JPH04330897A - Display photographing device - Google Patents

Abstract

PURPOSE:To photograph the image on a display with a video camera having the different vertical scanning frequency. CONSTITUTION:By a video camera 2, an image displayed on a CRT 13 is photographed. In a memory 42, the data corresponding to the difference between the vertical scanning frequency to drive the video camera 2 and the vertical scanning frequency to drive the CRT 13 are stored and during the period corresponding to the difference, a blanking signal is supplied to a video signal generating circuit 12. Thus, on the CRT 13, the display of the image corresponding to the period is prohibited.

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, for example, in measuring the brightness of a television receiver.

0002

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

Incidentally, in computer displays, the vertical scanning frequency is often set in a high range of 60 Hz or more. Images displayed on a computer display like this can be converted to NTSC.
When shooting with a PAL or PAL video camera,
Since the vertical scanning frequency is not synchronized, flickering occurs in the image, making image processing difficult.

To explain this flickering with reference to FIG. 3, the vertical scanning frequency of the video camera is now 60
Hz, and the vertical scanning frequency for computer display is 80Hz, each vertical scanning period is as shown in Fig. 3(a).
) and (b). That is, before the video camera has completed capturing one field of images, the next field of images will be displayed on the display. Assuming that images A to G as shown in FIG. 3(c) are displayed on the display corresponding to fields A to G in FIG. 3(b), the images captured by the video camera are as shown in FIG. 3(d).

That is, in the first field of the video camera (FIG. 3(a)), 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. Image B1 up to the end portion is displayed on the display following image A. Therefore, in the first field of the video camera, image B1 is captured following image A.

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

[0007] Thereafter, images will be similarly photographed in the third to fifth fields.

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

[0009]

[Problems to be Solved by the Invention] Conventional devices do not synchronize the vertical scanning frequencies of the display and the video camera when capturing the image displayed on the display with a video camera, so it is difficult to measure the display. There was a risk that it would cause problems.

[0010] The present invention has been made in view of the above situation, and it is an object of the present invention to enable accurate measurement of the brightness of the display even when the vertical scanning frequencies of the display and the video camera are different. be.

[0011]

[Means for Solving the Problems] A display photographing device of the present invention includes a display that displays an image at a predetermined horizontal and vertical scanning frequency, and at least a vertical scanning frequency of the horizontal and vertical scanning frequencies that corresponds to the vertical scanning frequency of the display. A video camera that captures the image being displayed on the display at a frequency different from the frequency, and a period for the difference in vertical scanning frequency between the display and the video camera, prohibiting the display of the image on the display, or prohibiting the display of the image by the video camera. The invention is characterized by comprising a controller that prohibits.

0012

[Operation] In the display photographing device with the above configuration,
Displaying images on the display or capturing images with the video camera is prohibited for a period corresponding to the difference in vertical scanning frequency between the display and the video camera. Therefore, it is possible to accurately photograph the brightness and the like on the display.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the structure of an embodiment of a display photographing apparatus according to the present invention. The display photographing device of this embodiment includes a display 1 that displays images to be photographed, a video camera 2 that photographs images displayed on the display 1, a measuring device 3 that processes images photographed by the video camera 2, and , this display 1
and a controller 4 that controls the video camera 2.

The display 1 outputs and displays the video signal output from the video signal generating circuit 12 on the CRT 13. The video signal generation circuit 12 is capable of generating a video signal in response to a synchronization signal input from the external synchronization signal input terminal 11.

The video camera 2 is configured to take an image displayed on the display 1 in synchronization with a synchronization signal inputted from an external synchronization signal input terminal 21, and output the image to the measurement device 3. There is.

The measuring device 3 includes a memory 31 that stores video data input from the video camera 2, and an arithmetic unit 32 that processes the data stored in the memory 31.

On the other hand, the controller 4 includes a synchronization generation circuit 40 that generates a synchronization signal to be supplied to the video camera 2, an address counter 41 that counts horizontal synchronization signals output from the synchronization generation circuit 40, and an address counter 41 that receives input from the address counter 41. Memory (R) that outputs data corresponding to the address
AM) 42, a CPU 43 that sets a predetermined count value in the address counter 41 and stores predetermined data in the memory 42, and a synchronization generation circuit that generates a composite synchronization signal (composite blanking signal) to be supplied to the display 1. 45, memory 42 and synchronization generation circuit 4
5 and a NOR gate 44 that supplies the signal input from 5 to the external synchronization signal input terminal 11 of the display 1.

Next, the operation will be explained with reference to the timing chart of FIG. The horizontal and vertical blanking PAL signals output from the synchronization generation circuit 45 are sent to the NOR gate 4.
4 to the video signal generating 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 PAL signals 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 synchronization signals output from the synchronization generation circuit 40 are supplied to the video camera 2, and the video camera 2 photographs the image displayed on the CRT 13 in synchronization with the synchronization signals. Images taken by the video camera 2 are supplied to the measuring device 3 and stored in its memory 31. The arithmetic unit 32 processes the data stored in the memory 31 and measures the characteristics of the CRT 13.

On the other hand, the CPU 43 stores in the memory 42 data corresponding to the difference between the vertical scanning frequency that the synchronization generating circuit 40 supplies to the video camera 2 and the vertical scanning frequency that the synchronization generating circuit 45 supplies to the display 1. That is,
As shown in FIG. 2(c), the memory 42 stores information indicating that the vertical scanning period of the video camera 2 (FIG. 2(a)) and the vertical scanning period of the display 1 (FIG. 2(b)) have started at the same time. Data that becomes logic H is stored while the vertical scanning period of the display 1 continues, and data that becomes logic L is stored for the period after the vertical scanning period of the display 1 ends until the vertical scanning period of the video camera 2 ends. ing.

The address counter 41 is connected to the synchronization generating circuit 40.
The horizontal synchronization signal inputted from the controller 42 is counted, and an address corresponding to the count value is output to the memory 42. The count value of the address counter 41 is reset by the synchronization generation circuit 40 every time a vertical synchronization signal is input. As a result, as shown in FIG. 2(c), the memory 42 outputs a signal that becomes logic H during the vertical scanning period of the display 1 and becomes logic L during a period corresponding to the difference between the vertical scanning periods of the display 1 and the video camera 2. , is output to the NOR gate 44.

The output of the NOR gate 44 is displayed on the display 1.
The blanking signal is input to the video signal generating circuit 12 via the external synchronizing signal input terminal 11 of the blanking signal. Therefore, the video signal generation circuit 12 does not display an image on the CRT 13 when a logic L signal is input from the memory 42. The resulting image displayed on the CRT 13 is shown in Figure 2 (
d).

That is, for example, in field A of fields A to G shown in FIG. 2(b), the signal for inhibiting double exposure (FIG. 2(c)) is not generated from the memory 42 during that time. Therefore, image A corresponding to field A is displayed on the CRT 13 as is.

On the other hand, in the B field, the double exposure prohibition signal (FIG. 2(c)) is generated in the first section, so the section of this double exposure prohibition signal in the image B in the B field The image B1 corresponding to
3 is not displayed. Then, the image B2 in the remaining section is displayed on the CRT 13.

Similarly, in FIG. 2(c), the image in the period indicated by logical L is not displayed on the CRT 13 (FIG. 2(d)).

As a result, the image actually captured by the video camera 2 is as shown in FIG. 2(e). For example, in the first field, image A is captured as is. However, since the image B1 is not displayed on the CRT 13, it is not captured. Next, in the second field, the image B2 in the B field is first imaged, and then, among the images in the C field, the image C1 in the period until the double exposure prohibition signal is generated is imaged.

Similarly, the range of images actually captured by the video camera 2 is essentially only the image of one field period on the display 1. Therefore,
The output of the video camera 2 is as shown in FIG.
It is constant in each field from field to fifth field. As a result, it is possible to prevent the measurement device 3 from erroneously measuring, for example, brightness.

In the above description, the display 1 is controlled by the double exposure prohibition signal, but the video camera 2 may also be controlled.

[0029]

As described above, according to the display photographing device of the present invention, the display of images on the display or the video camera is prohibited for a period corresponding to the difference in vertical scanning frequency between the display and the video camera. This makes it possible to accurately measure the characteristics of the display using the output of the video camera.

[Brief explanation of drawings]

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

[Fig. 2] Timing chart explaining the operation of the embodiment shown in Fig. 1.

[Fig. 3] Timing chart illustrating problems in conventional display photographing devices

[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 Noah Gate 45 Synchronization generation circuit

Claims (1)

[Claims] 1. A display that displays an image at a predetermined horizontal and vertical scanning frequency; and a display that displays an image at a frequency in which at least the vertical scanning frequency among the horizontal and vertical scanning frequencies is different from the vertical scanning frequency of the display. and a controller that prohibits display of the image on the display or prohibits the video camera from capturing an image during a period corresponding to a difference in vertical scanning frequency between the display and the video camera. A display photographing device characterized by: