KR100438299B1 - Method for controlling White Balance at a Multi-Screen and Multi-Screen Display Device using this Method - Google Patents

Abstract

According to an embodiment of the present invention, a method of adjusting white balance in a multi-screen according to the present invention includes converting a first video signal having an RGB format into a YUV format, converting a converted first video signal of a YUV format into an RGB format, and converting the RGB image into the RGB format. Normalizing the first image signal in a process of performing the step; Converting a second video signal having a YUV format into an RGB format and normalizing the second video signal in the process of converting the second video signal to the RGB format; And adjusting the white balance of the normalized first image signal or the second image signal using the digital color lookup table. The normalizing of the first and second image signals may include changing an RGB value corresponding to 0 and 255 levels among RGB values of the digital color lookup table to an RGB value corresponding to an intermediate level (gray); Inputting a multi-level gray pattern signal to the first image processor or the second image processor; Checking a output state of a full black level among the multi-level gray patterns output to the display unit and setting a bias value; And setting the R, G and B gain values by checking the output state of the full white level among the multi-level gray patterns output to the display unit. Such an embodiment of the present invention has the advantage of accurately adjusting the white balance of all the input signals by only one white balance adjustment.

Description

Method for controlling white balance at a multi-screen and multi-screen display device using this method

The present invention relates to a method of adjusting white balance in a multi-screen and a multi-screen display device using the same, in particular, different formats (f)

or white) standardization of the image signals input to the same signal, and then to adjust the white balance using a digital color look-up table (Digital Color Look-Up Table) white balance adjustment method in the multi-screen and using the same It relates to a screen display device.

In recent years, display devices have been developed in the trend of light weight, light weight, and large screen. As a display device that satisfies these advantages, flat panel display devices such as LCD and PDP have been in the spotlight. Among them, LCD is mainly used as a monitor such as a PC, and PDP is mainly used as a TV.

Meanwhile, as these various flat panel display devices are developed one after another, not only the size of the screen but also the quality of the image to be expressed is important. One of the technologies for improving the quality of the image is the white balance function.

White balance means that the balance of colors represented on the display may vary depending on the color temperature, so the mixing ratio of each RGB color is determined by the x, y coordinates and color temperature according to the CIE chromaticity diagram set by the Commission for International Illumination (CIE). This function is more important in the so-called multi-screen, which displays two screens simultaneously on one monitor.

1 is a block diagram showing the configuration of a conventional multi-screen display apparatus.

Referring to FIG. 1, a conventional multi-screen display apparatus includes a first image processor 110 for receiving a first image signal having an RGB format and performing various image processing; A second image processor 120 which receives a second image signal having a YUV format, performs various image processing, converts the image into an RGB format, and outputs the converted RGB format; A picture in picture (PIP) unit 130 for mixing the first and second image signals having an RGB format into a composite signal capable of realizing a multi-screen; A color lookup table 140 for giving a new RGB value to match the white balance of the synthesized signal generated by the PIP unit 130; And a display unit 15 for implementing a multi-screen according to the RGB value given by the color lookup table 140.

0); And the like.

Here, the RGB format is a representative video signal format output from a personal computer, etc., and the YUV format is a representative video signal format output from a video, a TV, and the like.

However, in the display device as described above, when the RGB value of the first image signal and the RGB value of the second image signal are different (the PC and the video that makes the first image signal and the second image signal, etc. are manufactured by each manufacturer or used part. As a result, there are many variations in performance. In other words, when the color coordinates of two image signals are not the same, even if the image has the same color, the display unit 150 may output differently.

In particular, when the RGB values of the input first and second video signals are different from each other, only one of them can be adjusted for white balance. In this case, the quality of the output video signal without the white balance adjustment is significantly degraded. In other words, there is a problem that the distorted image is output differently from the original image.

The present invention was created to solve the above problems, and standardizes an image signal input in different formats into one same signal, and then adjusts the white balance at once using a digital color lookup table, thereby displaying the multi-displayed. The goal is to present a new method for white balance adjustment on multi-screens that allows screens to have the same color.

Another object of the present invention is to provide a new multi-screen display apparatus in which screens displayed using the white balance adjustment method as described above have the same white balance.

1 is a block diagram showing the configuration of a conventional multi-screen display device;

2 is a view schematically showing the configuration of a multi-screen display device according to the present invention,

3 is a view showing a multi-level gray pattern used in the Bais value and R, G, B Gain value setting process according to the present invention,

4 is a diagram illustrating a multi-level gray pattern output to a display unit in a process of setting a bias value according to the present invention.

5 is a view showing a multi-level gray pattern output to the display unit in the process of setting the R Gain value according to the present invention,

6 is a view showing a multi-level gray pattern output to the display unit in the process of setting the G gain value according to the present invention,

7 is a view showing a multi-level gray pattern output to the display unit in the process of setting the B Gain value according to the present invention,

8 is a diagram illustrating a configuration of a system used for general white balance adjustment.

<Explanation of symbols for main parts of the drawings>

110: first image processor 120: second image processor

130: PIP section (Picture In Picture)

140: color look-up table 150, 270: display unit

210: first image processing unit 220: first color adjusting unit

230: second image processing unit 240: second color adjusting unit

250: PIP part

260: Digital Color Lookup Table 810: Color Meter

820: PC

In order to achieve the above object, a white balance adjustment method in a multi-screen according to the present invention includes converting a first video signal having an RGB format into a YUV format, and converting the converted first video signal of a YUV format into an RGB format. Normalizing the first image signal in a process of converting the image into the RGB format; Converting a second video signal having a YUV format into an RGB format and normalizing the second video signal in the process of converting the second video signal to the RGB format; And adjusting the white balance of the normalized first image signal or the second image signal using the digital color lookup table.

The normalizing of the first and second image signals may include changing an RGB value corresponding to 0 and 255 levels among RGB values of the digital color lookup table to an RGB value corresponding to an intermediate level (gray); Inputting a multi-level gray pattern signal to the first image processor or the second image processor; Checking a output state of a full black level among the multi-level gray patterns output to the display unit and setting a bias value; And setting the R, G and B gain values by checking the output state of the full white level among the multi-level gray patterns output to the display unit.

In the setting of the Bias value, if the Full Black Level is output as gray out of the multi-level gray pattern output to the display unit, the Bias value is increased by one step, and the Bias is set to the value of the previous step as soon as it turns black. If the full black level is output as black out of the multi-level gray pattern output to the display unit, the Bias value is sufficiently lowered to be output as gray, and then the Bias value is increased by one step, and the value of the previous step is changed to black. And setting the R gain value by multiplying an RGB value by an arbitrary large gain value such that a full white level is output in gray among the multi-level gray patterns output to the display unit. After making it, lower the R Gain value by one step and turn it to red. and setting the G Gain value by multiplying an RGB value by an arbitrary large Gain value such that a full white level is output in gray among the multi-level gray patterns output to the display unit. After making it, the G Gain value is lowered by one step and the moment it turns green, the G Gain value is set to the value of the previous step. The setting of the B Gain value is based on the RGB value. By multiplying any large gain value to make the Full White Level gray out of the multi-level gray pattern output to the display unit, lowering the B gain value by one step and then turning blue to the value of the previous step B And setting the gain value. The adjusting of the white balance may include a full white signal in the first image processor or the second image processor. A first step of inputting; A second step of checking whether the full white signal output to the display unit is in a desired white coordinate region by adjusting a R and G value of 255 levels of the digital color lookup table to enter the white left region; ; A third step of storing the adjusted RGB value as an RGB value of 255 levels of the digital color lookup table; And a fourth step of inputting a color signal of a next step into the first image processor or the second image processor, and storing the RGB values obtained by repeating the second and third steps in the digital color lookup table. According to another aspect of the present invention, there is provided a multi-screen display device, including: a first image processor converting a first image signal having an RGB format into a YUV format and performing various image processing; A first color adjusting unit converting the first image signal of the YUV format passed through the first image processing unit into an RGB format and normalizing the first image signal during the conversion process; A second image processor configured to perform various image processing after receiving a second image signal having a YUV format; A second color adjusting unit converting the second image signal of the YUV format passed through the second image processing unit into an RGB format and normalizing the second image signal during the conversion process; A PIP unit for mixing the first and second video signals having the standardized RGB format into a composite signal capable of realizing a multi-screen; A digital color lookup table for assigning RGB values according to white balance to the synthesized signal generated by the PIP unit; And a display unit for implementing a multi-screen according to the RGB value given in the digital color lookup table.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 schematically illustrates a configuration of a multi-screen display apparatus according to the present invention.

2, a multi-screen display apparatus according to the present invention includes: a first image processor 210 for receiving a first image signal having an RGB format and converting the image into a YUV format to perform various image processing; A first color adjusting unit 220 converting the first image signal of the YUV format passed through the first image processing unit into an RGB format and standardizing the first image signal during the conversion process; A second image processor 230 for performing various image processing after receiving a second image signal having a YUV format; A second color adjustment unit 240 for converting the YUV format image signal passed through the second image processing unit 230 into an RGB format and standardizing the second image signal during the conversion process; A PIP unit 250 for mixing the first and second video signals having a standardized RGB format into a composite signal capable of realizing a multi-screen; A digital color lookup table 260 (hereinafter referred to as a 'lookup table') which gives an RGB value according to the white balance to the synthesized signal generated by the PIP unit 250; And a display unit 270 for implementing a multi-screen according to the RGB value given by the lookup table 260. It is configured to include.

Next, a method of adjusting the white balance in the multi-screen according to the present invention through the multi-screen display device having the above configuration will be described.

First, when a first image signal having an RGB format is input to the first image processor 210, the first image signal is converted into a YUV format. At this time, the determinant used in the conversion process is as follows.

Y = 0.299R + 0.587G + 0.114B

U = -0.169R-0.331G + 0.500B

V = 0.500R-0.419G-0.081B

(RGB range: 0 to 255, Y range: 0 to 255, U and V range: -128 to +127)

The first video signal of the YUV format converted as described above is input to the first color adjusting unit 220 after various image processing such as image size adjustment.

Thereafter, the first image signal converted to the YUV format is converted to the RGB format after the color adjustment process. The determinant used in the conversion process is as follows. In this conversion process, standardization is performed.

R = 1Y + 1.402 V

G = 1Y-0.344U -0.714V

B = 1Y + 1.722U

In the color adjustment process, the Bias value and the R, G, and B gain values are set to standardize the first image signal converted into the YUV format, and thus the final RGB value is expressed as follows.

Output_R = Bias_R + (Gain_R * Input_R)

Output_G = Bias_G + (Gain_G * Input_G)

Output_B = Bias_B + (Gain_B * Input_B)

(In this case, each Bais, R, G, and B Gain values are adjustment variables of the linear system and are independent of each of RGB.)

Meanwhile, when the second image signal having the YUV format is input to the second image processor 230, the second image signal is input to the second color adjuster 240 after performing various image processing processes.

Thereafter, the second image signal is converted into the RGB format after the color adjustment process. The determinant used in the conversion process is as follows. In addition, the second video signal, like the first video signal, is standardized in this conversion process.

R = 1.164Y-0.0018U + 1.596 V

G = 1.164Y-0.391U-0.8135V

B = 1.164 Y + 2.018 U-0.0012 V

In the color adjustment process, the Bias value and the R, G, and B gain values are set for the standardization of the image signal, and thus the final RGB value is expressed as follows.

Output_R = Bias_R + (Gain_R * Input_R)

Output_G = Bias_G + (Gain_G * Input_G)

Output_B = Bias_B + (Gain_B * Input_B)

(In this case, each Bais, R, G, and B Gain values are adjustment variables of the linear system and are independent of each of RGB.)

On the other hand, the first and second video signals are standardized through color adjustment processes in the process of converting from the YUV format to the RGB format. Here, the standardization means to make the same size and shape of the video signal input in different forms to have the same color coordinates. For this standardization, in particular, the Bias value should be set such that the minimum Black levels of the two video signals are the same, and the R, G, and B gain values should be set so that the maximum White levels are the same.

First, the process of setting the Bias value is as follows.

Among the RGB values of the lookup table 260 set linearly, the RGB values corresponding to the 0 and 255 levels are changed to the RGB values corresponding to the intermediate level (for example, the 127 level). Therefore, if the level of the input 8-bit RGB signal is 0 or 225, that is, if the full black or full white, the color appearing on the screen is gray.

Thereafter, the multi-level gray pattern signal as shown in FIG. 3 is input to the first image processor 210 or the second image processor 230. The multi-level gray pattern signal is a color band signal divided into steps from a full black level to a full white level. Here, a 10-step gray pattern signal is used. Figure 3 shows a multi-level gray pattern used in the Bais value and the R, G, B Gain value setting process according to the present invention.

At this time, if the bias value of the input signal is less than 0, the full black level of the multi-level gray pattern signal output to the display unit 270 by the look-up table 260 set in advance is shown in (1) of FIG. The output is grayed out as shown. If it outputs in black, it means that the Bias value of the signal is greater than 0. In this case, the Bias value of the signal is sufficiently lowered to adjust the gray color. 4 illustrates a multi-level gray pattern output to the display unit in the process of setting a bias value according to the present invention.

After that, increase the Bias value by one step to find the correct Bias value. Then, as soon as gray turns black as shown in (2) of FIG. 4, the signal due to the Bias value corresponds to one level of the lookup table 260, so that the Bias value of the previous step is set to the 0 level of the lookup table. The corresponding bias value. Therefore, Bias is set to the above value.

Next, a process of setting the R, G, and B gain values will be described.

The process of setting the R, G, and B gain values also uses the lookup table 260 used in the process of setting the bias values. Therefore, if the level of the input RGB signal is 225, that is, if it is Full White, the color appearing on the screen is gray.

Thereafter, the multi-level gray pattern signal, used in the Bias value setting process, is input to the first image processor 210 or the second image processor 230.

If the current RGB signals are all 255 or more, the white portion of the multi-level gray pattern signal output to the display unit is output in gray as shown in (1) of FIG. At this time, if it is not gray, the RGB is multiplied by an arbitrary large gain value to make it output as gray as shown in (1) of FIG. 5. 5 is a diagram illustrating a multi-step gray pattern output to a display unit in a process of setting an R gain value according to the present invention.

Then, to find the correct R Gain value, the R Gain value of the current step is decreased by one step. Then, as soon as gray turns red as shown in (2) of FIG. 5, the signal due to the R gain value corresponds to the 254 level of the lookup table, so the R gain value of the previous step corresponds to the 255 level of the lookup table. R gain value. Therefore, the R Gain value is set to the above value.

This process can be repeated for G gain and B gain, and finally R, G, and B gain values can all be set. 6 illustrates a multi-step gray pattern output to the display unit in the process of setting the G gain value according to the present invention, and FIG. 7 illustrates a multi-step gray pattern output to the display unit in the process of setting the B Gain value according to the present invention. That is, in order to find the correct G gain value, the current G gain value is decreased by one step. Then, as soon as gray turns green as shown in (2) of FIG. 6, the signal by the G gain value corresponds to 254 levels of the lookup table, so the G gain value of the previous step corresponds to the 255 level of the lookup table. It will be G gain value. Therefore, the G gain value is set to the above value. In addition, the B gain value of the current step is decreased by one step to find the correct B gain value. Then, as soon as gray is changed to green as shown in (2) of FIG. 7, the signal by the B gain value corresponds to the level 254 of the lockup table, so that the G gain value of the previous step is set to the 255 level of the lookup table. It is the corresponding B gain value. Therefore, the B Gain value is set to the above value.

On the other hand, when the first and second video signals are standardized by setting the Bais value and the R, G, and B gain values as described above, white balance adjustment is then performed using the lookup table 260. In other words, since the two video signals are in a normalized state, the two video signals have the same color coordinates. Thus, the white balance needs to be adjusted for only one of the video signals.

Here, a method of adjusting the white balance based on the first video signal will be described with reference to FIG. 8. 8 shows the configuration of a system used for general white balance adjustment.

First, a full white signal is input to the first image processor 210. In this case, a sufficient operating time is ensured so that various devices, in particular, the display unit 270 are preheated.

Thereafter, the full color output from the display unit 270 is checked using the color meter 810 and the PC 820 to determine whether the white area is in the desired white coordinate area. In this case, if it is not in the desired white coordinate region, the R and G values of the 255 level of the lookup table 260 are adjusted using the PC 820 to enter the region. At this time, the B value is fixed.

Thereafter, the adjusted RGB value is stored as an RGB value of 255 levels of the lookup table 260, the gray level signal of the next level is input to the first image processor 210, and the process is repeated.

On the other hand, in the above process, it is better to correct the RGB value by inputting as many levels of color signals as possible, but in practice, a sufficient effect can be obtained only by inputting a few colors of a specific level. The specific level of color refers to, for example, Full White, Gray, Full Black.

The lookup table 260 set through the above process is applied to all standardized signals, that is, not only the first video signal but also the second video signal, so that accurate white balance is maintained even in a so-called multi-screen in which the two video signals are simultaneously displayed. do.

As described above, the above embodiments are disclosed for the purpose of illustration, and those skilled in the art will appreciate that various modifications, improvements, substitutions, and additions may be made without departing from the spirit of the present invention. Accordingly, the technical scope of the present invention should be defined by the appended claims.

As described above, the white balance adjusting method in the multi-screen according to the present invention and the multi-screen display apparatus using the same standardize the size and shape of all the video signals inputted to the display unit as one single signal so that one white balance is used. It is an advantage that the white balance of all the input signals can be exactly adjusted by adjustment alone.

In addition, since the white balance is adjusted using a digital color lookup table, it is much simpler than the conventional method. Since the value of the digital color lookup table can be changed at any time, it is possible to flexibly change the white balance according to the situation. There is an advantage.

Claims (8)

A first image processor converting a first image signal having an RGB format into a YUV format to perform various image processing; A first color adjusting unit converting the first image signal of the YUV format passed through the first image processing unit into an RGB format and normalizing the first image signal during the conversion process; A second image processor configured to perform various image processing after receiving a second image signal having a YUV format; A second color adjusting unit converting the second image signal of the YUV format passed through the second image processing unit into an RGB format and normalizing the second image signal during the conversion process; A PIP unit for mixing the first and second video signals having the standardized RGB format into a composite signal capable of realizing a multi-screen; A digital color lookup table for assigning RGB values according to white balance to the synthesized signal generated by the PIP unit; And And a display unit for implementing a multi-screen according to the RGB value given in the digital color lookup table. Converting the first video signal having the RGB format into the YUV format, converting the converted first video signal of the YUV format into the RGB format, and normalizing the first video signal in the RGB format; Converting a second video signal having a YUV format into an RGB format and normalizing the second video signal in the process of converting the second video signal to the RGB format; And And adjusting the white balance of the normalized first image signal or the second image signal using the digital color lookup table. The method of claim 2, wherein normalizing the first and second video signals comprises: Changing an RGB value corresponding to 0 and 255 levels among the RGB values of the digital color lookup table to an RGB value corresponding to an intermediate level (gray); Inputting a multi-level gray pattern signal to the first image processor or the second image processor; Checking a output state of a full black level among the multi-level gray patterns output to the display unit and setting a bias value; And Checking the output state of the full white level among the multi-level gray patterns output to the display unit, and setting the R, G, and B gain values, respectively. The method of claim 3, wherein setting the Bias value comprises: If the full black level is output as gray out of the multi-level gray pattern output to the display unit, increase the Bias value by one step, set the bias to the value of the previous step at the moment when it changes to black, and output the multi-level gray to the display unit. If the Full Black Level is output as black among the patterns, the Bias value is lowered enough to be output as gray, then the Bias value is increased by one step, and the screen is set to the value of the previous step as soon as it changes to black. How to adjust the white balance in The method of claim 3, wherein setting the R gain value comprises: By multiplying the RGB value by an arbitrary large gain value, the full white level is output as gray out of the multi-level gray pattern output to the display unit, and then lowering the R gain value by one step and then turning red. A method of adjusting the white balance in a multi screen, characterized by setting the R gain value as the value. The method of claim 3, wherein the setting of the G gain value comprises: Multiply the RGB value by an arbitrary large gain value so that the full white level is output as gray out of the multi-level gray pattern output to the display unit, and then lower the G gain value by one step and then turn green. How to adjust the white balance in the multi-screen, characterized in that the setting the G Gain value. The method of claim 3, wherein the setting of the B gain value comprises: Multiply the RGB value by an arbitrary large gain value so that the full white level is output as gray out of the multi-level gray pattern output to the display unit, and then decrease the B gain value by one step and then turn blue. How to adjust the white balance in the multi-screen, characterized in that the B Gain value to set the value. The method of claim 2, wherein adjusting the white balance comprises: A first step of inputting a full white signal to the first image processor or the second image processor; A second step of checking whether the full white signal outputted to the display unit is in a desired white coordinate region by adjusting a R and G value of 255 levels of the digital color lookup table to enter the white left region; ; A third step of storing the adjusted RGB value as an RGB value of 255 levels of the digital color lookup table; And a fourth step of inputting a color signal of a next step into the first image processor or the second image processor, and storing the RGB values obtained by repeating the second and third steps in the digital color lookup table. Characteristic white balance adjustment method.