JP3528555B2 - Video signal frequency characteristic evaluation method and video characteristic evaluation medium - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a display,
The present invention relates to a video frequency characteristic evaluation method for a video device such as a VTR and a DVD (digital video disc) player, and a video characteristic evaluation medium used therefor. And the present invention, in particular,
The cost and accuracy of the evaluation system will be improved.

[0002]

2. Description of the Related Art Conventionally, in the case of evaluating the frequency characteristic of a video device, the same signal contents are arranged in one horizontal scanning video section by arranging from low frequency region to high frequency region continuously or in spots. The frequency characteristic evaluation signal (test video signal) repeatedly used for each scanning line is used. And
The evaluation was performed by evaluating the pass frequency characteristics of the video equipment and display of the test video signal, or the frequency characteristics of recording and reproduction with a spectrum analyzer.

FIG. 3 shows a conventional test signal for video frequency characteristic evaluation. As shown in the figure, the sweeper signal shown in FIG. 7B is arranged so as to continuously change from a low frequency region to a high frequency region in one horizontal scanning video section, or the same is arranged so that the frequency is changed stepwise. There is a multi-burst signal shown in FIG. 6C, and the test signal has a configuration in which the contents of the video signal in one horizontal scanning section are repeated for each scanning line in one field. FIG. 4 shows a reproduced image of a conventional test signal for video frequency characteristic evaluation on a display, in which the frequency gradually increases from the left to the right of the screen.

[0004]

In the above-mentioned conventional evaluation method, since the spectrum analysis of one horizontal scanning section is performed,
The signal level detection processing time for each frequency is minute, a complicated signal processing circuit is required for signal processing, and the evaluation system becomes expensive and it is difficult to improve accuracy. Further, if each frequency is spotted and the time is increased to ensure accuracy, the number of frequency points in one horizontal scanning section decreases, making it difficult to measure detailed frequency characteristics from the low frequency range to the high frequency range. It was

An object of the present invention is to provide a video frequency characteristic evaluation method and a video characteristic evaluation medium which can easily and highly accurately evaluate the video frequency characteristic of a video equipment, a display or the like.

[0006]

In order to solve the above problems, the present invention provides (1) a luminance signal frequency characteristic evaluation signal of a video device,
A cross signal between each horizontal scanning line is used by using a signal in which the frequency of the luminance signal is changed for each of multiple horizontal scanning sections in the field.
Evaluate the frequency level of the horizontal scanning section that is not affected by the
Video signal frequency characteristic evaluation method characterized by deserves. (2) A video signal frequency characteristic evaluation method, wherein a signal obtained by changing the amplitude modulation frequency of the color signal for each arbitrary horizontal scanning section in the field is used as the color signal frequency characteristic evaluation signal of the video equipment. (3) As the luminance signal frequency characteristic evaluation signal of the video equipment,
A medium for evaluating video characteristics, characterized in that a signal in which a frequency of a luminance signal is changed for each of a plurality of horizontal scanning sections in a field is recorded. (4) A medium for evaluating image characteristics, characterized in that, as a color signal frequency characteristic evaluation signal for an image device, a signal in which the amplitude modulation frequency of the color signal is changed at every arbitrary horizontal scanning section in the field is recorded. Is provided.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a luminance signal and a color signal which are examples of a frequency characteristic evaluation signal (test video signal) used in the image frequency characteristic evaluation method and the image characteristic evaluation medium of the present invention. As shown in the drawing, the test luminance signal and color signal of the embodiment are characterized by arranging the video signal stepwise changing from a low frequency region to a high frequency region for each arbitrary horizontal scanning section in the field. A constant frequency and a constant amplitude are maintained in the horizontal scanning section. FIG. 2 shows a reproduced image on the display of the test luminance signal or color signal of the embodiment.

FIG. 1B shows a test luminance signal in one horizontal scanning section in the low frequency region. This signal is located at the beginning of one field and is located at the top of the screen shown in FIG. It is projected as a rough striped pattern. FIG. 1C shows a test luminance signal in one horizontal scanning section in the high frequency range.
It is located at the end of one field and is projected as a dense striped pattern at the bottom of the screen shown in FIG.

FIG. 1D shows a test color signal in one horizontal scanning section of the low frequency amplitude modulation area, which is located at the beginning of the field and is shown in FIG. 2 similarly to the luminance signal. It is projected on the top of the screen as a striped pattern of rough colors. FIG. 1 (E) shows a test color signal in one horizontal scanning section of the high frequency amplitude modulation area, which is located at the end of the field and has a dense color gradation at the bottom of the screen shown in FIG. It is projected as a striped pattern.

That is, in the test luminance signal and color signal of the embodiment, the video signal frequency changes stepwise in the vertical direction on the display screen every arbitrary horizontal scanning section.
The positional relationship of each frequency range with respect to the field may be opposite to the above, and the beginning part of the field may be a high frequency range and the end part may be a low frequency range. In this case, the upper part of the display screen is dense. It goes without saying that it becomes a striped pattern and the lower part becomes a rough striped pattern.

When used for evaluating the video frequency characteristic of the circuit system of the video equipment, the amplitude level of each frequency of the luminance signal and each amplitude modulation frequency level of the color signal may be constant, but it is used for visual evaluation of the display. In this case, the average luminance level Xy bar of the luminance signal, the average luminance level Xc bar of the color signal, or the amplitude Zy of the luminance signal and the color signal amplitude Zc shown in FIG. 1 may be set to a level at which visual evaluation is easy. .

[0012] A modulated color signal of the NTSC, PAL, SECAM system or the like is limited in frequency band during color modulation and demodulation, and thus the color signal frequency evaluation band is limited. May use RY, BY color difference signals or RGB component signals as the test color signals.

With the test video signal configuration as described above, each frequency characteristic analysis may be performed for each predetermined horizontal scanning section, whereby each sampling time for frequency characteristic evaluation for each video frequency is obtained. Sufficiently secured and highly accurate response evaluation becomes possible easily. Further, since frequency characteristic analysis can be performed for each horizontal scanning section, by assigning each frequency stepwise to the horizontal scanning line section excluding the synchronization signal in one field, the number of frequency spots in a wide range corresponding to the number of effective scanning lines can be obtained. Can be secured, and detailed frequency characteristics can be evaluated.

If the crosstalk between the scanning lines becomes a problem, the horizontal scanning section at the same frequency may be increased and the frequency level of the horizontal scanning section portion not affected by the crosstalk may be evaluated. Further, as a frequency characteristic evaluation system using the above test video signal, if the horizontal synchronization signal is used for the sequence switching of the frequency analysis filter and the sampling hold, the circuit configuration can be simplified and the cost can be reduced. An evaluation system can be created with.

The frequency spots in the horizontal scanning section are assigned in consideration of the accuracy of the video equipment evaluation system, the ease of visual evaluation of the display, and the situation of crosstalk between scanning lines. (H
Number). Depending on the situation, a plurality of frequency spots may be set within one horizontal scanning section. In this case, the total number N of frequency spots is N = L × M, depending on the number L of frequency spots in a predetermined horizontal scanning section and the number M of frequency spots in one horizontal scanning section, which is dramatically superior to the conventional multi-burst signal. You can set many evaluation points. This further promotes the merit of setting a large number of evaluation points for each horizontal scanning section, which is one of the features of the present invention, and enables detailed evaluation of video frequency characteristics. The above test video signal may be generated directly from the signal generator at the time of evaluation of each video equipment, but it is more convenient if it is recorded in a recording medium in advance and reproduced from the recording medium at the time of evaluation. Is good.

[0016]

As described above, by using the video frequency characteristic evaluation method and the video characteristic evaluation medium of the present invention, a video device,
It is possible to evaluate the video frequency characteristics of a display, etc. with a simple signal processing circuit, and it is possible to reduce the cost and accuracy of the evaluation system.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a frequency characteristic evaluation signal used in the present invention.

FIG. 2 is a diagram showing a reproduced image on a display of the frequency characteristic evaluation signal shown in FIG.

FIG. 3 is a diagram showing an example of a conventional frequency characteristic evaluation signal.

FIG. 4 is a diagram showing a reproduced image of the frequency characteristic evaluation signal shown in FIG. 3 on a display.

Claims (4)

(57) [Claims] 1. A signal obtained by changing the frequency of a luminance signal for each of a plurality of horizontal scanning sections in a field is used as a luminance signal frequency characteristic evaluation signal of a video device, and a signal between horizontal scanning lines is used .
Frequency level of horizontal scan section that is not affected by loss talk
Video signal frequency characteristic evaluation method and evaluating the Le. 2. A video signal frequency characteristic evaluation method, characterized in that, as the color signal frequency characteristic evaluation signal of the video equipment, a signal in which the amplitude modulation frequency of the color signal is changed for every horizontal scanning section in the field is used. . 3. A video characteristic evaluation medium, characterized in that, as the brightness signal frequency characteristic evaluation signal of the video equipment, a signal in which the frequency of the brightness signal is changed for each of a plurality of horizontal scanning sections in the field is recorded. 4. A video characteristic evaluation medium, characterized in that, as the color signal frequency characteristic evaluation signal of the video equipment, a signal in which the amplitude modulation frequency of the color signal is changed at every arbitrary horizontal scanning section in the field is recorded. .