JPH0530544A - Display photographing device - Google Patents

Abstract

PURPOSE:To photograph an image on a display by a video camera having different vertical scanning frequency. CONSTITUTION:An image displayed on a CRT 13 is photographed by the video camera 2. A memory 42 stores data corresponding to a difference between the vertical scanning frequency for driving the camera 2 and vertical scanning frequency for driving the CRT 13 and the image pickup charge of a CCD imager 22 is quickly discharged during a period corresponding to the difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display photographing device suitable for use in, for example, measuring the brightness of a television receiver.

[0002]

2. Description of the Related Art The vertical scanning frequency of a consumer television receiver is 60 Hz (NTSC system) or 50 Hz (PAL system). Therefore, the vertical scanning frequency of the raster scan type video camera corresponding to them is also set to 60 Hz or 50 Hz.

By the way, in a display for a computer, its vertical scanning frequency is often set in a high region of 60 Hz or higher. An image displayed on a computer display like this is displayed on the NTSC
When shooting with a video system or PAL video camera,
Since the vertical scanning frequencies are not synchronized, flickering occurs in the image, which makes image processing difficult.

The flicker will be described with reference to FIG. 3. Now, the vertical scanning frequency of the video camera is 60H.
z, vertical scanning frequency for computer display is 8
Assuming 0 Hz, each vertical scanning cycle is as shown in FIG.
And (b). That is, before the capture of the image for one field by the video camera is completed,
The image of the next field will be displayed on the display. If images of A to G as shown in FIG. 3C are displayed on the display corresponding to the fields of A to G of FIG. 3B, the image captured by the video camera is as shown in FIG. As shown in (d).

That is, in the first field (FIG. 3A) of the video camera, after the image A of the A field of the display is captured, the first field of the video camera of the image B of the B field of the display is captured. The image B1 up to the terminal end is displayed on the display following the image A. Therefore, in the first field of the video camera, the image B1 is captured after the image A.

In the second field of the video camera, the display of the image B1 has already been completed, so the remaining image B2 in the B field is first captured.
Then, subsequently, the image C1 of the image C of the C field up to the end portion of the second field is captured.

Hereinafter, in the third field to the fifth field, images are similarly taken.

As a result, the output of the video camera is shown in FIG.
As shown in (e), the output of the double-exposed portion becomes large, and the double-exposed position periodically changes and moves in each field. This is observed as a flicker.

When the image displayed on the display is photographed by the video camera, the vertical scanning frequencies of the display and the video camera are not synchronized.
There was a risk of hindering the measurement of the display.

Therefore, the present applicant has filed Japanese Patent Application No. 3-13047.
As No. 8, it was previously proposed to prohibit the display of images on the display for a period corresponding to the difference in vertical scanning frequency between the display and the video camera.

However, in the above proposal, since the display of the image on the display is prohibited during the period corresponding to the difference in the vertical scanning frequency between the display and the video camera, the effect of the afterglow characteristic of the phosphor of the display is affected. Appears and the brightness varies.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and even when the vertical scanning frequency of the display and that of the video camera are different, the brightness of the display does not fluctuate without changing the brightness. It enables to measure correctly.

[0013]

SUMMARY OF THE INVENTION A display photographing apparatus of the present invention is a display for displaying an image at predetermined horizontal and vertical scanning frequencies, and at least a vertical scanning frequency of the horizontal and vertical scanning frequencies is a vertical scanning of the display. A video camera for picking up an image displayed on the display at a frequency different from the frequency, and a controller for discharging the picked-up image data from the video camera for a period corresponding to a difference in vertical scanning frequency between the display and the video camera. And

[0014]

In the display photographing device having the above structure,
The image data captured by the video camera is discarded for a period corresponding to the difference in vertical scanning frequency between the display and the video camera. Therefore, the brightness and the like on the display can be captured correctly.

[0015]

1 is a block diagram showing the construction of an embodiment of a display photographing apparatus of the present invention. The display photographing apparatus of the present embodiment includes a display 1 for displaying a photographed image, a video camera 2 for photographing the image displayed on the display 1, a measuring apparatus 3 for processing an image photographed by the video camera 2, and This display 1
And a controller 4 for controlling the video camera 2.

The display 1 includes a video signal generating circuit 12
The output video signal is output and displayed on the CRT 13. The video signal generation circuit 12 can generate a video signal in response to the sync signal input from the external sync signal input terminal 11.

The video camera 2 shoots the image displayed on the display 1 by the CCD imager 22 in synchronization with the synchronizing signal input from the external synchronizing signal input terminal 21, and outputs the output to the measuring device 3. It is like this.

The measuring device 3 is composed of a memory 31 for storing image data input from the video camera 2 and an arithmetic device 32 for arithmetically processing the data stored in the memory 31.

On the other hand, the controller 4 is input from the sync generation circuit 40 for generating a sync signal to be supplied to the video camera 2, the address counter 41 for counting the horizontal sync signal output from the sync generation circuit 40, and the address counter 41. Memory (R that outputs the data corresponding to the address
AM) 42, a CPU 43 for setting a predetermined count value in the address counter 41 and storing predetermined data in the memory 42, and a sync generation circuit for generating a composite sync signal (composite blanking signal) supplied to the display 1. And 44.

Next, the operation will be described with reference to the timing chart of FIG. The horizontal and vertical blanking pulses output from the synchronization generation circuit 44 are input to the video signal generation circuit 12 of the display 1. The video signal generation circuit 12 generates a predetermined video signal in synchronization with the horizontal and vertical blanking pulses and outputs it to the CRT 13. As a result, a predetermined image is displayed on the CRT 13.

On the other hand, the horizontal and vertical sync signals output from the sync generation circuit 40 are supplied to the video camera 2, and the video camera 2 shoots the image displayed on the CRT 13 in synchronization with the sync signal. The image captured by the video camera 2 is supplied to the measuring device 3 and stored in the memory 31 thereof. The arithmetic unit 32 processes the data stored in the memory 31 and measures the characteristics of the CRT 13.

The CPU 43 stores in the memory 42 data corresponding to the difference between the vertical scanning frequency supplied by the synchronization generating circuit 40 to the video camera 2 and the vertical scanning frequency supplied by the synchronization generating circuit 44 to the display 1. .. That is, as shown in FIG. 2C, the memory 42 corresponds to the difference between the vertical scanning period of the video camera 2 (FIG. 2A) and the vertical scanning period of the display 1 (FIG. 2B). Data for which the logic L, the logic L, the other periods, and the logic H are stored.

The address counter 41 is a synchronization generating circuit 40.
The horizontal synchronization signal input by the counter is counted, and the address corresponding to the count value is output to the memory 42. The count value of the address counter 41 is reset each time the vertical synchronizing signal is input from the synchronization generating circuit 40. As a result, as shown in FIG. 2C, the memory 42 outputs a signal which becomes logical L immediately after the vertical scanning cycle of the video camera 2 starts and during the period corresponding to the difference between the vertical scanning cycles of the display 1 and the video camera 2. Output.

The signal output from the memory 42 is supplied to the video camera 2. In the video camera 2, during the period when the signal supplied from the memory 42 is logic L, CC
The charge of the D imager 22 is rapidly discharged. As a result, the data captured by the CCD imager 22 is as shown in FIG.

That is, for example, in the first field of the video camera 2, when the charge discharge signal is returned to logic H, the image of the A field on the display 1 is CC.
The image is captured by the D imager 22. When the display of the image of the B field is started after the display of the image of the A field of the display 1 is finished, the image is captured by the CCD imager 22. As a result, in the section of the first field of the video camera 2, the data in the state where the image of the B field is displayed above the display 1 and the image of the A field is displayed below the display 1 is the video as the first field data. It is output from the camera 2.

When the second field of the video camera 2 is started, the charge of the CCD imager 22 is again discarded while the signal supplied from the memory 42 is logic L. Then, after the signal supplied from the memory 42 returns to logic H, the image of the B field of the display 1 is captured, and when the display of the B field ends, the image of the subsequent C field is captured. As a result, the image of the second field of the video camera 2 is such that the image of the C field is displayed above the display 1 and the image of the B field is displayed below the display 1.

Further, in the third field of the video camera 2, the image of the D field of the display 1 is taken. In this case, the display 1 and the video camera 2
Since the vertical synchronization signals of
The image of the third field of is only the image of the D field of the display 1.

Thereafter, the image on the display 1 is similarly picked up by the video camera 2.

The data imaged by the CCD imager 22 is read out at a normal speed and becomes as shown in FIG. That is, an image having a constant brightness is obtained in each of the first to fifth fields. As a result, it is possible to prevent the measurement device 3 from erroneously measuring the luminance, for example.

[0030]

As described above, according to the display photographing apparatus of the present invention, the image data captured by the video camera is rapidly discarded during the period corresponding to the difference in the vertical scanning frequency between the display and the video camera. It is possible to correctly measure the characteristics of the display by using the output of

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a display photographing apparatus of the present invention.

FIG. 2 is a timing chart explaining the operation of the embodiment of FIG.

FIG. 3 is a timing chart for explaining a problem in the conventional display photographing device.

[Explanation of symbols]

 1 Display 2 Video Camera 3 Measuring Device 4 Controller 12 Video Signal Generation Circuit 13 CRT 40 Synchronization Generation Circuit 41 Address Counter 42 Memory 43 CPU 44 Synchronization Generation Circuit

Claims (1)

Claim: What is claimed is: 1. A display for displaying an image at predetermined horizontal and vertical scanning frequencies, and a frequency of at least a vertical scanning frequency of the horizontal and vertical scanning frequencies different from the vertical scanning frequency of the display. And a video camera that captures an image displayed on the display, and a controller that discards image data captured by the video camera for a period corresponding to a difference in vertical scanning frequency between the display and the video camera. Display photography device.