JPH0535247A - Masked picture generation system - Google Patents

Abstract

PURPOSE:To speedily obtain a clear image by generating no noise when a masked picture for discriminating between a picture generated by a work station, etc., and a part where an external image signal is to be inserted is rewritten. CONSTITUTION:A multi-window display method which inserts the external image signal into a multi-window picture is equipped with bit map memories 9 and 10 stored with the masked picture for discriminating between the part where the external image signal is inserted and the multi-window picture and also equipped with a switching circuit 6 which puts the two bit map memories in alternate writing and reading operation so that while one memory is in writing operation, the other is in reading operation and a changeover switch 8 which switches the outputs of the two bit map memories 9 and 10; and no picture noise is generated on the output side of the changeover switch 8 at the time of bit map rewriting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applicable to video terminals such as workstations, personal computers and CRTs.
The present invention relates to a multi-window display system in which image information from the outside such as a V camera is combined via a video signal.

[0002]

2. Description of the Related Art In the conventional multi-window display system of this type, external image information of a TV camera or the like is taken into a video terminal such as a workstation control unit, combined in an image memory inside the video terminal, and then displayed in a multi-window display. 3 (a) and the final video signal of a video terminal such as a workstation, which is combined with external image information by an external window synthesizing device and is then returned to the video terminal as the synthesized video signal. Figure 3
There is a multi-window method of (b).

[0003]

In the former case, there is a drawback that the control software becomes complicated because all the image synthesis is under the control of workstations and the like.

In the latter case, the window composition is not under the control of workstations and the like, so that the control software is simple. However, in order to determine the display priority between the internal and external image windows, one of the external image signals is used. You need a mask screen to mask parts. Hereinafter, it will be described with reference to FIG. 5 that a window screen having a priority order of an internal window and an external image window is synthesized by creating a mask screen. In FIG. 5A, it is assumed that two images are prioritized on the window screen by the external image signal.
FIG. 5B is a window screen created by a workstation or the like. If you want to compose this screen so that it will interrupt the two images in (a) above,
When a mask screen as shown in (c) is created and the screen in (a) is masked by the shaded area and is combined with the screen in (b), the finally obtained image in (d) is obtained. That is, the size of the window at the X and Y positions of the window and the priority information for determining which screen is upper or lower are sent to the external window synthesizing device to create a mask screen and synthesize the window screen easily. can get.

However, in this latter case, since the window composition is not under the control of the workstation, etc., the display execution speed of the external window compositing device must be faster than the display execution speed of the multi-window created by the workstation etc. by itself. There is a drawback that the final image after combining looks unnatural temporarily. Further, there is a drawback that screen noise at the time of window composition appears as shown in FIG. 4 when the composition speed is increased.

An object of the present invention is to prevent noise when rewriting a mask screen for distinguishing a screen created by a workstation or the like and a portion into which an external image signal is inserted in the latter method described above. It is to provide a mask screen generation method capable of obtaining a clear image at high speed.

[0007]

In order to solve this problem, the present invention has two sets of bitmap memory for storing a mask screen, and a window information group for creating a target multi-screen sent from a workstation or the like. For each group, one of the bitmap memories is the rewriting target and the other is the reading target. That is, when the window information is transmitted and the bitmap memory is being rewritten, the mask information is read from the other bitmap memory, and the reading is switched to the rewritten bitmap memory at the end of the information group. In order to realize this means, it is composed of two sets of bitmap memories, a switching control circuit for receiving and switching the end of the information group from the microcomputer, and a switch for switching each output of the above two sets of bitmap memories. Is characterized by.

[0008]

According to this structure, while one bit map memory is being rewritten, the other bit map memory that has already been rewritten is read, and at the end of rewriting, the target mask image is instantly displayed. And the screen noise at the time of rewriting is completely eliminated. Further, in the raster scan type display device, the screen noise can be erased quickly and easily without using a method of reducing the screen noise during the blanking period or during rewriting such as cycle stealing.

[0009]

The present invention will be described in detail below. FIG. 1 shows an embodiment of the present invention, in which 1 is a bit map memory 9, 1.
0 address input, 2 read / write of memory 9
te (R / W) enable / disable enable signals 2 and 3 enable / disable R / W of the memory 9
The enable signals 3 and 4 for controlling the ON / OFF are R / W signals of the bit map memories 9 and 10, 5 is a command group end signal indicating the end of mask screen rewriting, and 6 is an enable signal from the command group end signal 5 and switch switching. It is a switching control circuit for producing the signal 7.

FIG. 2A shows a concrete circuit example of the switching control circuit 6, which is a D-flip-flop 6-1 which changes its state by the command group end signal 5.

Next, the operation will be described. An address designating a bitmap position and data designating masking / non-masking are inputted from a microcomputer or the like into a bitmap memory for storing a mask screen. At this time, which of the bit map memories 9 and 10 is to be written is determined by the enable signals 2 and 3 generated from the switching control circuit 6.
Selected by. Further, which output of the bit map memory 9 or 10 is to be output to the display circuit is selected by the output state of the flip-flop 6-1 in the switching control circuit 6. Explaining with the timing chart of FIG. 2B, when the output of the flip-flop 6-1 is at “H” level, the enable signal 2 is a valid signal “H”,
The enable signal 3 becomes the invalid signal “L”. The switching signal 7 for inverting its state by the command group end signal 5 is the same signal as the enable signal 2, and when "H", the output of the bitmap memory 10 is valid, and when "L", the output of the bitmap memory 9 is valid. Validate.

Therefore, while the mask screen is being created, that is, during the rewriting, another mask screen is output and the newly created screen is displayed at the end of the rewriting, thereby eliminating the screen noise generated when the mask screen is rewritten. can do.

[0013]

As described above, according to the present invention, when application software that frequently rewrites a multi-window screen on a workstation is operated, there is no screen noise at the time of rewriting. There are advantages such as smooth movement.

[Brief description of drawings]

FIG. 1 is a mask screen generation circuit of an embodiment of the device of the present invention.

FIG. 2 is a timing chart showing an example of a switching control circuit used in the present invention and its operation.

FIG. 3 is an explanatory diagram of a conventional multi-window display method.

FIG. 4 is an example of screen noise during mask screen creation by a conventional method.

FIG. 5 is a diagram showing a screen creation procedure of a conventional multi-window display method.

[Explanation of symbols]

 1 Address input 2, 3 Enable signal 4 R / W signal 5 Command group end signal 6 Switching control circuit 6-1 Flip-flop 7 Switching signal 8 Switching switch 9, 10 Bitmap memory

Claims (1)

Claim: What is claimed is: 1. In a multi-window display method for embedding an external image signal in a multi-window screen, a mask screen for distinguishing from the multi-window screen is stored in a portion in which the external image signal is embedded. And a switching circuit for controlling writing and reading alternately so that one of the two sets of bit map memories is read when the other is written, and the two sets of bit map memories. A mask screen generation method, comprising: a changeover switch for switching each output of the bitmap memory so that screen noise does not appear at the output side of the changeover switch when the bitmap memory is rewritten.