KR20140041051A - Image quality processor, display device including the same, and image quality processing method - Google Patents

Abstract

The present invention relates to an image processing unit for controlling gamma reference voltages by color, a display device including the same, and an image processing method. The image processing unit according to an embodiment of the present invention comprises an average image level calculation unit which calculates an average image level from first digital image data including multiple pieces of color digital data; a digital data conversion unit which converts the first digital image data into second digital image data including the multiple pieces of color digital data and white digital data; and a gamma reference voltage control unit which calculates color ratios by color by analyzing the second digital image data by color and controls the peak brightness of an input image by adjusting a peak gamma reference voltage based on the color ratios by color and the average image level.

Description

IMAGE QUALITY PROCESSOR, DISPLAY DEVICE INCLUDING THE SAME, AND IMAGE QUALITY PROCESSING METHOD}

The present invention relates to an image processor for controlling a gamma reference voltage for each color, a display device including the same, and an image processing method.

2. Description of the Related Art [0002] As an information-oriented society develops, there have been various demands for a display device for displaying images. Recently, a liquid crystal display (LCD), a plasma display panel (PDP) Various flat panel display devices such as an organic light emitting diode (OLED) are being utilized.

The display device receives a video source from an external video source device, converts the video source to be suitable for display by the display panel, and displays an image. The video source input to the display device may include a plurality of color digital data. For example, the video source input to the display device may be RGB digital data including red digital data, green digital data, and blue digital data. More specifically, the display device displays an image by converting a plurality of color digital data into an analog data voltage and supplying the same to the display panel. However, the conventional display device displays an image by applying the same peak luminance for each color regardless of the color distribution of the image input to the display device. In this case, even if the color distribution of the input image is concentrated in any one color, the peak luminance is limited, so that there is a limit in color representation.

The present invention provides an image processing unit capable of dynamically expressing the color of a display image, a display device including the same, and an image processing method.

The image processor may include: an average image level calculator configured to calculate an average image level from first digital image data including a plurality of color digital data; A digital data converter configured to convert the first digital image data into second digital image data including the plurality of color digital data and white digital data; And calculating a color ratio for each color by analyzing the second digital image data for each color, and adjusting a peak gamma reference voltage based on the color ratio for each color and the average image level to control peak luminance of the input image. And a voltage controller.

A display device according to an embodiment of the present invention includes a display panel including data lines and gate lines; An average image level calculator configured to calculate an average image level from first digital image data including a plurality of color digital data; A digital data converter configured to convert the first digital image data into second digital image data including the plurality of color digital data and white digital data; And calculating a color ratio for each color by analyzing the second digital image data for each color, and adjusting a peak gamma reference voltage based on the color ratio for each color and the average image level to control peak luminance of the input image. An image processor including a voltage controller; A gamma reference voltage driver circuit for generating gamma reference voltages according to the gamma reference voltage data of the image processor; A data driving circuit converting the second digital image data into an analog data voltage using the gamma reference voltage and supplying the data voltages to the data lines; And a gate driving circuit sequentially supplying a gate pulse synchronized with the data voltage to the gate lines.

An image processing method according to an embodiment of the present invention includes calculating an average image level from first digital image data including a plurality of color digital data; Converting the first digital image data into second digital image data including the plurality of color digital data and white digital data; And analyzing the second digital image data for each color to calculate a color ratio for each color, and controlling peak luminance of the input image by adjusting a peak gamma reference voltage based on the color ratio for each color and the average image level. Include.

The present invention analyzes the color ratio of the input image and adjusts the peak gamma reference voltage for each color according to the color ratio to increase the peak luminance of the input image. As a result, the present invention can dynamically express the color of the display image according to the color distribution.

In addition, the present invention finds a color that is not used for a predetermined frame period, and controls the gamma reference voltage of the color that is not used to '0V'. As a result, the present invention can reduce power consumption.

1 is a block diagram schematically illustrating a display device according to an exemplary embodiment of the present invention.
FIG. 2 is a block diagram illustrating in detail the image processor of FIG. 1; FIG.
3 is a flowchart illustrating an image processing method according to an exemplary embodiment of the present invention.
4A-4D are graphs showing boosting of red gamma curves, green gamma curves, blue gamma curves, and white gamma curves.
5A is an exemplary diagram illustrating an input image and an image in which red peak luminance is increased according to an exemplary embodiment of the present invention.
5B is an exemplary diagram illustrating an input image and an image in which green peak luminance is increased according to an exemplary embodiment of the present invention.
5C is an exemplary diagram illustrating an input image and an image in which blue peak luminance is increased according to an exemplary embodiment of the present invention.
5D is an exemplary diagram illustrating an input image and an image in which white peak luminance is increased according to an exemplary embodiment of the present invention.
6 is a block diagram illustrating in detail a gamma reference voltage supply circuit according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The component name used in the following description may be selected in consideration of easiness of specification, and may be different from the actual product name.

1 is a block diagram schematically illustrating a display device according to an exemplary embodiment of the present invention. Referring to FIG. 1, a display device according to an exemplary embodiment of the present invention may include a display panel 10, a gate driving circuit 110, a data driving circuit 120, a gamma reference voltage supply circuit 130, and a timing controller 140. , The image processor 150, the host system 160, and the like. In the following embodiment, the display device is exemplified based on the implementation of an organic light emitting diode (OLED) device, but the present invention is not limited thereto. The display device according to an embodiment of the present invention may also be a flat panel display device such as a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), or the like. Can be implemented.

The display panel 10 is formed with data lines D and gate lines G intersecting with each other and a pixel array in which pixels are arranged in a matrix form at intersections of the data lines D and gate lines G, . Each of the pixels of the display panel 10 includes at least one thin film transistor (TFT), a driving TFT, an organic light emitting diode (OLED) element, and at least one capacitor. Each of the pixels controls an electric current flowing in the organic light emitting diode element using a switching TFT and a driving TFT to display an image. Specifically, since the driving TFT can control the amount of current flowing from the high potential voltage supplied to each of the pixels to the organic light emitting diode (OLED), the amount of light emitted from the organic light emitting diode (OLED) can also be adjusted. The display panel 10 may display an image in the form of bottom emission and top emission depending on the pixel structure.

The gate drive circuit 110 includes a plurality of gate drive ICs (integrated circuits). The gate drive ICs supply at least one or more gate pulses for controlling at least one or more switching TFTs of each of the pixels to the gate lines G of the display panel 10. The gate drive ICs can be mounted on a gate TCP (tape carrier package), and the gate TCP can be bonded to the display panel 10 by a TAB (tape automated bonding) process. Alternatively, the gate drive ICs may be directly formed simultaneously with the pixel array by a GIP (gate in panel) process.

The data driving circuit 120 includes a plurality of source drive ICs. The source drive ICs receive the second digital image data RGBW from the timing controller 140. The source drive ICs receive gamma reference voltages GMAs from the gamma reference voltage supply circuit 130 and calculate gamma compensation voltages using a voltage divider circuit. The source drive ICs convert the second digital image data RGBW into analog data voltages using gamma compensation voltages according to the source timing control signal from the timing controller 140, and synchronize the data voltages with gate pulses. The data lines D of the display panel 10 are supplied. The source driver ICs may be mounted on the source TCP and the source TCP may be bonded to the display panel 10 and the source PCB (printed circuit board) by a TAB process. Alternatively, the source drive ICs may be directly bonded to the display panel 10 by a COG (chip on glass) process.

The gamma reference voltage supply circuit 130 receives gamma reference voltage data Dgma from the image processor 150, generates gamma reference voltages GMAs according to the gamma reference voltage data Dgma, and generates a data driving circuit 120. Supplies). The gamma reference voltage supply circuit 130 will be described in detail later with reference to FIG. 6.

The timing controller 140 receives the second digital image data RGBW and a timing signal from the image processor 150. The timing signal may include a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, a dot clock, and the like. The timing controller 140 generates timing control signals for controlling the operation timing of the gate driving circuit 110 and the data driving circuit 120 based on the timing signal. The timing control signals include a gate timing control signal GCS for controlling the operation timing of the gate driving circuit 110 and a data timing control signal DCS for controlling the operation timing of the data driving circuit 120. The timing control circuit outputs the gate timing control signal GCS to the gate driving circuit 110, and outputs the second digital image data RGBW and the data timing control signal DCS to the data driving circuit 120.

The image processor 150 receives the first digital image data RGB and a timing signal from the host system 160. The image processor 150 converts the first digital image data RGB into the second digital image data RGBW and outputs the same to the timing controller 140. The first digital image data (RGB) includes a plurality of color digital data. For example, the first digital image data RGB may include red digital data R, green digital data G, and blue digital data B. FIG. The second digital image data RGBW includes not only a plurality of color digital data included in the first digital image data RGB, but also white digital data. For example, the second digital image data RGBW may include red digital data R, green digital data G, blue digital data B, and white digital data W. FIG.

In addition, the image processor 150 controls gamma reference voltages GMAs of the gamma reference voltage supply circuit 130 according to the color ratio for each color obtained by analyzing the second digital image data RGBW. Outputs (Dgma) The gamma reference voltage data Dgma includes a plurality of color gamma reference voltage data to be applied according to the color of the second digital image data RGBW. For example, when the second digital image data RGBW includes red digital data R, green digital data G, blue digital data B, and white digital data W, gamma reference voltage data The data may include red gamma reference voltage data, green gamma reference voltage data, blue gamma reference voltage data, and white gamma reference voltage data.

The image processor 150 outputs the second digital image data RGB ′ and the timing signal to the timing controller 140. The image processor 150 may be designed to be embedded in the timing controller 140 or the host system 160. A detailed description of the image processor 150 will be described later with reference to FIGS. 2, 3, 4A to 4D, and 5A to 5D.

The host system 160 includes a system-on-chip with a built-in scaler to convert the first digital image data RGB input from an external video source device into a data format having a resolution suitable for display on the display panel 10. (System on Chip) may be included. The host system 160 supplies the first digital image data RGB and timing signals to the image processor 150 through interfaces such as a low voltage differential signaling (LVDS) interface and a transition minimized differential signaling (TMDS) interface.

FIG. 2 is a block diagram illustrating in detail the image processor of FIG. 1. 3 is a flowchart illustrating an image processing method according to an exemplary embodiment of the present invention. 2, the image processor 150 according to an exemplary embodiment of the present invention includes an average image level calculator 151, a digital image data converter 152, and a gamma reference voltage controller 153. Hereinafter, the image processing method of the image processor 150 will be described in detail with reference to FIGS. 2 and 3.

First, the average image level calculator 151 receives the first digital image data RGB and calculates an average picture level APL from the first digital image data RGB. The first digital image data RGB includes a plurality of color digital data, hereinafter, the first digital image data RGB includes red digital data R, green digital data G, and blue digital data B. It will be described focusing on including. The average image level calculator 151 calculates the luminance data Y using the first digital image data RGB as shown in Equation 1, and then calculates the average value of the luminance data Y for one frame period, thereby averaging the average. The image level APL can be calculated.

On the other hand, it should be noted that the average image level calculator 151 can calculate the average image level APL also by a method different from the above-described method. For example, the average image level calculator 151 calculates a median or minimum value of the first digital image data RGB, and then averages the median or minimum values of the first digital image data RGB in one frame period. By calculating, the average image level APL can be calculated. The average image level calculator 151 outputs the average image level APL to the digital image data converter 152. (S101)

Second, the digital image data converter 152 receives the first digital image data RGB and converts the first digital image data RGB into the second digital image data RGBW. For example, the digital image data converter 152 converts the first digital image data RGB including the red digital data R, the green digital data G, and the blue digital data B into red digital data. R), green digital data G, blue digital data B, and white digital data W may be converted into second digital image data RGBW.

In detail, the digital image data converter 152 calculates the white digital data W using the red digital data R, the green digital data G, and the blue digital data B. FIG. For example, the digital image data converter 152 may calculate the minimum values of the red digital data R, the green digital data G, and the blue digital data B as the white digital data W. FIG.

Then, the digital image data converter 152 subtracts the red digital data R, the green digital data G, and the blue digital data B by each of the white digital data W as shown in Equation 3 below. The red digital data R, the green digital data G, and the blue digital data B are replaced with the values.

Meanwhile, it should be noted that the digital image data converter 152 may convert the first digital image data RGB to the second digital image data RGBW by a method different from that described above. The digital image data converter 152 outputs the second digital image data RGBW to the gamma reference voltage controller 153 and the timing controller 140. (S102)

The gamma reference voltage controller 153 includes a normalized data calculator 201, a gain value calculator 202, a gamma reference voltage data calculator 203, a look-up table 204, and a color analyzer 205. The gamma reference voltage controller 153 analyzes the second digital image data RGBW for each color to calculate a color ratio for each color, and calculates a peak gamma reference voltage based on the color ratio and the average image level APL for each color. The peak luminance of the input image is controlled by referring to S103 to S109, which will be described in detail with reference to the gamma reference voltage control method of the gamma reference voltage controller 153.

Third, the normalization data calculator 201 calculates average color normalization data for each color by normalizing the second digital image data RGBW for a predetermined period of time to calculate the color ratio for each color. The average normalized data for each color is related to the color ratio for each color. The smaller the average normalization data corresponding to one color is, the lower the color ratio of the corresponding color is. The larger the average normalization data corresponding to any one color, the larger the color ratio of the corresponding color is.

Specifically, the normalized data calculator 201 calculates normalized data corresponding to one frame period by color by dividing the total of digital data for each color in one frame period by the maximum value of the total of digital data for each color in one frame period. do. For example, the color-specific normalization data may include red normalization data NORr, green normalization data NORg, blue normalization data NORb, and white normalization data NORw. The normalization data calculation unit 201 divides the sum Sr of red digital data in one frame period by the maximum value Nr of the sum of red digital data in one frame period as shown in Equation 4, and normalizes the parameter Pnor. The red normalized data NORr may be calculated by multiplying by. For example, in the case of a display device having a 1920 × 1080 resolution, 1920 × 1080 red digital data is input during one frame period. When the digital data for each color is implemented with 10 bits, the sum Sr of red digital data of one frame period is the sum of the number of bits of 1920 × 1080 red digital data, and the red of one frame period. The maximum value Nr of the sum of the digital data will be 1920 × 1080 × 1023.

Since the second digital image data RGBW input to the display device is too large, the operation may be too complicated if the operation is performed using the second digital image data RGBW. If normalization is used, the size of the second digital image data RGBW may be maintained and the size thereof may be reduced, thereby simplifying the calculation. The normalization parameter Pnor indicates the degree of normalization performance. The larger the normalization parameter Pnor, the lower the normalization degree, and the smaller the normalization parameter Pnor, the larger the normalization degree. In addition, the normalization data calculator 201 may calculate the green normalization data NORg, the blue normalization data NORb, and the white normalization data NORw as shown in Equation 4.

Then, the normalization data calculation unit 201 calculates the average value of the normalization data NOR of the N (N is a natural number) frame period for each color as the average normalization data NORa. For example, the normalized data calculator 201 calculates the average value of the red normalized data NORri of the N frame period as the average red normalized data NORra, and averages the average value of the green normalized data NORg of the N frame period. Calculated as green normalized data (NORga). The normalized data calculator 201 calculates the average value of the blue normalized data NORb in the N frame period as the average blue normalized data NORba, and averages the normalized white normalized data NORw in the N frame period. The data can be calculated as NORwa. (S103)

Fourth, the gain value calculator 202 calculates a gain value for each color using the average image level APL and the average normalized data NORa for each color. For example, the gain value calculator 202 may calculate the red gain value Gr using the average image level APL and the average red normalized data NORra, as shown in Equation 5 below.

In Equation 5, Pnor means a normalization parameter, and Gmax means a maximum value that a gain value can have. In addition, the gain value calculating unit 202 may calculate the green gain value Gg, the blue gain value Gb, and the white gain value Gw as shown in Equation 5 below. (S104)

Fifth, the gamma reference voltage data calculator 203 receives initial gamma reference voltage data Dgmai stored in the look-up table 204 from the look-up table 204, and the gain value calculator 202. Color-specific gain values (Gr, Gg, Gb, Gw) are received. The gamma reference voltage data calculator 203 calculates gamma reference voltage data Dgma by summing gain values Gr, Gg, Gb, and Gw for each color according to the color of the initial gamma reference voltage data Dgmai. The initial gamma reference voltage data (Dgmai) includes initial red gamma reference voltage data (Dgmari), initial green gamma reference voltage data (Dgamgi), initial blue gamma reference voltage data (Dgambi), and initial white gamma reference voltage data (Dgamwi). The gamma reference voltage data Dgma may include red gamma reference voltage data Dgmar, green gamma reference voltage data Dgmag, blue gamma reference voltage data Dgmab, and white gamma reference voltage data Dgmaw. It may include. The gamma reference voltage data calculator 203 calculates the red gamma reference voltage data Dgmar by adding the red gain value Gr to the initial red gamma reference voltage data Dgmari, and then calculates the red gamma reference voltage data Dgmagi. The green gamma reference voltage data Dgmag is calculated by adding the green gain values Gg. In addition, the gamma reference voltage data calculator 203 calculates the blue gamma reference voltage data Dgmab by adding the blue gain value Gb to the initial blue gamma reference voltage data Dgmabi and calculates the initial white gamma reference voltage data Dgmawi. ) Is added to the white gain value Gw to calculate white gamma reference voltage data Dgmaw. The gamma reference voltage data calculator 203 supplies the gamma reference voltage data Dgma to the gamma reference voltage supply circuit 130, and the gamma reference voltage supply circuit 130 performs the gamma reference according to the gamma reference voltage data Dgma. Generate voltages GMAs.

4A-4D are graphs showing boosting of red gamma curves, green gamma curves, blue gamma curves, and white gamma curves. Referring to FIG. 4A, the initial red gamma reference voltage data Dgmari is calculated based on the first red gamma curve Cr1, and the red gamma reference voltage data Dgmar is larger than the first red gamma curve Cr1. The data is calculated based on the second red gamma curve Cr2 having a higher peak luminance. That is, in the case of an image having a high red color ratio, the red gamma reference voltage data Dgmar obtained by adding the initial red gamma reference voltage data Dgmari to the red gain value Gr may be added to the gamma reference voltage supply circuit 130. Supply. As a result, in the case of an image having a high red color ratio as shown in FIG. 5A, the present invention can increase red color expressive power by increasing red peak luminance.

Referring to FIG. 4B, the initial green gamma reference voltage data Dgmabi is data calculated based on the first green gamma curve Cg1, and the green gamma reference voltage data Dgmab is a second green gamma curve with higher peak luminance. It is data calculated based on (Cg2). That is, in the case of an image having a high green color ratio, the green gamma reference voltage data Dgmag obtained by adding the green gain value Gg to the initial green gamma reference voltage data Dgmagi is added to the gamma reference voltage supply circuit 130. Supply. As a result, in the case of an image having a high green color ratio as shown in FIG. 5B, the present invention can increase green color expression power by increasing green peak luminance.

Referring to FIG. 4C, the initial blue gamma reference voltage data Dgmabi is calculated based on the first blue gamma curve Cb1, and the blue gamma reference voltage data Dgmab is a second blue gamma curve with increased peak luminance. It is data calculated based on (Cb2). That is, in the case of an image having a high blue color ratio, the blue gamma reference voltage data Dgmab obtained by adding the blue gain value Gb to the initial blue gamma reference voltage data Dgmabi is added to the gamma reference voltage supply circuit 130. Supply. As a result, in the case of an image having a high blue color ratio as shown in FIG. 5C, the present invention can increase blue color expressive power by increasing blue peak luminance.

Referring to FIG. 4D, the initial white gamma reference voltage data Dgmawi is data calculated based on the first white gamma curve Cw1, and the white gamma reference voltage data Dgmaw is a second white gamma curve with increased peak luminance. It is data calculated based on (Cw2). That is, in the case of an image having a high white color ratio, the white gamma reference voltage data Dgmaw obtained by adding the initial white gamma reference voltage data Dgmawi to the white gain value Gw is added to the gamma reference voltage supply circuit 130. Supply. As a result, in the case of an image having a high white color ratio as shown in FIG. 5C, the present invention can increase white color expressive power by increasing white peak luminance.

As described above, the present invention analyzes the color ratio of the input image by normalizing the first digital image data RGB for each color, and adjusts the peak gamma reference voltage for each color according to the color ratio to peak the input image. Increase the brightness As a result, the present invention can dynamically express the color of the display image according to the color distribution. (S105)

Seventh, the gamma reference voltage controller 153 analyzes the color ratio for each color using the color analyzer 205 to find color digital data not input for a predetermined frame period. The color analyzer 205 receives the average normalized data NORa from the normalized data calculator 201, analyzes the average normalized data NORa for each color, and finds color digital data not input for a predetermined frame period. . The predetermined frame period may be implemented in a number of tens to tens of thousands of frame periods, and may be predetermined through a preliminary experiment. In particular, the predetermined frame period may be set differently when a static image is input and when a dynamic image is input. For example, the predetermined frame period may be set longer than when a dynamic image is input when a static image is input.

Specifically, the color analyzer 205 determines a case in which the sum of average normalized data for each color is less than or equal to a predetermined threshold value during M (M is a natural number) frame period. That is, the color analyzer 205 may add the sum of the average red normalization data NORra, the sum of the average green normalization data NORga, the sum of the average blue normalization data NORba, and the average white normalization data NORwa during the M frame period. ) Is determined in the case where the sum of the values is less than or equal to the predetermined threshold value. The predetermined threshold value may be predetermined through a preliminary experiment. For example, when the sum of the average red normalized data NORra during the M frame period is less than or equal to a predetermined threshold value, the color analyzer 205 may determine that the red color digital data R is not input during the M frame period. have.

When there is color digital data not input for a predetermined frame period, a gamma reference voltage corresponding to the color digital data does not need to be supplied for a predetermined frame period. Therefore, the color analyzer 205 generates a gamma reference voltage control signal of a corresponding color at a first logic level when the total sum of the average normalized data of one color for a predetermined frame period is less than or equal to a predetermined threshold value. If the sum of the average normalized data of one color during the period is larger than a predetermined threshold, a gamma reference voltage control signal of the corresponding color is generated at the second logic level. The gamma reference voltage control signals include a red gamma reference voltage control signal Cgmar, a green gamma reference voltage control signal Cgmar, a blue gamma reference voltage control signal Cgmar, and a white gamma reference voltage control signal Cgmaw. For example, when the R digital data R is not input for a predetermined frame period, the color analyzer 205 generates the red gamma reference voltage control signal Cgmar at the first logic level. The gamma reference voltage data calculator 203 of the gamma reference voltage controller 153 converts gamma reference voltage data of a corresponding color into predetermined values when any one of the gamma reference voltage control signals is input at a first logic level. do. For example, when the red gamma reference voltage control signal Cgmar of the first logic level is input, the gamma reference voltage data calculator 203 converts the red gamma reference voltage data Dgmar into a predetermined value. The predetermined value may be '0'. In addition, when the R digital data R is input for a predetermined frame period, the color analyzer 205 generates a red gamma reference voltage control signal Cgmar at a second logic level. When one of the gamma reference voltage control signals is input at a second logic level, the gamma reference voltage data calculator 203 outputs gamma reference voltage data of a corresponding color as it is. For example, when the red gamma reference voltage control signal Cgmar of the second logic level is input, the gamma reference voltage data calculator 203 may calculate the initial red gamma reference voltage data Dgmari and the red gain value Gr. The summed red gamma reference voltage data Dgmar is output as it is. A detailed description of the operation of the gamma reference voltage supply circuit 130 that receives the gamma reference voltage data Dgma will be described later with reference to FIG. 6. (S106 to S108)

6 is a block diagram illustrating in detail a gamma reference voltage supply circuit according to an exemplary embodiment of the present invention. Referring to FIG. 6, the DAC (Digital to Analog) 131 of the gamma reference voltage supply circuit 130 according to an embodiment of the present invention receives the gamma reference voltage data Dgma from the image processor 150. The gamma reference voltage data Dgma is a tap indicating the high potential voltage data indicating the high potential voltage VDD to be supplied to the high potential voltage terminal VDD_T and the tap voltages to be supplied to the tap voltage terminals TAB1_T to TABk_T. Contains voltage data. The DAC 131 of the gamma reference voltage supply circuit 130 supplies the high potential voltage VDD and the plurality of tap voltages to the voltage divider circuit 132 in which a plurality of resistors are arranged, thereby providing gamma reference voltages GMA1 to GMAk and k. Is a natural number).

2 and 3, when the gamma reference voltage data calculator 203 of the gamma reference voltage controller 153 receives one of the gamma reference voltage control signals at a first logic level. The gamma reference voltage data of the corresponding color is converted into predetermined values. For example, when the red gamma reference voltage control signal Cgmar of the first logic level is input, the gamma reference voltage data calculator 203 converts the red gamma reference voltage data Dgmar into a predetermined value. The predetermined value may be '0'. In this case, both the high potential voltage data and the tap voltage data of the gamma reference voltage data Dgma may be converted into predetermined values, and thus, the high potential voltage terminal and the tap voltage terminals of the gamma reference voltage supply circuit 130 may be converted into a predetermined value. '0V' voltage can be supplied. Alternatively, only the tap voltage data that controls the high potential voltage data of the gamma reference voltage data Dgma may be converted to a predetermined value, and thus, the high potential voltage terminal of the gamma reference voltage supply circuit 130 may be converted into a predetermined value. Voltage is supplied but '0V' voltage may be supplied to the tap voltage terminals. That is, the present invention uses the color analyzer 205 to find a color that is not used for a predetermined frame period, and controls the gamma reference voltage of the color that is not used to '0V'. As a result, the present invention can reduce power consumption.

As described above, the present invention analyzes the color ratio of the input image and adjusts the peak gamma reference voltage for each color according to the color ratio to increase the peak luminance of the input image. As a result, the present invention can dynamically express the color of the display image according to the color distribution. In addition, the present invention finds a color that is not used for a predetermined frame period, and controls the gamma reference voltage of the color that is not used to '0V'. As a result, the present invention can reduce power consumption.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the present invention should not be limited to the details described in the detailed description, but should be defined by the claims.

10: display panel 110: gate drive circuit
120: data driving circuit 130: gamma reference voltage supply circuit
131: DAC 132: voltage divider circuit
140: timing controller 150: image processor
151: average image level calculator 152: digital image data converter
153: gamma reference voltage controller 160: host system
201: normalized data calculator 202: gain value calculator
203: gamma reference voltage data calculator 204: look-up table
205: color analysis unit

Claims (15)

An average image level calculator configured to calculate an average image level from first digital image data including a plurality of color digital data;
A digital data converter configured to convert the first digital image data into second digital image data including the plurality of color digital data and white digital data; And
A gamma reference voltage for controlling the peak luminance of the input image by analyzing the second digital image data for each color to calculate a color ratio for each color, and adjusting a peak gamma reference voltage based on the color ratio for each color and the average image level. An image processing unit comprising a control unit. The method according to claim 1,
The gamma reference voltage controller is
A normalization data calculator configured to normalize second digital image data for each color for a predetermined period of time to calculate the color ratio for each color to calculate average normalized data;
A gain value calculating unit calculating a gain value for each color using the average normalization data for each color and the average image level;
A look-up table for storing initial gamma reference voltage data; And
And a gamma reference voltage data calculator configured to calculate gamma reference voltage data by adding gains for each color according to colors of initial gamma reference voltage data. 3. The method of claim 2,
The normalized data calculation unit,
The sum of digital data for each color in one frame period is divided by the maximum value of the total digital data for each color in one frame period to calculate normalized data corresponding to one frame period for each color, and N (N is a natural number) frame for each color. And an average value of the normalized data of the period as average normalized data. 3. The method of claim 2,
The gain value calculation unit,
When Gr is the gain value, APL is the average image level, NORra is the average normalization data, Pnor is the normalization parameter, and Gmax is the maximum value that the gain can have.
Equation

The image processing unit characterized in that to calculate the gain value for each color using. 3. The method of claim 2,
The gamma reference voltage controller is
And a color analyzer configured to analyze the color ratio for each color to find color digital data not input for a predetermined frame period. 6. The method of claim 5,
The color analysis unit,
It is determined that the sum of the average normalized data for each color is less than or equal to a predetermined threshold for a predetermined frame period. Occurs at one logic level, and generates a gamma reference voltage control signal of the corresponding color at a second logic level when the sum of the average normalized data of any one color during the predetermined frame period is greater than the predetermined threshold value. An image processing unit characterized by. The method according to claim 6,
The gamma reference voltage data calculation unit,
When the gamma reference voltage control signal of the corresponding color is input at the first logic level, the gamma reference voltage data of the corresponding color is converted into a predetermined value, and the gamma reference voltage control signal of the corresponding color is input at the second logic level. And output the gamma reference voltage data of the corresponding color without being converted. Calculating an average image level from first digital image data including a plurality of color digital data;
Converting the first digital image data into second digital image data including the plurality of color digital data and white digital data; And
Analyzing the second digital image data for each color to calculate a color ratio for each color, and controlling peak luminance of an input image by adjusting a peak gamma reference voltage based on the color ratio for each color and the average image level. Image processing method. The method of claim 8,
Analyzing the second digital image data for each color to calculate the color ratio for each color, and controlling the peak luminance of the input image by adjusting the peak gamma reference voltage based on the color ratio for each color and the average image level.
Calculating average normalized data by normalizing the second digital image data for each color for a predetermined period of time to calculate the color ratio for each color;
Calculating gain for each color using the average normalization data for each color and the average image level; And
And calculating gamma reference voltage data by adding the gain values for each color according to the color of the initial gamma reference voltage data stored in the look-up table. The method of claim 9,
In order to calculate the color ratio for each color, normalizing the second digital image data for each color for a predetermined period and calculating average normalization data may include:
Normalized data corresponding to one frame period is calculated for each color by dividing the total of digital data for each color in one frame period by the number of digital data for each color in one frame period, and normalizing N (N is a natural number) frame period for each color. And calculating the average value of the data as average normalized data. The method of claim 9,
Computing the gain value for each color using the average normalization data for each color and the average image level,
When Gr is the gain value, APL is the average image level, NORra is the average normalization data, Pnor is the normalization parameter, and Gmax is the maximum value that the gain can have.
Equation

The image processing method, characterized in that for calculating the gain value for each color. The method of claim 9,
Analyzing the second digital image data for each color to calculate the color ratio for each color, and controlling the peak luminance of the input image by adjusting the peak gamma reference voltage based on the color ratio for each color and the average image level.
And analyzing the color ratio for each color to find color digital data not input for a predetermined frame period. 13. The method of claim 12,
Analyzing the color ratio for each color to find color digital data not input for a predetermined frame period,
It is determined that the sum of the average normalized data for each color is less than or equal to a predetermined threshold for a predetermined frame period. Occurs at one logic level, and generates a gamma reference voltage control signal of the corresponding color at a second logic level when the sum of the average normalized data of any one color during the predetermined frame period is greater than the predetermined threshold value. An image processing method characterized by the above. 14. The method of claim 13,
Computing the gamma reference voltage data by adding the gain value for each color according to the color of the initial gamma reference voltage data stored in the look-up table,
When the gamma reference voltage control signal of the corresponding color is input at the first logic level, the gamma reference voltage data of the corresponding color is converted into a predetermined value, and the gamma reference voltage control signal of the corresponding color is input at the second logic level. And output the gamma reference voltage data of the corresponding color without being converted. A display panel including data lines and gate lines;
An average image level calculator configured to calculate an average image level from first digital image data including a plurality of color digital data; A digital data converter configured to convert the first digital image data into second digital image data including the plurality of color digital data and white digital data; And calculating a color ratio for each color by analyzing the second digital image data for each color, and adjusting a peak gamma reference voltage based on the color ratio for each color and the average image level to control peak luminance of the input image. An image processor including a voltage controller;
A gamma reference voltage driver circuit for generating gamma reference voltages according to the gamma reference voltage data of the image processor;
A data driving circuit converting the second digital image data into an analog data voltage using the gamma reference voltage and supplying the data voltages to the data lines; And
And a gate driving circuit which sequentially supplies gate pulses synchronized with the data voltages to the gate lines.

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