JPS586346B2 - color - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Generally, in a color video signal recording/reproducing device such as a color video tape recorder, the luminance signal is set to 3.8 to 5, for example.
．． Since recording is performed by low carrier frequency modulation using 4 MHz as a carrier wave, and the chromaticity signal is recorded by amplitude modulation using, for example, 688 KHz as a carrier wave, it is difficult to evaluate the noise ratio.

The present invention relates to a color noise ratio measuring method for a color video signal recording/reproducing apparatus such as a color video tape recorder, and is particularly designed to be able to practically determine the color noise ratio.

An embodiment of the color noise ratio measuring method for the color video signal recording and reproducing apparatus of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a video tape recorder for measuring the color-to-noise ratio, and a terminal 1a is connected to a video signal reproduced by the video tape recorder 1, and a terminal 1b is connected to, for example, 3. A parsed signal (subcarrier signal) of 58 MHz is obtained.

The color video signal obtained at this terminal 1a is supplied to a synchronous separation circuit 2 and a switching circuit 3, respectively.

Further, the burst signal obtained at the terminal 1b is supplied as a color lock signal to the color bar signal generator 4, and the output signal of the sync separation circuit 2 is supplied to the color par signal generator 4 to generate the color bar signal. A color bar signal synchronized with the synchronization signal of the video tape recorder 1 is obtained at the output of the device 4.

The color bar signal obtained from the output of the color bar signal generator 4 is supplied to a mixing circuit 5.

6 indicates a standard noise generator that generates white noise;
This standard noise generator 6 is designed to be able to adjust the level of the white noise it generates.

A clear white noise at the level obtained at the output of the standard noise generator 6 is supplied to the mixing circuit 5.

In this case, the white noise from the standard noise generator 6 may be supplied to the mixing circuit 5 via a predetermined filter, if necessary.

A standard noise color bar signal obtained by mixing white noise and a color par signal obtained at the output of this mixing circuit 5 is supplied to a switching circuit 3, and the output signal of this switching circuit 3 is sent to a color television receiver constituting a monitor. Supply to 7.

This switching circuit 3 switches between the output video signal from the color video signal recording and reproducing device 1 and the standard noise color bar signal from the mixing circuit 5 in synchronization with the vertical synchronization signal from the sync separation circuit 2, thereby producing a color television receiver. 7.

In this case, the switching circuit 3 reproduces the standard noise color bar signal from the mixing circuit 5 on a portion corresponding to, for example, the middle 1/3 vertical period of the video screen 7a of the color television receiver 7, and reproduces the standard noise color bar signal from the mixing circuit 5 on the video screen 7a of the color television receiver 7. This output video signal is reproduced in the portion 7a, that is, the portion corresponding to the upper 1/3 vertical period and the lower 1/3 vertical period.

In the present invention, first, for example, the color bar signal generator 4
This color bar signal was recorded on a recording medium by the color video tape recorder 1, which was used to measure the noise ratio by closing the connection switch 8, and then opened the connection switch 8 and recorded it on this recording medium. The color par signal is reproduced, and the reproduced color par signal is obtained at the output terminal 1a of the color video signal recording and reproducing device 1. Therefore, this color par signal is supplied to the switching circuit 3, and is also supplied to the output of the mixing circuit 5. The obtained standard noise color par signal is supplied to the switching circuit 3.

Therefore, on the video screen 7a of the color television receiver 7, the upper and lower 1/3 portions 7b and 7 are
The color par signal from the color video signal recording and reproducing device 1 is reproduced at c, and the standard noise power color bar signal from the mixing circuit 5 is reproduced at the middle 1/3 portion 7d of the video screen 7a.

In the present invention, the level of white noise generated by the standard noise generator 6 is adjusted to visually distinguish the color bars on the upper and lower parts 7b and 7c of the video screen 7a and the color bar on the middle part 7d. The color noise ratio is determined based on the noise level of this standard noise generator 6.

As described above, according to the present invention, the color noise ratio of a color video tape recorder can be easily determined and is extremely practical.

Additionally, color noise on a color screen generally looks visually different depending on its hue, but according to the present invention, the color noise ratio is determined by visually comparing the color pars on the video screen, so the color noise can be determined for each hue, making it possible to determine the color-to-noise ratio that is faithful to visual perception.

Further, according to the present invention, the color par signal generator 4 is controlled in accordance with the synchronization signal from the video tape recorder 1, and the switching circuit 3 is controlled in synchronization with the vertical synchronization signal from the video tape recorder 1. Therefore, the connection point between the standard noise color bar signal on the video screen 7a of the television receiver 7 and the reproduced image of the color par signal from the video tape recorder 1 becomes good.

Although the above example describes the case of measuring the color noise ratio of a color video tape recorder, it is of course possible to similarly measure the color noise ratio of color video signal recording and reproducing apparatuses having other configurations. .

Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and that other configurations may be adopted without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating an embodiment of a color noise ratio measuring method for a color video signal recording and reproducing apparatus according to the present invention, and FIG. 2 is a diagram illustrating the present invention. 1 is a color video tape recorder to be measured, 2 is a synchronous separation circuit, 3 is a switching circuit, 4 is a color bar signal generator, 5 is a mixing circuit, 6 is a standard noise generator, and 7 is a television receiver.

Claims (1)

[Claims] 1) A power driven in synchronization with the standard noise signal of a standard noise generator whose noise level can be adjusted and the synchronization signal of the color video signal recording and reproducing device to be measured) The color par signal from the one-bar signal generator The standard noise color bar signal obtained by mixing the color par signal from the color par signal generator is vertically synchronized with the reproduced color par signal obtained by recording and reproducing the color par signal from the color par signal generator. The standard noise color par signal and the reproduced color bar signal from the color video signal recording and reproducing device to be measured are displayed on the same video screen of the monitor by switching in synchronization with the signal. A color video signal characterized in that the noise level of the output of the standard noise generator is adjusted so as to match visually, and the color noise ratio of the color video signal recording and reproducing device is determined based on the noise level. Color noise ratio measurement method for recording/playback equipment.