KR20040083698A - Color Controlling Method of Digital Broadcasting Receiver - Google Patents

Abstract

PURPOSE: A color adjustment method for a digital broadcasting receiver is provided to minimize a video output deviation irrespective of an ADC(Analog to Digital Converter) component deviation. CONSTITUTION: An offset value and a gain value are set up(S401). A channel value of a reference color for offset adjustment is calculated(S402). The offset value is adjusted until the channel value is within a permission error range(S403-S405). The difference of channel values of reference colors for channel adjustment is calculated(S406). The gain value is adjusted until the channel value difference is within a permission error range(S407-S409). It is checked whether the channel value of the reference color for offset adjustment is within the permission error range(S411). If the channel value of the reference color for offset adjustment is within the permission error range, offset and gain adjustment values are stored(S412).

Description

Color Controlling Method of Digital Broadcasting Receiver

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital broadcast receiver, and more particularly, to a method for adjusting a color of a digital broadcast receiver, which is suitable for minimizing the variation of video output between sets caused by component variation.

Hereinafter, the prior art will be described with reference to the accompanying drawings.

FIG. 1 is a schematic block diagram of a general digital broadcast receiver. The digital broadcast receiver 100 receives an analog broadcast signal (RF signal) and an external input signal (Component) and converts the signal into an arbitrary format to display the display ( As a display device, there is an ADC (Analog to Digital Converter) that converts an analog video signal into digital data as a chip set.

Typically, the ADC is composed of an analog block and a digital block, and each chip variation is large in the process of converting an analog signal into digital data.

This deviation is further increased due to a circuit path to the ADC chip set or errors in peripheral passive components.

Therefore, even when a video signal of the same pattern is inputted, device output (RGB, Y, Cb / Cr) characteristics are different for each set.

Therefore, the above conventional technology has the following problems.

Due to the deviation of the DAC and peripheral circuits, the device output characteristics (RGB, Y, Pb / Pr) are different for each set, and if the degree is severe, the quality is judged to be poor during the quality inspection, which causes a decrease in yield.

An object of the present invention is to provide a method for adjusting a color of a digital broadcast receiver for minimizing video output variation regardless of ADC component variation.

Another object of the present invention is to reduce the defective rate to improve the yield.

1 is a schematic block diagram of a general digital broadcast receiver

2 is a system diagram for color adjustment according to the present invention;

3A is a diagram showing digital data values on a test pattern and its RGB color space used in the present invention.

3B is a diagram showing digital data values of Y (Luminance) components of a test pattern used in the present invention.

3C and 3D show digital data values of Cb / Cr (Color Difference) components of a test pattern used in the present invention.

4 is a flowchart showing a color adjustment method according to the present invention

** Description of the symbols for the main parts of the drawings **

21: test pattern generator 22: digital broadcast receiver

23: display panel

The color adjusting method of the digital broadcasting receiver according to the present invention includes a first step of setting an offset and a gain value, a second step of calculating a channel value of an offset adjustment reference color, and until the channel value falls within an allowable error range. A third step of adjusting an offset, a fourth step of calculating a channel value difference between gain adjustment reference colors, a fifth step of adjusting gain until the channel value difference falls within an allowable error range, and And a sixth step of checking whether the channel value is within the allowable error range, and a seventh step of storing the offset and gain adjustment values if the check result is not within the allowable error range.

Preferably, the process is characterized in that for each of the Y, Cb, Cr channels.

Preferably, when the channel is a Y channel, the channel value of the offset adjustment reference color is an average Y value of black color.

Preferably, when the channel is a Cb channel, the channel value of the offset adjustment reference color is an average Cb value of black and white colors.

Preferably, when the channel is a Cr channel, the channel value of the offset adjustment reference color is an average Cr value of black and white colors.

Preferably, checking whether the channel value of the offset adjustment reference color is within an allowable error range, adjusting the offset value if it is out of the allowable error range, and refreshing the image frame and returning to the second step. It is characterized by consisting of steps.

Preferably, when the channel is a Y channel, a channel value difference between the gain adjustment reference colors is a difference between a Y channel value of black and a Y channel value of white.

Preferably, when the channel is a Cb channel, the channel value difference between the gain adjustment reference colors may be a difference between a Cb channel value of yellow and a Cb channel value of blue.

Preferably, when the channel is a Cr channel, the channel value difference between the gain adjustment reference colors is a difference between a Cr channel value of cyan and a Cr channel value of red.

Preferably, the fifth step includes checking whether the channel value difference of the gain adjustment reference colors is within an allowable error range, adjusting the gain value if it is out of the allowable error range, and refreshing the image frame. And returning to the second step.

The method may return to the second step if the average channel value of the offset adjustment reference color is out of an allowable error range in the sixth step.

Preferably, the step of adjusting the offset value is O _i + β (U _i when O _i is the current offset setting value, β is the offset coefficient, U _i is the channel value of the reference color for offset adjustment, and U _T is the target value. -U _T ) characterized in that the step of calculating.

Preferably, the adjusting of the gain value may include Gi + α (Δi − ΔT) when G _i is a current gain setting value, α is a gain factor, Δi is a channel value difference of a reference color for gain adjustment, and ΔT is a target value. It is characterized in that the step of calculating.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

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

2 is a system configuration diagram for color adjustment according to the present invention.

In order to adjust the color of the digital broadcast receiver 22, the test pattern generator 21 and the display panel 23 are connected to the digital broadcast receiver 22 as in the case of production.

The test pattern generator 21 generates a test pattern in the form of a vertical color bar. Since the digital broadcast receiver 22 has different paths output for each input type, the test pattern generator 21 generates a test pattern. A test pattern is inputted to the digital broadcast receiver 22 by dividing it into an analog broadcast signal (RF signal) and an external input signal (Component) so that color can be adjusted.

3A is a diagram illustrating digital data values of a test pattern and an RGB component of a test pattern, wherein vertical color bars of the test pattern are white (WHT), yellow (YEL), cyan (Cyan) and green ( It consists of eight colors: Green: GRN), Magenta (MGT), Red (RED: RED), Blue (BLU), and Black (Black: BLK).

The digital data values of Y (Luminance) and Cb / Cr (Color Difference) components for the colors are shown in FIGS. 3B, 3C, and 3D, respectively.

When the test pattern is input, the CPU inside the digital broadcasting receiver 22 reads the image data value (Y / Cb / Cr) from the image memory of the video signal processing chip and offsets the analog to digital converter (ADC) in software. Adjust Offset and Gain.

Table 1 below shows reference colors used for offset adjustment for each channel (Y / Cb / Cr).

channel Reference color (U _i ) for offset adjustment Y Black (BLk) Cb Black (BLK), white (WHT) Cr Black (BLK), white (WHT)

The reference color for offset adjustment is determined based on the Y / Cb / Cr digital data value for each color of the test pattern illustrated in FIGS. 3A to 3D. The offset of the Y (Luminance) channel is adjusted using black (BLK). The offset of the Cb channel is adjusted using black (BLK) and white (WHT) having the same Cb value.

The offset of the Cr channel is adjusted using black (BLK) and white (WHT) having the same Cr value.

Table 2 below shows reference colors used for gain adjustment for each channel (Y / Cb / Cr).

channel Reference color for gain adjustment Y Black (BLK), white (WHT) Cb Yellow (YEL), Blue (BLU) Cr Cyan, red

As in the case of the offset, the reference color used to adjust the gain is also determined based on the Y / Cb / Cr digital data value for each color of the test pattern shown in FIGS. 3A to 3D. The channel value difference between white (WHT) which is the maximum and black (BLK) which is the minimum of Y is adjusted. The gain of the Cb channel is adjusted by the channel value of yellow (YEL) having the minimum Cb and blue (BLU) having the maximum Cb. Use to adjust.

The gain of the Cr channel is adjusted using the channel value difference between cyan (CYN) having the minimum Cr and red (RED) having the maximum Cr.

Next, the process of adjusting the offset and gain by the CPU will be described.

4 is a software algorithm for color adjustment of the digital broadcast receiver according to the present invention. First, initial values of an offset O _i and a gain G _i are set (S401).

The offset O _i is set to 64 and the gain G _i is set to 128.

Then, the average channel value U _i of the reference color for offset adjustment of the image data input to the digital broadcast receiver 22 is measured (S402).

The reference color for offset adjustment for each channel (Y / Cb / Cr) is according to Table 1 above.

For example, for the Y (Luminance) channel, U _i is the average value of the Y channel of black (BLK), for Cb channel U _i is the average value of the Cb channel of black (BLK) and white (WHT) and U for the Cr channel. _i is the average value of the Cr channel of black (BLK) and white (WHT).

Subsequently, it is checked whether U _i is within an allowable error range based on the target value U _T (U _T −ε ≤ Ui ≤ U _T + ε, and ε is an allowable error) (S403). In this case, the offset value is reset according to Equation 1 (S404), the image frame is refreshed (S405), and then returned to the step 402 (S402).

O _{i + 1} = O _i + β (U _i + U _T )

Here, β is an offset coefficient and has a value of 1.04.

Then, the loops of steps 404 (S404), 405 (S405), 402 (S402) and step 403 (S403) are repeated until the U _i falls within the allowable error range.

Subsequently, when the Ui falls within the allowable error range, the channel value difference Δi of the reference color for gain adjustment of the corresponding video signal is calculated (S406).

The channel value difference Δi of the gain adjustment reference colors is the difference in Y / Cb / Cr values between the gain adjustment reference colors shown in Table 2 above.

For example, the channel value difference Δi of the reference color for gain adjustment of the Y channel is the difference between the Y channel value of the black BLK and the Y channel value of the white WHT.

Then, it is checked whether Δi is in the allowable error range based on the target value ΔT (S407). If the value is out of the allowable error range, the gain value is reset according to Equation 2 (S408) and the image frame is adjusted. After refreshing (S409), the process returns to the above step 402 (S402).

G _{i + 1} = G _i + α (Δi-ΔT)

Is the gain factor and has a value of 1.04.

Then, the process is repeated until the U _i falls within the allowable error range and the Δ i falls within the allowable error range.

Then, when Δi falls within the allowable error range, the image frame is refreshed (S410), and it is determined whether or not it is within the allowable error range based on the target value U _T (U _T −ε ≦ U _i ≦ U _T + ε, ε (Tolerance error) check again (SS411).

As such, the reason that the DC test U _i is because after the adjusting the gain, so the value having the U _i and Δi is the correlation between the U _i can not escape out of the allowable error range.

As a result of the check, if the U _i is out of the allowable error range, the process returns to step 402 (S402). If the U _i is within the allowable error range, the offset and gain setting values are transmitted to the EEPROM in the digital broadcast receiver 22. Save (S412).

After the above process is performed for the Y, Cb, and Cr channels, the display panel 23 displays " adjustment completed " to complete color adjustment.

Since the color adjustment process must be performed for each of Y / Cr / Cb of the analog broadcast signal (RF signal) and the external input signal (Component), a total of 12 adjustment values are stored in the EEPROM.

The present invention as described above has the following effects.

First, even if there are component deviations, the video output variation can be reduced, thus providing the best image quality to the customer.

Second, the yield can be improved because the defects caused by the video output deviation can be reduced.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the examples, but should be defined by the claims.

Claims (13)

A first step of setting an offset and a gain value; Calculating a channel value of an offset adjustment reference color; Adjusting an offset until the channel value is within an allowable error range; Calculating a channel value difference between the gain adjustment reference colors; A fifth step of adjusting gain until the channel value difference is within an allowable error range; A sixth step of checking whether a channel value of the offset adjustment reference color is within an allowable error range; And, And a seventh step of storing an offset and a gain adjustment value if the check result is within the allowable error range. The method of claim 1, And performing the process for each of Y, Cb and Cr channels. The method of claim 1, If the channel is a Y channel, the channel value of the reference color for offset adjustment is A color adjusting method of a digital broadcasting receiver, characterized in that the average Y value of black color. The method of claim 1, If the channel is a Cb channel, the channel value of the reference color for offset adjustment is A method of adjusting a color of a digital broadcast receiver, characterized in that the average Cb value of black and white colors. The method of claim 1, If the channel is a Cr channel, the channel value of the reference color for offset adjustment is A method of adjusting the color of a digital broadcast receiver, characterized in that the average Cr value of black and white colors. The method of claim 1, The third step is Checking whether a channel value of the offset adjustment reference color is within an allowable error range; If the test result is out of the allowable error range, adjust the offset value, And refreshing the video frame and returning to the second step. The method of claim 1, If the channel is a Y channel, the channel value difference of the reference colors for gain adjustment is A color adjusting method of a digital broadcasting receiver, characterized in that the difference between the Y channel value of black and the Y channel value of white. The method of claim 1, If the channel is a Cb channel, the channel value difference of the reference colors for gain adjustment is A color adjustment method of a digital broadcast receiver, characterized in that the difference between the Cb channel value of Yellow and the Cb channel value of Blue. The method of claim 1, If the channel is a Cr channel, the channel value difference between the gain adjustment reference colors is A color adjusting method of a digital broadcasting receiver, characterized in that it is a difference between a Cyan Cr channel value and a Red Cr channel value. The method of claim 1, The fifth step is Checking whether a channel value difference of the gain adjustment reference colors is within an allowable error range; Adjusting a gain value if it is out of an allowable error range; And refreshing the image frame and returning to the second step. The method of claim 1, In the sixth step And if the average channel value of the offset adjustment reference color is out of the allowable error range, returning to the second step. The method of claim 6, Adjusting the offset value When O _i is the current offset setting value, β is the offset coefficient, U _i is the channel value of the reference color for offset adjustment, and U _T is the target value. Comprising the step of calculating O _i + β (U _i -U _T ) color adjustment method of a digital broadcast receiver. The method of claim 10, Adjusting the gain value When G _i is the current gain setting value, α is the gain factor, Δi is the channel value difference of the reference color for gain adjustment, and ΔT is the target value. Calculating color Gi + α (Δi − ΔT).