JPH04128879A - System for displaying image - Google Patents

Abstract

PURPOSE:To eliminate the flicker of a screen by displaying the image data of an odd number field only on an odd numberth scanning line and displaying the image data of an even number field only on an even numberth scanning line in a system that an NTSC video signal is displayed on a CRT display device whose scanning system is different. CONSTITUTION:The inputted NTSC signal is A/D-converted by an A/D converter 1 and discriminated by a field discrimination circuit 2 at the same time. When it is the odd number field, a switch for input data 3 is switched to an odd number field memory 4 and the image data is written in the memory 4. Simultaneously, a switch for output data 6 is switched to an even number field memory 5 and the image data is read out from the memory 5. On the other hand, when the inputted signal is the even number field, the image data is written in the memory 5 and the image data is read out from the memory 4. On the CRT display 12, the data from the memory 4 is displayed only on the odd numberth scanning line of the display screen and it is not displayed on the even numberth scanning line. On the other hand, the data from the memory 5 is displayed only on the even numberth scanning line and it is not displayed on the odd numberth scanning line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image display method, and particularly to an image display method for displaying NTSC video signals on CRT display devices having different scanning frequencies and scanning methods.

[Conventional technology]

A conventional example of this type of image display method will be explained with reference to the drawings.

FIG. 3 is a block diagram showing an example of a conventional image display method.

In Figure 3, the input NTSC video signal is A/D
The field of the input NTSC video signal is A/D converted by the converter 301, and the field of the input NTSC video signal is determined by the field determination circuit 302. If it is an odd field image signal, the input data switch 203 is sent to the odd field memory 304. At the same time, the output data switch 306 is switched to the even field memory 305, and the image data is transferred from the even field memory 305 to the CRT.
It is output to the D/A converter 311 in synchronization with the scanning frequency of the display 312.

On the other hand, when the input NTSC video signal is an even field signal, the input data switch 303 is switched to the even field memory 305, the image data is written to the even field memory 305, and at the same time, the output data The switch 306 is switched to the odd field memory 304 to transfer the image data from the odd field memory 304 to the D/D in synchronization with the scanning frequency of the CRT display 312.
Output to A converter 311.

By repeating the above-described operations alternately according to the fields of the input NTSC video signal, the NTSC video signal was displayed on the CRT display 312 with different scanning frequencies.

A display screen when displaying on a non-interlaced scanning CRT display using this type of conventional image display method will be described with reference to the drawings.

Figure 4 shows image data using the conventional method shown in Figure 3.
It is a figure which shows the process until it displays on the display screen of RT display.

In FIG. 4, image data of an odd field of an NTSC video signal is sequentially stored in an odd field memory 304 starting from the first scanning line, and similarly, image data of an even field is stored sequentially into an even field memory 305 starting from the first scanning line.

When displaying an image, the CRT display 312 uses non-interlaced scanning, so the image is displayed according to the scanning lines of the CRT.
Image display is performed by repeating an odd field display operation in which the image data in the odd field memory 304 is sequentially displayed and an even field display operation in which the image data in the even field memory 305 is sequentially displayed.

[Problem to be solved by the invention]

In the conventional image display method described above, image data of odd and even fields are alternately switched and displayed on a non-interlaced scanning CRT display. The first image data of the odd field of the NTSC signal and the first image data of the even field are displayed alternately on the second scanning line, and if the three image data are not significantly different, the field The drawback is that it appears to flicker in synchronization with the frequency.

[Means to solve the problem]

The image display method of the present invention includes an A/D converter that A/D converts an NTSC video signal, and an input data switch that outputs image data from the A/D converter to either a first or second data bus. a first image memory that stores odd fields of the image data input from the input data switch via the first data bus;
a second image memory for storing even fields of the image data inputted from the input data switch via the second data bus; and images from the first image memory and the second image memory. In an image display system having at least a D/A converter for D/A converting data, image data of an odd field of an input NTSC video signal is synchronized with the scanning frequency of the NTSC video signal and At the same time as writing to the image memory, even field image data is read out from the second image memory in synchronization with the scanning frequency of the CRT display device for display and displayed only on the even numbered scanning lines of the CRT display device. a first output control means for outputting the image data of the even field read out to the D/A converter; At the same time, the image data of the odd field is read out from the first image memory in synchronization with the scanning frequency of the CRT display device, and is displayed only on the odd scanning line of the CRT display device. a second output control means for outputting the image data of the odd field read out to the D/A converter; and an operation of the first and second output control means in synchronization with the field of the NTSC video signal. and switching means for alternately repeating the switching.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, this embodiment includes an A/D converter 1 that A/D converts an input NTSC video signal, a field discrimination circuit 2 that determines whether the input NTSC video signal is an odd field or an even field, An input data switch 3 that separates the image data from the A/D converter 1 into odd field image data and even field image data based on a discrimination signal from the field discrimination circuit 2; and an odd field memory 4 that stores the odd field image data. and,
an even field memory 5 that stores even field image data; a write address counter 7 that generates a write address for image data to the odd field memory 4 and even field memory 5 from an input NTSC video signal; and an input NTSC video signal. CR that displays video signals
T display 12, a display address counter 8 which synchronizes and generates a display address of the CRT display 12 at the same time as an address for reading image data from the odd field memory 4 and an even field is generated, and a write address counter 7 or a display address. An address switch 9 sends out switching of the address signal from the counter 8 based on a field discrimination signal, and a discrimination signal from the field discrimination circuit 2 separates the read image data from the odd field memory 4 and the even field memory 5. An output data switch 6, an output data switch 10 that turns on and off in synchronization with the discrimination signal of the field discrimination circuit 2 and the display signal of the display address counter 8, and image data from the odd field memory 4 and the even field memory 5. It is configured to include a D/A converter 11 for converting into an NTSC video signal.

FIG. 2 is a diagram showing the process of displaying image data on the display screen of a CRT display according to this embodiment.

Next, the operation of this embodiment will be explained.

The input NTSC video signal is A/D converted by the A/D converter 1, and at the same time, the field is discriminated by the field discrimination circuit 2. If it is an odd field, the input data switch 3 is switched to the odd field memory 4. , the write address counter 7 is switched to the odd field memory 4 by the address switch 9, and the image data from the A/D converter 1 is written to the odd field memory 4 in synchronization with the scanning frequency of the NTSC video signal. at the same time,
The output data switch 6 is switched to the even field memory 5, and the address switch 9 switches the display address counter 8.
is switched to the even field memory 5, and image data is read out from the even field memory 5 in synchronization with the scanning frequency of the CRT display 12.

On the other hand, when the input NTSC signal is an even field, the input data switch 3 is switched to the even field memory 5, the address switch 9 switches the write address counter 7 to the even field memory 5, and the A/D The image data from the converter 1 is written into the even field memory 5 in synchronization with the NTSC video signal. At the same time, the output data switch 6 is switched to the odd field memory 4, the address switch 9 switches the display address counter 8 to the odd field memory 4, and the CRT display 1 is switched to the odd field memory 4.
Image data is read out from the odd field memory 4 in synchronization with the scanning frequency of 2.

When the output image data is from the odd field memory 4, the output data switch 10 selects CR from the field discrimination signal and the address value of the display address counter 8.
Image data is output only to the odd-numbered scanning lines of the T display 12, while in the case of image data output from the even-numbered field memory 5, image data is output only to the even-numbered scanning lines of the CRT display 12. The image data output from the output data switch 10 is D/A converted by the D/A converter 11 and displayed on the CRT display 12.

Next, we will discuss the process of displaying image data on the display screen in the second section.
This will be explained using figures.

The case where the image is displayed on the non-interlaced scanning type CRT display 12 will be explained. The image data output from the odd field memory 4 is sent to the CRT display 1.
On the other hand, the image data output from the even field memory 5 is displayed only on the odd-numbered scanning lines of the display screen 201 of the CRT display 12, and is not displayed on the even-numbered scanning lines of the display screen 201 of the CRT display 12. This operation is repeated in synchronization with the field of the input NTSC video signal, such that only the grain scanning lines are displayed and the odd-numbered scanning lines are not displayed.

As a result, the image data in the odd field memory 4 and the image data in the even field memory 5 are not displayed on the same scanning line on the display screen 201.

〔Effect of the invention〕

As explained above, the present invention writes an NTSC video signal field by field into an odd field memory and an even field memory, and a non-interlace scanning type CRT.
When displayed on a display device, the image data in the odd field memory is displayed only on the odd numbered scanning lines of the CRT display device, and the image data in the even field memory is displayed only on the even numbered scanning lines of the CRT display device. By adopting the display configuration, different image data from the odd field memory and the even field memory are displayed on the same scanning line on the screen of the CRT display device, thereby eliminating the flickering of the display screen as in the past. There is an effect that can be done.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing the process of displaying image data according to this embodiment on the display screen of a CRT display, and Fig. 3 is a conventional image display method. FIG. 4 is a block diagram showing an example of the process of displaying image data on the display screen of a CRT display using the conventional method shown in FIG. 1.301... A/D converter, 2,302...
Field discrimination circuit, 3.303... Input data switch, 4,304... Odd field memory, 5゜30
5... Even field memory, 6,306... Output data switch, 7,307... Write address counter, 8,308... Display address counter, 9°309
...Address switch, 10...Output data switch, 11,311...D/A converter, 12゜312
・CRT display, 201,401...CRT
Display screen of display, 201a. 401a... Odd field display screen, 201b. 401b... Even field display screen.

Claims (1)

[Claims] An A/D converter that A/D converts an NTSC video signal, an input data switch that outputs image data from the A/D converter to either a first or second data bus, and the input data switch a first image memory that stores odd fields of the image data input from the input data switch via the first data bus; and a first image memory that stores odd fields of the image data input from the input data switch via the second data bus. An image display system comprising at least a second image memory for storing an even field of an input field, and a D/A converter for D/A converting image data from the first image memory and the second image memory. NTS
The image data of the odd field of the C video signal is transmitted to the NTS
At the same time, image data of an even field is written to the first image memory in synchronization with the scanning frequency of the C video signal, and at the same time, even field image data is read out from the second image memory in synchronization with the scanning frequency of the CRT display device to be displayed. a first output control means for outputting the even field image data read out to be displayed only on an even numbered scanning line of the CRT display device to the D/A converter; and the even field image data of the NTSC video signal. is written into the second image memory in synchronization with the scanning frequency of the NTSC video signal, and at the same time, reading odd field image data from the first image memory in synchronization with the scanning frequency of the CRT display device. a second output control means for outputting the image data of the odd field read out to be displayed only on the odd numbered scanning line of the CRT display device to the D/A converter; and switching means for alternately repeating the operations of the first and second output control means.