JPS63174490A - Video movement detecting device - Google Patents

Abstract

PURPOSE:To obtain a detecting device capable of real time detection with simple constitution and without omission in time by A/D converting a video signal to store every certain period and comparing the stored contents with a new A/D converted output. CONSTITUTION:The video signal 2 from a video camera 1 is converted into a digital signal by an A/D converter 3. The digital video signal is stored in a reference video memory 5 by gating a gate circuit 4 which opens every certain period, for instance, every five fields. The reference video memory 5 always outputs the digital signal to a comparator 6. Meanwhile, the A/D converter 3 always outputs new video as a digital signal to the comparator 6, so that the comparator 6 compares (subtracts) both digital signals and outputs a movement detection signal 7 if the compared result shows the difference between them is more than a certain value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video motion detection device used for security systems, sports scene analysis, and the like.

[Prior Art] As a conventional motion detection device, there is a video motion detection method in which a video camera image is converted into an electrical signal and then motion is detected. This will be explained with reference to FIG. In the same figure, (1
) is a video camera, (3) is an A/D converter that converts the video signal (2) from the video camera (1) into a digital signal, (4) is a first gate circuit that opens at regular intervals, (5) is a reference video memory, (8) is a second gate circuit that opens at regular intervals, (8) is a comparison video memory,
(10) is an arithmetic device such as a microcomputer that compares the outputs from the two memories (5) and (8) and outputs a motion detection signal (7).

Next, the operation of the conventional video motion detection device described above will be explained.

An image is converted into a video signal (2) by a video camera (1), and the video signal is converted into a digital signal by an A/D converter (3). The first gate circuit (4) is opened at regular intervals and the digital signal is stored in the reference video memory (5). Similarly, the second gate circuit (8) is opened at regular intervals, and the second digital signal is also stored in the comparison video memory (8). These two video memories (5), (
9) is input to the arithmetic unit (10), and if there is a difference of -h above a certain value, the arithmetic unit (10) outputs a motion detection signal (7).

[Problems to be solved by the invention] In the conventional video motion detection device, the video memory (5),
Since the comparison of the outputs in step (9) was performed using an arithmetic unit (10) such as a microcomputer, the comparison operation took time. The time series is shown in FIG. In other words, the memory for two images (5), the reference image and the comparison image;
(!3) is required, which poses problems such as making the device large-scale. Moreover, there is a problem that motion cannot be detected during the calculation time of the calculation device (10). Furthermore, if the update of the reference image is set for a long time, there is a problem that shadows from the sun may be detected.

This invention was made to solve the above-mentioned problems, and is a video motion detection system that has a simple configuration, can perform time-wise and complete detection, and can prevent malfunctions caused by sunlight, etc. The purpose is to provide equipment.

[Means for Solving the Problems] The video motion detection device according to the present invention stores a reference video output from an A/D converter that converts a video signal into a digital signal at regular intervals via a gate circuit. It is provided with a memory and a comparator that compares the output from the A/D converter with the stored contents of the reference video memory.

[Function] The video motion detection device according to the present invention does not require a comparison video memory, has a simplified configuration, and can compare the stored contents of the reference video memory and the output from the A/D converter without using an arithmetic device. Since this is done on a device, it is a real-time (immediate processing) video comparison, and a time-wise and complete detection operation can be obtained.
Furthermore, the degree of freedom in timing of updating the reference video memory is limited.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an example of a video motion detection device according to the present invention, and the same parts as those in the conventional device are denoted by the same reference numerals, and a description thereof will be omitted.

In the figure, (6) is a comparator that compares the output from the A/D converter (3) and the memory contents of the reference video memory (5), and if there is a difference of more than a certain value, motion is detected. The signal (7) is sent out.

Next, the operation will be explained.

An image is converted into a video signal (2) by a video camera (1), and roughly converted from an analog signal to a digital signal by an A/D converter (3). Here, since the gate circuit (4) is opened at regular intervals, for example every five fields as shown in FIG. 2, the digital signal is stored in the reference video memory (5). A digital signal is constantly output from this reference video memory (5) to a comparator (6). On the other hand, A/
A new image is always output from the D converter (3) to the comparator (6) as a digital signal. A comparator (6) compares (subtracts) both digital signals and outputs a motion detection signal (7) if there is a difference of more than a certain value.

Here, the digital signal from the reference video memory (5) and the digital signal from the A/D converter (3) are compared using a hardware comparator (6) without using an arithmetic device such as a microcomputer. and one memory (5
) only need to be prepared, which simplifies the configuration. In particular, since no calculation time is required for the above comparison, video images are compared every field, and detection operations can be performed without any temporal omission.

Further, the timing of updating the reference video memory (5) can be changed depending on the purpose. For example, if the update interval is set long, it will be possible to detect not only fast movements but also slow movements; conversely, if the update interval is set short, very slow brightness changes such as shadows from the sun may be falsely detected. can be avoided.

In the above embodiment, a device that inputs a video signal from a video camera (1) was explained, but it can also be applied to a device that inputs a signal from a general television receiver or a video tape recorder and analyzes video motion. can also be used.

Furthermore, the motion detection signal (7) can be used as image information for each pixel, and can also be used to emit a signal only when the sum of detected pixels exceeds a certain number.

[Effects of the Invention] As described above, according to the present invention, the output from the A/D converter for converting a video signal into a digital signal and the output from the A/D converter are stored at regular intervals from the reference video memory. Because the output is compared with the output of
In addition to simplifying the configuration, since images can be compared every field, a detection device with no omissions in time can be obtained, and furthermore, there are advantages such as greater flexibility in the timing of updating the reference image memory.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a video motion detection device according to an embodiment of the present invention, FIG. 2 is a time series diagram showing how motion detection is performed by the device of the present invention, and FIG. 3 is a block diagram of a conventional video motion detection device. FIG. 4 is a block diagram showing the configuration and a time sequence diagram showing the state of motion detection in the conventional device. (2)...Video signal, (3)...A/D converter, (
4)...Gate circuit, (5)...Reference video memory,
(6)... Comparator. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) An A/D converter that converts a video signal into a digital signal, a reference video memory that stores the output from the A/D converter at regular intervals via a gate circuit, and a A video motion detection device comprising: a comparator that compares the output of the reference video memory with the stored content of the reference video memory and outputs a motion detection signal if there is a difference.