JPS63217786A - Image recorder - Google Patents

Abstract

PURPOSE:To record only at the time of having a difference from a previous value and to reduce the storage capacity of a main recording part by temporarily recording an image pickup picture signal as the previous value in a sub-recording part, comparing the image signal of this sub-recording part with the subsequently image pickup image signal and recording a video signal having the difference according to the comparison result in the main recording part. CONSTITUTION:The video signal 1 image picked up by a monitor camera or the like is guided to the comparison input of a comparator 7 and guided to the sub-recording part 5 and the main recording part 12 respectively through switches 4, 6. The picture signal of the sub-recording part 5 is added to the reference input of the circuit 7 and the output of the circuit 7 is inputted to a control part 2. A synchronizing signal extracted from a synchronizing extracting circuit 13 is inputted to this control part 2, and the reading of the switches 4, 6 and the sub-recording part 5 is controlled by the control part 2. The image picked up picture signal by the sub-recording part 5 is temporarily recorded as the previous value, this recorded image signal is compared with the subsequently image picked up image signal, the image signal is in which the difference is generated according to the comparison result is recorded in the main recording part 12 and the capacity is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image recording device, and particularly to an image recording device for a surveillance camera device used for crime prevention and the like.

〔overview〕

The present invention provides an apparatus for recording images captured by a surveillance camera or the like, which compares an image signal captured previously with an image signal captured later, and records a change in the recording section when a change occurs. This reduces the capacity of the recording section and shortens the required image playback time.

[Conventional technology]

BACKGROUND ART Conventionally, all image signals captured by a surveillance camera device such as a security camera within a certain period of time are recorded.

[Problem that the invention seeks to solve]

In the conventional image recording apparatus described above, all image signals captured within a certain period of time are recorded, so all image signals that do not change are also recorded, and the recording unit requires a large-capacity recording medium. Furthermore, when reproducing the recorded images, the same images continued without any change, and the observer needed a lot of time to extract the necessary images. Furthermore, there is a problem in that the recording time of image signals is restricted due to wasteful recording.

The present invention provides image recording that reduces the capacity of the recording section and shortens the image playback time by comparing the image signal taken before and the image signal taken later, and recording if there is a change. The purpose is to provide equipment.

[Means for solving problems]

The present invention provides an image recording device that records a captured image signal in a main memory, including a sub-recording section that temporarily records the captured image signal as a previous value, and a sub-recording section that records the captured image signal as a previous value. Il# is provided with a comparison circuit that compares the captured image signal and a control means that causes the main recording section to record an image signal that has a difference as a result of the comparison result of the comparison circuit.

[Effect]

The captured image signal is once recorded in the sub-recording section as a previous value. Next, the captured image signal is compared with the previous image signal recorded in this sub-recording section, and if a change has appeared, the currently captured image signal is recorded in the main recording section.

As a result, only the image signal when a change occurs is recorded in the main recording section.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

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

The captured image signal 1 is guided to a comparison input of a comparison circuit 7, and is also guided to a sub recording section 5 via a switch 4 and to a main recording section 12 via a switch 6.

The image signal of the sub-recording section 5 is given to the reference input of the comparison circuit 7, and the output of the comparison circuit 7 is given to the control section 2.

A synchronization signal extracted by the synchronization extraction circuit 13 is input to the control section 2, and the control section 2 also inputs the synchronization signal extracted by the synchronization extraction circuit 13.
The output signal controls the switch 4 that guides the input image signal to the sub-recording section 5, the switch 6 that guides the input image signal to the main recording section 12, and the reading of the sub-recording section 5.

The sub-recording section 5 is composed of a memory having a capacity capable of storing at least one frame's worth of image signals, and the stored image signals are read out in synchronization with the image signals input later by a control signal 8 from the control section 2. and is applied to the comparator circuit 7.

Further, the comparison circuit 7 is capable of comparing, pixel by pixel, the previous value image signal stored in the sub-recording section 5 and the later value image signal inputted later, using a well-known image processing technique. The image signals of the front value and the rear value are compared to detect the difference between the two images. This pixel comparison can be performed by arranging comparators in parallel to compare a plurality of pixels at the same time.

Next, the operation of the embodiment of the present invention will be explained.

First, when recording the previous value in the sub-recording section 5, the switch 4 is closed by the control signal 3 output from the control section 2, and the input image signal is recorded in the sub-recording section 5. At this time, the switch 6 is in an open state, and no image signal is recorded in the main recording section 12. After the image signal is recorded in the sub-recording section 5,
Switch 4 is in an open state. The image signal recorded in this sub-recording section 5 becomes the previous value, is read out in synchronization with the image signal captured later by the control signal 8 of the control section 2, and is guided to the comparison circuit 7.

The image signal captured later is guided to the comparison circuit 7, and compared in units of corresponding pixels with the image signal of the previous value read out in synchronization from the sub-recording section 5, and it is determined whether a difference has occurred. When a difference occurs, a signal 10 is output to the control section 2.

When the control section 2 receives the signal 10 indicating that a difference has occurred between the previous value and the subsequent value, it closes the switch 6 using the control signal 11 and outputs an image signal of the subsequent value to the main recording section 12. and record it. In this case, the determination of whether or not a difference has occurred is made not only based on a difference in one pixel, but also when a difference occurs in several consecutive screens or when a difference occurs over several pixels in the main record. It is preferable to record it in the unit 12 and not record slight differences such as those caused by superimposition of noise.

FIG. 2 shows an example of an image recorded in the sub-recording unit 5 using the previous value, and FIG. 3 shows an example of an image recorded in the main recording unit 12 by transplantation. In FIG. 2, only a desk 15 is recorded on the screen 14, but in FIG. 3, a desk 15 and a person 17 are recorded on the screen 16. In this way, since there is a difference between the screen 14 and the screen 16 in the presence or absence of the person 17, the screen 16 is recorded in the main recording section 12 by the judgment detection of the comparison circuit 7.

The transplanted image signal, which has changed from the previous value in this way, is recorded in the main recording section 12, but at the same time, the control section 2 controls the switch 4 to record this image signal in the sub-recording section 5. ,
The previously recorded image signal is updated to the previous value.

In surveillance camera devices such as security cameras, there are many cases in which the captured images do not change much, and the same image is captured over a long period of time, so the capacity of the main recording section can be reduced.

Although the present embodiment is configured as described above, as shown in FIG. The switch 6 is closed each time a change is detected by the control signal 11, and the image signal is recorded in the main recording section 12, and this main recording section is used to record the image signal using an analog signal such as a video tape recorder. The device may record only images that have changed with respect to the previous value. In this case, the main recording section does not convert it into an analog signal and record it.

Further, although the synchronization signal is extracted separately from the image signal by the synchronization extraction circuit 13, it may be extracted from the image signal.

〔Effect of the invention〕

As explained above, the present invention calculates the difference between the image signal captured previously and the image signal captured later, and when a change occurs, outputs the image signal captured later to the recording section to generate an image signal. (Only the necessary images can be recorded, and the time required to extract the necessary images can be significantly shortened using a recording device with a small recording capacity.)

Particularly in a surveillance camera device that takes images with little change, the effect of reducing the capacity of its recording section is significant.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. Figure 2 is an example of an image of the recorded previous value. Figure 3 shows an example of a recorded transplant image. FIG. 4 is a block diagram showing another embodiment of the present invention. 1... Image signal, 2... Control unit, 3.8.11...
・Control signal, 4.6...Switch, 5...Sub-recording section, 7...Comparison circuit, 9...Previous value signal, 10...
Signal, 12... Main recording section, 13... Synchronization extraction circuit,
18...AD conversion circuit. Patent Applicant NEC Corporation 1 - Agent Patent Attorney Naotaka IdeExample Figure 1

Claims (1)

[Claims] (1) In an image recording device that records captured image signals in a main memory, there is a sub-recording unit that temporarily records the captured image signal as a previous value, and a sub-recording unit that records the image signal recorded in this sub-recording unit and a subsequent image. 1. An image recording apparatus comprising: a comparison circuit for comparing the image signals obtained by the comparison circuit; and a control means for causing the main recording section to record an image signal that has a difference based on the comparison result of the comparison circuit.