KR20050081589A - Apparatus and method for transmitting digital visual interface video data - Google Patents

Abstract

The present invention relates to a DVI image transmission device and a method of a set top box, and to a gray level processing corresponding DVI image output from a video processor in accordance with a corresponding DVI image transmission mode of a digital display device connected to the set top box. In this case, the predetermined DVI video is reproduced normally by minimizing image quality degradation that may occur in the digital display device by having different DVI video transmission modes. To this end, the present invention, according to the predetermined DVI (Digital Visual Interface) image transmission command input from the outside according to the DVI image transmission mode determined by determining the transmission mode of the corresponding DVI image, image processing through the video processor in the set-top box The gradation conversion of the corresponding DVI image is carried out to be transmitted to the corresponding digital display device in the same DVI video transmission mode as the DVI video transmission mode through a predetermined DVI video input / output port.

Description

Apparatus and method for transmitting Digital Visual Interface video data of set-top box

The present invention relates to a DVI image transmission device and a method of a set-top box, such that a normal image can be reproduced through a corresponding screen even when the set-top box is connected to a PC-based monitor such as an LCD or a PDP as well as a DTV.

In general, the DVI (Digital Visual Interface) standard used in the PC industry and the DVI standard used in the CE industry have different characteristics in addition to the timing information and the resolution information. In the PC industry, the black level is defined as 0 and the peak white level is defined as 255. In the CE industry, the EIA861 standard defines the black level as 16 and the white level as 235.

Therefore, when the set-top box 1 which exports a general video signal according to the EIA standard is connected to the DVI input of the PC-type monitor 2 such as LCD or PDP as shown in FIG. Rather than connecting to the DTV 3 of the screen, contrast degradation and image quality deterioration occur, which causes black to appear.

Therefore, the new DVI video is transmitted to the set-top box so that the picture quality can be reproduced normally even when connecting the set-top box that supports both component, RGB analog and DVI output with the DVI input of the monitor of PC series such as LCD or PDP. The device needs that method.

Accordingly, the present invention was developed to satisfy the above-mentioned needs. Even when the set-top box is connected to a PC-based monitor such as LCD or PDP, the set-top box can be reproduced as it is. It is an object of the present invention to provide a DVI video transmission device and a method thereof.

In accordance with this purpose, the present invention provides a different DVI video transmission mode depending on the characteristics of the monitor by gradually processing the corresponding DVI video output from the video processor in accordance with the DVI video transmission mode of the digital display device connected to the set-top box. In order to minimize image quality deterioration occurring in a digital display device having a high resolution, a normal image is reproduced through a corresponding screen.

To this end, the present invention, the first step of determining the transmission mode of the DVI image according to a predetermined DVI (Digital Visual Interface) image transmission command input from the outside;

A second step of variably converting the corresponding DVI image, which is image-processed and output through a video processor in the set-top box according to the DVI image transmission mode determined in the first step;

And a third step in which the set-top box transmits the gray level converted DVI image to the corresponding digital display device in the same DVI image transmission mode as the DVI image transmission mode through a predetermined DVI image input / output port. Allow DVI video to be sent from the box.

And a DVI video transmission mode determination unit for determining a transmission mode of the corresponding DVI video under the control of a microcomputer in the set-top box according to a predetermined DVI (Digital Visual Interface) video transmission command input from the outside.

A DVI image gradation conversion unit for variably converting the corresponding DVI image according to the DVI image transmission mode determined by the DVI image transmission mode determination unit and outputting the image through a video processor in the set-top box;

An image output path selector for selectively activating an external output path of the grayscale converted by the DVI image grayscale conversion unit under the control of the microcomputer;

DVI image transmission apparatus of a set-top box including a DVI image input / output port selectively activated by the image output path selector to transfer the grayscale converted by the DVI image grayscale converter to a predetermined digital display device connected thereto To be done.

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

First, a set-top box to which the DVI video transmission apparatus of the present invention is applied will be described with reference to FIG. 2.

In FIG. 2, the DVI video transmission apparatus of the present invention is electrically connected to a general video and audio signal processing apparatus as shown, and the video and audio processing apparatus includes a tuner unit 100 for receiving a transmission packet stream transmitted from a broadcasting station. ), And a transport packet stream decoder 110 for VSB / QPSK decoding the transport packet stream received by the tuner unit 100, and audio information in the transport packet stream decoded by the VSB / QPSK decoding at the transport packet stream decoder 110. And a transport packet stream demultiplexer 120 for separating video information and additional information, and an audio decoder 130 and a video decoder 140 for decoding audio and video information separated from the transport packet stream demultiplexer 120, respectively. And a video processor 150 for image processing the video information decoded by the video decoder 140, and inputted through user key manipulation. It consists of a user UI unit 160 for processing a predetermined user command and the set-top box microcomputer 170 for managing and controlling the entire system of the set-top box and the DVI video transmission system according to the present invention.

In addition, the DVI video transmission apparatus of the present invention connected to the above-described video and audio signal processing apparatus, as shown in FIG. 2, is a predetermined DVI (Digital Visual Interface) input from the outside through the user UI unit 160 A DVI image transmission mode determination unit 180 for determining a transmission mode of a corresponding DVI image under the control of a microcomputer 170 that manages and controls the entire system of the set-top box according to an image transmission command, and the DVI image transmission mode In accordance with the DVI image transmission mode determined by the determination unit 180, a DVI image gradation converter 190 for variably converting the corresponding DVI image, which is processed and output through the video processor in the set-top box, and the DVI image An image output path selector 200 for selectively activating the external output path of the grayscale converted by the gray level converter 190 under the control of the microcomputer 170, and the image output path Are selectively activated by the taekbu 200 comprises a DVI video input / output port 210 for transmitting a predetermined digital display device connected to the DVI video gradation conversion by the gradation conversion DVI video unit 190.

In the DVI video transmission apparatus of the present invention, the set-top box according to a predetermined DVI (Digital Visual Interface) video transmission command input from the outside through the user UI unit 160 first Under the control of the microcomputer 170 that manages and controls the entire system of the video processor 150, it is determined which transmission mode the corresponding DVI image is processed and output.

The determination mode of the DVI video mode is to determine the transmission mode of the corresponding DVI video according to a predetermined DVI (Digital Visual Interface) video transmission command input from the outside, selectively determining through a user command, or when DVI connection It is preferable to determine the transmission mode of the corresponding DVI image through the DVI connection notification information transmitted from the digital display device.

That is, when the digital display device is connected to the set-top box through a predetermined DVI video input / output port 210, the DVI connection notification information transmitted through the DVI video input / output port 210 may be transferred to the microcomputer of the set-top box. In the state in which 170 is temporarily stored in a buffer not shown therein, when a predetermined DVI (Digital Visual Interface) image transmission command is input from the outside through the user UI unit 160, the DVI is temporarily stored in the buffer. Read connection notification information, and extract and determine which DVI video transmission mode is used by a digital display device connected to the DVI video input / output port therefrom. It is preferable to set the display mode by dividing the DVI image expansion mode corresponding to the LCD monitor and the EIA standard of the series and the DVI image standard mode of the VESA DVI standard.

Next, when the DVI video transmission mode is determined through the DVI video transmission mode determination unit 180, the DVI video grayscale conversion unit 190 is connected to the DVI video transmission mode determined by the DVI video transmission mode determination unit 180. Accordingly, the gradation conversion of the corresponding DVI image, which is processed and output through the video processor 150 in the set-top box.

That is, the DVI image gray scale conversion unit 190 maintains or enlarges the gray level of the DVI image output through the video processor 150 as appropriate for the DVI image transmission mode determined by the DVI image transmission mode determination unit 180. Or zoom out.

Specifically, the DVI image transmission mode discrimination unit 180 is configured in a state in which a look-up table for which a gradation conversion method suitable for a plurality of DVI image transmission modes is preset is set in the DVI image gradation conversion unit 190 in advance. In case of determining which transmission mode is the DVI image, the look-up table in which the gradation conversion method suitable for the DVI image transmission mode is set may be selectively used, thereby changing the corresponding DVI image that is processed by the video processor 150 and output. Gradation conversion to

For example, when the DVI image transmission mode of the digital display device is a DVI image extension mode corresponding to the PC monitor LCD monitor and the VESA standard, the DVI image gradation conversion unit presets the DVI image represented by 16 to 235 gradations. By converting the lookup table of the conversion method to 0 ~ 235 gradations, and in the DVI video standard mode corresponding to the EIA DVI standard, it bypasses the DVI image represented by 16 ~ 235 gradations to maintain the existing gradation processing rules. Do it.

Finally, the image output path selector 200 selectively activates the external output path of the grayscale image converted by the DVI image grayscale conversion unit 190 under the control of the microcomputer 170, and inputs / outputs a DVI image. The output port 210 is selectively activated by the image output path selector 200 and transmits the grayscale converted DVI image by the DVI image gray converter 190 to a predetermined digital display device.

As described above, the DVI video transmission apparatus according to the present invention is gradually processed to transmit the corresponding DVI video output from the video display in accordance with the DVI video transmission mode of the digital display device connected to the set-top box. It is possible to minimize the deterioration of image quality caused by the digital display device having the image transmission mode.

Next, the DVI image gray scale conversion mode according to the present invention will be described in more detail with reference to FIG. 3. FIG. 3 is a characteristic graph of converting a DVI image of 16 to 235 gray levels into a DVI image of 0 to 255 gray levels. DVI video data transmission characteristics of the corresponding lookup table in the video extended mode are as follows.

If (input <16) output = 0; Else if (16 <= input, 256) output = (input-16) * 256/220

Endif If (output> 225) output = 255; Endif

In the DVI video standard mode, the DVI video data transmission characteristics of the corresponding lookup table are as follows.

If (input <16) output = 16;

Else if (16 <= input, 256) output = input Endif

Such gradation conversion can be implemented by using a lookup table prepared for non-linear image data conversion linearly or by adjusting gain or offset of the Color Space Conversion Matrix coefficient. It is preferable to use the DVI level mode change or the Color Space Conversion change through the user interface menu.

Next, a DVI video transmission mode will be described in more detail with reference to FIGS. 4A to 4C. First, as shown in FIG. 4A, a DVI video transmission mode according to the present invention is inputted with 700 mV as an RGB input voltage for a PC and an ADC. It is processed as 0 ~ 255 digital value. As a result, the VESA DVI level for the PC is also processed from 0 to 255 digital values, so the monitor outputs a signal without any difference in brightness between the two input switching. At this time, when the DVI signal and RGB analog signal output by STB's EIA standard are connected together, it is difficult to maintain the contrast and brightness between the two inputs. That is, when the EIA DVI signal is processed by the VESA DVI monitor, black appears as much as 16 levels, and white that sinks as much as 20 levels is reproduced. As a result, the image with deteriorated contrast is reproduced. The compensation method according to the DVI gray level mismatch is presented from the set top box side. That is, the contrast deterioration due to the gray level mismatch between the monitor and the set top box is easily distinguished by the user's subjective judgment. Add a way to select the DVI level to export from the box, and classify it as DVI Video Standard Mode / DVI Video Extended Mode. Therefore, as shown in FIG. 4B, in the DVI video standard mode, the digital RGB signal level before converting the DVI video to the TMDS signal has a gray level value of black 16 / white 255 shown in the EIA standard. As shown in 4c, in DVI video extension mode, the digital RGB signal level before converting DVI video to TMDS signal has the value of black 0 / white 255 shown in the VESA standard, and supports analog RGB and VESA DVI. In case of the monitor, the DVI video input is basically recognized as 0 ~ 255, and when the set top box output DVI level is output as 16 ~ 235, the user experiences a lower image quality than the analog RGB interface. As can be seen, if the set-top box output can be scaled from 0 to 255 like the VESA DVI video standard, this problem can be solved.

Next, a DVI video transmission method according to the present invention will be described with reference to FIG. 5.

As shown in FIG. 5, the DVI image transmission method according to the present invention monitors a predetermined DVI (Digital Visual Interface) image transmission command input from the outside through the user UI unit (S500). In the case of inputting (S501), according to the input DVI image transmission command, it is determined which transmission mode is the corresponding DVI image which is processed by the video processor under the control of the microcomputer managing and controlling the entire system of the set-top box. .

The determination mode of the DVI video mode is to determine the transmission mode of the DVI video according to a predetermined DVI (Digital Visual Interface) video transmission command input from the outside, or selectively determined through a user command (S502), or When the DVI connection is performed, it is preferable to determine the transmission mode of the corresponding DVI image through the DVI connection notification information transmitted from the digital display device (S503).

That is, when the digital display device is connected to the set top box through a predetermined DVI video input / output port, the microcomputer of the set top box does not show the DVI connection notification information transmitted through the DVI video input / output port. When a predetermined DVI (Digital Visual Interface) image transmission command is input from the outside through the user UI unit while temporarily storing in the buffer, the DVI connection notification information temporarily stored in the buffer is read and the DVI image input / output is performed therefrom. Extract and determine which DVI video transmission mode is used by a digital display device connected to the port. Where possible, the DVI video transmission mode extends the DVI video corresponding to the LCD monitor of the PC series and the EIA standard. It is preferable to set the mode separately from the DVI video standard mode of the VESA DVI standard.

Next, when the DVI video transmission mode is determined in step S502 or S504, the corresponding DVI video, which is processed and output through the video processor in the set-top box, is variably according to the determined DVI video transmission mode. Gradulate

That is, the predetermined DVI image gray level conversion unit preset in the set-top box maintains the gray level of the DVI image output through the video processor (S505, S507) as appropriate for the DVI image transmission mode (S506) or enlarges (S506). Or to reduce (S508).

Specifically, when it is determined which transmission mode the DVI video is in a state in which a look-up table preset for each of the DVI video transmission modes is preset in the DVI video gray conversion unit, the corresponding DVI video is determined. By selectively using a lookup table in which a gradation conversion method suitable for an image transmission mode is set, a gradation conversion of a corresponding DVI image that is processed by an image processor and output is performed.

For example, when the DVI image transmission mode of the digital display device is a DVI image extension mode corresponding to the PC monitor LCD monitor and the VESA standard, the DVI image gradation conversion unit presets the DVI image represented by 16 to 235 gradations. By converting the lookup table of the conversion method to 0 ~ 235 gradations, and in the DVI video standard mode corresponding to the EIA DVI standard, it bypasses the DVI image represented by 16 ~ 235 gradations to maintain the existing gradation processing rules. Do it.

Lastly, the present invention is terminated by transmitting a predetermined DVI image in which the gray level is converted or the gray level is maintained to the predetermined digital display device connected through the selected and activated external output path (S510) (S510).

As described above, the DVI image transmission method according to the present invention is different from each other depending on the characteristics of the monitor by gradually processing the corresponding DVI image output from the video display in accordance with the DVI image transmission mode of the digital display device connected to the set-top box. Image degradation in digital display devices with DVI video transmission mode can be minimized.

As described in detail above, the DVI video transmission method according to the present invention, by varying the corresponding DVI video output from the video processor in accordance with the DVI video transmission mode of the digital display device connected to the set-top box to monitor the characteristics As a result, the image quality can be minimized in digital display devices having different DVI video transmission modes, so that normal images can be reproduced through the corresponding screen.

Although the invention has been described in detail only with respect to the specific examples described, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

1 is a view illustrating a connection between a typical set top box and a display device;

2 is a view showing a DVI image transmission apparatus of the set-top box according to the present invention,

3 is a view for explaining in detail the DVI image gray scale conversion mode according to the present invention;

4a to 4c are views illustrating in more detail the DVI video transmission mode used in the present invention;

5 is a view showing a DVI video transmission method of the set-top box according to the present invention.

Explanation of symbols on the main parts of the drawings

100: tuner unit 110: transmission packet stream decoder

120: transmission packet stream demultiplexer 130: audio decoder

140: video decoder 150: video processor

160: user UI unit 170: microcomputer

180: DVI image transmission mode determination unit 190: DVI image gradation conversion unit

200: Video output path selector 210: DVI video input / output port

220: RGB interface unit 230: VGA card

Claims (5)

Determining a transmission mode of a corresponding DVI image according to a predetermined DVI (Digital Visual Interface) image transmission command input from the outside; A second step of variably converting the corresponding DVI image, which is image-processed and output through a video processor in the set-top box according to the DVI image transmission mode determined in the first step; And a third process of transmitting the grayscale converted DVI image in the second process to a corresponding digital display device in the same DVI video transmission mode as the DVI video transmission mode through a predetermined DVI video input / output port. , DVI video transmission of set-top box. The method of claim 1, wherein the first process comprises; Determining the transmission mode of the corresponding DVI video according to a predetermined DVI (Digital Visual Interface) video transmission command input from the outside, the corresponding DVI image through the user command or the DVI connection notification information transmitted from the digital display device at the time of DVI connection DVI transmission method of the set-top box, characterized in that for determining the transmission mode of the image. The method of claim 1, wherein the first process comprises; A step 1-1 in which the set-top box temporarily stores DVI connection notification information transmitted when a digital display device is connected to the set-top box through the DVI image input / output port; According to a predetermined DVI (Digital Visual Interface) image transmission command input from the outside, a first step of reading the DVI connection notification information stored temporarily in step 1-1 and extracts the DVI image transmission mode information of the corresponding digital display device therefrom. 1-2 course; And a first step of determining the transmission mode of the corresponding DVI image to be transmitted to the digital display device by the set top box through the DVI image transmission mode information extracted in step 1-2. DVI video transmission method. The method of claim 1, wherein the second process comprises: When a predetermined DVI video transmission mode is determined in the first step in a state where a gray scale conversion method suitable for a plurality of DVI video transmission modes is preset, a lookup table suitable for the corresponding DVI video transmission mode is determined. Through the video processor in the set-top box through the video processing, characterized in that the gradation conversion of the corresponding DVI video, DVI video transmission method of the set-top box. A DVI image transmission mode determination unit for determining a transmission mode of the corresponding DVI image under the control of a microcomputer in the set-top box according to a predetermined DVI (Digital Visual Interface) image transmission command input from the outside; A DVI image gradation conversion unit for variably converting the corresponding DVI image according to the DVI image transmission mode determined by the DVI image transmission mode determination unit and outputting the image through a video processor in the set-top box; An image output path selector for selectively activating an external output path of the grayscale converted by the DVI image grayscale conversion unit under the control of the microcomputer; And a DVI video input / output port selectively activated by the video output path selector to transmit the grayscale video converted by the DVI video grayscale converter to a predetermined digital display device connected thereto. Transmission device.