KR100896498B1 - Image Processing System and Method thereof - Google Patents

Abstract

The present invention relates to a system and method for minimizing color distortion of an OSD that may occur during transmission of CCIR601 / 656 4: 2: 2 format.

In the present invention, the video image data and the OSD image data stored in the memory are input to the video processor due to the synchronization signal, the OSD data is subjected to video blending and alpha blending processing through a process such as size adjustment in the data merge block Overlaid through the image data is overlaid, and the OSD data correction process for the OSD color difference signal through a color difference signal correction process, and then converted to 4: 2: 2 format to reduce the amount of data transmitted to the display device; and The method is presented.

CCIR, CCIR601 / 656, 4: 2: 2 format conversion, color difference correction

Description

Image Processing System and Method

1 is a schematic block diagram of an image processing apparatus in a conventional CCIR601 / 656 environment.

2 is an explanatory diagram of a 4: 2: 2 conversion process in 4: 4: 4 format in a CCIR601 / 656 environment.

FIG. 3 is a GUI diagram illustrating an OSD distortion problem generated when a CCIR601 / 656 4: 2: 2 format is transmitted.

4 is a block diagram of an embodiment of an image processing apparatus according to the present invention.

5 is a detailed block diagram of a color difference signal correction processing block according to an embodiment of the present invention.

6 is a flowchart of an embodiment of an image processing method of the present invention.

The present invention relates to an image processing technology for minimizing image and color distortion that may occur in an artificial image, such as OSD (On Screen Display) or graphics during image data transmission. More specifically, in the image transmission method, only half of the luminance component information is transmitted from the transmitter and reproduced based on the received color component information in order to output the final image from the receiver. As the continuity of color is continued and expressed naturally, the artificial OSD image relates to image processing technology for minimizing distortion that may appear depending on pixel size and shape and adjacent color information.

CCIR Recommendation 601 (CCIR Rec. 601) is a protocol that defines the coding parameters of digital TVs originally used in studios and is used in many other applications such as MPEG-2. The RGB or YCbCr signal is used as a video encoding target signal, and the 4: 4: 4, 4: 2: 2, 4: 2: 0 format is specified. In the case of RGB, only the 4: 4: 4 format is specified. It also specifies the parameter values used when obtaining YCbCr from an RGB signal. CCIR Recommendation 656 also defines the interface relationships of digital video signals in television systems using 525 and 626 lines.

Data transmitted in the CCIR601 / 656 environment is classified into Y information representing a luminance component of an image and Cb and Cr information representing a chroma component of an image. Among them, the luminance component is an area in which the eyes of the human body reacts sensitively and is very important data, and the color component is an area insensitive to the luminance component. Various types of transmission methods have been devised to reduce the amount of image data transmitted by appropriately controlling the color component information by using the characteristics of the human body.

As an invention for reducing the amount of video data, Japanese Patent Laid-Open No. 1998-054520 (an input processing device for MPEG-2 video coding) has been disclosed. The present invention discloses decoding the 8-bit input data defined in CCIR 601/656 to generate video reference signals in the case of a video timing reference code, and to demultiplex Y and C video data in the case of a valid video code. A CCIR 601/656 decoder, a color converter for converting an RGB signal converted from an analog signal to a digital signal into a YCbCr signal, and a 4: 2: 2 format for a 4: 4: 4 format YCbCr signal output from the color converter. A 4: 2: 2 decimation filter for converting a signal to a signal of the analog signal, an analog reference signal generator for generating a reference signal and a 4: 2: 2 decimation filter control signal by receiving a YC or RGB input, and a YUV input signal A multiplexer for multiplexing the output of the 4: 2: 2 decimation filter and the output of the CCIR decoder, and 4 for converting an output signal of the 4: 2: 2 format of the multiplexer into a 4: 2: 0 format 2: 0 decimation fill The present invention relates to an MPEG-2 video encoder input processing device comprising a video receiver.

However, the present invention is effective in processing general MPEG-2 video signals, but has limitations in processing OSD images in digital TV.

The video processing circuit of a standard digital TV receiver has a video input interface connected to a memory and a memory controller, the memory controller performing buffering of video data according to MPEG in video, video data according to CCIR 601/656, and digitized analog signals. And a raster generator is also connected to the memory controller as well as to the display unit, the display unit comprising a display format conversion circuit and an OSD overlay circuit. In general, methods for overlaying a graphic image (eg, OSD image) on a video image used in a multimedia broadcasting image include receiving an OSD image and a video image loaded in a storage device or processing an OSD-only chip. After inputting an OSD image, the video is simply mixed with a stored video image in a video processor, processed in accordance with a transmission format, and then output to a display device.

FIG. 1 reads two different images (OSD image, video image) configured in 4: 4: 4 format from memory, overlays the OSD image on the video image through simple merge between the two images, and transmits the image. This is a block diagram showing the flow of conversion to 4: 2: 2 format to reduce data and then output to the display device.

2 is an exemplary diagram artificially expressing a problem that may occur when processing an OSD image. In FIG. 2, bright green portions of the original image data [A] are OSD image data artificially inserted at odd-numbered pixel positions, and when the image is transmitted in CCIR601 / 656 4: 2: 2 format, As shown in the sampled data, color information of the OSD image expressed in bright green is skipped and transmitted by the 4: 2: 2 transmission characteristic. After the interpolation is performed in 4: 4: 4 format to express the final image information, as shown in [C], the color information of OSD is removed and the adjacent red color information is restored, unlike the original image. Since it is superimposed on the OSD image, it can be expressed in a different form from the original OSD image, which is a problem of OSD quality.

FIG. 3 is a graphical representation of an example in which an OSD issue may occur tentatively when transmitted in CCIR601 / 656 4: 2: 2 format. Referring to FIG. 3, there is no problem even after transmission since the portion displayed in orange from the start point of the left image is continuous color information. However, since the beginning of the "Brightn" character is 41 pixels odd because the color boundary is different, when transferred and restored in 4: 2: 2 format, white is removed and cannot be restored as shown in [D]. Since the orange color is restored, the image is overlaid, resulting in an OSD quality problem. This problem does not only occur when the 4: 4: 4 format video is converted to 4: 2: 2 format, but also occurs when the 4: 4: 4 format video is converted to 4: 2: 0 format.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide an image processing apparatus and an image processing method for reducing color distortion that may be caused by image format conversion.

As a technical idea for achieving the object of the present invention, in the present invention, a memory for storing video image data and OSD or graphic image data, and the video image data and OSD or graphic image data in the memory is 4: 4 A video processor inputted due to a synchronization signal in a: 4 format, and an overlay unit for overlaying the OSD or graphic image data through video blending with alpha data through a process such as size adjustment in a data merge block. And a chrominance signal corrector for performing a correction process on an OSD or graphic image chrominance signal in the overlaid data, and in a 4: 2: 2 format to reduce the amount of data transmitted by the chrominance corrected overlaid image data. A format converter for converting, and the 4: 2: 2 format overlaid video. The apparatus and method including a display for displaying the received data is provided.

Hereinafter, a configuration of an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a block diagram of an embodiment of the present invention for improving the OSD quality. As shown in FIG. 4, a memory 100 for storing OSD image data and video image data in a 4: 4: 4 format in which an RGB signal converted from an analog signal to a digital signal is converted into a YCbCr signal, and the memory; OSD image data and video image data in 4: 4: 4 format are received from the 100 based on the synchronization signal, and the overall image data is received by the overlay unit 210, the color difference signal compensator 220, and the format converter 230. A video processor 200 for processing; In the image processing apparatus including a display unit 300 for receiving and displaying 4: 2: 2 overlaid image data from the video processor 200, the video image data stored in the memory 100 and OSD or Graphic image data is input to the video processor 200 due to a synchronization signal, and the OSD or graphic image data is subjected to alpha blending processing with the video image data through a process such as size adjustment in the overlay unit 210. Overlayed. The overlaid image data is processed by the color difference signal corrector 220 for the OSD or graphic image color difference signal, and then is reduced to 4: 4: 2 format by the format converter 230 to reduce the amount of data transmitted. Converted to and output to the display unit 300.

In addition, the overlayer 210 processes the luminance signals and the chrominance signals of the two input images on a pixel basis. The transparency of the OSD or graphic image overlaid on the video image is determined by an alpha value set by a user. Is determined.

5 is a detailed block diagram of the color difference signal correction processing block 220 according to the embodiment of the present invention. As shown in FIG. 5, the color difference signal corrector 220 of the present invention includes a color difference signal corrector 222 and a divider 224. The chrominance signal corrector 222 receives OSD or graphic image data and video image data overlaid from the overlay unit 210, and receives OSD or graphic image data detection signal and receives OSD or graphic image data. Know the location and size of the. In this case, when the start position of the OSD or graphic image data is an odd pixel, the color difference signal of the adjacent pixel is corrected. As a method of correcting a color difference signal, various known methods may be used. For example, as a color signal correction method applicable to a video signal format having a luminance signal and two color signals, first, a delay in units of lines to correct data mixed with a plurality of color signals in a vertical direction is performed between different lines. Vertically correct using data. The color correction is performed for each color signal component from the vertically corrected result and stored in a first-in first-out memory, and time-axis alignment is performed in line order. In addition, a method of obtaining a corrected color signal by performing one or more horizontal corrections in accordance with a video signal format which includes a plurality of horizontal correction units for each color signal. The overlay image data of which color difference correction is completed is sent from the divider 224 to the format converter 230.

In addition, the color difference signal correction unit 222 obtains position information of the OSD or graphic image data, and when odd pixels exist in the start pixel or the end pixel on the line of the OSD or graphic image data, The color difference value of the adjacent pixel is corrected. That is, by correcting the neighboring pixel to include the color difference component information of the odd pixel in the adjacent pixel on the same line where the odd pixel exists, so that the adjacent pixel has the color difference information of the color difference signal disappeared after 4: 2: 2 format conversion. In this case, the original color difference signal may be reconstructed to minimize distortion based on the color difference information included in the adjacent pixel.

6 is a flowchart for explaining a color difference signal correction processing method of the present invention.

Receiving input of 4: 4: 4 format OSD or graphic image data and 4: 4: 4 format video image data in the memory (S100) and the overlay unit included in the video processor Due to the synchronization signal, the OSD or graphic image data in 4: 4: 4 format and the video image data in 4: 4: 4 format are received, and the luminance signal and the color difference signal of the two input image data are processed in units of pixels. Outputting a control signal including the overlaid image data of the two images and the position and size of the OSD or graphic image data (S110), and the color difference signal correction processor included in the video processor, for example, from the overlay unit; In response to the input of the overlaid image data and the control signal by an alpha blending method, an OSD or a graphic image is applied to the control signal. Determining a start position to be displayed in synchronization and starting with odd pixels, performing a process of correcting the adjacent chrominance signal on a pixel-by-pixel basis to output image data overlaid with chrominance corrected OSD or graphic image data (S120); Converting the luminance signal and the chrominance signal having the 4: 4: 4 format structure into a 4: 2: 2 format by a format converter included in the video processor and transmitting the converted 4: 2: 2 format to a display unit (S130) and the display unit And displaying the overlaid image (S140). At this time, only half of the luminance signal is transmitted.

Correction of the color difference signal includes obtaining position information of the OSD or graphic image data, and a color difference value of adjacent pixels on the same line when odd pixels exist in a start pixel or an end pixel on a line of the OSD or graphic image data. It includes the step of correcting. That is, by correcting the neighboring pixel to include the color difference component information of the odd pixel in the adjacent pixel on the same line where the odd pixel exists, so that the adjacent pixel has the color difference information of the color difference signal disappeared after 4: 2: 2 format conversion. In this case, the original color difference signal may be reconstructed to minimize distortion based on the color difference information included in the adjacent pixel.

In addition, after the 4: 2: 2 characteristic is taken into account in the OSD or graphic GUI data production, color information that can interact with each other may be further improved by applying the color difference signal correction processing method.

Although the embodiment of the present invention has been described with reference to converting a 4: 4: 4 format image to 4: 2: 2 format, the same applies to converting a 4: 4: 4 format to 4: 2: 0 format. Is applicable. In this case, the horizontal chrominance signal correction is the same as when converting to 4: 2: 2 format, but the vertical chrominance signal correction determines whether the start pixel or the end pixel on the same column is an odd pixel, In this case, the color difference value of neighboring pixels on the same column is corrected. That is, by correcting the neighboring pixel to include the color difference component information of the odd pixel in the adjacent pixel on the same column where the odd pixel exists, so that the adjacent pixel has the color difference information of the color difference signal disappeared after 4: 2: 0 format conversion. In this case, the original color difference signal may be reconstructed to minimize distortion based on the color difference information included in the adjacent pixel.

According to the present invention, when a normal video image and an artificial image such as an OSD image or a graphic are merged and transmitted in a 4: 2: 2 format, the artificial image such as an OSD may be corrected by performing a correction process on the color difference signal of the OSD or the graphic image. There is an effect to improve the color and image distortion that can occur,

In addition, after the 4: 2: 2 characteristic is considered in the OSD or graphic GUI data production, the color information that can interact between the color boundaries can be further improved by applying the color difference signal correction processing method of the present invention. It has an effect.

Claims (10)

An overlay unit for overlaying graphic image data on the video image data; A color difference signal corrector for correcting a color difference signal of the overlaid image data; A color difference format conversion unit for converting a color difference format of the image data in which the color difference signal is corrected, The color difference signal correction obtains position information of the graphic image data, and corrects color difference values of adjacent pixels on the same line when odd pixels exist in a start pixel or an end pixel on a line of the graphic image data. Image processing device. The method according to claim 1, The color difference corrected overlay image data input to the color difference format converter is a 4: 4: 4 color difference format, and the color difference corrected overlay image data output from the color difference format converter is a 4: 2: 2 color difference format. Image processing device. delete An overlay unit for overlaying graphic image data on the video image data; A color difference signal corrector for correcting a color difference signal of the overlaid image data; A color difference format conversion unit for converting a color difference format of the image data in which the color difference signal is corrected, The color difference signal correction obtains position information of the graphic image data, corrects color difference values of adjacent pixels on the same line when odd pixels exist in a start pixel or an end pixel on a line of the graphic image data, and the graphic image And correcting the color difference values of adjacent pixels on the same column when odd pixels exist in the start pixel or the end pixel on the column of data. The method according to claim 4, The color difference corrected overlay image data input to the color difference format converter is a 4: 4: 4 color difference format, and the color difference corrected overlay image data output from the color difference format converter is 4: 2: 0 color difference format. Image processing device. Overlaying graphic image data on the video image data; Correcting the color difference signal of the overlaid image; Converting a color difference format of the corrected image data; Correcting the color difference signal, Obtaining position information of the graphic image data; And correcting color difference values of adjacent pixels on the same line when odd pixels exist in the start pixel or the end pixel on the line of the graphic image data. The method according to claim 6, The converting of the color difference format comprises converting the corrected image data having a 4: 4: 4 color difference format into a 4: 2: 2 color difference format. delete Overlaying graphic image data on the video image data; Correcting the color difference signal of the overlaid image; Converting a color difference format of the corrected image data; Correcting the color difference signal, Obtaining position information of the graphic image data; Correcting color difference values of adjacent pixels on the same line when odd pixels exist in a start pixel or an end pixel on a line of the graphic image data; And correcting color difference values of adjacent pixels on the same column when odd pixels exist in a start pixel or an end pixel on the column of the graphic image data. The method according to claim 9, The converting of the color difference format comprises converting the corrected image data having a 4: 4: 4 color difference format into a 4: 2: 0 color difference format.

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