KR101633107B1 - Method for Increasing Color Gamut and Display Device using the same - Google Patents

Abstract

The present invention relates to a method of analyzing RGB data for each pixel and setting a target correlated color temperature of RGB data for each pixel; And correcting the brightness of the RGB data for each pixel according to the set target correlated color temperature.

Color reproduction, correlation color temperature, display device,

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color reproduction method of a display device,

The present invention relates to a color reproduction method of a display device and a display device using the same.

2. Description of the Related Art [0002] With the development of information technology, as a market of a display device that is a connection medium between a user and information has grown, organic light emitting displays (OLED), liquid crystal displays (LCDs) (Plasma Display Panel: PDP) have been increasingly used.

The display device as described above is utilized in various industrial fields such as a computer such as a notebook computer or a mobile phone in the field of consumer electronics such as a television (TV) and a video.

In general, the chromaticity of the light source or the reference white can be expressed by the temperature of the nearest region on the radiation curve instead of the coordinate on the two-dimensional color chart, which is called a correlated color temperature (CCT) or color temperature. The color temperature is used as a numerical value indicating the degree to which a white color is close to a certain color.

The higher the color temperature, the higher the blue color, and the lower the color temperature, the more red color is included in the display device. In the color temperature characteristic, the preference varies depending on the country. Therefore, in order to utilize the display device in various fields and various places, a technique capable of changing the color recall rate according to the characteristics of the input image in the image implementation should be proposed.

The present invention for solving the above problems of the background art is to provide a color reproduction method of a display device capable of contributing to an increase in perceived brightness, an increase in perceived contrast and a reduction in power consumption so as to realize an optimal brightness suitable for an application field in image realization And a display device using the same.

According to an aspect of the present invention, there is provided an image processing method comprising: analyzing RGB data for each pixel and setting a target correlated color temperature of RGB data for each pixel; And correcting the brightness of the RGB data for each pixel according to the set target correlated color temperature.

In the correlated color temperature setting step, it is determined whether or not the values of RGB data per pixel are identical, and the target correlated color temperature can be set when the RGB data values of the pixels are the same.

The determination of whether or not the values of RGB data per pixel are identical may use colors ranging from white to low gradation.

The step of correcting the brightness of the RGB data for each pixel can shift the tristimulus value through the lookup table derived from the just noticeable difference value of the cognitive correlated color temperature for each color temperature.

The step of correcting the brightness of RGB data per pixel includes the steps of deriving a color coordinate of x and y with respect to the target correlated color temperature, a step of converting the color coordinates of x and y into tristimulus values (X, Y, Z) And moving the extreme value.

The step of deriving the color coordinates can be performed with the luminance of RGB data per pixel fixed.

The step of moving the trinity extremity may move at least one of the trinity extremes.

According to another aspect of the present invention, A color reproducing unit that analyzes pixel-by-pixel RGB data supplied from the timing control unit, sets a target correlated color temperature of RGB data per pixel, and corrects brightness of RGB data per pixel according to a set target correlated color temperature; And a display panel for displaying an image by RGB data corrected by the color reproducing unit.

The color reproducing unit determines whether or not the values of the RGB data for each pixel are identical, and if the values of the RGB data for the pixels are the same, the brightness of RGB data for each pixel can be corrected according to the set target correlated color temperature.

The color reproducing unit may correct at least one of the tristimulus values through a lookup table derived from the cognitive contrast color temperature of the perceptually correlated color temperature for each color temperature to correct the brightness of the RGB data for each pixel according to the set target correlated color temperature have.

The present invention provides a color reproduction method of a display device capable of contributing to an increase in perceived brightness, an increase in perceived contrast and a reduction in power consumption in order to realize an optimal brightness suitable for an application field in image realization, and a display device using the same .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Color Reproduction Method of Display Device>

FIG. 1 is a flowchart for explaining a color reproduction method of a display device according to an embodiment of the present invention, FIG. 2 is a view for explaining a characteristic model of a display device and a target lookup table creation process, FIG. 4 is a graph showing a color temperature or a contrast test result according to a color temperature, FIG. 5 is a graph showing a cognition sensitivity which appears bright at the same luminance for each color temperature, FIG. 6 is a graph showing a cognitive sensitivity Fig.

Correlated color temperature (CCT) of white and gray levels is set for each display device. The color reproduction method of the display device according to the embodiment of the present invention raises the perceived brightness and the just noticeable difference (JND) so as to realize the optimal brightness according to each situation, 1.

First, if RGB data per pixel is input, it is determined whether or not the input RGB data values are the same (S10). The determination of whether or not the input RGB data values are identical may use colors ranging from white to low gradation ranges. In this step, for example, if the RGB data value is not R = G = B, the target correlated color temperature is not set and RGB data is output (S23)

Next, the target correlated color temperature of RGB data per pixel is set when the input RGB data values are the same, that is, when the RGB data value is R = G = B. (S13) The target correlated color temperature is CIE 1931 colorimetric system), but it is not limited thereto.

Next, the color coordinates of x and y for the set target correlated color temperature are derived (S15). At the derivation of the color coordinates, the luminance of the RGB data for each pixel, that is, Y is fixed. Here, the derivation process of the color coordinates of x and y with respect to the target correlated color temperature is based on the color temperature (T).

Next, the color coordinates of x and y are converted into tristimulus values (X, Y, Z). (S17) Tristimulus values X, Y and Z are based on light- Color (X), brightness (Y), and saturation (Z). Here, the conversion of the color coordinates of x and y to the tristimulus values (X, Y, Z) can be performed using an equation. For example, when the color coordinates of x and y are as shown in the following Equation 1, it can be converted into tristimulus values (X, Y, Z) by using Equation (2).

Next, the tristimulus values X, Y, and Z are shifted. (S19) When the tristimulus values X, Y, and Z are shifted, at least one of the tristimulus values X, Y, have. The tristimulus values (X, Y, Z) can be shifted through the lookup table derived from the perceived contrast value of the perceptually correlated color temperature for each color temperature. Since the lookup table stores data corresponding to the perceived contrast of the perceived color temperature of each color temperature, the tristimulus values (X, Y, Z) are shifted based on the characteristics.

For example, the perceived contrast of the perceived correlated color temperature for each color temperature of white can be derived as shown in Table 1 below.

As shown in Table 1, when the perceived contrast of the perceptually correlated color temperature is derived for each color temperature of white color, the perceived contrast (JND) is 183K when the CCT is 3000K, and the contrast is when the CCT is 6000K JND) is 619, and when the correlated color temperature (CCT) is 10000K, the perceived contrast (JND) can be set to 1641K or the like.

In addition, a method of moving the tristimulus values (X, Y, Z) can be applied to a GOG using a gain, an offset, and a gamma, but is not limited thereto.

Next, the brightness of the RGB data for each pixel is corrected based on the movement of the tristimulus value (X, Y, Z) according to the set target correlated color temperature (S21). In this step, Is generated as R'G'B 'data corrected for each pixel through the process.

For example, the pixel-specific RGB data to be modulated is a white reference point via a modulation process on the basis of the _{(R max, G max, B} max) R '= R / 255 * R max, G' = G / 255 * G max, B '= B / 255 * B _max and is generated as R'G'B' data corrected for each pixel.

As described above, the color reproduction method of the display device creates a characteristic model of the display device as shown in FIG. 2, and when the input RGB data is equal to R = G = B, R'G ' B is realized, it is possible to realize an image which can feel bright even if the same luminance is visually displayed according to the increase of the correlated color temperature according to the characteristics of the display device.

As shown in Fig. 2, if a lookup table to be combined with the characteristic model of the display device and the perceived contrast of the correlated color temperature is created, the color reproduction method of the display device can proceed to the flow as shown in Fig.

As shown in FIG. 4 and FIG. 5, when the correlated color temperature increases during image display using a conventional display device, the perceived contrast increases. In addition, it can be seen that, even when the correlated color temperature increases, even if the same luminance is displayed visually.

Referring to the photograph of sunlight in the dotted line area of the embodiment as compared with the comparative example of FIG. 6, since the image output is induced so that the perceived brightness of the white area becomes bright in the embodiment, The margin for power consumption can be expected to increase. Therefore, by converting the input color coordinates of the input RGB data to R = G = B into a predetermined look-up table, a display device with high brightness can be realized.

<Display device>

FIG. 7 is a schematic block diagram of a display apparatus according to an embodiment of the present invention, and FIG. 8 is a configuration diagram of a color reproducing section.

7, the display device according to an exemplary embodiment of the present invention includes a timing control unit TCN, a color display unit ICG, a scan driver SDRV, a data driver DDRV, and a display panel PNL. do.

The display panel PNL may be any one of a plasma display panel, an organic light emitting display panel, and a liquid crystal display panel, but is not limited thereto. However, in the embodiment, a liquid crystal display panel including a transistor substrate and a color filter substrate on which the display panel (PNL) faces with a liquid crystal layer interposed therebetween will be described as an example. The display panel PNL includes a pixel array SP for displaying video data. The pixel array SP of the transistor substrate includes transistors (hereinafter referred to as TFTs) formed at intersections of the data lines DL1 to DLn and the scan lines SL1 to SLm, and pixel electrodes connected to the TFTs. Each of the liquid crystal cells of the pixel array SP is driven by a voltage difference between a data voltage applied to the pixel electrode that charges the data voltage through the TFT and a common voltage applied to the common electrode, The image of the video data is displayed by adjusting the transmission amount of light.

The timing control unit TCN supplies timing signals such as the digital RGB data, the vertical synchronizing signal Vsync, the horizontal synchronizing signal Hsync, the data enable signal DE and the dot clock CLK from the outside And receives the system signal CS. The timing controller TCN transmits three RGB digital video data to the data driver DDRV using a mini-LVDS (low-voltage differential signaling) interface method in order to reduce the swing width of EMI and data voltages on the data transmission path. The timing controller TCN supplies a driving signal such as a data timing control signal SSC, SOE, POL or the like for controlling the data driver DDRV using the timing signals Vsync, Hsync, DE and CLK, And a scan timing control signal (GSP, GSC, GOE) for controlling the operation timing of the scan signal. The timing control unit TCN controls the timing of the scan timing control so that the digital RGB data input at a frame frequency of 60 Hz can be reproduced in the pixel array of the display panel PNL at a frame frequency of 60 x i (i is a positive integer) The frequencies of the signals GSP, GSC and GOE and the data timing control signals SSC, SOE and POL can be multiplied by a frame frequency of 60 x i Hz.

The scan driver SDRV includes a shift register for sequentially shifting the scan voltage in response to the scan timing control signals GSP, GSC, and GOE supplied from the timing controller TCN. The scan driver SDRV includes scan registers SL1 to SLm, And sequentially supplies a signal (or a scan pulse).

The data driver DDRV samples and latches the digital RGB data according to the mini LVDS clock and the RGB data of the mini LVDS interface standard, and converts the RGB data into data of a parallel data system. The data driver DDRV converts digital RGB data converted into a parallel data transmission scheme into positive / negative polarity RGB data voltages (positive polarity / negative polarity) in response to a polarity control signal POL using positive / negative gamma reference voltages And supplies it to the data lines DL1 to DLn.

The color reproduction unit ICG analyzes RGB data per pixel for the image supplied from the timing control unit TCN and sets the target correlated color temperature of the RGB data for each pixel and corrects the brightness of the RGB data for each pixel according to the set target correlated color temperature . The color representation unit ICG determines whether or not the values of RGB data per pixel are the same, and performs correction according to the set target correlated color temperatures when the RGB data values of the pixels are the same. At this time, the color reproducing unit (ICG) moves at least one of the tristimulus values through the lookup table derived from the just noticeable difference value of the perceptually correlated color temperature for each color temperature, and calculates the brightness And supplies the corrected R'G'B 'data to the data driver DDRV.

Referring to FIG. 8, the color reproduction unit ICG includes a correlated color temperature setting unit CCT, a lookup table (LUT), and a data correction unit CMP.

The correlated color temperature setting unit CCT determines whether or not the input RGB data values are the same when RGB data for each pixel is inputted from the timing control unit TCN. At this time, the determination of whether or not the input RGB data values are identical can use colors ranging from white to low gradation ranges. The correlated color temperature setting unit CCT sets the target correlated color temperature and outputs RGB data if, for example, the RGB data value is not R = G = B. If R = G = B is not satisfied, do. On the other hand, when the input RGB data values are the same, that is, when the RGB data value is R = G = B, the correlated color temperature setting unit CCT sets the target correlated color temperature of RGB data per pixel. Here, the target correlated color temperature may be implemented based on the color space coordinates of the CIE 1931 standard colorimetric system (CIE 1931), but is not limited thereto.

The lookup table (LUT) stores data capable of correcting the perceived contrast of the perceptually correlated color temperature for each target color temperature. To this end, the data stored in the look-up table (LUT) can be created through the following flow. First, the color coordinates of x and y for the set target correlated color temperature are derived. When the color coordinate is derived, the luminance of RGB data for each pixel, that is, Y is fixed. Here, the process of deriving the color coordinates of x and y with respect to the target correlated color temperature is based on the color temperature (T).

Next, the lookup table (LUT) converts the color coordinates of x and y to tristimulus values (X, Y, Z). The tristimulus values (X, Y, Z) are based on the light-object-sense, which is the basic three elements of color, and mean color (X), brightness (Y) and chroma (Z) respectively. Here, the conversion of the color coordinates of x and y to the tristimulus values (X, Y, Z) can be performed by using Equation 2 described above.

Next, the tristimulus values (X, Y, Z) are moved. When moving the tristimulus values (X, Y, Z), at least one of the tristimulus values (X, Y, Z) can be shifted for each RGB data. The tristimulus values (X, Y, Z) can be shifted through the lookup table derived from the perceived contrast value of the perceptually correlated color temperature for each color temperature. Since the lookup table stores data corresponding to the perceived contrast of the perceived color temperature of each color temperature, the tristimulus values (X, Y, Z) are shifted based on the characteristics.

For example, the perceived contrast of the perceived correlated color temperature for each color temperature of white can be derived as shown in Table 2 below.

As shown in Table 2, when the perceived contrast of the perceptually correlated color temperature is derived from the white color temperature, the perceived contrast (JND) is 183K when the CCT is 3000K and the perceived contrast (CCT) is 6000K when the correlated color temperature JND) is 619, and when the correlated color temperature (CCT) is 10000K, the perceived contrast (JND) can be set to 1641K or the like.

In addition, a method of moving the tristimulus values (X, Y, Z) can be applied to a GOG using a gain, an offset, and a gamma, but is not limited thereto.

The data correction unit CMP corrects the brightness of the RGB data for each pixel according to the target correlated color temperature set according to the data created in the lookup table (LUT). The data correction unit (CMP) generates the R'G'B 'data corrected for each pixel by performing the data modulation process on the RGB data per pixel input first.

For example, the data correction unit (CMP) is through a modulation process, if a pixel-specific RGB data modulation is based on the white reference point _{(R max, G max, B} max) R '= R / 255 * R max, G' = G / 255 * _Gmax , B '= B / 255 * _Bmax G'B 'data corrected for each pixel as shown in FIG.

The display device according to the present invention creates a characteristic model of the display device as shown in FIG. 2 described above. When the input RGB data is equal to R = G = B, the R'G ' Up table (LUT) that implements B is used. Therefore, it is possible to realize an image that can feel bright even if the luminance of the display device exhibits the same luminance as the correlation color temperature increases. Meanwhile, the present invention changes the RGB value for the purpose of increasing brightness over the full white color temperature set value, and a lookup table (LUT) can be used for this purpose. The lookup table (LUT) may be formed in an internal or external memory, which may be included in a timing control unit (TCN).

It is an object of the present invention to provide a color reproducing method of a display device capable of contributing to an increase in perceived brightness, an increase in perceived contrast and a reduction in power consumption, and a display device using the method, .

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart for explaining a color reproduction method of a display device according to an embodiment of the present invention; FIG.

2 is a diagram for explaining a characteristic model of a display device and a process of creating a target lookup table;

3 is a diagram for explaining a color reproduction method through a look-up table;

FIG. 4 is a graph of a color temperature or contrast test result for each color temperature.

FIG. 5 is a graph showing cognitive sensitivity which appears bright at the same luminance per color temperature.

6 is a view showing an image for comparing the comparative example and the embodiment.

7 is a schematic block diagram of a display device according to an embodiment of the present invention;

8 is a configuration diagram of a color reproduction section;

DESCRIPTION OF THE REFERENCE NUMERALS

TCN: Timing control section ICG: Color representation section

DDRV: Data driver SDRV: Scan driver

PNL: display panel SP: pixel array

Claims (10)

Analyzing RGB data for each pixel to determine whether the RGB data values of the pixels are the same or not; Setting a target correlated color temperature of the pixel-by-pixel RGB data; Correcting the brightness of the RGB data for each pixel according to the set target correlated color temperature; And And outputting the pixel-by-pixel RGB data, Wherein the step of performing the setting and the step of correcting are performed only when the RGB data values of the pixels are equal to each other, and the outputting step outputs the corrected RGB data per pixel, Wherein the step of performing the setting and the step of performing correction are not performed when the values of the RGB data for each pixel are not identical. delete The method according to claim 1, Wherein the determination of whether or not the pixel-by-pixel RGB data values are identical uses a color ranging from white to low gradation intervals. The method according to claim 1, Wherein the step of correcting the brightness of the pixel- And moving the tristimulus value through a lookup table in which a value of a noticeable difference of a perceptually correlated color temperature for each color temperature is derived. The method according to claim 1, Wherein the step of correcting the brightness of the pixel- Deriving a color coordinate of x and y with respect to the target correlated color temperature, Converting the color coordinates of x and y into tristimulus values (X, Y, Z) And moving the tristimulus value. 6. The method of claim 5, The step of deriving the color coordinates includes: Wherein the color reproduction is performed based on the color temperature while the luminance of the RGB data for each pixel is fixed. 6. The method of claim 5, The step of shifting the tristimulus value comprises: And at least one of the tristimulus values is moved. A timing controller; And a controller that analyzes the RGB data of each pixel supplied from the timing controller to determine whether the RGB data values of the pixels are identical or not, and when the RGB data values of the pixels are the same, the target correlated color temperature And a color reproducing unit for correcting and outputting the brightness of the RGB data for each pixel according to the set target correlated color temperature. And And a display panel for displaying an image by the RGB data outputted by the color reproducing section, Wherein the color reproducing section outputs the pixel-by-pixel RGB data without correcting when the pixel-by-pixel RGB data values are not identical. delete 9. The method of claim 8, The color reproducing section may include: And the brightness of the RGB data for each pixel is corrected according to the set target correlated color temperature by moving at least one of the tristimulus values through the lookup table derived from the just noticeable difference value of the perceptually correlated color temperature for each color temperature / RTI &gt;

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