JPS63283369A - Picture memory device - Google Patents

Abstract

PURPOSE:To enlarge a special effect function by D/A converting one of the output digital signal of a first and a second storing means according to the selecting state of a selecting means. CONSTITUTION:In the first memory 2, only the high order m bits of a digital video signal of n bits are stored and in the second memory 4, only the high order m bits or low order (n-m) bits are selectively stored. At least one of the digital video signals read from the first and the second memories 2, 4 is D/A converted. Accordingly, the contents of the storage of the second memory 4 can be arbitrarily set. Thereby, in order to obtain a special effect having a solarization effect, the memory can be effectively used.

Description

[Detailed description of the invention] Technical field The present invention relates to an image memory device for storing video signals.

BACKGROUND ART Recently, in video tape recorders, video disc players, etc., video signals are A/D-converted and written into a memory storage location corresponding to the position of the video signal on the screen, and the stored contents of the memory are read out and converted into D. Some devices are equipped with an image memory device that performs /A conversion and outputs the image. By using such an image memory device, special effects such as solarization effects can be easily produced on the playback screen.

However, conventional image memory devices have the disadvantage that the memory is not used effectively. For example, when a video signal is converted into a 6-bit digital signal, during normal playback, the 6-bit digital signal is written to the memory and the 6-bit digital signal is read from the memory. However, in order to obtain the solarization effect, only the upper 2 or 3 bits of the 6-bit digital signal are written to the memory, and the digital signal corresponding to the number of written bits is read out, so the memory location for the lower bits is is not used.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image memory device that uses memory effectively to expand special effect functions.

The image memory device of the present invention includes A/D converting means for A/D converting an input video signal into an n-bit digital signal;
a first storage means for storing the upper m-bit digital video signal of the n-bit digital video signal outputted from the /D conversion means and outputting the stored contents;
a selection means for selecting one of a digital video signal of bits and a digital video signal of lower (nm) bits of the n-bit digital video signal, and a digital video signal selected by the selection means is stored. and a second storage means for outputting the stored contents in synchronization with the output operation of the first storage means, and a D/A converter for at least one of the output digital signals of the first and second storage means according to the selection state of the selection means. It is characterized by comprising a D/A conversion means for converting the data.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the image memory device shown in FIG. 1, which is an embodiment of the present invention, an input video signal is converted into an 8-bit digital signal by an A/D converter 1 at a predetermined timing. A
The output of the upper 4 bits of the /D converter 1 is supplied to the first memory 2. Further, the output of the upper 4 bits and the output of the lower 4 bits of the A/D converter 1 are selectively supplied to the second memory 4 by the switch 3. The switch 3 is switched in synchronization with the write timing of the memory 2.4. Writing and reading of the first and second memories 2 and 4 are controlled by a memory control circuit 5.

The first and second memories 2 and 4 have storage locations for one field of the video signal. The read digital video signal from the first memory 2 is supplied to the 8-bit D/A converter 6 as the upper 4 bit input signal, and the read digital video signal from the second memory 4 is supplied to the switch 7.8.

Switch 7.8 is a four-circuit, two-contact changeover switch,
This corresponds to switching of the switch 3, and is switched in synchronization with the read timing of the memories 2 and 4. The switch 7 selectively supplies either the read digital video signal of the second memory 4 or the 4-bit signal at ground potential to the D/A converter 6 as a lower 4-bit input signal, and the switch 8 One of the 4-bit read digital video signal and the 4-bit signal at ground potential is supplied to a 4-bit D/A converter 9. The respective output signals of the D/A converters 6 and 9 are added by an adder 10 and output. Note that the switch 7.8 and the D/A converter 6.9 form a D/A conversion means.

In the image memory device according to the present invention having such a configuration,
First to third switches3. When 7.8 is the selected position a, the upper 4 bits of the 8-bit output digital video signal of the A/D converter 1 are supplied to the first memory 2 and written, and the upper 4 bits of the 8-bit output digital video signal of the A/D converter 1 are The lower four bits are supplied to the second memory 4 via the switch 3 and written therein. The memory control circuit 5 generates a write command pulse to the first and second memories 2.4 according to the horizontal and vertical synchronization signals of the input video signal, and the write command pulse causes the first and second memories 2.4 to write. Each supplied 4-bit digital video signal is sequentially written at a predetermined timing.

The storage positions of the first and second memories 2.4 are changed and designated by an address counter (not shown) every time a write command pulse is generated, and correspond to the position of the video signal on the screen. Immediately after the write command pulse disappears, a read command pulse is generated to the first and second memories 2.4, and the contents (4 and the data) of the storage location specified according to the output of the address counter are read out. . The 4-bit digital video signal read from the first memory 2 is supplied to the D/A converter 6 as an upper 4-bit signal,
The 4-bit digital video signal read from the second memory 4 is supplied via the switch 7 to the D/A converter 6 as a lower 4-bit signal. Therefore, an 8-bit precision video signal is output from the D/A converter 6. On the other hand, D/A
Since the ground potential is supplied from the switch 8 to the input of the converter 8, a DC component corresponding to the 0 level input of the analog video signal is generated at the output of the D/A converter 8.

This DC component and the output signal of the D/A converter 6 are combined into an adder 1
0 is added, and the adder 10 outputs a video signal substantially equal to the input video signal.

Next, the first to third switches 3. If 7.8 is the selected position, the upper 4 bits of the 8-bit output digital video signal of the A/D converter 1 are stored in the first memory 2.
The upper 4 bits are supplied to the second memory 4 via the switch 3 and written in response to the write command pulse. The contents written in the first and second memories 2.4 are read out in response to a read command pulse, and
The 4-bit digital video signal read from the D/
The 4-bit digital video signal, which is supplied as the upper 4-bit signal to the A converter 6 and read from the second memory 4, is supplied to the D/A converter 9 via the switch 8. D
Since the ground potential is supplied from the switch 7 to the input of the lower 4 bits of the /A converter 6, the D/A converter 6 outputs a 4-bit precision video signal with respect to the input video signal.
The D/A converter 9 also outputs the same 4-bit precision video signal as the D/A converter 6. Therefore, the output signal of the adder 10 also becomes a 4-bit precision video signal with respect to the input video signal, and a solarization effect can be obtained.

Next, when the first to third switches 3.7.8 are in the selection position, the memory control circuit 5 converts the digital video signal supplied to the first memory 2 into each field by operating a switching means (not shown). A write command pulse is generated to write all fields, and a write command pulse is generated to write only one field out of every four fields of the digital video signal supplied to the second memory 4. Further, the read command pulse is sent to the first and second memories 2.
4 occur at the same timing and in synchronization with writing to the first memory 2. Therefore, in the case of an input video signal that represents a different image for each field as shown in FIG. 2 (ω),
The first memory 2 causes the D/A converter 6 to output a video signal that is different for each field with 4-bit accuracy with respect to the input video signal. The D/A converter 9 outputs video signals representing different images for every four fields, as shown in FIG. Therefore, the output video signals of the D/A converters 6.9 are combined by the adder 10 to obtain a video signal having an afterimage effect representing an image as shown in FIG. 2(C).

In the embodiment of the present invention described above, the input video signal is converted into 8-bit digital data and the upper 4 bits are supplied to the first memory 2 and the lower 4 bits are supplied to the second memory 4, but the present invention is not limited to this. For example, the top 5 bits are
The lower 3 bits may be supplied to the second memory.

Also, the input video signal is not limited to 8 bits, but 6 bits.

The present invention can also be applied to devices that use 7-bit, 0-bit, or 9-bit digital data.

Further, in the embodiment of the present invention described above, the output video signals of the D/A converters 6 and 9 are added by the adder 10, but as shown in FIG. Alternatively, the output video signals may be output. In this case, the writing to the second memory 4 is stopped after one field has been written, and the switch 11 is changed as necessary while watching the image based on the video signal output from the D/A converter 6. 2 The image stored in the memory 4 can be displayed on the screen.

Further, as shown in FIG. 4, the outputs of the first and second memories 2.4 are supplied to the 8-bit input D/A converter 13 via the digital processing circuit 12, and the output of the D/A converter 13 is A single D/A converter may be sufficient as the output of this device. In this case, the digital processing circuit 12 processes the first and second signals at a digital level according to the mode control signal.
The outputs of the memories 2.4 may be added together and supplied to the D/A converter 13, or only the outputs of one of the first and second memories 2 and 4 may be supplied to the D/A converter 13 and the above-mentioned It is possible to obtain an operation similar to that shown in FIG.

Effects of the Invention As described above, in the image memory device of the present invention, the first storage means stores only the upper m bits of the n-bit digital video signal, and the second storage means stores the n-bit digital video signal. The upper m bits or the lower (n
-m) Since the bits are selectively stored and at least one of the digital video signals read from the first and second storage means is D/A converted, the storage contents of the second storage means can be arbitrarily set; Memory can be used effectively to obtain special effects accompanied by solarization effects. You can also combine images to create an afterimage effect, or convert 1 field memory into 2 field memories as needed.
Alternatively, since the 1 frame memory can be used as a 2 frame memory, it is easy to store an image for 1 field or 1 frame in the second storage means and read it out arbitrarily to obtain an image without adding memory. can do.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. FIG. 3 is a block diagram showing another embodiment of the present invention. Explanation of symbols of main parts 1... A/D converter 2.4... Memory 6, 9. 13...D/A converter 10...
・Adder

Claims (1)

[Claims] A/D conversion means for A/D converting an input video signal into an n-bit digital signal; and an upper m of the n-bit digital video signals output from the A/D conversion means.
a first storage means for storing a digital video signal of bits and outputting the stored contents; and a digital video of lower (n-m) bits of the upper m-bit digital video signal and the n-bit digital video signal. a second storage means for storing the digital video signal selected by the selection means and outputting the stored contents in synchronization with the output operation of the first storage means; , D/A conversion means for D/A converting at least one of the output digital signals of the first and second storage means according to the selection state of the selection means.