JPH09219874A - Method and device for generating information for copy prevention signals of video program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide copy prevention signals by comparing the size of the color difference signal component of color video signals with a certain settable threshold value level for each scene of color video images and supplying the information of '1' and '0' to a flag bit depending on being larger or smaller. SOLUTION: Component-encoded color video signals are supplied to an information- for-copy-prevention-signal addition circuit 13 and a color difference signal detection circuit 10. The color difference signal detection circuit 10 detects the color difference signal component and supplies the information of color saturation to one of the inputs of a comparator circuit 11. The comparator circuit 11 compares it with the certain settable determined threshold value level added to the other input and outputs the result to an information-for-copy-prevention-signal generation circuit 12. The information-for-copy-prevention-signal generation circuit 12 outputs the information for the copy prevention signals to the information-for-copy-prevention-signal addition circuit 13 corresponding to the result. In this case, the information for the copy prevention signals is added to the color video signals and used for the control of the phase modulation of color burst signals when component signals are converted to composite signals.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method and an apparatus for processing a color video signal,
In particular, video programs such as video tape recorders (VT
R) or video cassette recorder (VCR) to prevent or prohibit copy recording (recording),
The present invention relates to a method and apparatus for generating information for copy protection.

[0002]

2. Description of the Related Art In recent years, various methods for preventing or prohibiting copy recording of a video program on a video tape by a VTR or VCR have been proposed or implemented.

For example, as shown in the prior art US Pat. No. 4,577,216, a color video signal is modified so that it is normal when the modified signal is received by a conventional color television receiver. Color video is recorded on a videotape, but when recorded signals are played back and received, color noise is generated in the color video, and the video is recorded on the videotape by making it unsightly. A way to remind you is provided.

That is, when a color burst signal of a color video signal is phase-modulated by noise or an appropriate signal to modify the signal, the modified signal is burst in a color subcarrier reproducing circuit of a conventional color television receiver. A video tape recorded with a modified color video signal, which does not affect the phase modulation of the signal, is recorded on a VTR or VC.
When reproduced at R, the VTR or VCR changes the phase of the chrominance signal in response to the phase modulated color burst signal. As a result, unsightly color noise appears on the screen when the video tape is played back, and the recording on the video tape is being discouraged.

[0005]

However, in practice, the phase-modulated color burst signal may affect the color subcarrier reproduction circuit of the conventional color television receiver. In particular, an unsightly striped color noise may occur on a screen of a video scene with high color saturation.

Originally, such a copy protection method affects only the function of the video recording / reproducing apparatus, but needs not to affect the function of the conventional color television receiver. It is an issue.

In view of the above problems, the present invention transforms a color video signal in order to prevent or prohibit copying and recording a video program on a video tape.
It is to provide an improved method and apparatus for use.

In particular, by improving the conventional technique in which the color burst signal of the color video signal is phase-modulated to transform the color video signal into a copy protection signal, the recorded and reproduced image of the transformed color video signal is unsightly. It is an object of the present invention to provide an improved method and apparatus in which color noise is not generated when a modified color video signal having a high image quality is directly received by a conventional color television receiver.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, according to the present invention, in the prior art, a conventional color television receiver receives a color video signal processed for signal protection for copy protection. In this case, particularly, a color noise having a striped pattern is likely to occur in a color image scene having a high color saturation. Therefore, in the present invention, first, the information regarding the color is detected for each scene of the color image. Next, based on the detected information, information is generated to instruct whether or not to modulate the phase of the color burst signal to make it a copy protection signal. As a specific example, the magnitude of the color difference signal component of the color video signal for each scene is compared with a predetermined threshold level that can be set, and if it is greater than the threshold level,
For example, information of flag bit 0 is given, and if not large, information of flag bit 1 is given.

If such information is added to the color video signal, in the stage where the component signal is converted to the composite signal, the color burst signal is kept at the reference phase in the case of the flag bit 0, and the flag bit is kept. For the case of 1, the phase of the color burst signal can be modulated, if desired, resulting in an improved copy protection signal.

As a result, when a conventional color television receiver receives a color video signal having a copy protection signal processed according to the present invention, in the prior art, the phase of the color burst signal with respect to the scene where color noise is likely to occur. Is not modulated, there is an effect that a color image without color noise can be obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method for generating copy protection signal information for a video program, which is used in transforming a color video signal in order to prevent the video program from being copied and recorded. A first step of extracting color difference signal information from the signal and comparing the magnitude with a predetermined threshold level that can be set;
A second step of generating copy protection signal information according to the comparison result obtained in the first step, and a third step of adding the copy protection signal information to the color video signal in a predetermined format. According to another aspect of the present invention, there is provided an apparatus for generating information for a copy protection signal of a video program used for transforming a color video signal to prevent copy recording of the video program. The color difference signal information detection circuit means for extracting color difference signal information from the input color video signal, and the color difference signal information output from the color difference signal information detection circuit means supplied to one input terminal to the other input. A comparing circuit means for comparing the magnitude with a settable predetermined threshold level applied to the terminal, and an output terminal of the comparing circuit means And a copy protection signal information generating circuit means for generating predetermined copy protection signal information according to a result of comparing the color difference signal information with the threshold level, and an output terminal of the copy protection signal information generating circuit means. And a copy protection signal information adding circuit means for adding the copy protection signal information to the input color video signal in a predetermined format. If is added to the color video signal, the color burst signal remains at the reference phase for the case of flag bit 0 and for the case of flag bit 1 at the stage of converting from the component signal to the composite signal. If necessary, the phase of the color burst signal can be modulated, and an improved copy protection signal can be obtained.

As a result, when a conventional color television receiver receives a color video signal having a copy protection signal processed according to the present invention, in the prior art the phase of the color burst signal relative to the scene susceptible to color noise. Is not modulated, there is an effect that a color image without color noise can be obtained.

An embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) In the embodiment shown in FIG. 1, a component-coded color video signal is supplied to a copy protection signal information addition circuit 13 and a color difference signal detection circuit 10. The color difference signal detection circuit 10 detects the color difference signal component, and compares the color saturation information with the comparison circuit 11
To one input.

The comparison circuit 11 compares the magnitude of the amplitude of the color difference signal with a predetermined threshold level that can be set and is applied to the other input, and the result is sent to the copy protection signal information generation circuit 12. Output.

The copy protection signal information generation circuit 12 generates copy protection signal information according to the comparison result. As a simple concrete example, it is compared for each field of each scene whether or not the amplitude of the color difference signal exceeds 50% of the specified maximum amplitude. 50% depending on the result of this comparison judgment
In the following cases, the copy protection signal information for causing the color burst of at least several tens of scanning lines to be phase-modulated per field is generated in the following cases.

The output of the copy protection signal information generation circuit 12 is supplied to the copy protection signal information addition circuit 13, where the copy protection signal information is added to the input color video signal. The copy protection signal information added to the color video component signal in this way is finally used for phase modulation control of the color burst signal at the stage where the component signal is converted into a composite signal.

(Second Embodiment) In FIG. 2, the component-coded color video signal is supplied to a copy protection signal information addition circuit 13. On the other hand, (RY) of the color difference component extracted from the color video signal
The signal is supplied to the absolute value circuit 20, where the absolute value of the amplitude of the (RY) signal is taken and the value is output to the low pass filter circuit 21. This low pass filter circuit 2
1 removes the high-frequency signal component contained in the signal of the absolute value of the (RY) signal, and supplies only the low-frequency signal component to one input of the comparison circuit 11.

The comparison circuit 11 compares the amplitude of the signal output from the filter with a predetermined threshold level that can be set and is applied to the other input, and the comparison result is a copy protection signal information generation circuit. Output to 12.

The copy protection signal information generating circuit 12 generates copy protection signal information in accordance with the comparison result, as in the case of FIG. The generated copy protection signal information signal is supplied to the copy protection signal information addition circuit 13 and is added to the color video signal input thereto as in the case of FIG. 1 and output.

As described above, when a conventional color television receiver receives a color video signal according to the related art in which the phase of the color burst signal is simply modulated and modified in order to prevent copying, unsightly color noise is received. May occur, and in particular, it tends to appear remarkably in a scene of an image with high color saturation, whereas according to the present invention, the color information of the screen is detected for each scene to affect the color television receiver. In a scene that is easily given, the phase of the burst signal is not modified and deformed, and in a scene that does not affect, the phase is modulated and information for controlling the modification is generated. As a result, it is possible to obtain a copy protection signal for the conventional color television receiver, which has a function of preventing the copy recording of the video program without affecting the image quality.

Although the magnitude of the amplitude of the (RY) signal of the color difference component is compared with the threshold level in the embodiment of FIG. 2, it may be the (BY) signal, and the I signal, Obviously, the Q signal may be used. Furthermore, although the (RY) signal is the object of comparison alone, it may be said that a synthesized signal such as the (RY) signal + (BY) signal may be the object of comparison. There is no end.

In the embodiments of FIGS. 1 and 2, a specific example of the threshold level is selected to be 50% of the specified maximum amplitude value of the color difference signal for explanation, but it is limited to 50%. It goes without saying that the value may be a value other than 50% instead of the value.

In the embodiments of FIGS. 1 and 2, the case where a component-encoded color video signal is input has been described, but it is also possible to convert or process a composite signal to extract a color difference signal and process it. It goes without saying that it is possible. Furthermore, it is clear that it can be applied not only to digital signals but also to analog signals.

Further, it is instructed to detect the color information for each scene of each color image and modulate the phase of the burst signal of at least several tens of lines per field in the scene which does not affect the conventional color television receiver. Alternatively, although a specific example of generating copy signal information to be controlled is shown, it goes without saying that it is also possible to generate and add information as to whether or not to modulate the phase for each scanning line.

As described above, it is needless to say that the present invention is not limited to the above embodiment and various modifications can be made. All modifications that are within the true technical idea and scope of the present invention are included in the scope of the claims.

[0027]

As described above, according to the present invention, when a conventional color television receiver receives a color video signal having a copy protection signal processed by the present invention,
In the prior art, since the phase of the color burst signal is not modulated with respect to a scene where color noise is likely to occur, there is an effect that a color image without color noise can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram according to an embodiment of the present invention;

FIG. 2 is a block diagram according to an embodiment of the present invention.

[Explanation of Codes] 10 Color Difference Signal Detection Circuit 11 Comparison Circuit 12 Copy Protection Signal Information Generation Circuit 13 Copy Protection Signal Information Addition Circuit 20 Absolute Value Circuit 21 Low Pass Filter Circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Ishikawa, 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (12)

[Claims] 1. A method for generating copy protection signal information for a video program used to transform a color video signal to prevent copy recording of the video program, the color difference signal information being generated from the color video signal. And a second step of generating copy protection signal information according to the comparison result obtained in the first step, and a first step of comparing the magnitude with a predetermined threshold level that can be set. A method for generating copy protection signal information of a video program, comprising a third step of adding the copy protection signal information to the color video signal in a predetermined format. 2. The copy protection of a video program according to claim 1, wherein the (RY) signal is taken out as the color difference signal information in the first step and compared with a predetermined threshold level that can be set. How to generate signaling information. 3. The copy protection of a video program according to claim 1, wherein a (BY) signal is taken out as the color difference signal information in the first step and compared with a predetermined threshold level that can be set. How to generate signaling information. 4. A composite signal of (RY) signal + (BY) signal is taken out as the color difference signal information in the first step, and is compared with a certain settable threshold level. A method for generating information for a copy protection signal of a video program according to claim 1. 5. A method for generating copy protection signal information for a video program as claimed in claim 1, characterized in that, in the first step, the I signal is compared with a certain settable threshold level that can be set. 6. A method for generating copy protection signal information for a video program as claimed in claim 1, characterized in that, in the first step, the Q signal is compared with some predetermined threshold level that can be set. 7. The copy protection signal information of a video program according to claim 1, wherein in the first step, the composite signal of the I signal + Q signal is compared with a predetermined threshold level that can be set. How it happens. 8. The color difference signal information in the first step, wherein the absolute value of the color difference signal is taken, and the signal obtained through the low pass filter is compared with a predetermined threshold level that can be set. Method for generating information for copy protection signals of the described video program. 9. In the second step, if the color difference signal information is smaller than the threshold level in accordance with the result of the level comparison in the first step, the composite color video signal of the composite color video signal is displayed for a predetermined specific period. 2. The method for generating copy protection signal information of a video program according to claim 1, wherein the copy protection signal information for modulating the phase is generated. 10. The method for generating copy protection signal information of a video program according to claim 9, wherein the specific period corresponds to at least several tens of lines per field. 11. A device for generating information for a copy protection signal of a video program, which is used in transforming a color video signal to prevent copy recording of the video program, the color difference from an input color video signal. Color difference signal information detection circuit means for extracting signal information, and a settable predetermined threshold value to which color difference signal information output from the color difference signal information detection circuit means supplied to one input terminal is added to the other input terminal A copy protection circuit connected to an output terminal of the comparison circuit means for comparing the level and the size, and generating a predetermined copy protection signal information according to the result of comparing the color difference signal information with the threshold level. A signal information generating circuit means and an output terminal of the copy protection signal information generating circuit means,
An apparatus for generating copy protection signal information of a video program, comprising copy protection signal information adding circuit means for adding the copy protection signal information to the input color video signal in a predetermined format. . 12. The color difference signal information detection circuit means forms an absolute value of the amplitude of the color difference signal extracted from the input color video signal, and the signal of the absolute value is passed through a low pass filter circuit to obtain required color difference signal information. An apparatus for generating copy protection signal information for a video program as claimed in claim 11, further comprising: