data to obtain R1, G1, Create B1 data.

The first rendering unit 104 converts the primary 4-color data (W1, R1, G1, B1) of each pixel supplied from the data conversion unit 102 to the primary color data of adjacent pixels to the M+ display panel. Secondary 4-color data (W2, R2, G2, B2) is generated by primary rendering according to the subpixel arrangement of (40) (S6). For example, the first rendering unit 104 uses the rendering method shown in FIG. 7 .

7 is a diagram for explaining a method of rendering RGB data into M+WRGB data according to an embodiment of the present invention.

In FIG. 7 , RGB data means Ri, Gi, and Bi data, WRGB data means W1, R1, G1, and B1 data, which are primary color data, and WRGB' data corresponding to M+ WRGB data is secondary color data. Indicates W2, R2, G2, B2 data.

Referring to FIG. 7, RGB1, RGB2, RGB3, RGB3, RGB5 data of each pixel, which is input data, is converted into primary data WRGB1, WRGB2, WRGB3, WRGB4, WRGB5, and WRGB6 data through the above-described data conversion unit 102. is converted The first rendering unit 104 properly distributes the primary data WRGB1, WRGB2, WRGB3, WRGB4, WRGB5, and WRGB6 by color to adjacent pixels using the rendering equation according to the embodiment shown in FIG. Secondary data WRGB'1, WRGB'2, and WRGB'3 data corresponding to WRGB data are created.

WRGB'1 data is generated by referring to WRGB1 data and WRGB2 data for each color. WRGB'1 data is generated by assigning weight a to WRGB1 data, summing the result of assigning weight b to WRGB2 data, and then dividing by k corresponding to the sum of weights a and b.

WRGB'2 data is generated by referring to WRGB2 data, WRGB3 data, and WRGB4 data for each color. WRGB'2 data is generated by adding weight c to WRGB4 data, weight d to WRGB3 data, weight e to WRGB4 data, and then dividing by k corresponding to the sum of weights c, d, and e. do.

WRGB'3 data is generated by referring to WRGB4 data and WRGB5 data for each color. WRGB'3 data is generated by assigning a weight f to WRGB4 data, summing the result of assigning a weight h to WRGB5 data, and dividing by k corresponding to the sum of weights f and h.

It can be seen from FIG. 7 that WRGB'1, WRGB'2, and WRGB'3 data sequentially correspond to sub-pixels of four pixels (WRG pixel, BWR pixel, GBW pixel, and RGB pixel).

The edge determination unit 105 includes an edge strength detection unit 106 and a gain determination unit 108 .

The edge intensity detection unit 106 receives only the W1 data of each pixel from the data conversion unit 102 and applies the Sharpen Mark shown in FIG. Each edge strength is detected (S8).

8 is a diagram for explaining a pixel edge analysis method using a sharpen mask according to an embodiment of the present invention.

Referring to FIG. 8 , optimal coefficients (-m, n) (0<m, n≤1) are set in each of the 3*3 cells of the sharpen mask SM according to a designer's preliminary experiment. A center cell of the sharpen mask SM may be set to a coefficient n, and 8 cells adjacent to the center cell vertically, left, right, and diagonally may be set to a coefficient -m. The size of the sharpen mask SM may be variable.

The edge intensity detection unit 106 converts the coefficients (-m, n) of the sharpen mask SM into primary W data W(i-1,j-1) to W(i+1,j+1) of 3*3 pixels. ), respectively, the edge strength (S_H) in the horizontal direction, the edge strength (S_V) in the vertical direction, and the first order W data W (i, j) of the current pixel (i, j) An edge intensity (S_DH) in one diagonal direction and an edge intensity (S_DL) in a second diagonal direction from upper left to lower right are calculated as shown in Equation 1 below, respectively.

<Equation 1>

S_H = n*W(i, j)-m*W(i-1, j)-m*W(i+1, j)

S_V = n*W(i, j)-m*W(i, j-1)-m*W(i, j+1)

S_DH = n*W(i, j)-m*W(i-1, j+1)-m*W(i+1, j-1)

S_DL = n*W(i, j)-m*W(i-1, j-1)-m*W(i+1, j+1)

The edge intensity detection unit 106 detects edge intensities (S_H, S_V, S_DH, S_DL) in various directions for each pixel corresponding to the center cell of the sharpen mask SM while shifting the sharpen mask SM in units of pixels. .

The gain determiner 108 compares the edge intensities (S_H, S_V, S_DH, and S_DL) of each pixel supplied from the edge intensity detector 106 with a reference value, and determines whether each pixel has an edge and the edge direction according to the comparison result. and a gain value (DM) of each pixel according to edge direction and edge direction is determined (S10).

When the absolute values of S_H, S_DH, and S_DL are all greater than the reference value and the absolute value of S_V is equal to the reference value, the gain determiner 108 may determine the corresponding pixel (i, j) as an edge in the vertical direction. When the absolute values of S_V, S_DH, and S_DL are all greater than the reference value and the absolute value of S_H is equal to the reference value, the gain determiner 108 may determine the corresponding pixel (i, j) as an edge in the horizontal direction. When the absolute values of S_H, S_V, and S_DL are all greater than the reference value and the absolute value of S_DH is equal to the reference value, the gain determiner 108 determines the corresponding pixel (i, j) as an edge in the first diagonal direction. there is. When the absolute values of S_H, S_V, and S_DH are all greater than the reference value and the absolute value of S_DL is equal to the reference value, the gain determiner 108 determines the corresponding pixel (i, j) as an edge in the second diagonal direction. there is. The gain determiner 108 determines that the pixel (i, j) is not an edge when all absolute values of S_H, S_V, S_DH, and S_DL are equal to the reference value or none of the absolute values are equal to the reference value. can

When the edge direction is determined, the gain determiner 108 determines a preset gain value DM according to the edge direction. The gain value DM may be preset in the range of 0 to 1 according to the edge direction by a designer. Gain values DM for edges in the vertical direction and first and second diagonal directions may be equal to each other with a first gain value greater than 0, and gain values DM for edges in the horizontal direction may be greater than 0 and It may be set to a second gain value smaller than the 1 gain value. When the gain determination unit 108 determines that the corresponding pixel is not an edge, the gain value DM is set to 0 so that the secondary data of the non-edge pixel is not affected by the secondary rendering process.

The second rendering unit 110 uses different secondary rendering methods for each pixel according to whether each pixel has a W subpixel (WRG pixel, BWR pixel, GBW pixel) or does not have a W subpixel (RGB pixel). The secondary color data of the corresponding pixel is converted into tertiary color data by applying the W1 data and the gain value (DM) of , and the tertiary color data is stored as a primary frame (S20).

Since the position of the RGB pixels without the W subpixel in the M+ display panel 40 is regular, the second rendering unit 110 determines whether the current pixel is a pixel without the W subpixel or the W subpixel according to the dot clock count value. It is possible to determine whether a pixel has a pixel.

When the second rendering unit 110 is an RGB pixel without a W subpixel (S22; N), the secondary 3-color data (R2, G2, B2) of the RGB pixel is performed by secondary rendering using Equation 2 below. ) is converted into tertiary 3-color data (R3, G3, B3) by applying the W1 data and the gain value (DM) (S24), and the tertiary color data (R3, G3, B3) is stored as a 1st frame (S28).

<Equation 2>

R3 = R2 + W1*DM

G3 = G2 + W1*DM

B3 = B2 + W1*DM

Accordingly, when an RGB pixel without a W subpixel is a white edge, the product of the W1 data of white gradation and the gain value DM is added to the secondary 3-color data R2, G2, B2, respectively, to obtain 3-order 3-color data. By converting into color data (R3, G3, B3), the tertiary three-color data (R3, G3, B3) expresses white proportional to the W1 data. On the other hand, when an RGB pixel without a W subpixel is included in a black edge (W1=0) or is not an edge pixel (DM=0), the secondary 3-color data (R2, G2, B2) remains 3-order 3-color data (R2, G2, B2). It is used as color data (R3, G3, B3).

When the second rendering unit 110 has a W subpixel (WRG pixel, BWR pixel, GBW pixel) (S22; Y), by secondary rendering using Equation 3 below, only the W2 data of the corresponding pixel W1 data and gain value (DM) are applied to convert to W3 data, and the remaining secondary 2-color data (R2/G2, B2/R2, or G2/B2) is converted into tertiary 2-color data (R3/G3) as it is. , B3/R3, or G3/B3) (S26), and stores the 3rd 3-color data (W3/R3/G3, B3/W3/R3, or G3/B3/W3) as the 1st frame. (S28).

<Equation 3>

W3 = W2*(1-DM) + W1*(DM)

R3 = R2

G3 = G2

B3 = B2

Accordingly, W2 data of each pixel (WRG pixel, BWR pixel, GBW pixel) having a W sub-pixel is converted into W3 data according to the W1 data and the gain value DM. For example, for each pixel (WRG pixel, BWR pixel, GBW pixel) having a W sub-pixel, when the W1 data is a black gradation and the gain value (DM) is 1, the W2 data is intermediate by the above-described primary rendering. Even if converted into grayscale, W3 data may represent black of W1 data instead of W2 data. In addition, when W1 data is a white gradation in each pixel (WRG pixel, BWR pixel, GBW pixel) having a W sub-pixel, since the W2 data is also a white gradation, the W3 data can represent the same white as the W2 data and the W1 data. .

Accordingly, the white line and the black line can be continuously and clearly displayed by displaying white using all three sub-pixels without light emission of the W sub-pixel of an adjacent pixel in the RGB pixel corresponding to the white line.

The third rendering unit 112 determines whether the edge direction is the horizontal direction from the gain value DM supplied to the gain determination unit 108 (S30). When the gain value DM does not indicate the horizontal direction (S30; N), the third rendering unit 122 converts the primary frame supplied from the second rendering unit 110 into an output image (Wo, Ro, Go, Bo). ) is supplied (S50). When the gain value DM indicates the horizontal direction (S30; Y), the third rendering unit 122 reinforces the edge line in the horizontal direction in the first frame and stores it as a second frame (S40). The frames are supplied as output images (Wo, Ro, Go, Bo) (S50).

When the pixel corresponding to the edge in the horizontal direction is an RGB pixel without a W subpixel (S42; N), the third 3-color data (R3, R3, B3) of the RGB pixel is unchanged. It is stored as a secondary frame (S46).

The third rendering unit 112 performs tertiary rendering using Equation 4 below when the pixel corresponding to the edge in the horizontal direction is a pixel (WRG pixel, BWR pixel, or GBW pixel) having a W subpixel (S42; Y). Accordingly, the tertiary color data is converted into 4th color data by applying the W1 data and the gain value (DM) (S44), and the 4th color data is stored as a 2nd frame (S46).

<Equation 4>

R4(n-2) = R3(n-2) + W1*DM

G4(n-1) = G3(n-1) + W1*DM

B4(n-1) = B3(n-1) + W1*DM

W4(n-1) = W3(n-1) - W1*DM

W4(n+1) = W3(n+1) - W1*DM

R4(n+1) = R3(n+1) + W1*DM

G4(n+1) = G3(n+1) + W1*DM

B4(n+2) = B3(n+2) + W1*DM

Referring to Equation 4, the tertiary color data of each of the R/G/B/W subpixels adjacent to the nth RGB pixel to the left and the W/R/G/B subpixels adjacent to the right are W1 data and gain It can be seen that it is corrected by the value DM and converted into 4th color data.

In other words, among the n-2th BWR pixels adjacent to the left and right of the nth RGB pixel, the tertiary color data R3(n-2) of the R subpixel and the tertiary color data G3(n-1) of the n-1th GBW pixel 1), B3(n-1), W3(n-1), and the tertiary color data W3(n+1), R3(n+1), G3(n+1) of the n+1th WRG pixel , 4th color data R4(n-2), G4(n-1), and B4 by applying W1*DM to each of the 3rd color data B3(n+2) of the B subpixel among the n+2th BWR pixels. (n-1), W4(n-1), W4(n+1), R4(n+1), G4(n+1), B4(n+2), convert the 4th color data to 2 save to car frame W1*DM value is added to each of R3(n-2), G3(n-1), B3(n-1), R3(n+1), G3(n+1), B3(n+2) data It can be seen that W1*DM value is subtracted from each of W3(n-1) and W3(n+1) data.

Accordingly, the W1 data corresponding to the RGB pixels included in the white edge line in the horizontal direction is transmitted to the RGB pixels according to the gain value (0<DM<1) and to the left and right adjacent four-color subpixels (R /G/B/W), all subpixels included in the white line emit light, so the continuity and sharpness of the white line can be improved.

9 is a diagram illustrating a comparison between an enlarged portion of a grill pattern displayed in the prior art and a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 9(a) , a vertical drawing pattern in which black pixel lines BL and white pixel lines WL extending in the vertical direction are alternately arranged in the horizontal direction is supplied to an input image.

Referring to FIG. 9(b), in the prior art display device, the nth RGB pixel Pn corresponds to the white pixel line WL, but displays black by the above-described primary rendering, whereas the nth RGB pixel corresponds to the white pixel line WL. Each of the n-1th RGW pixel (Pn-1) and the n+1th WRG pixel (Pn+1) adjacent to (Pn) from left to right corresponds to a black pixel line (BL), but W subpixels are formed by primary rendering. It can be seen that there is a disadvantage in that the black pixel line BL and the white pixel line WL are not clearly displayed by emitting light in an intermediate gray level (for example, 175 gray level).

Referring to FIG. 9(c) , in the display device according to the embodiment of the present invention, the nth RGB pixel Pn displays white by the above-described primary and secondary rendering, whereas the nth RGB pixel Pn ) and the n-1th RGW pixel (Pn-1) and the n+1st WRG pixel (Pn+1) each of the W subpixels adjacent to the left and right display black by the above-mentioned primary and secondary rendering, It can be seen that the pixel line BL and the white pixel line WL are clearly displayed.

On the other hand, referring to FIGS. 9(b) and (c), in the WRGB display device, in pixels having W subpixels (WRG pixels, BWR pixels, and GBW pixels) to express white, W subpixels are used as high It can be seen that while light is emitted in a gray level, in order to match the color temperature, the G and B subpixels adjacent to the W subpixel are gradually lighted in a low gray level.

10 is a diagram showing a comparison of grill patterns in a vertical direction displayed in a display device according to an embodiment of the present invention and a prior art.

Referring to FIG. 10 , when displaying a vertical grill pattern in which a black pixel line and a white pixel line extending in the vertical direction alternate in the horizontal direction, in a display device according to the prior art, RGB pixels included in the white pixel line By displaying black and displaying white by a combination of its RGB pixel and the W sub-pixels of the left and right adjacent pixels, it can be seen that the black pixel line and the white pixel line are not clearly displayed.

On the other hand, in the display device according to the exemplary embodiment of the present invention, the RGB pixels included in the white pixel line express white and the pixels included in the black pixel line express black, so that the black pixel line and the white pixel line are clearly displayed. Able to know.

11 is a diagram illustrating a comparison of grill patterns in a horizontal direction displayed in a display device according to an exemplary embodiment of the present invention and a prior art.

Referring to FIG. 11 , when displaying a horizontal grill pattern in which a black pixel line and a white pixel line extending in the horizontal direction alternate in the vertical direction, in a display device according to the prior art, RGB pixels included in the white pixel line Since black is displayed and the W subpixel displays white in each of the pixels having the W subpixel, it can be seen that the white pixel line in the horizontal direction is displayed in a dotted line form.

On the other hand, in the display device according to the exemplary embodiment of the present invention, the RGB pixels included in the white pixel line represent white, and all the subpixels in each pixel having the W subpixel emit light, so that the white pixel line continuously and clearly. displayed can be seen.

12 and 13 are diagrams illustrating a comparison between resolution authentication results for a horizontal grill pattern and a vertical grill pattern displayed in a display device according to an exemplary embodiment of the present invention and a prior art.

In order to obtain resolution certification of the display device, when displaying the grill pattern as shown in FIGS. 12 and 13, the white line luminance Lw and the black line luminance Lb are measured and the contrast modulation defined by Equation 5 below is performed. Modulation; hereinafter Cm) value should be close to 1.

<Equation 5>

Cm = (Lw - Lb)/(Lw + Lb)

Referring to FIG. 12, when displaying a vertical grill pattern, the white line luminance (Lw) measured from the display device according to the prior art is 1, the black line luminance (Lb) is 0.5, and the Cm value is 0.33. Therefore, while the prior art is difficult to obtain resolution certification, the white line luminance (Lw) measured from the display device according to the embodiment of the present invention is 1, the black line luminance (Lb) is 0.01, and the Cm value is 0.99. It can be seen that the example can satisfy all the resolution authentication conditions and improve the resolution expressiveness.

Referring to FIG. 13 , when a horizontal grill pattern is displayed, the white line luminance (Lw) is 1 and the black line luminance (Lb) is 0.01 in both the display devices according to the prior art and the exemplary embodiment, so that the Cm value is 0.99. Therefore, the resolution authentication condition can be satisfied. Furthermore, it can be seen that in the display device according to the exemplary embodiment, the continuity and sharpness of the white line in the horizontal direction are improved compared to the prior art, so that the resolution expressiveness can be improved.

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.

10: timing controller 20: data driving unit
30: gate driver 40: display panel
50: gamma voltage generator 100: image processing module
102: data conversion unit 104: first rendering unit
105: edge determination unit 106: edge strength detection unit
108: gain determination unit 110: second rendering unit
112: third rendering unit

Claims (16)

A method for processing an image to be supplied to a display panel in which each pixel has three subpixels among white, red, green, and blue subpixels and has a subpixel arrangement structure different from an adjacent pixel,
converting 3-color data in pixel units into primary 4-color data;
generating secondary 4-color data corresponding to the sub-pixel arrangement of the display panel by rendering using the primary 4-color data adjacent to the primary 4-color data for each color;
determining whether each pixel has an edge by analyzing a pixel edge using primary white data among primary 4-color data of a plurality of pixels;
When the current pixel is a first pixel without the white subpixel, secondary 3-color data corresponding to the first pixel among the secondary 4-color data according to an edge of the first pixel is Applying the primary white data and converting it into tertiary 3-color data;
When the current pixel is a second pixel having the white subpixel, secondary white data among secondary three-color data corresponding to the second pixel is converted to the primary pixel of the second pixel according to an edge of the second pixel. An image processing method further comprising the step of applying white data and converting it into tertiary white data. The method of claim 1,
The step of determining whether each pixel has an edge
A sharpen mask having a plurality of coefficients corresponding to each of the plurality of pixels is applied to the primary white data of the plurality of pixels in the horizontal, vertical, and first diagonal directions of the corresponding pixel corresponding to the center cell of the sharpen mask. and detecting edge intensities in a plurality of directions including a second diagonal direction;
and determining whether the corresponding pixel is an edge and an edge direction according to the edge strength in the plurality of directions, and determining a gain value according to whether the corresponding pixel is an edge and the edge direction. The method of claim 2,
The secondary 3-color data corresponding to the first pixel is obtained by multiplying each of the secondary 3-color data of the first pixel by the primary white data of the first pixel and the gain value of the first pixel. By doing so, the image processing method is converted into the tertiary 3-color data. The method of claim 3,
The secondary white data of the second pixel is obtained by multiplying the secondary white data by a value obtained by subtracting the gain value of the second pixel from 1, and the primary white data of the second pixel and the gain value of the second pixel. An image processing method that is converted into the tertiary white data by adding a value multiplied by . In any one of claims 2 to 4,
When the edge direction of the corresponding pixel is horizontal,
tertiary color data of each of a plurality of subpixels of different colors adjacent to the first pixel to the left and of a plurality of subpixels of different colors adjacent to the right side, the primary white data of the first pixel and converting into 4th color data by applying a value multiplied by the gain value of the first pixel. The method of claim 5,
When the first pixel is the n-th pixel,
A value obtained by multiplying the primary white data by the gain value is subtracted from the tertiary white data of the n−1 th pixel and the tertiary white data of the n+1 th pixel, respectively;
tertiary red data of the n-2 th pixel, tertiary green and blue data of the n-1 th pixel, tertiary red and green data of the n+1 th pixel, and tertiary blue data of the n+2 th pixel, respectively An image processing method of adding a value obtained by multiplying the primary white data and the gain value to . An image processing module for processing an image to be supplied to a display panel in which each pixel has three subpixels among white, red, green, and blue subpixels and has a subpixel arrangement structure different from an adjacent pixel,
After converting the 3-color data in pixel units into primary 4-color data, generating secondary 4-color data corresponding to the subpixel arrangement of the display panel by rendering the primary 4-color data;
According to the edge of the pixel using the primary white data among the primary 4-color data, the primary white data of the first pixel is applied to secondary 3-color data of the first pixel without the white subpixel to obtain 3 converting into primary 3-color data, and converting secondary white data among secondary 3-color data of a second pixel having the white subpixel into tertiary white data by applying primary white data of the second pixel image processing module. The method of claim 7,
The image processing module,
a data converter for converting the 3-color data into the primary 4-color data;
a first rendering unit which generates the secondary 4-color data by rendering using the primary 4-color data supplied from the data conversion unit and adjacent primary 4-color data for each color;
an edge determiner configured to determine whether each pixel has an edge by analyzing a pixel edge using primary white data of a plurality of pixels supplied from the data converter;
When secondary 3-color data supplied from the first rendering unit corresponds to the first pixel, secondary 3-color data of the first pixel according to the edge of the first pixel supplied from the edge determination unit converting data into tertiary 3-color data by applying primary white data of the first pixel supplied from the edge determination unit;
When secondary 3-color data supplied from the first rendering unit corresponds to the second pixel, secondary white data of the second pixel is determined according to an edge of the second pixel supplied from the edge determination unit. and a second rendering unit configured to apply the primary white data of the second pixel supplied from the edge determination unit and convert the primary white data into tertiary white data. The method of claim 8,
The edge determination unit
A sharpen mask having a plurality of coefficients corresponding to each of the plurality of pixels is applied to the primary white data of the plurality of pixels in the horizontal, vertical, and first diagonal directions of the corresponding pixel corresponding to the center cell of the sharpen mask. and an edge intensity detection unit configured to detect edge intensities in a plurality of directions including a second diagonal direction;
Determine whether the corresponding pixel has an edge and an edge direction according to the edge strength in the plurality of directions supplied from the edge intensity detection unit, determine whether a corresponding pixel has an edge and determine a gain value according to the edge direction, and determine the gain value of the corresponding pixel and the first order An image processing module comprising a gain determining unit supplying white data to the second rendering unit. The method of claim 9,
The second rendering unit
The secondary 3-color data of the first pixel is obtained by adding a result of multiplying the primary white data of the first pixel by the gain value of the first pixel to each of the secondary 3-color data of the first pixel. An image processing module that converts to 3-order 3-color data. The method of claim 10,
The second rendering unit
The second pixel is obtained by multiplying the secondary white data by a value obtained by subtracting the gain value of the second pixel from 1 and adding a value obtained by multiplying the primary white data of the second pixel by the gain value of the second pixel. An image processing module for converting secondary white data of to the tertiary white data. The method of claim 11,
When the gain value of the corresponding pixel supplied from the gain determination unit indicates the horizontal direction,
Among the tertiary 3-color data of each pixel supplied from the second rendering unit, a plurality of sub-pixels of different colors adjacent to the first pixel to the left, and a plurality of sub-pixels of different colors adjacent to the first pixel and a plurality of sub-pixels of different colors to the right A third method for converting the tertiary color data of each of the subpixels into 4th color data by applying a value obtained by multiplying the primary white data of the first pixel supplied from the gain determiner by the gain value of the first pixel; An image processing module that further includes a rendering unit. The method of claim 12,
The third rendering unit
When the first pixel is the n-th pixel,
subtracting a value obtained by multiplying the primary white data by the gain value from the tertiary white data of the n−1 th pixel and the tertiary white data of the n+1 th pixel, respectively;
tertiary red data of the n-2 th pixel, tertiary green and blue data of the n-1 th pixel, tertiary red and green data of the n+1 th pixel, and tertiary blue data of the n+2 th pixel, respectively An image processing module that adds a value obtained by multiplying the primary white data by the gain value. The image processing module according to any one of claims 7 to 13;
the display panel;
and a panel driver configured to drive the display panel so that the image supplied from the image processing module is displayed on the display panel. The method of claim 14,
The display panel
A WRG pixel having a white/red/green subpixel arrangement;
A BWR pixel having a blue/white/red subpixel arrangement;
A GBW pixel having a green/blue/white subpixel arrangement;
It includes RGB pixels having a red/green/blue subpixel arrangement;
The first pixel corresponds to the RGB pixel, and the second pixel corresponds to any one of the WRG pixel, the BWR pixel, and the GBW pixel;
When the image supplied from the image processing module includes a black line pattern and a white line pattern in pixel line units,
The first pixel included in the first pixel line displaying the white line pattern displays white luminance using all of its red, green, and blue subpixels, and the second pixel included in the first pixel line represents white luminance using its own white sub-pixel;
The display device of claim 1 , wherein both the first pixel and the second pixel included in the second pixel line displaying the black line pattern display black luminance. The method of claim 15
When the white line pattern is in the horizontal direction,
The display device of claim 1 , wherein the first and second pixels included in the first pixel line displaying the white line pattern display white luminance using all subpixels.

Images