KR100949188B1 - Method for processing image of the ccd - Google Patents

Abstract

The present invention relates to a video signal processing method of a CCD, in the video signal processing method of a CCD having a CMYG color array in a CCTV image processing device, each 10-bit CMYG digital signal input from the CCD sensor through the color interpolation method Converting to a 10-bit first luminance Y and color difference CbCr signal; Interpolating the luminance (Y) and color difference (CbCr) signals into an 8-bit RGB signal; Performing color correction on the image signal interpolated by the RGB signal and converting the image signal into an 8-bit second luminance Y and color difference CbCr signal satisfying the ITU-601 format; Encoding the second luminance (Y) and color difference (CbCr) signal and outputting the analog video signal; Adjusting auto exposure (AE) and auto white balance (AWB) with reference to the RGB signal, the second luminance (Y), and a color difference (CbCr) signal; Characterized in that it comprises a.

Description

Method of processing video signal of CDC {METHOD FOR PROCESSING IMAGE OF THE CCD}

The present invention relates to a video signal processing method of a CCD, and in particular, by processing the image by converting the luminance and color difference signal output from the CCD sensor to RGB, more precise image processing is possible, in particular, the adjustment of the automatic white balance or automatic exposure It relates to a video signal processing method of a CCD that can be processed easily and accurately.

In general, digital cameras or camcorders use Charge Coupled Device (CCD) or CMOS instead of film. Millions of light-receiving elements are concentrated in the CCD, and each light-receiving element detects the brightness of an input image corresponding to one pixel. Since only the brightness of light is detected through the CCD, the image output through the CCD is a black and white image instead of a color image visually recognized by a human. Therefore, in order to obtain a color image from the image input through the CCD, a color filter is applied to each pixel to obtain a color image according to a predetermined color format to obtain a color image.

The color filters include primary color filters using red, green, and blue RGB color filters, and CMYG colors of cyan, magenta, yellow, and green. It can be divided into a complementary color filter using a filter.

The CMYG color format is widely used as a color format method of a camcorder because the sensitivity of the color is better than that of the RGB color format.

On the other hand, in the image processing apparatus for CCTV (closed-circuit television), as shown in Figure 1 for the image output from the CCD camera in the DSP (digital signal processor) board to process the image and the processed image is output through the display And will be shown to the outside.

Here, the CCD camera is composed of a CCD sensor having a CMYG color format used for NTSC / PAL (National Television System Committee / Phase Alternating Line). The image output from the internal CCD sensor is output as a digital value having a CMYG color format via an A / D converter.

That is, as shown in FIG. 2, each pixel of the CCD in the CCD camera includes cyan (hereinafter referred to as "Cy"), yellow (hereinafter referred to as "Ye"), pink (hereinafter referred to as "Mg"), and Color information of green (hereinafter, referred to as "G") is stored, and the final output is an interlace scanned signal in which the upper pixel and the lower pixel are added.

Processing modules of the DSP board for processing this CMYG color format are shown in more detail in FIG. 3.

Referring to FIG. 3, the (Mg + Cy), (Ye + G), (Mg + Cy), and (Ye + G) signals input by the 10 bits from the CCD pass through the cell corrector 1 to the defect cell. The cell is calibrated and luminance processing (Y process) and color difference processing (C Precess) are performed through the luminance processing unit 2 and the color difference processing unit 3. The gamma correction units 4 and 5 perform a gamma correction process on the luminance (Y) signal and the color difference (CbCr) signal that are output through this, and then process the NTSC / PAL encoder through the encoder unit 6. Image processing is performed through DAC.

At this time, the timing generator 8 transmits a drive signal to the CCD, and the external interface 9 has an external interface of 12C.

Here, the AE / AWB adjusting unit 7 processes the auto exposure AE and the auto white balance AWB using the color difference CbCr signal.

The auto exposure (AE) and auto white balance (AWB) process the image using a color difference (CbCr) signal. In the related art, the processing of the auto white balance (AWB) approaches the color difference (CbCr) value of 128. (Based on 8 bits). Therefore, if it is lower than 128, the color difference (CbCr) value is increased. If it is higher than 128, the color difference (CbCr) value is lowered.

The automatic exposure (AE) processing uses a method of converging the luminance Y value by using the luminance Y value if the luminance Y value is too high compared to a predetermined target value and increasing it if it is too low.

However, conventionally, since only the color difference (CbCr) value is used in the processing of auto exposure (AE) and auto white balance (AWB), it is not possible to cope with a too bright or dark image signal, that is, a signal having a high or low luminance (Y) value. There is no appropriate countermeasure for signals having a large color difference (which is too biased in one of R, G, and B), which causes color noise and resolution degradation and inferior image processing efficiency.

The present invention has been made to solve the above problems, in the CCD image processing method of the CCD having a CMYG color array in the image processing method, a 10-bit CMYG digital signal input from the CCD sensor to the color interpolation method Converting each of the 10-bit first luminance (Y) and first color difference (CbCr) signals through each other; Interpolating the first luminance (Y) and first color difference (CbCr) signals into an 8-bit RGB signal; Performing color correction on the image signal interpolated by the RGB signal and converting the image into an 8-bit second luminance Y and a second color difference CbCr signal satisfying the ITU-601 format; Encoding and outputting the second luminance (Y) and second color difference (CbCr) signals as an analog video signal, and automatically referring to the RGB signal and the second luminance (Y) and second color difference (CbCr) signals. Adjusting exposure (AE) and automatic white balance (AWB), wherein adjusting the automatic exposure (AE), the RGB signal, the second luminance (Y) and the second color difference (CbCr) signal Receiving and collecting; In accordance with the target boundary set for the RGB value, excluding a second luminance Y value for the RGB value that is outside the set target boundary from the collection and based on a space where the collected second luminance Y values converge. And adjusting the AE of the image by adjusting the value of the second luminance Y so that the value of the two luminance Y converges to the target luminance Y value.

Preferably, the adjusting of the automatic white balance (AWB) comprises: receiving and collecting the RGB signal, the second luminance (Y), and a second color difference (CbCr) signal; Excluding from the collection an RGB signal for a second luminance (Y) value that is outside the set target boundary, in accordance with the target boundary set for the second luminance (Y) value; Excluding RGB from the collection of the mutual difference values of the second color differences Cb and Cr that deviate from the set target boundaries according to the target boundary set with respect to the mutual difference values of the second color differences Cb and Cr; And calculating the average by summing the collected RGB values, and adjusting the R / G / B values so that each value (R / G / B) of the RGB values converges around the average to adjust the automatic white balance (AWB) of the image. Characterized in that it comprises a step of adjusting.

More preferably, the step of adjusting the automatic white balance (AWB) of the image is to adjust each value (R / G / B) of the corresponding R / G / B value when the R / G / B value is smaller than the collected average value. When the R / G / B value is larger than the collected average value, each value (R / G / B) of the corresponding R / G / B value is decreased to adjust the automatic white balance (AWB).

More preferably, adjusting the automatic exposure (AE) of the image increases the second luminance (Y) value when the second luminance (Y) value is smaller than the target luminance (Y) value, When the (Y) value is larger than the target luminance Y value, the second exposure value Y is decreased to adjust the automatic exposure AE.

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The image signal processing method of the CCD shown in the present invention has an effect of enabling more precise image processing by processing an image by converting the luminance and color difference signals output from the CCD sensor into RGB.

In addition, it converts RGB converted image into YCbCr signal and adjusts auto white balance and auto exposure by referring to YCbCr and RGB at the same time, unlike the conventional method, so that image processing efficiency is increased and easy auto white balance and auto exposure can be adjusted. It is effective.

In addition, by converting an image converted into RGB into a YCbCr signal, it is also possible to use it universally by conforming to the ITU-601 format.

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

Hereinafter, the present invention, by processing the image by converting the luminance and chrominance signal output from the CCD sensor to RGB, more precise image processing is possible, in particular, it is possible to easily and accurately handle the adjustment of the automatic white balance or automatic exposure Although the method of processing a video signal of a CCD will be described as a preferred embodiment, the technical idea of the present invention is not limited to this and can be variously implemented by those skilled in the art.

In the image processing apparatus for closed-circuit television (CCTV), the image signal output from the CCD camera is processed by a digital signal processor (DSP) board, and the processed image is output through a display and displayed to the outside.

Here, the CCD camera is composed of a CCD sensor having a CMYG color format used for NTSC / PAL (National Television System Committee / Phase Alternating Line). The image output from the internal CCD sensor is output as a digital value having a CMYG color format via an A / D converter. That is, each pixel of the CCD in the CCD camera stores the color information of Cyan, Yellow, Yee, Pink, Mg, and Green, and the final output is interlaced with the upper and lower pixels. Interlace) The scanned signal is output.

4 is a block diagram showing processing modules of the DSP board to which the present invention is applied.

Referring to the figure, the DSP board gamma corrects the CMYG color output from the CCD sensor, sets and adjusts the auto exposure (AE) and auto white balance (AWB), and the timing generator 18 is NTSC / PAL. Timing of the 525H / 625H, CCD sensor drive, A / D converter input signal, DSP V-SYNC, H-SYNC and the timing is adjusted and generated.

Looking at this in more detail, the digital signals ((Mg + Cy), (Ye + G), (Mg + Cy), (Ye + G)) output from the interlaced CCD sensor for CCTV are input to the automatic correction unit (11). It automatically corrects the defect cells and corrects the wrong or low-value pixels.

The corrected output signal is input to the color interpolation unit 12 that processes color interpolation, and the color interpolation unit 12 uses the line memory to convert the input signal into luminance (Y) and color difference (CbCr). The signal is processed and output as 10 bits of data. Here, the luminance (Y) signal is Y ((Mg + Ye) + (G + Cy)), and the color difference (CbCr) signal is Cb ((Mg + Cy)-(G + Ye)), Cr ((Mg + Ye)-(G + Cy)). In this case, the line memory is a selection for increasing the yield of color interpolation, and extracts (Mg + Ye) and (G + Cy) in an adaptive manner with a boundary value with surrounding cells.

The luminance Y and color difference CbCr signals thus output are converted into 8-bit RGB signals by the first image converter 13. Such RGB signal conversion of luminance Y and chrominance CbCr signals is possible in a variety of ways, including conventional bilinear interpolation.

The 8-bit RGB signal thus output is transmitted to the color corrector 14 and the AE / AWB adjuster 17, respectively. The color corrector 14 corrects colors for natural colors because the frequency characteristics of silicon and each color filter do not coincide with human color responsiveness, and other colors may be included in the RGB value. Use the color matrix to correct the color values.

In the meantime, the color-corrected RGB signal is converted into luminance (Y) and color difference (CbCr) signals through the second image converter 15, and gamma-corrected to the display device through the gamma correction unit 16. Correction process is performed. At this time, the second image converter 15 converts the color-corrected RGB signal into luminance (Y) and color difference (CbCr) signals that conform to the International Telecommunication Union (ITU) -601 format. .

The process of converting the RGB signal into luminance (Y) and color difference (CbCr) signals in accordance with the ITU-601 format by the second image converter 15 is illustrated in FIG. 5.

On the basis of 8 bits, the luminance (Y) range is limited to 16 to 235 and the color difference (CbCr) range is limited to 16 to 240 in both the first method (Mode 0) and the second method (Mode 1). Luminance (Y) and color difference (CbCr) signal conversion of the RGB signal in accordance with the format is performed.

On the other hand, the gamma correction unit 16 performs image processing only on the luminance Y signal, and the color difference (CbCr) signal passes. Thereafter, the luminance rollback is performed through the luminance processor 20 for processing a bright portion of the screen, and the digital effect processor 21 processes the digital effect of the signal and the OSD. The processed image is processed by NTSC / PAL encoder through the encoder unit 22 to perform image processing through the DAC and output as a video signal.

Here, the timing generator 18 transmits a drive signal to the CCD and generates a gain adjustment and an A / D conversion drive signal of the A / D converter, and the external interface 19 has an external interface of 12C.

As described above, the AE / AWB adjusting unit 17 receives an 8-bit RGB signal converted by the first image converter 13 and simultaneously converts the ITU-601 by the second image converter 15. The format luminance Y and color difference CbCr signals are received. That is, the luminance (Y) value and the color difference (CbCr) value of the RGB value generated by the first image converter 13 and the ITU-601 format converted by the second image converter 15 are automatically exposed (AE). ) And automatic white balance (AWB).

The determination of the automatic exposure (AE) and the automatic white balance (AWB) will be described in detail with reference to FIGS. 6 and 7.

Automatic White Balance (AWB) has the characteristic that the human eye always recognizes white as white regardless of the light source, but the color of the image, including white, is different for each light source because silicon and color filters react differently according to the frequency of the light source. It looks different and compensates for this phenomenon so that a constant color can be maintained even if the light source changes.

For this automatic white balance (AWB), the AE / AWB adjusting unit 17 collects RGB values by using the luminance (Y) and color difference (CbCr) signals and RGB values of the ITU-601 format as a reference.

First, referring to FIG. 6, the AE / AWB adjusting unit 17 sets a target boundary for the mutual difference between the target boundary of the luminance (Y) value and the color difference (Cb, Cr) according to the user's setting (S11, S12). In operation S13, the RGB values generated by the first image converter 13 and the luminance (Y) and color difference (CbCr) values of the ITU-601 format converted by the second image converter 15 are collected. ).

Thereafter, the collected luminance (Y) value is checked, and the luminance (Y) value is compared with the set target boundary, and RGB for the deviation from the predetermined target boundary is excluded from the collection (S14 and S16). That is, if too large or too small for the target luminance (Y) (eg Y = 255, Y = 0), the corresponding RGB is excluded from the collection.

In addition, the collected color difference (CbCr) value is checked, and the difference between the color difference (Cb, Cr) is compared with the set target boundary, and the RGB for the deviation from the preset target boundary is excluded from the collection (S15, S16). . In other words, it excludes RGB that has a difference that is too large compared to the difference between the target Cb and Cr.

Thereafter, the selected RGB values are collected by excluding the index below the reference value (S17), the total collected RGB values are summed, and then an average of the values is calculated (S18). The automatic white balance (AWB) of the image is adjusted by performing a convergence process of increasing or decreasing the R / G / B value so that each value (R / G / B) of the RGB values converges around the average (S19). .

On the other hand, autoexposure (AE) adjusts the exposure time and gain appropriately according to the ambient light conditions, so that the system overall maintains the optimal dynamic range.

For this automatic exposure (AE), the AE / AWB adjusting unit 17 collects the luminance (Y) value by using the luminance (Y) and color difference (CbCr) signals and RGB values of the ITU-601 format as a reference.

Referring to FIG. 7, the AE / AWB adjusting unit 17 sets target values of luminance (Y) values and target boundaries of RGB values according to a user's setting (S21 and S22), and the first image converter 13. In operation S23, an RGB value generated through the second value and a luminance Y value and a color difference CbCr value of the ITU-601 format converted by the second image converter 15 are collected.

Thereafter, the collected RGB values are checked and the RGB values fall into the set target boundary to exclude luminance (Y) values for the RGB values that deviate from the preset target boundary (S24, S25). That is, a signal having a large R / G / B difference as a signal having a large or small R / G / B value (eg, R (255), G (0), and B (0)) is excluded.

Thereafter, the selected luminance (Y) value is collected by excluding an index below the reference value (S26), and the luminance value is too low according to the target value of the luminance (Y) value based on the luminance (Y) value converging in a predetermined space. Adjusts the auto exposure (AE) of the image by converging to increase and decrease the luminance value that is too high (S27). In other words, if the luminance Y is too large or too small compared to the target luminance Y, the luminance Y value is adjusted by lowering or increasing the luminance Y value.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited to the drawing.

1 is a block diagram of a CCTV image processing apparatus according to the prior art.

2 is a view for explaining a color interpolation process in the CMYG color format according to the prior art.

3 is a block diagram of a processing module of a DSP board for processing the CMYG color format according to the prior art.

4 is a block diagram of a processing module of the DSP board to which the present invention is applied.

5 is a view for explaining a process of converting an RGB signal into a luminance (Y) and a color difference (CbCr) signal conforming to the ITU-601 format according to the present invention;

6 is a flowchart illustrating a process of determining automatic white balance (AWB) according to the present invention.

7 is a flowchart illustrating a determination process of automatic exposure (AE) according to the present invention.

Claims (5)

In the video signal processing method of CCD having CMYG color array in CCTV image processing device, Converting the 10-bit CMYG digital signal input from the CCD sensor into 10-bit first luminance Y and first color difference CbCr signals through color interpolation, respectively; Interpolating the first luminance (Y) and first color difference (CbCr) signals into an 8-bit RGB signal; Performing color correction on the image signal interpolated by the RGB signal and converting the image into an 8-bit second luminance Y and a second color difference CbCr signal satisfying the ITU-601 format; Encoding the second luminance (Y) and second color difference (CbCr) signals to output an analog video signal; And Adjusting automatic exposure (AE) and automatic white balance (AWB) with reference to the RGB signal and the second luminance (Y) and second color difference (CbCr) signals; Adjusting the automatic exposure (AE), Receiving and collecting the RGB signal, the second luminance (Y), and a second color difference (CbCr) signal; Excluding from the collection a second luminance (Y) value for an RGB value that is outside the set target boundary, in accordance with the target boundary set for the RGB value; And Based on the space in which the collected second luminance Y values converge, the second luminance Y value is adjusted so that the second luminance Y converges to the target luminance Y value so that the automatic exposure AE of the image is adjusted. Adjusting; CCD image signal processing method comprising a. The method of claim 1, Adjusting the automatic white balance (AWB), Receiving and collecting the RGB signal, the second luminance (Y), and a second color difference (CbCr) signal; Excluding from the collection an RGB signal for a second luminance (Y) value that is outside the set target boundary, in accordance with the target boundary set for the second luminance (Y) value; Excluding RGB from the collection of the mutual difference values of the second color differences Cb and Cr that deviate from the set target boundaries according to the target boundary set with respect to the mutual difference values of the second color differences Cb and Cr; And Adjust the auto white balance (AWB) of the image by summing the collected RGB values and calculating the average, and adjusting the R / G / B values so that each value (R / G / B) of the RGB values converges around the average. Making; CCD image signal processing method comprising a. The method of claim 2, Adjusting the automatic white balance (AWB) of the image is to increase each value (R / G / B) of the corresponding R / G / B value if the R / G / B value is smaller than the collected average value, If the G / B value is larger than the collected average value, each value (R / G / B) of the corresponding R / G / B value is reduced to adjust the automatic white balance (AWB). . delete The method of claim 1, The adjusting of the auto exposure (AE) of the image may increase the second luminance (Y) value when the second luminance (Y) value is smaller than the target luminance (Y) value, and the second luminance (Y) value is increased. And adjusting the autoexposure (AE) by reducing the second luminance (Y) value when larger than a target luminance (Y) value.

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