JPH09247654A - Monitor camera system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the technology displaying smoothly a motion of an object image to be monitored when the object image is moved. SOLUTION: An image processing section 2 of a transmission section applies band compression to an output video signal S1 of a camera 1 and a data transmission section 3 transmits the resulting video signal to a reception section as a transmission line signal S2. A data reception section 6 of a reception section decodes the signal, an image processing section 7 expands the band and the result is displayed on a video monitor 8 and monitored. A control section 5 of the transmission section controls the image processing section 2 based on motion information S3 from a motion detection section 4 to increase the band compression rate of the video signal when the motion quantity S3 is high thereby increasing the frame frequency and making the frequency band of the transmission line signal S2 constant. Simultaneously band compression information S4 is sent to the reception section as the transmission line signal S2 through time division superimposition or the like with the video signal. The data reception section 6 of the reception section separates the band compression information S4 and a control section 9 conducts the band expansion processing in response to the band compression information S4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention transmits an output video signal of a video camera through a transmission path having a limited band, displays and monitors a subject image, and displays a smooth motion of the subject image. The surveillance camera system that performs

[0002]

2. Description of the Related Art In a conventional surveillance camera system, when an output video signal of a video camera is transmitted through a transmission path having a limited band, so-called frame dropping is performed to reduce the transmission band, and the resolution of a subject image to be monitored is reduced. Have secured. However, when the subject image has a motion, the resolution is lowered, but there is a problem that the motion is unnatural and difficult to see due to a frame drop.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a technique for smoothly displaying the movement of a subject image to be monitored when the subject image moves.

[0004]

When there is a motion in a subject image, the transfer band is reduced by lowering the band of the video signal to be transmitted and increasing the frame frequency (the number of frames per unit time) for transmission. Without widening, the motion is smoothly displayed and monitored at the resolution and the number of gradations corresponding to the motion image having originally low resolution.

[0005]

FIG. 1 is a schematic block diagram of (A) transmitting section and (B) receiving section of an embodiment of a surveillance camera system according to the present invention. In the transmission unit of the surveillance camera system, the image signal S1 output from the video camera 1 is compressed by the image processing unit 2 into a band corresponding to the transmission line band of the transmission line S2. The band-compressed video signal is encoded into a transmission path signal by the data transmission section 3 and transmitted to the reception section as a transmission path signal S2. In the receiving unit, the data transmission unit 6 decodes the same transmission path signal, and the image processing unit 7 performs band extension such as time axis interpolation, and the video monitor 8
And the subject image of the video camera 1 is monitored. The control unit 5 of the transmission unit controls the image processing unit 2 based on the motion amount information S3 from the motion amount detection unit 4 to increase the band compression rate of the video signal and increase the frame frequency when the motion amount S3 is large. To make the band of the transmission path signal S2 constant. At the same time, the band compression rate information S4 is transmitted to the receiving unit together with the video signal as the transmission path signal S2 by time division superposition or the like. In the receiving unit, the data receiving unit 6 receives the band compression rate information S.
4 is separated and the control unit 9 performs a band expansion process according to the band compression rate information S4.

FIG. 2 shows a surveillance camera system 1 according to the present invention.
It is a schematic block diagram of the (A) transmission part and the (B) reception part of an Example. In the transmitting unit, the output video signal of the video camera 1 is converted into a digital video signal by the analog / digital converter 21, and the switching unit 22 controlled by the control unit 27 switches and writes the frame memory 23 or 24. The other written frame memory 24 or 23 is read by switching the data signal and the address signal by the switch 25 controlled by the control unit 27, and the data signal is transmitted to the transmission path signal S2 by the data transmitting unit 26 together with the compression rate information S4 of the video signal. Encode and transmit to the receiver.

Here, the control unit 27 on the transmission side outputs the video camera 1 that outputs from the turning drive unit 14 of the video camera 1.
Of the frame memories 23 and 24 according to the motion amount information S3 of
The number of pixels to be read from and the frame frequency are controlled. FIG.
FIG. 3 is a conceptual diagram of a memory map showing a writing status and a reading status of the frame memories 23 and 24. The output video signal of the video camera 1 is sent to one of the frame memories, for example 23, at addresses 0, 1, 2, 3, ... The video signals are sequentially written to 1, 2, 3, ... When the video camera 1 does not move, the reading is performed from the other frame memory 24 in which the video signal is written first, at the addresses 0, 1, 2, corresponding to the pixels in the horizontal direction of the memory map 41 as in the writing. 3, ...
And addresses 0, 1, 2, corresponding to the pixels in the vertical direction.
.. are sequentially read at a frame frequency slower than the television rate that matches the band of the transmission path, and are transmitted to the receiving side through the data transmitting unit 26. When the video camera 1 is moving, for example, when the subject image moves by two pixels in one frame period, the horizontal and vertical read addresses are doubled and the addresses corresponding to the horizontal pixels of the memory map 42 are doubled. .. and addresses 0, 2, 4, .. send.

Here, an example is shown in which the motion amount of the subject image is detected by acquiring the motion amount of the video camera from the driving device of the video camera 1, but the present invention is not limited to this, and, for example, sequentially. It is also possible to detect the motion amount of the subject image from the difference between the plurality of frames to be written and perform the same processing as above.

In the receiving section, the transmission path signal S2 is decoded by the data receiver 28 into a video signal, and is switched to one of the frame memories 30 and 31 by the switch 29 controlled by the control section 35 and written. The other written frame memory 31 or 30 is read by switching the data signal and the address signal by the switch 32 controlled by the controller 35, and displayed on the video monitor 34 as an analog signal by the digital / analog converter 33.

Here, the control unit 35 on the receiving side determines the number of pixels and the frame frequency read from the frame memories 30 and 31 according to the compression ratio information S4 of the video signal separated from the transmission path signal S2 by the data receiving unit 28. Control. The video signal decoded by the data receiving unit 28 corresponds to one of the frame memories, for example, addresses 0, 1, 2, 3, ... Write to addresses 0, 1, 2, 3, ... Sequentially. When the video signal is not compressed, the reading is performed from the other frame memory 31 in which the video signal has been written first, at addresses 0, 1, 2, 3, ..., Corresponding to the pixels in the horizontal direction of the memory map 41. , And addresses 0, 1, 2, 3, ... Corresponding to the pixels in the vertical direction are repeated at the television rate until the transmission of the video signal to one of the frame memories is completed and displayed on the monitor. When the video signal is compressed to, for example, 1/4, the horizontal and vertical read addresses are set to 1/2, and the addresses 0, 0, 1, corresponding to the pixels in the horizontal direction of the memory map 41 are set.
1, ..., And the address 0 corresponding to the pixel in the vertical direction,
The same address is read twice such as 0, 1, 1, ... And the number of pixels is interpolated and read out, and displayed on the video monitor 34. In this case, the frame memory switching rate is 4
Doubled and movement is smoother.

The compression ratio information of the video signal transmitted from the transmission unit to the reception unit is obtained from the number of clocks of a predetermined fixed period which enters the horizontal period and the vertical period from the horizontal synchronization signal and the vertical synchronization signal transmitted together with the video signal. It can also be calculated.

FIG. 4 is a schematic block diagram of (A) transmitting section and (B) receiving section of another embodiment of the surveillance camera system according to the present invention. In the transmission unit, the output video signal of the video camera 1 is converted into a digital video signal by the analog / digital converter 51, and is switched and written into one of the frame memories 53 or 54 by the switching unit 52 controlled by the control unit 57. The other frame memory 54 or 53 written
Is read by switching the data signal and the address signal with the switch 55 controlled by the control unit 57. The read parallel signal is converted into a serial signal by the parallel / serial converter 71, and is encoded into the transmission path signal S2 by the data transmission unit 56 together with the compression rate information S4 of the video signal and transmitted to the reception unit.

Here, the control unit 57 on the transmission side controls the frame frequency read from the frame memories 53 and 54 according to the motion amount information S3 of the video camera 1 output from the turning drive device 4 of the video camera 1, and By controlling the bit shift amount of the parallel / serial converter 71,
Controls the number of bits per pixel. For example, if the number of bits per pixel is 8 bits when there is no motion,
When the amount of motion is 4 bits and the frame frequency is doubled, the band of the video signal on the transmission path becomes constant. It should be noted that an example in which the movement amount of the subject image is detected by obtaining the movement amount S3 of the video camera from the driving device of the video camera 1 is shown. It is also possible to detect the amount of movement and perform the same processing as above.

In the receiving section, the transmission path signal S2 is decoded into a video signal by the data receiver 58 and converted into a parallel signal by the serial / parallel converter 72 controlled by the control section 65. The output video signal is switched to one of the frame memories 60 and 61 by the switch 59 controlled by the controller 65 and written. The data signal and the address signal are switched and read from the other written frame memory 61 or 60 by the switcher 62 controlled by the controller 65, and displayed on the video monitor 64 as an analog signal by the digital / analog converter 63.

Here, the control section 65 on the receiving side changes the bit shift amount of the serial / parallel converter 72 according to the compression rate information S4 for the video signal separated from the transmission path signal S2 by the data receiving section 58. Thus, a parallel video signal corresponding to each pixel is obtained. The same video signal is sequentially written into one of the frame memories 60 or 61 as described above, and is read out from the other frame memory to be displayed, so that the video is moving and the number of bits per pixel, that is, the number of gradations is increased. For a small number of images, the frame memory is switched quickly so that the display movement of the subject image is smooth.

In the above embodiment, the band compression rate of the video signal from the transmission side to the reception side is transmitted while being superimposed on the video signal. However, the present invention is not limited to this, and horizontal synchronization transmitted with the video signal is performed. It is also possible to calculate the band compression rate of the video signal from the cycle of the signal and the vertical synchronizing signal and the clock of a predetermined fixed cycle. That is, the number of images per frame is obtained from the effective number of clocks in one horizontal period and the effective horizontal sync signal in one vertical period. By comparing with the standard number of pixels per frame, The compression rate is obtained.

[0017]

The present invention is embodied in the form described above, and has the following effects.

In a surveillance camera system for transmitting a video signal output from a video camera through a transmission path of a certain band and displaying the subject image of the video camera on a video monitor, etc. By compressing the band of the video signal to be transmitted and increasing the frame frequency of the video signal to be transmitted, the motion can be displayed smoothly at the resolution corresponding to the originally low-resolution motion image without expanding the transmission band. Can be monitored.

Motion amount information is obtained from the drive device of the video camera, and the band of the video signal to be transmitted is compressed according to the motion information, in accordance with the motion of the subject image due to the turning of the camera,
By increasing the frame frequency of the video signal to be transmitted, it is possible to easily obtain the amount of movement in the case of a camera turning or the like in which the movement of an image generally becomes large.

The amount of motion of a subject image is detected by image processing from the video signal output from the video camera, the band of the video signal to be transmitted is compressed according to the amount of motion, and the frame frequency of the video signal to be transmitted is increased. So, even if only the subject moves, it can be dealt with.

The band compression of the video signal to be transmitted is performed by reducing the resolution of the image, which is suitable for transmission of a moving image having a reduced resolution.

The image resolution can be reduced by reducing the number of pixels in each frame, so that the intended purpose can be easily achieved.

The number of pixels is reduced by setting the range of movement of the object image within one frame period by moving the video camera as one pixel with respect to the pixel when the video camera is stationary, and thereby the resolution due to the motion is reduced. A transmission image is obtained that is consistent with a decrease in

The band compression of the video signal to be transmitted is performed by reducing the gradation of the image, which is suitable for transmitting a moving image having a reduced resolution which does not require the number of gradations.

By transmitting the band compression ratio of the video signal as additional information of the video signal through the transmission path together with the video signal, expanding the band of the video signal on the basis of the information and displaying it on a video monitor. Band compression rate can be transmitted directly.

The band compression rate of the video signal is calculated from the cycle of the horizontal sync signal and the vertical sync signal transmitted together with the video signal and the clock of a predetermined constant cycle, and the band of the video signal is expanded and displayed on the video monitor. By doing so, the band compression rate can be transmitted without additional information.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of (A) transmission unit and (B) reception unit of an embodiment of a surveillance camera system according to the present invention.

FIG. 2 is a schematic block diagram of (A) transmitting unit and (B) receiving unit of one embodiment of the surveillance camera system of the present invention.

FIG. 3 is a conceptual diagram of a memory map showing a writing state and a reading state of a frame memory.

FIG. 4 is a schematic block diagram of (A) transmission unit and (B) reception unit of another embodiment of the surveillance camera system according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Video camera 2 Image processing unit 3 Data transmission unit 4 Motion amount detection unit 5 Control unit 6 Data reception unit 7 Image processing unit 8 Video monitor S1 Video signal S2 Transmission path signal S3 Motion amount information S4 Band compression rate 14 Driving device 21 Analog / Digital converter 22,25 Switching device 23,24 Frame memory 26 Data transmission unit 27 Control unit 28 Data receiving unit 29,32 Switching device 30,31 Frame memory 33 Digital / analog converter 34 Video monitor 35 Control unit 41,42 Memory map 51 Analog / digital converter 52, 55 Switcher 53, 54 Frame memory 71 Parallel / serial converter 56 Data transmitter 57 Control unit 58 Data receiver 72 Serial / parallel converter 59, 62 Switcher 60, 61 frame Memory 63 digit / Analog converter 64 the video monitor 65 control unit

Claims (9)

[Claims] 1. A surveillance camera system for transmitting a video signal output from a video camera through a transmission path of a constant band, and displaying the subject image of the video camera on a video monitor to monitor the movement amount of the subject image. A surveillance camera system characterized by compressing the band of a video signal to be transmitted according to the above, and increasing the frame frequency of the video signal to be transmitted. 2. A motion amount information is obtained from a driving device of a video camera, the motion amount information is used to compress a band of a video signal to be transmitted according to a motion of a subject image due to a turning of a camera, and the like. The surveillance camera system according to claim 1, wherein the frame frequency is increased. 3. A motion amount of a subject image is detected by image processing from a video signal output from a video camera, a band of the video signal to be transmitted is compressed according to the motion amount, and a frame frequency of the video signal to be transmitted is increased. The surveillance camera system according to claim 1, wherein 4. The surveillance camera system according to claim 1, wherein the band compression of the video signal to be transmitted is performed by reducing the resolution of the image. 5. The surveillance camera system according to claim 4, wherein the resolution of the image is reduced by reducing the number of pixels in each frame. 6. The reduction in the number of pixels is performed with respect to the pixels when the video camera is stationary, by setting the range in which the subject image moves within one frame period when the video camera moves as one pixel. The surveillance camera system according to claim 5. 7. The surveillance camera system according to claim 1, wherein the band compression of the video signal to be transmitted is performed by reducing the gradation of the image. 8. The band compression ratio of the video signal is transmitted as the additional information of the video signal through the transmission path together with the video signal,
The surveillance camera system according to claim 1, wherein the video signal band is expanded based on the information and displayed on a video monitor. 9. A video signal band compression rate is calculated from the period of a horizontal synchronizing signal and a vertical synchronizing signal transmitted together with the video signal and a clock of a predetermined constant period, and the band of the video signal is expanded to a video monitor. The surveillance camera system according to claim 1, which is displayed.