JPH11261967A - Image monitor system and decoder for its coding signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image monitor system where a frame memory is not required to multiplex an image signal, the received image signal is inexpensively multiplexed, the signal is recorded after compression coding and image quality deterioration of the input image signal is easily controlled at compression coding. SOLUTION: The image monitor system receiving a plurality of moving image signals is provided with a synchronizing signal generating section 108 that synchronizes the received image signals, a changeover section 103 that selects any of a plurality of input images based on a vertical synchronizing signal generated from the synchronizing signal generating section 108, a compression coding section 105 that applies inter-frame compression to the selected image signal and recording sections 106, 107 that record the compressed signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to MPEG2 (ISO
TECHNICAL FIELD The present invention relates to an image monitoring system for recording and transmitting a multi-input video signal using an image compression encoder of an interlace image signal represented by / IEC13818-2) and a decoding device for the encoded signal.

[0002]

2. Description of the Related Art A surveillance system using a TV camera has two or more camera inputs in order to widen a surveillance area, and switches these images simultaneously by synthesizing frames or at regular intervals by a frame switcher. Monitoring systems that perform recording and transmission have been put to practical use. Hereinafter, the configuration and operation of a conventional monitoring system for a four-input and two-input simultaneous recording VTR will be described with reference to the drawings.

FIG. 9 is a block diagram of a conventional image monitoring recording / reproducing apparatus. Image signals from the cameras 901 and 902 are switched for each field by a switch 903 and input to a video circuit 904. Here, a signal for switching the switch 903 is supplied to the servo circuit 905 by RF.
It is created as a switching pulse 906.

The RF switching pulse 906 generated by the servo circuit 905 is applied to the head A in the VTR,
A head for recording the image signal supplied to the cylinder 907 containing B and output from the video circuit is selected. For example, when the RF switching pulse 906 is high, recording is performed by the head A, and when the RF switching pulse 906 is low, recording is performed by the head B.
At the time of reproduction, an image corresponding to a desired camera is reproduced by reproducing only a signal of a head corresponding to a camera to be reproduced.

FIG. 10 is a block diagram of an image monitoring and recording apparatus for switching images by a conventional frame switcher. Here, cameras 1001, 1002, 1003, 10
Image signal output from the frame switcher 1
005. The input image signal is switched by the frame switcher 1005 and recorded on the VTR 1006.

[0006] Inside the frame switcher 1005,
Image signals input from each camera are stored in a frame memory 10
07, 1008, 1009, and 1010, the input signals are switched by a switch 1011 and output as an output image signal of a frame switcher 1005. As described above, the conventional image monitoring recording / reproducing apparatus can record and reproduce two inputs.

[0007]

However, the conventional frame switcher 1005 has a problem that a large number of frame memories are required for multiplexing multi-input images, which increases the hardware size and costs. .

In a two-input recording apparatus combined with a VTR, multiplexing is performed by recording in separate areas using two heads, which is a feature of the VTR.
When recording on a medium that records in the same area other than the TR, or when recording a signal obtained by compressing and encoding a digitized signal using MPEG2 or the like, there is a problem that a number of compression encoding devices are required for the number of inputs. there were.

The present invention solves such a conventional problem. A plurality of input image signals are multiplexed with a small amount of hardware, and the signals are compression-encoded and recorded on a recording medium such as a disk. It is an object of the present invention to provide an image monitoring system that transmits, transmits, and decodes them to reproduce an image signal.

[0010]

In order to achieve the above object, the present invention provides a synchronizing signal generator for synchronizing an input image signal, a switch for switching the input image signal, and interlacing the switched image signal. It is provided with an interframe predictive compression encoder for interlaced signals for performing interframe predictive compression encoding of signals.

Therefore, according to the present invention, multiplexing of input images can be realized at low cost by realizing multiplexing of input images without using an image memory for multiplexing input images. By minimizing the deterioration of the compression efficiency, the image quality of the multiplexed image can be minimized.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, in an image monitoring system to which a plurality of moving image signals are input, a synchronizing signal generating section for synchronizing input image signals, A switching unit that switches a plurality of input images based on a vertical synchronization signal generated by a generation unit, a compression encoding unit that compresses the switched image signal between frames, and a recording unit that records the compressed signal. It is intended to have.

According to a second aspect of the present invention, in an image monitoring system to which a plurality of moving image signals are input, a synchronizing signal generating section for synchronizing input image signals and a synchronizing signal generating section generated by the synchronizing signal generating section are provided. A switching unit that switches a plurality of input images based on the vertical synchronization signal, a compression encoding unit that compresses the switched image signals between frames, and a network interface unit that transmits the compressed signals. It is like that.

According to a third aspect of the present invention, in an image monitoring system to which a plurality of moving image signals are input, a synchronizing signal generating section for synchronizing the input image signals and the synchronizing signal generating section generate A switching unit for switching between a plurality of input images based on the vertical synchronization signal, a selection unit for selecting whether or not to filter the switched image signals, and compression coding for compressing the selected image signals between frames. And a recording unit for recording the compressed signal.

According to a fourth aspect of the present invention, in an image monitoring system to which a plurality of moving image signals are input, a synchronizing signal generator for synchronizing input image signals and a synchronizing signal generator generated by the synchronizing signal generator are provided. A switching unit for switching between a plurality of input images based on the vertical synchronization signal, a selection unit for selecting whether or not to filter the switched image signals, and compression coding for compressing the selected image signals between frames. And a network interface unit for transmitting the compressed signal.

According to a fifth aspect of the present invention, there is provided a decoding apparatus for decoding a signal compressed and encoded by the image monitoring system according to the first, second, third or fourth aspect. And a reproduction image memory for storing the decoded compressed image signal, and an address generation unit for generating a read address of the reproduction image so as to output only a desired field from the reproduction image memory. .

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
1 shows a configuration of a two-input image monitoring system according to the embodiment. In this embodiment, the camera 101
The camera 102 outputs an image signal to the switch 103 in synchronization with an external synchronization signal.

Here, the synchronization signal is supplied to the synchronization signal generator 108.
This signal is used to synchronize the image signal in the vertical direction, and corresponds to a vertical synchronization signal, a composite synchronization signal, a black burst signal, and the like. A switch 103 switches signals from the cameras 101 and 102 in synchronization with a synchronization signal. The switch 103 switches and selects a signal from the cameras 101 and 102 for each field at a timing of vertical synchronization.

The selected image signal is digitized by an analog-to-digital (A / D) converter 104 and input to an interframe predictive compression encoder 105 for an interlace signal. Here, since the output signals from the cameras 101 and 102 are analog signals, they are digitized by the analog / digital converter 104. However, when the input signals are digital signals, the analog / digital converter 103
Is not required.

The digitized image signal is compressed by an inter-frame predictive compression encoding unit 105 for an interlace signal, and further recorded on an optical disk 107 by an optical pickup 106.

In this embodiment, the data is recorded on an optical disk. Of course, a hard disk, a large-capacity floppy disk, a tape medium, or the like can be used as long as the medium can record digital signals.

FIG. 2 shows an input image signal 201 from each of the cameras a and b, a vertical synchronizing signal 203, a switch 103, and an output image signal 204 selected by the switch 103.
Shows the relationship. Image 201 is a field image output from camera a, and image 202 is a field image output from camera b. Each field image is output in synchronization with the vertical synchronization signal 203.

Here, the switch 103 is connected to the vertical synchronizing signal 20.
3, the image is selected by the camera a when the signal is Low (the period when the level of the signal 203 is low), and Hi is selected.
When the camera b is selected at the time of gh, the output image from the switch 103 becomes the image 204 in which the images from the camera a and the camera b are alternately output. However, as shown in FIGS. 3A and 3B, since this image is an image from a camera different for each field, when viewed in a frame image, FIG.
become that way.

MPEG2 (ISO / IEC13818-
The inter-frame prediction compression coding method of the interlace signal represented by 2) includes a field motion vector and a field orthogonal transformation based on a field image in a means of inter-frame prediction and intra-frame compression.
In the case of an image having a small correlation between fields, such as the frame image in FIG. 3B, since these are usually selected, the image in FIG. 3B can be coded with little deterioration.

(Second Embodiment) FIG. 4 shows a two-input image monitoring system in which a recording unit comprising an optical pickup and an optical disk according to the first embodiment is replaced with a network interface 401. 1 shows a system.

In the configuration of the two-input image monitoring system shown in FIG. 4, 101 to 105 and 108 are the same as those in the first embodiment, and the description is omitted here. Therefore, the signal of the interlace signal compressed by the inter-frame predictive compression encoder 105 is transmitted to a digital line such as an ISDN or a LAN via the network interface 401. This makes it possible to monitor or record the image multiplexed by the monitoring system at a remote location.

(Third Embodiment) FIG. 5 shows an embodiment of a two-input image monitoring system. In this monitoring system configuration 1
Reference numerals 01 to 107 and 108 are the same as those in the first embodiment, and a description thereof will be omitted.

A digital image signal output from the analog / digital converter 104 is input to a switch 502 and a filter 501, respectively. The filter 501 is implemented by one or a combination of spatial and temporal filters, and limits the band of a part or the whole part of the input digital image signal. This band limitation is performed to increase the compression efficiency when encoding. That is, since the band-limited image signal is concentrated in the band where the energy is limited, it is possible to compress the signal that is not band-limited to a smaller code amount (high compression).

The digital image signal band-limited by the filter 501 is input to the switch 502. The switch 502 selects one of the band-limited image output from the filter 501 and the non-band-limited image directly output from the analog-to-digital converter 104 according to a signal from the switch 503, and outputs the selected image to the encoding unit 105 I do. The encoding unit 105 encodes the input digital image, and at the same time, selects an important field image from the two field images corresponding to the two cameras 101 and 102, and generates a selection signal based on the result. Output to the switch 503.

In the case of a surveillance system, if there is an intruder, the image of the camera capturing the intruder is important, so that it is necessary to output a signal for selecting the camera. In this case, for example, the encoding unit 105 creates a selection signal by using the fact that the motion vector of the field image of the intruder being photographed is detected or the inter-frame difference information is increased.

For example, when the signal of the camera 101 is important, while the signal of the camera 101 is digitized by the analog / digital converter 104, the signal is directly input to the encoding unit 105. Since the switch 502 operates in synchronization with the switch 103, the switch 503 switches to input a signal from the synchronization signal generator 108 directly to the switch 502 by a selection signal. On the other hand, when the signal of the camera 102 is important, the switch 502
Is switched so that a signal obtained by inverting the signal of the synchronization signal generation unit 108 by the inverter 504 by the selection signal is input to the switch 502.

Similarly, when the images of the two cameras 101 and 102 are both important or not important, the high or low level is input to the switch 502 so that one of them is selected. A selection signal is applied to the switch 503 to make a selection.

Therefore, according to this embodiment, of the images from the two cameras 101 and 102, an important image can be compression-encoded and recorded with higher image quality. Further, when the images from the two cameras are not important, the compression rate can be further increased by limiting the bandwidth of both, so that the recording medium having the same capacity can record for a long time. It becomes possible.

Further, the selection signal output from the encoding unit 105 shown in FIG.
May be a signal generated by a signal from a sensor corresponding to the above. In this case, the selection signal is created by setting the sensors corresponding to the cameras 101 and 102 to A and B, and when the sensors A and B are on (detected) or off (undetected), the switch 503 is turned on. A signal for selecting high or low is created so as not to be switched by the synchronization signal. When one of the sensors A and B is ON (detection), the synchronization signal is used to switch the camera corresponding to the ON sensor so that the filter 501 is not selected when the switch 103 is switched. A selection signal is created to select the signal of 108 directly or inverted.

(Fourth Embodiment) FIG. 6 shows a two-input image monitoring system in which a recording unit composed of an optical pickup and an optical disk according to the third embodiment is replaced with a network interface 401. Is shown. In the configuration of the monitoring system shown in FIG.
Reference numerals 108 and 501 to 503 are the same as those of the third embodiment.

In this monitoring system, the signal of the interlace signal compressed by the interframe predictive compression encoder 105 is transmitted to a digital line such as an ISDN or a LAN via a network interface 401. This makes it possible to monitor and record the image multiplexed by the monitoring system at a remote location.

(Fifth Embodiment) FIG. 7 shows the first to fifth embodiments.
14 shows a configuration of an inter-frame predictive compression / decoding device which is a decoder for decoding a coded signal recorded or transmitted by the two-input image monitoring system shown in the fourth embodiment.

An input terminal 701 is an input terminal for the encoded compressed image signal. The compressed image signal input from the terminal 701 is input to the variable-length code decoding unit 702 and is subjected to variable-length decoding. Among the compressed image signals subjected to the variable length decoding, the motion vector information is output to the address generator 709, and the other information is output to the inverse orthogonal transformer 703. The inverse orthogonal transform unit 703 performs an inverse orthogonal transform on the compressed image signal that has been subjected to the variable length decoding, and further inputs the result to the inverse quantization unit 704 to be inversely quantized. The dequantized compressed image signal is added to the predicted image signal output from the reproduced image memory 706 by the adder 705, and the reproduced image memory 706 is again added.
Output to

The reproduced image memory 706 outputs the reproduced image indicated by the motion vector information output from the variable length code decoding section 702 to the adder 705 as a predicted image signal.
Therefore, the address generator 709 outputs an address for outputting a reproduced image indicated by the input motion vector information as a read address. An address generator 709 converts a write address for recording an image output from the adder 705 and a reproduced image into a spatial filter 707.
A read address for output to the output terminal 708 is generated. The spatial filter 707 is a reproduction image memory 7
The image signal inputted from 06 is subjected to a spatial filter process and output to an output terminal 708.

FIG. 8 shows a part of the reproduced image memory.
Assuming that the space of the reproduced image memory is horizontal X and vertical Y, one frame of the reproduced image is recorded as shown by the hatched portion in FIG. Here, hatched portions A and B indicate pixels of the respective field images.

The conventional decoder first outputs the hatched portion A, then outputs the hatched portion B, and generates an address to be output in such an order in the address generator. In the present invention, an address indicating an image of only the hatched area A or B is generated by the address generation unit in accordance with a field switching signal input from the external terminal 701.

Thus, it is possible to select and decode and reproduce only one of the two multiplexed image signals. In addition, the spatial filter 707 reduces image deterioration due to repetition in a field. As described above, according to the embodiment, it is possible to multiplex two-input image signals without increasing the memory for multiplexing the two-input image signal and the memory for decoding the multiplexed signal. Has an effect. Further, since the image data is multiplexed for each field image, the image can be compressed without deteriorating the compression efficiency of the image.

[0043]

According to the present invention, an image monitoring system with reduced costs can be realized. Furthermore, by restricting the bandwidth of the input image having low importance, the compression ratio of the non-important image can be increased, and the recording time can be extended in the case of only the non-important image. Has the effect that the quality of important images can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a first embodiment of an image monitoring system of the present invention.

FIG. 2 is a diagram showing the operation principle of field image switching.

FIG. 3 is a diagram showing an image in which a field image is switched;

FIG. 4 is a schematic block diagram showing a second embodiment of the image monitoring system of the present invention.

FIG. 5 is a schematic block diagram showing a third embodiment of the image monitoring system of the present invention.

FIG. 6 is a schematic block diagram showing a fourth embodiment of the image monitoring system of the present invention.

FIG. 7 is a schematic block diagram showing an embodiment of a decoding device for decoding a signal of the image monitoring system of the present invention.

FIG. 8 is a diagram showing contents of a reproduced image memory of a decoder.

FIG. 9 is a schematic block diagram of a conventional image monitoring recording / reproducing apparatus.

FIG. 10 is a schematic block diagram of another conventional image monitoring recording / reproducing apparatus.

[Explanation of symbols]

 101 Camera 102 Camera 103 Switch 104 Analog-to-Digital Converter 105 Encoding Unit 106 Optical Pickup 107 Optical Disk 108 Synchronization Signal Generation Unit 401 Network Interface 501 Filter 502 Switch 503 Switch 701 Input Terminal 702 Variable Length Code Decoding Unit 703 Inverse Orthogonal Transformation Unit 704 Inverse quantization unit 705 Adder 706 Reconstructed image memory 707 Spatial filter 708 Output terminal 709 Address generation unit

Claims (5)

[Claims] An image monitoring system that receives a plurality of moving image signals as inputs, a synchronization signal generator for synchronizing the input image signals, and a plurality of inputs based on a vertical synchronization signal generated by the synchronization signal generator. An image monitoring system, comprising: a switching unit that switches an image; a compression encoding unit that compresses the switched image signal between frames; and a recording unit that records the compressed signal. 2. An image monitoring system in which a plurality of moving image signals are input, a synchronization signal generator for synchronizing the input image signals, and a plurality of inputs based on a vertical synchronization signal generated by the synchronization signal generator. An image monitoring system, comprising: a switching unit that switches an image; a compression encoding unit that compresses the switched image signal between frames; and a network interface unit that transmits the compressed signal. 3. An image monitoring system which receives a plurality of moving image signals as inputs, comprising: a synchronization signal generator for synchronizing the input image signals; and a plurality of inputs based on a vertical synchronization signal generated by the synchronization signal generator. A switching unit for switching an image, a selection unit for selecting whether or not to filter the switched image signal, a compression encoding unit for compressing the selected image signal between frames, and recording the compressed signal An image monitoring system, comprising: 4. An image monitoring system which receives a plurality of moving image signals as inputs, a synchronizing signal generator for synchronizing the input image signals, and a plurality of inputs based on a vertical synchronizing signal generated by the synchronizing signal generator. A switching unit for switching an image, a selection unit for selecting whether or not to filter the switched image signal, a compression encoding unit for compressing the selected image signal between frames, and transmitting the compressed signal. An image monitoring system, comprising: a network interface unit for performing an operation. 5. A decoding device for decoding a signal compressed and encoded by the image monitoring system according to claim 1, 2, 3, or 4, wherein the decoded compressed image signal is stored. Playback image memory,
A decoding device for generating a read address of a reproduced image so as to output only a desired field from the reproduced image memory.