KR100581866B1 - Method and apparatus for white balance adjustment, and display panel comprising the same - Google Patents

Abstract

White balance adjustment method according to the invention, the step of inputting an analog image; Converting the analog image into digital data by A / D conversion; Outputting luminance data by converting color coordinates of the digital data; Detecting an error between the luminance data and the reference luminance data; And adjusting the weight of the A / D conversion according to the error. Therefore, first, the white balance adjustment can be performed without feeding back the image output of the PDP panel. That is, white balance adjustment is performed by correction of the analog circuit. Therefore, an optical sensor, a D / A converter, and the like, which are required to feed back the image output of the PDP panel to perform white balance adjustment, are not necessary. Second, even when a Y / Pb / Pr signal is directly received by the PDP, as in a digital TV, white balance adjustment may be performed.

Description

Method and apparatus for white balance adjustment and display panel comprising the same

1 is a block diagram showing a configuration of a white balance adjusting device of a plasma display panel according to the prior art.

2 is a block diagram showing a white balance adjusting apparatus of the plasma display panel disclosed in Korean Laid-Open Patent Publication No. 1999-0065838.

3 is a flowchart illustrating a white balance adjustment method according to an embodiment of the present invention.

FIG. 4 is a flowchart for describing a white balance adjusting method according to the modification of FIG. 3.

5A to 5C are graphs for explaining a weight adjustment method of A / D conversion in the white balance adjustment method of the present invention.

6 is a block diagram illustrating a white balance adjusting apparatus according to an exemplary embodiment of the present invention.

7 is a block diagram illustrating a white balance adjusting device according to another preferred embodiment of the present invention.

8 is a block diagram illustrating a white balance adjusting device according to another preferred embodiment of the present invention.

9 is a block diagram illustrating an embodiment of a display device to which the white balance adjusting device of the present invention can be applied.

The present invention relates to an image processing apparatus, and more particularly, to an apparatus for adjusting white balance of an image.

Generally, the human eye feels white under any light source (for example, sunlight, fluorescent light, incandescent light, etc.), but when viewed through a video camera's image tube, it becomes red or blue depending on the light source. This is due to the color temperature of the light source. If the color temperature is high, the color becomes blue, and if the color temperature is low, the color becomes red.

If you adjust a white subject to reproduce white under a certain light source, other colors can be reproduced correctly. This adjustment is called white balance adjustment.

Fig. 1 is a diagram showing the configuration of a white balance adjusting device of a plasma display panel (hereinafter referred to as PDP) according to the prior art.

Referring to FIG. 1, reference numeral 110 denotes an analog / digital converter that receives analog image data, divides it into R, G, and B, and converts it into a digital signal, and reference numeral 120 denotes an output from the analog / digital converter 110. The W / B correction unit determines data for white balance adjustment (hereinafter, referred to as W / B) according to the R, G, and B signals to be included in the R, G, and B signals, and outputs the same. The driver outputs the R, G, and B signals input from the W / B corrector 120 to the PDP to display an image signal.

The W / B correction unit 120 is a ROM (Read-Only Memory) in which correction data for W / B adjustment is stored at each address, and is specified according to image data of R, G, and B inputted. The correction data stored at the address is output. At this time, if the address is determined, the same correction data is output since the data is maintained until the user changes. In other words, when an address is specified, the corresponding data is output.

For example, if address and output data are the same, output address 1 occurs if address 1 is specified, output data 2 occurs if address 2 is specified, and output data 255 occurs if address 255 is specified. do.

As a result, in the prior art having the above configuration, the data for W / B adjustment is determined according to the input image data of R, G, and B, and accordingly the operation of displaying the image signal on the PDP is performed.

At this time, since the function to be adjusted according to the external light source is not included, the user recognizes the external light source and changes the data for the W / B adjustment output from the W / B correction unit 120 using a remote controller or the like. do.

However, the above operation has a problem in that the operation is cumbersome, and in order to adjust the W / B of each panel due to the characteristics of the PDP, it is difficult to change the W / B correction data suitable for the characteristics of the panel after a lot of trial and error. There is a problem with this.

FIG. 2 is a block diagram illustrating a white balance adjusting device of a plasma display panel disclosed in Korean Laid-Open Patent Publication No. 1999-0065838 as a prior art for solving such a problem. The white balance adjusting device may include an image correcting unit 210 which receives analog image data and changes and outputs the image data according to the correction data for white balance (W / B) adjustment; An A / D converter 220 for converting the R, G, and B signals output from the image corrector 210 into digital signals; A driver 230 for displaying an image signal on a plasma display panel (PDP) according to the R, G, and B signals output from the A / D converter 220; A sensor (240) for detecting color coordinates and luminance values generated in the PDP; A memory 250 in which a standard color coordinate of a unique area and a standard luminance value, which is a brightness to be expressed, are stored in the PDP; An error detector (260) for comparing the color coordinates and the luminance value detected by the sensor with a standard value of a memory to obtain an error thereof; And a D / A converter 270 for converting the error signal output from the error detection unit into an analog signal and outputting the value to the image correction unit as the correction data for W / B adjustment. The prior art provides convenience in use by automatically performing W / B adjustment according to the state of the screen being output. As a result, the domestic patent performs W / B adjustment according to the state of the screen output from the PDP, that is, the color coordinate and the luminance value, so that the best screen is displayed.

The prior art involves a procedure for measuring the PDP output by the sensor 240, and includes a D / A converter 270 for converting the detected error signal into an analog signal, which makes the component complicated.

In order to solve the above problems, the present invention is to provide an efficient method and apparatus for adjusting white balance of a display panel.

According to an aspect of the present invention, there is provided a method of adjusting a white balance, comprising: (a) inputting an analog image; (b) converting the analog image into digital data by A / D conversion; (c) converting color coordinates of the digital data to output luminance data; (d) detecting an error between the luminance data and the reference luminance data; And (e) adjusting a weight of the A / D conversion according to the error.

In the step (a), the analog R, G, and B video signals may be sequentially input, and the steps (b) to (e) may be sequentially repeated. Here, in step (a), the maximum value of the analog R, G, and B images may be input. In step (d), the ratio of the reference luminance data to R, G, and B may be 76 to 150 to 29.

In step (e), the gain weight of the A / D conversion may be adjusted according to the error. In the step (e), the offset weight of the A / D conversion may be adjusted according to the error.

According to another aspect of the present invention, a method of adjusting a white balance includes: (a) inputting a first analog image and a second analog image; (b) converting the first and second analog images into first and second digital data by A / D conversion; (c) outputting first and second luminance data by converting color coordinates of the first and second digital data; (d) detecting an error between the first and second luminance data and reference luminance data; And (e) adjusting a weight of the A / D conversion according to the error.

In the step (e), the gain of the A / D conversion may be adjusted so that the first and second luminance data match the reference luminance data within a predetermined range.

In the step (e), the offset of the A / D conversion may be adjusted so that the first and second luminance data match the reference luminance data within a predetermined range.

In addition, the step (e), (e1) adjusting the gain of the A / D conversion to match the first luminance data and the reference luminance data within a predetermined range; And (e2) after the step (e1), adjusting the offset of the A / D conversion so that an error between the first and second luminance data and the reference luminance data is within a predetermined range.

White balance adjustment apparatus according to the present invention for achieving the above technical problem, A / D conversion unit for converting an analog input image into a digital image; A color coordinate converter for converting color coordinates of the converted digital image and outputting digital luminance data; And an image correction unit for detecting a difference between the digital luminance data and the reference luminance data and correcting an image by changing a weight of the A / D converter according to the difference.

The white balance adjusting device selects an output of the color coordinate conversion unit when the analog input image is an RGB image, selects an output of the A / D conversion unit when the analog input image is a digital TV image, and outputs the output to the image correction unit. A selection unit may be further provided.

According to an aspect of the present invention, a display panel includes an A / D conversion unit for converting an analog input image into a digital image; A color coordinate converter for converting color coordinates of the converted digital image and outputting digital luminance data; And an image correction unit for detecting a difference between the digital luminance data and the reference luminance data and correcting an image by changing a weight of the A / D converter according to the difference.

The display panel selects an output of the color coordinate converter if the analog input image is an RGB image, and selects an output of the A / D converter if the analog input image is a digital TV image, and outputs the output to the image correction unit. It may be further provided.

Hereinafter, the configuration and operation of a method and apparatus for adjusting white balance according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The first of the technical ideas for adjusting the white balance of the present invention is that the video output of the PDP panel is not fed back. That is, white balance adjustment is performed by correction of the analog circuit. Therefore, an optical sensor, a D / A converter, and the like, which are required to feed back the image output of the PDP panel to perform white balance adjustment, are not necessary.

The second aspect of the technical idea for white balance adjustment of the present invention is to enable white balance adjustment even when a Y / Pb / Pr signal is directly received by the PDP, such as a digital TV.

A third aspect of the technical idea for white balance adjustment of the present invention is to adjust the gain and the offset of the analog circuit, respectively.

3 is a flowchart illustrating a white balance adjustment method according to an embodiment of the present invention.

Referring to FIG. 3, first, an analog image is input (S300). After step S300, the analog image is converted into digital image data (step S302). After the step S302, the color coordinates of the digital image data are converted (step S304). After step S304, a difference from the reference luminance data is detected (step S306). After step S306, the A / D converted image is corrected (step S308).

In operation S300, the analog image may be an RGB image input from a computer or the like, or a digital TV image input as an YPbPr image. After the step S300, the analog image is converted into a digital image.

Due to the nonuniformity of the analog circuit, the gain error, the offset error, and the like during the conversion process of steps S300 and S302, white is not output even when a completely white image is input. In particular, apart from white distortion due to variations in phosphor characteristics and digital logic in an actual display panel, white distortion due to unevenness in an analog circuit of an image input stage is very large. Therefore, calibrating the analog circuit of the video input stage is the key to white balance adjustment.

The present invention does not directly adjust the white balance by directly measuring the luminance of the display panel. In other words, the video output of the PDP panel is not fed back. That is, white balance adjustment is performed by the correction of the analog circuit itself. Therefore, an optical sensor, a D / A converter, and the like, which are required to feed back the image output of the PDP panel to perform white balance adjustment, are not necessary.

In step S304, color coordinates of the digital image data are converted. As described above, the present invention corrects distorted white data while the input image passes through the analog circuit itself. To this end, if an image of RGB color coordinates is input from a computer or the like, the image is converted into data of color coordinates including luminance. Luminance is generally represented by the letter Y. Color coordinate data including luminance (Y), as is well known, there are YCbCr color coordinates, YIQ color coordinates and YPbPr color coordinates of digital TV images.

In step S306, the difference between the color coordinate converted digital data and the reference data is detected. In other words, in order for RGB image inputs to be mixed to output accurate white, the R / G / B luminance ratio should be 76/150/29. In the present invention, the white balance is adjusted using this point. Therefore, assuming that the R / G / B image is input to 76/150/29, when the maximum digital output value of the R / G / B image is based on 255 levels, the digital reference luminance data should be 76, 150, 29. do. If the digital output for red (R) yields 72, the error is 4.

In step S308, as much as the error detected in step S304 to correct the A / D conversion. In other words, in the above example, the weight of the A / D conversion can be adjusted so that the digital output of red (R) is 76.

The weight of the A / D conversion adjusted here may be a gain or an offset. In the above example, error 4 may be corrected by increasing the gain, and error 4 may be corrected by adjusting the offset.

The R / G / B reference luminance data exemplified above may be 76, 150, 29 based on the 255 level maximum value, or at least 76/150/29 ratio is adjusted so as to maintain the white balance.

When the analog R, G, and B video signals are sequentially input in step S300, steps S302 to S308 described above with respect to red (R) are repeatedly performed for green (G) and blue (B) to adjust white balance. Can be.

FIG. 4 is a flowchart for describing a white balance adjusting method according to the modified example of FIG. 3, which is a method of adjusting white balance based on two first and second points.

Referring to FIG. 4, first, a first analog image and a second analog image are input (S400). After operation S400, the first analog image and the second analog image are converted into a first digital image and a second digital image, respectively (S402). After operation S402, color coordinates of the first digital image and the second digital image are converted (operation S404). After step S404, a difference from the reference luminance data is detected (step S406). After step S406, the A / D conversion gain is adjusted to match the first digital image with the first reference value (step S408). After the step S408, the offset of the A / D conversion is adjusted so that the first digital image and the second digital image match the first reference value and the second reference value within a predetermined range (step S410).

5A to 5C are graphs for explaining a weight adjustment method of A / D conversion in the white balance adjustment method of the present invention.

Referring to FIGS. 4 and 5A, values obtained by inputting a first analog image and a second analog image in operation S400 are first inputs and second inputs displayed on the input shaft of FIG. 5A. The first and second digital images A / D converted in step S402 are the first and second outputs displayed on the output shaft of FIG. 5A. The maximum value of the output shaft may be, for example, 255 levels. When the measured A and B points are ideally adjusted to the reference points Aref and Bref, perfect white balance is achieved.

)가 기준점(Bref)에 맞도록 이득 조정된 경우이다. 기준선 상하로 해칭된 부분은 허용오차 범위를 의미한다. 즉 이득 조정 후에도, 제1 조정출력점(

)은 아직 허용오차 범위 밖에 있는 것이다.FIG. 5B is a graph after the gain of the A / D conversion in FIG. 5A is adjusted. Here, the second adjustment output point (

) Is the gain adjusted to fit the reference point (Bref). The parts hatched above and below the baseline represent the tolerance range. That is, even after gain adjustment, the first adjustment output point (

) Is still outside the tolerance range.

)이 기준점 Bref 을 벗어났지만, 제1조정출력점(

)와 제2조정출력점(

)이 공히 허용오차 범위내에 들어간 것을 볼 수 있다. 이 경우 적정한 화이트 밸런스가 이루어진 것이다.5C is a graph after the offset of the A / D conversion in FIG. 5B is adjusted. By the offset adjustment, the second adjustment output point (

) Is outside the reference point Bref, but the first adjustment output point (

) And the second regulated output point (

) Can be seen to fall within tolerance. In this case, proper white balance is achieved.

6 is a block diagram illustrating a white balance adjusting apparatus according to an exemplary embodiment of the present invention, and includes an A / D converter 600, a color coordinate converter 604, and an image corrector 606.

The A / D converter 600 converts an analog input image IN, for example, an RGB image input, into a digital image 602 and outputs it. The color coordinate conversion unit 604 converts the color coordinates of the converted digital image 602 from, for example, RGB color coordinates to YPbPr color coordinates, and outputs digital luminance data Y to the image correction unit 606.

The image correction unit 606 detects a difference between the digital luminance data and the reference luminance data, and corrects the image by changing the weight of the A / D converter according to the difference. The method of changing the weight is the same as shown and described in FIGS. 5A-5B.

FIG. 7 is a block diagram illustrating a white balance adjusting device according to another exemplary embodiment of the present invention, wherein the A / D converter 700, the color coordinate converter 704, the image corrector 706, and the first selection are shown. The unit 712 and the second selection unit 710 are provided. The difference from FIG. 6 is that the first selector 712 and the second selector 710 are added.

The embodiment shown in FIG. 7 is an input image of the A / D converter 700, and when various types of images such as an RGB image IN1 input from a computer or the like, or a digital TV image IN2 are input, A first selector 712 is provided to select one of them. The decision of the selection may be determined by an external user or may be determined by device auto recognition.

Depending on which image is selected, the feedback for image correction varies. When the RGB image IN1 is selected by the first selector 712, the output of the color coordinate converter 704 is selected to feed back the luminance data Y. The color coordinate converter 704 converts, for example, from an RGB color coordinate to an YPbPr color coordinate, and outputs digital luminance data (Y).

When the digital TV image IN2 is selected by the first selector 712, the image of the YPbPr color coordinate is input, so that digital luminance data Y is directly output from the A / D converter 700 that has A / D converted. Obtained.

Accordingly, the second selector 710 selects a signal path so that the digital luminance data Y is output to the image corrector 706.

The image correction unit 706 detects a difference between the digital luminance data and the reference luminance data, and corrects the image by changing the weight of the A / D converter according to the difference. The method of changing the weight is the same as shown and described in FIGS. 5A-5B.

FIG. 8 is a block diagram illustrating a white balance adjusting device according to another preferred embodiment of the present invention. The first A / D converter 800, the first color coordinate converter 804, and the first image corrector are shown. 806, a second A / D converter 808, a second color coordinate converter 814, a second image corrector 812, and a first selector 818.

In the drawings, reference numerals IN1 and IN2 may be, for example, RGB image inputs and digital TV image inputs as first and second analog inputs, respectively.

The white balance processing path shown in FIG. 8 is bifurcated.

The first path converts the RGB analog input IN1 into RGB digital data 802 by the first A / D converter 800, and then converts it into YPbPr color coordinate by the first color coordinate converter 804. The luminance data Y is fed back to the first image corrector 806 to adjust gain and offset of the first A / D converter 800.

The second path converts the YPbPr analog input IN2, which is a digital TV input, to the YPbPr digital data 810 by the second A / D converter 808, and converts the dual digital luminance data Y into a second image report. The feedback to the government 812 is performed to adjust the gain and offset of the second A / D converter 812. The second color coordinate converter 814 converts the digital YPbPr data 810 back to the RGB digital data 816.

The first selector 818 selects and outputs one of the digital RGB data 802 of the first path and the digital RGB data 816 of the second path.

As a result, the final output OUT of FIG. 8 may be digital data obtained by adjusting white balance with respect to an RGB analog image or digital TV image signal input from the outside, and may be connected to the logic controller 902 of FIG. 9.

9 is a block diagram illustrating an embodiment of a display device to which the white balance adjusting device of the present invention can be applied.

Referring to the drawings, a typical driving apparatus of the plasma display panel includes an image processor 900, a controller 902, an address driver 906, an X driver 908, and a Y driver 904. The image processing unit 900 converts an external analog image signal into a digital signal, and internal image signals, for example, 8-bit red (R), green (G), and blue (B) image data, clock signals, vertical and horizontal, respectively. Generate sync signals. The controller 902 generates driving control signals SA, SY, and SX according to an internal image signal from the image processor 900. The address driver 906 generates a display data signal by processing the address signal SA among the driving control signals SA, SY, and SX from the controller 902, and generates the display data signal through the address electrode lines. To apply. The X driver 908 processes the X driving control signal SX among the driving control signals SA, SY, and SX from the controller 902 and applies the X driving control signal SX to the X electrode lines. The Y driver 904 processes the Y driving control signal SY among the driving control signals SA, SY, and SX from the controller 902 and applies the Y driving control signal SY to the Y electrode lines.

The white balance adjusting device according to the present invention is included in the image processing unit 900 of FIG. 9 and can operate in the display device.

In addition, the white balance adjustment method of the present invention can be embodied as computer readable codes on a computer readable recording medium. Computer-readable recording media include any type of recording device that stores programs or data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, flash memory, optical data storage, and the like. Here, the program stored in the recording medium refers to a series of instruction instructions used directly or indirectly in an apparatus having an information processing capability such as a computer to obtain a specific result. Thus, the term computer is used to mean all devices having an information processing capability for performing a specific function by a program, including a memory, an input / output device, and an arithmetic device, regardless of the name actually used. In the case of a device for driving a panel, its use is limited to a specific field of panel driving, and in reality, it is a kind of computer.

In particular, the panel driving method according to the present invention is written in a schematic or ultra-high-speed integrated circuit hardware description language (VHDL) or the like on a computer, and connected to a computer-programmable integrated circuit such as a field programmable gate array (FPGA). Can be implemented. The recording medium includes such a programmable integrated circuit.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the present invention has the following effects.

First, white balance adjustment may be performed without feeding back the image output of the PDP panel. That is, white balance adjustment is performed by correction of the analog circuit. Therefore, an optical sensor, a D / A converter, and the like, which are required to feed back the image output of the PDP panel to perform white balance adjustment, are not necessary.

Second, even when a Y / Pb / Pr signal is directly received by the PDP, as in a digital TV, white balance adjustment may be performed.                     

The invention is not limited to the examples described above and represented in the drawings. Those skilled in the art taught by the above-described embodiments, many modifications to the above-described embodiments are possible by substitution, erasure, merging, etc. within the scope and object of the present invention described in the following claims.

Claims (15)

(a) inputting an analog image; (b) converting the analog image into digital data by A / D conversion; (c) converting color coordinates of the digital data to output luminance data; (d) detecting an error between the luminance data and the reference luminance data; And (e) adjusting the weight of the A / D conversion according to the error; white balance adjustment method comprising the. The method of claim 1, In the step (a), analog R, G, B image signals are sequentially input, and the steps of performing the steps (b) to (e) by sequentially repeating the white balance adjustment method. The method of claim 2, Step (a), White balance adjustment method characterized in that for inputting the maximum value of the analog R, G, B image. The method of claim 3, wherein in step (d), The ratio of the reference luminance data to R, G, B is 76 to 150 to 29, characterized in that the white balance adjustment method. The method of claim 1, wherein step (e) And adjusting gain gain of the A / D conversion according to the error. The method of claim 1, wherein step (e) And adjusting the offset weight of the A / D conversion according to the error. (a) inputting a first analog image and a second analog image; (b) converting the first and second analog images into first and second digital data by A / D conversion; (c) outputting first and second luminance data by converting color coordinates of the first and second digital data; (d) detecting an error between the first and second luminance data and reference luminance data; And (e) adjusting the weight of the A / D conversion according to the error; white balance adjustment method comprising the. The method of claim 7, wherein the step (e), And adjusting the gain of the A / D conversion so that the first and second luminance data match the reference luminance data within a predetermined range. The method of claim 7, wherein the step (e), And adjusting the offset of the A / D conversion so that the first and second luminance data match the reference luminance data within a predetermined range. The method of claim 7, wherein the step (e), (e1) adjusting a gain of the A / D conversion so that the first luminance data and the reference luminance data match within a predetermined range; And (e2) after the step (e1), adjusting the offset of the A / D conversion so that an error between the first and second luminance data and the reference luminance data is within a predetermined range. . An A / D converter for converting an analog input image into a digital image; A color coordinate converter for converting color coordinates of the converted digital image and outputting digital luminance data; And And an image correction unit detecting a difference between the digital luminance data and the reference luminance data and correcting an image by changing a weight of the A / D converter according to the difference. The method of claim 11, And selecting an output of the color coordinate converter if the analog input image is an RGB image, and selecting an output of the A / D converter if the analog input image is a digital TV image, and outputting the output to the image correction unit. Features a white balance adjuster. To adjust the white balance of the display panel, An A / D converter for converting an analog input image into a digital image; A color coordinate converter for converting color coordinates of the converted digital image and outputting digital luminance data; And And an image correction unit detecting a difference between the digital luminance data and the reference luminance data and correcting an image by changing a weight of the A / D converter according to the difference. The method of claim 13, And selecting an output of the color coordinate converter if the analog input image is an RGB image, and selecting an output of the A / D converter if the analog input image is a digital TV image, and outputting the output to the image correction unit. Display panel. A computer-readable recording medium having recorded thereon a program for executing the method of any one of claims 1 to 10.

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