JP2001036814A - Chroma signal replacing circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chroma signal replacing circuit to enable visual recognition of background video of the superimpose display by enhancing visibility of the superimpose display. SOLUTION: A color difference signal of a color which is desired to be displayed is generated according to setting from an MPU 100 by a chroma generating circuit 150 of the chroma signal replacing circuit. A timing signal to control a selector circuit 140 is generated to decide a display area to replace the color difference signals by a timing generating circuit 160. The color difference signals in an optimal display area are replaced by switching the color difference signal generated by the chroma generating circuit 150 and a color difference signal of an inputted video signal by the selector circuit 140 to be controlled by output of the timing generating circuit 160. The video signal formed only by replacing color difference is obtained by combination of the color difference signal to be outputted from the selector circuit 140 and a luminance signal delayed by a delay circuit 170 if necessary (in accordance with processing time of the color difference signal).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chroma signal exchanging circuit used to insert a video such as a superimposed image into a video signal displayed on various displays.

[0002]

2. Description of the Related Art Conventionally, superimposition of characters, symbols, and the like for video display on various displays has been described.
It is generally realized using a device called OSD (On Screen Display Controller). FIG. 5 shows a specific example of the conventional superimposition. In the illustrated example, a superimposed image 30 of white characters is provided by the OSD 20 on the original display image 10. Further, recently, in order to provide more effective display and operation means, not only characters but also various graphics displays are often performed. These are realized by replacing an analog or digital video signal with a signal prepared in advance.

[0003]

However, in the above-mentioned conventional method, since the video signal including the luminance signal is exchanged, the original video signal is completely replaced. The original video signal, which is the background of the video, is completely invisible. In particular, in order to improve the visibility of the superimposed display, when a large area is filled as a background such as a character display as shown in FIG.

In order to compensate for such a drawback, as shown in FIG. 7, by darkening the image in the background area where the superimposed display is performed, the original image can be seen.
Means for improving the visibility of the superimposed display is realized. However, this method only lowers the brightness of the background area of the superimposed display, so that in order to enhance visibility, the brightness and color used for the superimposed display can be limited, and various methods can be used. This hinders display.

On the other hand, as means for changing the color of an arbitrary area of the video display, video data is stored in a memory in advance,
A method of processing the data is conceivable. But,
Data reading, processing, and writing from a memory are required, and expensive circuits such as a high-performance processor and a high-speed and large-capacity memory are required for application to moving image video.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a chroma signal switching circuit which improves the visibility of a superimposed display and enables a background image of the superimposed display to be visually recognized.

[0007]

According to the present invention, there is provided a chroma signal switching circuit for inputting a video signal including a luminance signal and a color difference signal and replacing a part or all of the color of a video. A luminance signal input unit that inputs the luminance signal, a color difference signal input unit that inputs the color difference signal, a color signal generation circuit that generates the prepared signal, and a color difference signal input from the color difference signal input unit. Selection control means for selecting and outputting the signal stored in the color signal generation circuit; and timing control for matching the output timing of the color difference signal output from the selection control means with the luminance signal input by the luminance signal input means. Means for replacing only the color difference signal of the video signal with a previously prepared signal.

In the chroma signal interchange circuit of the present invention, the color difference signal input by the color difference signal input means is input to one input terminal of the selection control means, and the signal prepared in advance in the color signal generation circuit is supplied to the selection control means. Is input to the other input terminal. The selection control means exchanges the color difference signals by selecting and outputting the input signal of each input terminal according to the display area in which the images are exchanged. Further, the timing control means delays the luminance signal by the time required for the color difference signal replacement processing, and outputs the color difference signal and the luminance signal with the same timing.

In this manner, only the color difference signal of the video signal can be replaced with a previously prepared signal, and the replaced color difference signal and luminance signal can be output with the same timing. Therefore, it is possible to improve the visibility of the superimposed display and visually recognize the image of the background of the superimposed display.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a chroma signal switching circuit according to the present invention. FIG.
FIG. 1 is a block diagram illustrating a configuration example of a chroma signal replacement circuit according to an embodiment of the present invention. The chroma signal exchange circuit of the present example includes a microcontroller 100, a YC separation circuit 110, and selector circuits 120, 130, and 140.
, A chroma generation circuit 150 and a timing generation circuit 16
0 and a delay circuit 170.

Microcontroller (MPU) 100
Controls the entire chroma signal interchange circuit, and performs a process of exchanging a color difference signal of an arbitrary area of the input video signal with a previously prepared color difference signal. This MPU 100
It is assumed that a color difference signal to be replaced with a color difference signal of an input video signal, an area to be replaced with the color difference signal, and the like are set in advance by an input from an operation unit (not shown). The YC separation circuit 110 separates a luminance (Y) signal and a color difference (C) signal included in a composite video signal (composite signal).

That is, the chroma signal interchange circuit of the present embodiment is configured to handle both a video signal in which a luminance signal and a color difference signal are separated and a video signal in which a luminance signal and a color difference signal are combined. The composite video signal is separated by a YC separation circuit 110 and then input to selector circuits 120 and 130 as input means. The selector circuit 120 selects an input color difference signal, and selects and outputs one of the input color difference signals depending on whether or not the input video signal is a composite signal.
The selector circuit 130 selects the input luminance signal. Depending on whether the input video signal is a composite signal,
One of the input luminance signals is selected and output.

Next, in FIG. 1, a circuit composed of a selector circuit 140, a chroma generation circuit 150, a timing generation circuit 160, and a delay circuit 170 indicated by a broken line frame A replaces a color difference signal of an input video signal. . The chroma generation circuit 150 generates a color difference signal that replaces the color difference signal of the input video signal. A color difference signal prepared in advance is set in the chroma generation circuit 150. The timing generation circuit 160 generates a timing for determining an area where the color difference signals are to be replaced.
The color difference signal from the chroma generation circuit 150 and the color difference signal from the selector circuit 120 are selected on the basis of the timing generated by the control circuit 120, and are output as output color difference signals. The delay circuit 170 delays the luminance signal according to the signal delay caused by processing the color difference signal.

Hereinafter, the operation of the chroma signal switching circuit having such a configuration will be sequentially described. First, when the input video signal is a composite video signal, the YC separation circuit 110 separates the input video signal into a luminance signal and a color difference signal, and the luminance signal is supplied to the selector circuit 130 and the color difference signal is supplied to the selector circuit 1.
20. If the signal is not a composite video signal, the luminance signal is directly input to the selector circuit 130 and the color difference signal is input to the selector circuit 120. Selector circuit 1
Reference numerals 20 and 130 select an input video signal whose color difference signal is to be replaced in accordance with the setting from the MPU 100. This setting is performed from an operation unit or the like via a bus or an I / O port.

The following processing is performed on the luminance signal and the color difference signal selected by the selector circuits 120 and 130. First, the chroma generation circuit 150
In accordance with the setting from U100, a color to be displayed, that is, a color difference signal after replacement is generated. As the color difference signal, a sine wave having an amplitude and a phase set by the MPU 100 and synchronized with the subcarrier frequency of the input video signal may be generated. The extraction of the subcarrier can be performed from the color burst of the input video signal selected and set. However, there are many other methods for such signal generation, and the present invention does not limit the specific method for generating these color difference signals.

The timing generation circuit 160 selects the display area for replacing the color difference signal by the selector circuit 1.
A timing signal for controlling the control signal 40 is generated. The vertical synchronizing signal (V-Sync) and the horizontal synchronizing signal (H
−Sync), a signal that changes after a certain time set by the MPU 100 may be generated. The measurement of the elapsed time includes a method of realizing the measurement by counting a high-speed clock synchronized with the synchronization signal of the video signal.
There are many other methods for generating such a timing signal, and the present invention does not limit the specific method for generating these timing signals.

The color difference signal generated by the chroma generation circuit 150 and the color difference signal of the input video signal are converted by the timing generation circuit 1
Switching by the selector circuit 140 controlled by the output of 60 switches the color difference signals of an arbitrary display area. The color difference signal output from the selector circuit 140 and, if necessary (according to the processing time of the color difference signal), the delay circuit 17
By combination with the luminance signal delayed by 0, a video signal in which only the color difference is replaced is obtained.

The above-mentioned chroma signal exchange circuit,
By combining the above-described conventional superimposing circuit, that is, performing a character display process such as the OSD 20 or a graphics display process on the video signal obtained by the configuration shown in FIG. In addition, a character display that allows the user to view a background image can be realized. As a result, a white superimposed display 42 can be displayed on a background area 40 having a desired color as shown in FIG. 2, and the original image can be visually recognized through the background area 40. is there.

With the above configuration, the following effects can be obtained by replacing the color difference signal of the video signal with a previously prepared signal. (1) The visibility of characters and the like can be improved by exchanging the background color of the area where the characters are displayed. (2) Unlike the case where the background of the display area is used to improve the visibility of the character display and the like in the past,
You can see the background video. (3) Compared to the method of increasing the visibility by lowering the luminance of the background image in the character display area, the degree of freedom in colors and luminance used for character display and the like can be increased, and various displays can be performed. (4) A simple special effect can be added to a video signal. (5) Similar processing can be realized at a lower cost compared to a method of storing input video data in a memory and processing it by a processor or the like.

Next, as another embodiment of the present invention, a configuration in a case where a chroma signal exchange circuit is digitized will be described. FIG. 3 is a block diagram in a case where the configuration of the broken line area A shown in FIG. 1 is configured to be digitally processed.
The chroma signal exchange circuit of the present example includes an A / D converter 210
, A Cr / Cb setting register 220, and a D / A converter 2
30, the selector circuit 240, and the timing generation circuit 2
50 and a delay circuit 260.

The A / D converter 210 converts an input video signal into a digital data stream. The Cr / Cb setting register 220 holds the color difference data (Cr / Cb), which is the display color after the replacement, and the color difference data (Cr / Cb) is set by the MPU 100 described above. The timing generation circuit 250 generates a timing for controlling the area where the color difference is exchanged, and the selector circuit 240 generates the color difference data of the input video and Cr / Cb.
The color difference data set in the setting register 220 is selected. The delay circuit 260 delays the digitized luminance data, and the D / A converter 23
“0” converts each digital data string output from the selector circuit 240 and the delay circuit 260 into an analog color difference signal and a luminance signal and outputs the analog color difference signal and the luminance signal.

Hereinafter, the operation of the chroma signal switching circuit having such a configuration will be sequentially described. First, the input luminance signal and color difference signal are converted by the A / D converter 210 into a digital data sequence sampled by a sampling clock. At the same time, the video synchronization signal is sampled and output. The chrominance data string is Rec. Red color difference data Cr and blue color difference data Cb based on standards such as 601
There are two types. On the other hand, the Cr / Cb setting register 220
Holds the colors to be displayed, that is, the values of the replaced red color difference data Cr and blue color difference data Cb, according to the settings from the MPU 100.

Therefore, the data strings Cr and Cb output from the A / D converter 210 and the Cr / Cb setting register 22
The data strings Cr and Cb held at 0 are connected to the selector circuit 240 controlled by the timing generation circuit 250 which operates in the same manner as the timing generation circuit 160 described above.
To obtain a data string in which Cr and Cb are exchanged. The D / A converter 230 converts the chrominance data string obtained as described above and the luminance data string delayed by the delay circuit 260 as necessary into an analog signal. A video signal in which the color difference has been replaced is obtained.

FIG. 4 is a block diagram showing a superimpose generating circuit which can be added to the configuration shown in FIG. That is, in the case of a configuration for performing digital processing as shown in FIG. 3, it is possible to insert a processing circuit such as a character display or a graphic display into this configuration. In the configuration shown in FIG. 4, a luminance setting register 310 and a selector circuit 320 are inserted in a stage preceding the A / D converter 230, and the selector circuit 320 is controlled by the timing circuit 250 in accordance with the superimposed display. Note that the brightness setting register 3
In 10, a luminance data string is set in advance from the MPU 100.

Thus, by selecting the luminance data sequence from the delay circuit 260 and the luminance data sequence from the register circuit 310, a luminance data sequence Y including a superimposed display is generated, and the D / A conversion is performed. Output to the container 230. At present, video processing is mostly performed digitally, and once digitized, the color difference signal switching circuit has the advantage that it can be realized with a simple configuration and operation.

[0026]

As described above, the chroma signal switching circuit according to the present invention is a chroma signal switching circuit which receives a video signal including a luminance signal and a color difference signal and switches a part or all of the color of a video. Only the color difference signal of the video signal is replaced with a previously prepared signal. For this reason, it is possible to improve the visibility of the superimposed display and to visually recognize the background image of the superimposed display.

Specifically, the visibility of characters and the like can be improved by changing the background color of the area in which characters are displayed. Also, unlike the case where the background of the display area is conventionally painted out, which has conventionally been used to improve the visibility of character display and the like, the background image can be viewed. Further, as compared with a method of lowering the luminance of the background image in the character display area to increase the visibility, the color and luminance used for the character display and the like can be given more flexibility, and various displays can be performed. Also,
Simple special effects can be added to the video signal. Further, similar processing can be realized at a lower cost than a method in which input video data is stored in a memory and processed by a processor or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a chroma signal switching circuit according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a specific example of a superimposed display when a superimposed circuit is combined with the circuit shown in FIG. 1;

FIG. 3 is a block diagram showing a configuration example when a part of the chroma signal exchange circuit shown in FIG. 1 is digitized.

FIG. 4 is a block diagram showing a configuration example of a superimpose circuit that can be combined with the circuit shown in FIG. 3;

FIG. 5 is an explanatory diagram showing a specific example of a conventional superimposed display.

FIG. 6 is an explanatory diagram showing a specific example of a conventional superimposed display.

FIG. 7 is an explanatory diagram showing a specific example of a conventional superimposed display.

[Explanation of symbols]

100 microcontroller, 110 YC separation circuit, 120, 130, 140 selector circuit, 15
0: Chroma generation circuit, 160: Timing generation circuit, 170: Delay circuit

Claims (6)

[Claims] 1. A chroma signal interchange circuit for inputting a video signal including a luminance signal and a color difference signal and exchanging a part or all of a color of a video, comprising: a luminance signal input means for inputting the luminance signal; A color difference signal input unit that inputs a color difference signal, a color signal generation circuit that generates the previously prepared signal, and a color difference signal input from the color difference signal input unit and a signal stored in the color signal generation circuit. Selection control means for outputting, and timing control means for matching output timings of the chrominance signal output from the selection control means and the luminance signal input by the luminance signal input means, wherein only the chrominance signal of the video signal is output. A chroma signal exchanging circuit, wherein the signal is exchanged with a signal prepared in advance. 2. The chroma signal switching circuit according to claim 1, further comprising means for inputting a video signal comprising a composite signal of said luminance signal and color difference signal by separating said luminance signal and color difference signal. 3. The chroma signal exchange circuit according to claim 1, wherein an analog signal prepared in advance is exchanged for the analog color difference signal of the analog video signal. 4. Converting an analog video signal into digital,
2. The chroma signal exchanging circuit according to claim 1, wherein data prepared in advance is exchanged for the digital color difference data. 5. The image processing apparatus according to claim 1, further comprising a setting unit that sets an area for replacing the color difference signal of the video signal and the prepared signal to an arbitrary area on a display screen.
Chroma signal replacement circuit as described. 6. The chroma signal exchange circuit according to claim 1, wherein a superimpose circuit for performing superimpose display is connected to an area where the color difference signal of the video signal and the previously prepared signal are exchanged. .