KR20110047669A - Method and apparatus for correcting color of display device - Google Patents

Abstract

PURPOSE: A color correcting method of a display device and apparatus thereof are provided to improve image quality by controlling chromatic according to an imaging parameter. CONSTITUTION: Input data of a color compensation space is converted into corresponding color data. Chromatic data is calculated from corresponding color data. A gain value is calculated by using maximum gain value and chromatic data(S24). Input data is calculated by using the gain value(S26).

Description

METHOD AND APPARATUS FOR COLOR CALIBRATION OF DISPLAY DEVICE {METHOD AND APPARATUS FOR CORRECTING COLOR OF DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a method and apparatus for correcting color of a display device capable of emphasizing color expression by adjusting saturation in real time according to an image condition.

Recently, organic light emitting diode (OLED) display devices, along with liquid crystal displays (LCDs), have emerged as image display devices. LCD displays images by using the electrical and optical characteristics of liquid crystals having anisotropy such as refractive index and dielectric constant, and realizes gradation by adjusting the light transmittance through which each pixel passes through the polarizing plate in the direction of the liquid crystal array according to the data signal. do. An OLED display is a self-luminous device that emits an organic light emitting layer by recombination of electrons and holes. The OLED display device has high brightness, low driving voltage, and ultra thin film. The OLED display implements gradation by adjusting the magnitude of the current supplied to the OLED pixel by the driving circuit of each pixel according to the data signal.

As image display apparatuses develop in the direction of high resolution and high definition, color reproducibility is improved. In particular, the OLED display device is a self-luminous element and has the advantage of better color expression than other display devices. In order to highlight these advantages, a technique capable of emphasizing color expression is required. Saturation can be adjusted to a high level by emphasizing the color expression, but if the saturation is too high, the viewer's eyes may be excessively stimulated to give a visually rejection reaction. In addition, when the saturation is adjusted, there should be no change in the hue, and in order to apply the method of adjusting the saturation to the display device, a simple operation capable of real-time processing is further required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color correction method and apparatus for a display device, which can improve image quality by adjusting saturation in real time according to image conditions and saturation without changing color.

In order to achieve the above object, a color correction method of a display device according to an aspect of the present invention converts the input data (R / G / B) of the three primary color spaces to the corresponding color data (RG / YB) of the corresponding color color space Making a step; Calculating chroma data (S) from the corresponding color data (RG / YB); Calculating a gain value (k, k is an integer) that is adaptively changed according to the saturation data (S) by using the saturation data (S) and a preset maximum and minimum gain value; Correcting the input data R / G / B using the gain value k.

The gain value has a lower gain as the saturation data S is higher, and has a higher gain value as the saturation data S is lower. The saturation data S is calculated through a root calculation operation of Equation 5 below using the corresponding color data RG / YB. The gain value k is calculated through the calculation of Equation 4 below using the saturation data S, the maximum gain value k _MAX , and the minimum gain value k _MIN . It is set to a value of at least one, or the maximum gain value is set to two, and the minimum gain value is set to one. The input data R / G / B is corrected to correction data R '/ G' / B 'through the calculation of Equation 6 below using the gain value k.

According to another aspect of the present invention, a color correcting apparatus of a display device includes: a color space converter for converting input data (R / G / B) of three primary color spaces into corresponding color data (RG / YB) of a corresponding color color space; Saturation data S is calculated from the corresponding color data RG / YB, and the gain is adaptively varied according to the chroma data S by using the chroma data S and a preset maximum and minimum gain value. A gain value calculator for calculating a value (k, k is an integer); And a data correction unit for correcting the input data R / G / B using the gain value.

The color correction device of the present invention is applied to an organic light emitting diode display device or a liquid crystal display device.

The color correction method and apparatus of the display device according to the present invention adaptively calculate a gain value k for emphasizing only the saturation component S according to the input data without changing the hue H, and calculates the gain value. By correcting the input data using (k), it is possible to display a clear image with enhanced saturation without changing the color.

In addition, the gain value k varies according to the saturation component S of the original image, so that a high saturation image has a low gain value (k; minimum 1), and a low saturation image has a high gain value (k; maximum 2), the saturation can be emphasized when the saturation of the input image is low, while the original image can be maintained when the saturation is high, thereby reducing eye fatigue.

Therefore, the OLED display device or the liquid crystal display device using the color correction method and apparatus according to the present invention can display a bright and clear image with saturation accentuated according to the original image.

1 is a flowchart illustrating a color correction method of a display device according to an exemplary embodiment of the present invention, and FIG. 2 is a block diagram illustrating a color correction apparatus of another display device according to an exemplary embodiment of the present invention. Hereinafter, the description will be given with reference to FIGS. 1 and 2.

The method and apparatus for correcting colors shown in FIGS. 1 and 2 correspond to input data (R / G / B) of three primary colors (RGB) color spaces in a corresponding color color space (Opponent Color Space) in step 22 (S22). The color space conversion section 22 for linear conversion to color data I / RG / YB and the corresponding color data I / RG / YB from the color space conversion section 22 in step 24 (S24) A gain value calculation unit 24 for calculating chroma data S indicating purity and a gain value k for adaptively emphasizing only chroma components according to the chroma data S without color change, and step 26; In S26, a data correction unit 26 for correcting the input data R / G / B by using the gain value k from the gain value calculation unit 24 is provided.

In operation 22 (S22), the color space converter 22 converts input data (R / G / B) of the three primary colors (RGB) color space into corresponding color data (RG / YB) of the corresponding color color space (Opponent Color Space). Convert to linear. The corresponding color space includes four colors of red, yellow, green, and blue representing the primary colors, and a red-green pair and a yellow-blue pair as shown in FIG. Since the physiological features of the human visual system are used, they can be used as efficient color feature values. In the corresponding color space shown in FIG. 2, the 'I' component has lightness, the 'RG' component has a red-green relationship, and the 'YB' component has a yellow-blue ( Blue) relationship. The color space conversion unit 22 performs a calculation using Equation 1 below and linearly converts the input data R / G / B into corresponding color data RG / YB, or uses three lookup data R / G using a lookup table. Linear conversion is performed using the mapping method of G / B) to corresponding color data (RG / YB).

In step 24 (S24), the gain value calculator 24 calculates chroma data S indicating the purity of the color using the corresponding color data RG / YB from the color space converter 22, and changes the color. The gain value k for adaptively emphasizing only the saturation component is calculated according to the saturation data S without any adaptation.

In general, the corresponding color data I / RG / YB may be converted into chroma data S and color data H by an operation using Equation 2 below. The color data H for expressing the color means the size of the angle θ in the YB-RG coordinate system shown in FIG. 3, and the saturation data S for expressing the purity of the color is YB shown in FIG. 3. -RG means the size of the distance (L) from the origin in the coordinate system.

 When multiplying a specific gain value k by the corresponding color data RG / YB to emphasize only the saturation data S, that is, the saturation components, the color data H does not change and the saturation data ( Only S) can be adjusted. In other words, it can be seen that the chroma data S is changed by a specific gain value k, but the color data H is not affected by the gain value k.

A gain value k for emphasizing only the saturation component is calculated using the saturation data S calculated from the corresponding color data RG / YB corresponding to the input data R / G / B. If the gain value k is large, the saturation data S may be increased to display vivid colors. On the contrary, if the gain value k is small, color components may be lost and a result closer to the gray image may be displayed. 4 illustrates that the saturation is changed according to the magnitude of the gain value k. As shown in FIG. 4, as the gain value k increases, the saturation of the image increases, and as the gain value k decreases, the saturation of the image decreases to show a characteristic close to the gray image (k = 0.25). Can be. Therefore, if the gain value k is large, the color can be clearly displayed, but if the gain value k is too large (k = 2), the lubrication of the object is not clear and excessive stimulation is applied to the human eye, resulting in a bad image. Since it is displayed, it is desirable to change the gain value k adaptively according to the image condition. Accordingly, the present invention calculates the gain value k using the saturation data S according to the input data as shown in Equation 4 in order to adaptively adjust the saturation according to the image condition, that is, the input data.

In Equation 4, k _MAX represents the maximum gain value preset by the designer, k _MIN represents the minimum gain value preset, the total number of gray levels, and S represents the chroma value calculated from the corresponding color data (RG / YB) of one pixel. Means data. The maximum gain value (k _MAX ) and the minimum gain value (k _MIN ) are preset through many image analysis of the designer, and are not particularly limited. However, the maximum gain value (k _MAX ) has a value of 1 or more for color enhancement. Preferably, for example, the maximum gain value k _MAX may be set to two, and the minimum gain value k _MIN may be set to one.

On the other hand, in order to simplify the calculation of calculating the saturation data (S) can be approximated as shown in the following equation (5). When the calculation to calculate the saturation data (S) is applied to the approximation instead of Equation 2 as shown in Equation 5 below, the operation becomes simple, and thus, real-time operation is possible.

In step 26 (S26), the data correction unit 26 corrects the input data R / G / B using the gain value k from the gain value calculating unit k, so that only the saturation component is changed without changing the color. Output the highlighted correction data R '/ G' / B '. The data correction unit 26 calculates and outputs correction data R '/ G' / B 'through an operation as shown in Equation 6 below using the input data R / G / B and the gain value k. do.

As described above, the color correction method and apparatus according to the present invention adaptively calculates a gain value k for emphasizing only the saturation component S according to the input data without changing the hue H, and calculates the gain value ( By correcting the input data using k), it is possible to display a clear image with enhanced saturation without changing the color.

6a to 6c show the image of the present invention to which the color correction method according to the present invention is applied in comparison with the original image and the gain value (k), and FIGS. 7a and 7b are chroma components of the image and the original image of the present invention. 8A and 8B illustrate the color components of the present invention and the original image.

It can be seen from the original image shown in FIG. 6A that the image having a bright and vivid color can be displayed as shown in FIG. 6C using the gain value k adaptively variable according to the original image as shown in FIG. 6B. . In particular, as shown in FIGS. 6B and 6C, the lower saturation region has a larger gain value k so that the saturation is emphasized so that the image appears brighter and clearer, and in the high saturation region, the gain value k is 1; It can be seen that the color of the original image is maintained by having a close value. Therefore, in the high saturation region, it is possible to suppress artifacts at the boundary of the image due to excessive emphasis of the saturation and to reduce eye fatigue due to the irritating color.

In addition, although the saturation component of the image of the present invention shown in FIG. 7B is clearly emphasized by using the gain value k according to the original image according to the saturation component of the original image shown in FIG. 7A, it is illustrated in FIG. 8A. The color component of the original image and the color component of the image of the present invention shown in Figure 8b can be seen that there is no change. Therefore, the present invention can display a bright and clear image by emphasizing only saturation while maintaining color balance.

9 is a block diagram schematically illustrating an OLED display to which a color correction device according to an exemplary embodiment of the present invention is applied.

The OLED display shown in FIG. 9 includes an image display unit 12 for displaying an image through OLED pixels, a data driver 8 for driving a data line DL of the image display unit 12, and an image display unit 12. The gate driver 10 for driving the gate line GL, the color correction unit 4 for correcting and outputting the input data by highlighting the chroma component, and the correction data from the color correction unit 4 A timing controller 6 for supplying the driver 8 and controlling the data driver 8 and the gate driver 10 is provided.

As described above with reference to FIGS. 1 and 2, the color corrector 4 converts input data (R / G / B) of the three primary colors (RGB) color space into corresponding color data of the corresponding color color space (Opponent Color Space). I / RG / YB) to calculate the saturation data (S) by linear conversion, and to calculate the gain value (k) to adaptively emphasize only the saturation components according to the saturation data (S) without changing the color. The input data R / G / B are corrected and output using the gain value k. Here, the gain value k varies according to the saturation component S from the input data R / G / B, and the higher the saturation of the image, the lower the gain value (k; minimum 1) and the lower saturation of the image. It is set to have a high gain value k (maximum 2). Accordingly, the color corrector 4 emphasizes saturation when the saturation of the input image is low, while reducing the eye fatigue by maintaining the original image when the saturation is high.

The timing controller 6 aligns the output data of the color correcting section 4 and outputs it to the data driver 8. In addition, the timing controller 6 controls the driving timing of the data driver 8 by using a plurality of synchronization signals from the color correction unit 4, that is, a dot clock, a data enable signal, a horizontal synchronization signal, and a vertical synchronization signal. A data control signal and a gate control signal for controlling the driving timing of the gate driver 10 are generated and output.

The data driver 8 converts the digital image data from the timing controller 6 into an analog data signal (current or voltage signal) using a gamma voltage in response to the data control signal from the timing controller 6 to display the image display unit ( 12 to the data line DL.

The gate driver 10 sequentially drives the gate line GL of the image display unit 12 in response to the gate control signal of the timing controller 6.

The image display unit 12 displays an image through a pixel matrix in which a plurality of pixels are arranged, and each pixel R / G / B connected to a data line DL, a gate line GL, and a power line PL. Sub-pixel PXL is provided. Each subpixel PXL includes at least switching and driving transistors SM and DM and one capacitor Cst to drive the OLED element. The switching and driving transistors SM and DM are formed of PMOS or NMOS transistors. The switching transistor SM is turned on by the gate turn-on voltage supplied to the gate line DL, and the data signal supplied to the data line DL is supplied to the capacitor C by the driving voltage VDD and the data signal. Charged with a differential voltage. The driving transistor DM supplies a driving current according to the difference voltage charged to the capacitor C to emit light of the OLED element, and the OLED displays a gray scale proportional to the driving current. The image display unit 12 may display a bright and clear image by displaying the correction data in which the saturation is emphasized through the color correction unit 4.

10 is a block diagram schematically illustrating a liquid crystal display device to which a color correction device according to an exemplary embodiment of the present invention is applied.

The liquid crystal display shown in FIG. 10 includes an image display unit 112 for displaying an image, a data driver 108 for driving a data line DL of the image display unit 112, and a gate line (for example) of the image display unit 112. The gate driver 110 for driving GL, the color correction unit 104 for correcting and outputting the input data by emphasizing the saturation component, and the data driver 108 by arranging the correction data from the color correction unit 104. And a timing controller 106 for controlling the data driver 108 and the gate driver 110.

As described above with reference to FIGS. 1 and 2, the color correction unit 104 converts input data (R / G / B) of the three primary colors (RGB) color space into corresponding color data of the corresponding color color space (Opponent Color Space). Saturation data (S) is calculated by linear conversion to (I / RG / YB), and a gain value (k) for adaptively emphasizing only saturation components according to saturation data (S) without color change is calculated and calculated The input data R / G / B are corrected and output using the gain value k. Here, the gain value k varies according to the saturation component S from the input data R / G / B, and the higher the saturation of the image, the lower the gain value (k; minimum 1) and the lower saturation of the image. It is set to have a high gain value k (maximum 2). Therefore, the color corrector 104 emphasizes saturation when the saturation of the input image is low, while reducing the eye fatigue by maintaining the original image when the saturation is high.

The timing controller 106 sorts the output data of the color corrector 104 and outputs the data to the data driver 108. In addition, the timing controller 106 controls the driving timing of the data driver 108 by using a plurality of synchronization signals from the color correction unit 104, that is, a dot clock, a data enable signal, a horizontal synchronization signal, and a vertical synchronization signal. A data control signal and a gate control signal for controlling the driving timing of the gate driver 110 are generated and output.

The data driver 108 converts the digital image data from the timing controller 106 into an analog data signal (pixel voltage signal) using a gamma voltage in response to the data control signal from the timing controller 106 to display the image display unit 112. Is supplied to the data line DL.

The gate driver 110 sequentially drives the gate line GL of the image display unit 112 in response to the gate control signal of the timing controller 106.

The image display unit 112 displays an image through a pixel matrix in which a plurality of pixels are arranged, and each pixel uses a combination of R / G / B subpixels that adjust light transmittance by varying the liquid crystal array according to the data signal. Implement Each subpixel includes a thin film transistor TFT connected to a gate line GL and a data line DL, a liquid crystal capacitor Clc connected in parallel with the thin film transistor TFT, and a storage capacitor Cst. The liquid crystal capacitor Clc charges the data signal supplied to the pixel electrode through the thin film transistor TFT and the difference voltage between the common voltage Vcom supplied to the common electrode and drives the liquid crystal according to the charged voltage to thereby transmit light. Adjust. The storage capacitor Cst keeps the voltage charged in the liquid crystal capacitor Clc stable. The image display unit 112 may display a bright and clear image by displaying the correction data whose saturation is enhanced through the color correction unit 104.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical 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 defined by the claims.

1 is a flowchart illustrating a color correction method of a display device according to an exemplary embodiment of the present invention.

2 is a block diagram illustrating a color correction device of a display device according to an exemplary embodiment of the present invention.

3 shows a general corresponding color space coordinate system;

4 shows general saturation and color coordinates.

FIG. 5 is a diagram illustrating a test image according to a gain value calculated by the gain value calculator shown in FIG. 2.

6A to 6C are diagrams illustrating an image to which a color correction method according to the present invention is applied in comparison with an original image and a gain value k.

7a and 7b is a view showing a comparison of the chroma components of the image and the original image of the present invention.

8a and 8b is a view showing a comparison of the color components of the present invention and the original image.

9 is a block diagram illustrating an OLED display to which a color correction device according to an exemplary embodiment of the present invention is applied.

10 is a block diagram illustrating a liquid crystal display device to which a color correction device according to an exemplary embodiment of the present invention is applied.

Claims (16)

Converting input data (R / G / B) of the three primary color spaces into corresponding color data (RG / YB) of the corresponding color color space; Calculating chroma data (S) from the corresponding color data (RG / YB); Calculating a gain value (k, k is an integer) that is adaptively changed according to the saturation data (S) by using the saturation data (S) and a preset maximum and minimum gain value; Correcting the input data (R / G / B) using the gain value (k). The method according to claim 1, The gain value (k) has a low gain value as the saturation data (S) is high, and has a high gain value as the saturation data (S) is low. The method according to claim 1, The saturation data (S) is calculated through the following arithmetic operation using the corresponding color data (RG / YB).

The method of claim 3, The gain value k is calculated through the following calculation using the chroma data S, the maximum gain value k _MAX , and the minimum gain value k _MIN . .

The method according to claim 4, And the maximum gain value k _MAX is set to a value of at least one. The method according to claim 4, The maximum gain value (k _MAX ) is set to 2, and the minimum gain value (k _MIN ) is set to 1, the color correction method of the display device. The method according to claim 4, The input data R / G / B is corrected by the correction data R '/ G' / B 'through the following mathematical operation using the gain value k. Way.

A color space conversion unit for converting input data R / G / B of three primary color spaces into corresponding color data RG / YB of a corresponding color color space; Saturation data S is calculated from the corresponding color data RG / YB, and the gain is adaptively varied according to the chroma data S by using the chroma data S and a preset maximum and minimum gain value. A gain value calculator for calculating a value (k, k is an integer); And a data correction unit for correcting the input data (R / G / B) using the gain value (k). The method according to claim 8, The gain value (k) has a low gain value as the saturation data (S) is high, and has a high gain value as the saturation data (S) is low. The method according to claim 8, And the gain value calculating unit calculates the chroma data (S) through the following root calculation using the corresponding color data (RG / YB).

The method according to claim 10, The gain value calculating unit calculates the gain value k through the following calculation using the saturation data S, the maximum gain value k _MAX , and the minimum gain value k _MIN . Color correction device of the device.

The method of claim 11, And the maximum gain value (k _MAX ) is set to a value of at least one. The method of claim 11, The maximum gain value (k _MAX ) is set to 2, and the minimum gain value (k _MIN ) is set to 1, the color correction device of the display device. The method of claim 11, The data correction unit corrects the input data R / G / B through the following mathematical operation using the input data R / G / B and the gain value k. B '), the color correction device of the display device characterized by the above-mentioned.

The organic light emitting diode display device which displays the image data output from the color correction device as described in any one of Claims 8-14 on the organic light emitting diode display part. The image data output from the color correction device in any one of Claims 8-14 is displayed on a liquid crystal display part, The liquid crystal display device characterized by the above-mentioned.

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