JP2006211166A - Monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a conventional monitoring system that it is difficult to particularize what is imaged because the image is indistinct at a locally dark place and a lighted place. <P>SOLUTION: A histogram generating circuit 7 generates a histogram of motion vectors used for an MPEG decoder 5. A motion area detection circuit 8 detects addresses (MBA) of an image region denoting motion vectors with a predetermined threshold value or over among the motion vectors configuring the histogram. A contour correction circuit 9 carries out contour correction for surrounding one or more entire image regions corresponding to one or more detected addresses as one rectangular region. A contrast emphasis circuit 10 applies contrast emphasis processing to decoded image signals in one rectangular region whose contour is corrected in a way of increasing the dynamic range of an image contour part. A monitor 13 displays a motion detection region by surrounding it with a frame and displays an image whose contrast is emphasized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a monitoring system, and more particularly, to a monitoring system that decodes compressed and encoded image data of a video signal with many still images obtained by imaging a monitoring target with a monitoring camera and performs monitoring based on the decoded image.

  Conventionally, surveillance systems using surveillance cameras often use human vision to monitor images of video signals obtained by capturing surveillance targets with surveillance cameras. Unattended parking lots and automatic cash deposits When monitoring a machine (ATM) or the like, images without motion are monitored or recorded for a long time. And searching for a target place with motion from the captured image relies on human vision. In order to record and monitor a video signal obtained by imaging a monitoring target with the monitoring camera, for example, a time lapse VTR is recorded on a magnetic tape at a predetermined interval and recorded on the magnetic tape. The video signal is reproduced and displayed, and the reproduced image is monitored by human vision.

  However, human visual monitoring as described above requires long-term attention, so there is a limit to performing it for a long time, and there is a possibility of oversight or misunderstanding. For this reason, in order to monitor a place where a still image continues for a long time, a monitoring system that visually displays a place where movement has occurred is necessary.

  In addition, when recording a video signal to be monitored in a time lapse VTR, the recording operation is performed even if there is no change in the monitoring target, so that the recording capacity of the magnetic tape is wasted and the monitoring target is not monitored. Even if a change occurs, the recorded video signal is interrupted due to intermittent recording, and it may be difficult to determine the details of the video.

  Therefore, conventionally, a video signal captured by a surveillance camera is encoded by the MPEG (Moving Picture Experts Group) method, and a motion detection unit that detects the motion of the obtained encoded video data, and a time zone in which the motion is detected. There is known a monitoring system including a recording control unit that records the video signal in detail and records video signals in other time zones in a simple manner (see, for example, Patent Document 1).

  Conventionally, in a monitoring system that includes a wide-area monitoring camera that captures the entire monitoring range and a target camera that tracks the target, a rough shape of the target is extracted from the image of the wide-area monitoring camera, and conforms to the image from the target camera. There is also known a monitoring system in which correction is made in this way (see, for example, Patent Document 2).

JP-A-11-18076 JP 2003-264822 A

  However, the conventional monitoring system described in Patent Document 1 detects the presence or absence of motion of video data by video motion detection, and switches the recording method between moving and non-moving portions to moving image recording and still image recording. Although this is intended to save, it is difficult to specify the location of the image reproduced from the portion where the motion of the monitoring target is recorded.

  Further, in the conventional monitoring system described in Patent Document 1, an image becomes unclear in a place where local darkness or light is lit, and the contrast of the entire screen is greatly affected by the local light and darkness. Even if the target area can be specified, it may be difficult to specify what is reflected in the area.

  On the other hand, the conventional monitoring system described in Patent Document 2 is a system that extracts a rough shape of an object and tracks it, but this is merely “extracting” an image of a target area of a wide-area monitoring camera. If the image is unclear due to local brightness or darkness, it is difficult to specify what is reflected.

  The present invention has been made in view of the above points, and when decoding image data obtained by encoding a video signal with a lot of still images obtained from a surveillance camera, a region having motion is automatically extracted by a motion vector. Accordingly, an object of the present invention is to provide a monitoring system capable of reducing the leakage of monitoring by human vision.

  Another object of the present invention is to enhance the contrast of an image of a moving area in a decoded image so that the image portion to be monitored becomes clear and a place with little movement in a parking lot or a local area. It is an object of the present invention to provide a monitoring system that can identify a person or an object in a place where lighting is lit.

  In order to achieve the above object, the first invention decodes encoded image data obtained by compressing and encoding a video signal to be monitored output from a surveillance camera by the MPEG method, and the decoded image signal In a monitoring system for monitoring with a monitoring target image displayed on a display device, a decoding means for decoding encoded image data, and a histogram for creating a macroblock unit histogram based on a motion vector used for decoding by the decoding means Corresponding to one or more addresses detected by the creating means, an address detecting means for detecting an address of an image area showing a motion vector equal to or greater than a predetermined threshold among the motion vectors constituting the histogram, and the address detecting means Contour correction means for performing contour correction that encloses one or more entire image areas as one rectangular area, and contour correction A contour signal generating means for generating a contour signal corresponding to the contour of one rectangular region whose contour has been corrected by the means, and receiving the contour signal as an input together with a decoded image signal decoded by the decoding means; And display means for displaying the contour signal as a frame.

  In this invention, one or more entire image regions having a motion vector equal to or greater than a threshold value are subjected to contour correction that is surrounded by one rectangular region as a motion detection region, a contour signal corresponding to the contour of the rectangular region is generated, and a decoded image is generated. Since the contour signal is displayed as a frame in the image based on the signal, the area surrounded by the frame in the image to be monitored can be displayed as a moving area.

  In order to achieve the above object, in addition to the first invention, the second invention is the maximum and minimum luminance values of one or more image regions in one rectangular region whose contour is corrected by the contour correcting means. A maximum value / minimum value detecting means for detecting a value, and information of one rectangular area subjected to contour correction, and a maximum value and a minimum value of luminance as input together with a decoded image signal decoded by the decoding means, and contour correction Contrast enhancement means for performing contrast enhancement processing for increasing the dynamic range of the image contour portion based on the maximum value and the minimum value of the luminance of the decoded image signal in one rectangular area. The display means receives as input the decoded image signal and the contour signal which have been subjected to the contrast enhancement processing by the contrast enhancement means, and the contrast of one rectangular region whose contour has been corrected is enhanced. Around the image, and displaying a frame by contour signal.

  In the present invention, the dynamic range of the image contour portion of one rectangular region whose contour has been corrected is increased based on the maximum value and the minimum value of the luminance of one or more image regions within one rectangular region whose contour has been corrected. Since the contrast enhancement processing is performed, a frame based on the contour signal can be displayed around the image in which the contrast of one rectangular region whose contour is corrected is enhanced.

  According to the present invention, one or more entire image regions having a motion vector equal to or greater than a threshold value are subjected to contour correction that is surrounded by one rectangular region as a motion detection region, and a contour signal corresponding to the contour of the rectangular region is generated, Since the contour signal is displayed as a frame in the image based on the decoded image signal, the region surrounded by the frame is displayed as a moving region in the image to be monitored. It is possible to easily visually identify where there is movement in the frame, and it is possible to greatly reduce the human visual leakage.

  In addition, according to the present invention, based on the maximum value and the minimum value of the brightness of one or more image regions in one rectangular region whose contour has been corrected, the dynamics of the image contour portion of one rectangular region whose contour has been corrected By applying contrast enhancement processing that increases the range, a frame based on the contour signal is displayed around the image where the contrast of one contour-corrected rectangular region is enhanced. Even in the case, the motion area can be clearly displayed by emphasizing the contrast of only the motion area, and people and objects can be identified in places where there is little movement in a parking lot or where there is local illumination. can do.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a system configuration diagram of an embodiment of a monitoring system according to the present invention. As shown in the figure, in this monitoring system, a video signal picked up by a monitoring camera 1 is input as encoded image data obtained by high-efficiency compression encoding by a known MPEG method, and the motion of the encoded image data is shown. This is a monitoring system that combines a motion region detection device 4 that detects a certain region and a contrast enhancement device 10 that makes it possible to display the region clearly by enhancing the contrast of only that region.

  In FIG. 1, a video signal with a large number of still images obtained by imaging a subject to be imaged by the surveillance camera 1 is supplied to an MPEG encoder 2, where it is encoded with a high-efficiency compression encoding by a well-known MPEG method. After the data is converted into a bit stream, it is supplied to a recording / reproducing apparatus 3 such as a VTR and recorded on a recording medium such as a magnetic tape, while being supplied to an MPEG decoder 5 in the motion area detecting apparatus 4 and decoded. The

  Since the configurations of the MPEG encoder 2 and the MPEG decoder 5 are well known, detailed description thereof is omitted, but the MPEG decoder 5 is based on the motion vector by the motion compensation circuit (MC circuit) 51 when decoding the input bit stream. Perform motion compensation. The motion vector is a signal representing how much the macroblock (an image is divided into a region of 16 pixels vertically and 16 pixels horizontally and a unit for motion compensation) and represents how much the image has moved from the previous picture or the subsequent picture. The amount of motion in the direction (mvx) and the vertical direction (mvy) is encoded.

  In addition, the above picture includes an I picture (intra-frame encoded image) for intra-coding the encoding target frame image without referring to other images, and a past I picture for the encoding target frame image. The difference is encoded using a P picture (interframe forward prediction encoded image) for encoding the difference as a reference image and past and future I pictures or P pictures as reference images for the encoding target frame image. There is a B picture (bidirectional predictive coded image). A P picture may be encoded using a past P picture as a reference image.

  The MPEG decoder 5 uses the MC circuit 51 to decode the encoded image data using the motion vector used in the predictive encoding of the P picture and B picture, and stores the decoded image data in the storage device 6. Further, the motion vector histogram creation circuit 7 calculates the absolute value of the amount of motion in the horizontal direction (mvx) and the vertical direction (mvy) for the motion vector shown in FIG. Further, a histogram as shown in FIG. 2B is created so as to obtain an appropriate frequency for each macroblock.

  Based on the histogram from the motion vector histogram creation circuit 7, the motion region detection circuit 8 detects a motion vector having a large value exceeding a threshold value (indicated by a dotted line in FIG. 2B) set in the histogram of one picture. The obtained macroblock address (MBA) is detected as a motion area, and the detection result (MBA) is output to the contour correction circuit 9.

  The contour correction circuit 9 performs contour correction so as to form a rectangle surrounding an area (picture) by MBA input as a motion area. The outline correction is shown in FIG. FIG. 3A shows a plurality of areas 21 indicated by the MBA inputted to the contour correction circuit 9, which are relatively clustered within a range within one screen, but the whole is a rectangular area. is not. The contour correction circuit 9 performs the contour correction based on the inputted plurality of regions 21 by the MBA, as shown in FIG. 3B, to form one rectangular region 22 surrounding the whole of the plurality of regions 21.

  A plurality of MBAs indicating one rectangular area 22 obtained as a result of the contour correction by the contour correction circuit 9 are output from the contour correction circuit 9 to the MPEG decoder 5. The MPEG decoder 5 outputs a decoded frame image signal subjected to motion compensation through the video output unit and supplies it to the contrast enhancement circuit 10 and the delay adjustment circuit 11.

  At this time, in the video output unit, the MPEG decoder 5 has maximum and minimum luminance values of a plurality of image regions (motion detection regions) corresponding to a plurality of MBAs indicating one rectangular region 22 input from the contour correction circuit 9. The maximum value and minimum value information is also stored in the storage device 6 and output to the contrast enhancement circuit 10. Further, the MPEG decoder 5 detects motion at the video output unit when outputting image data of a plurality of image regions (motion detection regions) corresponding to a plurality of MBAs indicating one rectangular region 22 input from the contour correction circuit 9. A rectangular outline signal surrounding the area is generated and output to the contrast enhancement circuit 10.

  The contrast enhancement circuit 10 performs processing that increases the dynamic range of the image contour portion of the decoded frame image signal in the motion detection region based on the maximum and minimum luminance values of the motion detection region, for example, black An image signal with enhanced contrast is output to the terminal 12a of the switch 12 by performing expansion, white expansion, or correction by a γ coefficient (γ correction).

  The switch 12 is a switch that selects one of the input signals of the terminals 12a and 12b and outputs the selected signal to the monitor 13. The switch 12 is stored in the storage device 6 based on a switching signal (not shown) from the motion region detection device 4. When the decoded frame image signal in the motion detection area is output from the contrast enhancement circuit 10, the image signal with the contrast enhanced which is connected to the terminal 12 a and output from the contrast enhancement circuit 10 is selected and sent to the monitor 13. When an image signal in a region other than the motion detection region is supplied and output from the contrast enhancement circuit 10, an image signal that is switched and connected to the terminal 12b and output from the delay adjustment circuit 11 is selected. And supplied to the monitor 13.

  The delay adjustment circuit 11 is a circuit that outputs the input image signal with a delay time equivalent to the processing time of the contrast enhancement circuit 10, and is provided for time adjustment with the output image signal of the contrast enhancement circuit 10. Yes. The switching signal of the switch 12 can be easily generated because it can be generated simply by designating the upper left and lower right of the rectangular area from the contour correction circuit 9.

  As a result, an image is displayed on the screen of the monitor 13 in which the contrast of the image portion of the motion detection region is emphasized so that the contrast of the image portion of the region other than the motion detection region is independent and the dynamic range of the contour is increased. Thus, even if there is a light source or darkness in a part of the image, a clear image obtained by performing contrast correction suitable for only the motion detection region can be obtained.

  In addition, since the contour signal is displayed on the monitor 13 as a frame surrounding the image portion of the motion detection region in the decoded image, the motion portion of the image can be easily specified, so the motion in the image to be monitored The part can be visually judged immediately.

  When an I picture is input to the MPEG decoder 5, the motion vector is not encoded in the I picture, and thus the above motion vector is held in the storage device 6. Even if the motion vector does not reach the detectable level set as the threshold value, the position in the image is specified by holding the above motion vector in the storage device 6 unless it is cleared by an external switch or the like. You can continue.

  As described above, according to the present embodiment, MPEG motion vectors are used for image contour extraction, and the maximum luminance of an image inside the contour of one rectangular region surrounding the motion detection region detected using the motion vector is detected. Since the value and the minimum value are detected, and contrast enhancement is performed so that the dynamic range of the image contour is increased based on the maximum value and the minimum value, the image in the motion detection region can be made a clear image.

  In the above embodiment, contrast enhancement is performed on the image signal inside the outline of one rectangular area surrounding the motion detection area detected using the motion vector. A contour signal indicating the contour of the region may be output together with the decoded image signal, and the contour signal may be displayed as a frame on the monitor to visually identify the motion region portion in the decoded image to be monitored.

It is a block diagram of one embodiment of a monitoring system of the present invention. FIG. 2 is an operation explanatory diagram of an example of a motion vector histogram creation circuit in FIG. 1. FIG. 2 is an operation explanatory diagram of an example of a contour correction circuit in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surveillance camera 2 MPEG encoder 3 Recording / reproducing apparatus 4 Motion area detection apparatus 5 MPEG decoder 6 Storage apparatus 7 Motion vector histogram creation apparatus 8 Motion area detection circuit 9 Contour correction circuit 10 Contrast enhancement circuit 11 Delay adjustment circuit 12 Switch 13 Monitor 21 Motion detection area 22 Rectangular area 51 MC (motion compensation) circuit

Claims (2)

The encoded image data obtained by compressing and encoding the video signal to be monitored output from the surveillance camera by the MPEG method is decoded, and the decoded image signal is monitored by the image to be monitored displayed on the display device. In the monitoring system to perform
Decoding means for decoding the encoded image data;
A histogram creating means for creating a macroblock unit histogram based on a motion vector used in decoding by the decoding means;
Address detecting means for detecting an address of an image area indicating a motion vector equal to or greater than a predetermined threshold among the motion vectors constituting the histogram;
Contour correcting means for performing contour correction surrounding one or more entire image areas corresponding to one or more addresses detected by the address detecting means as one rectangular area;
Contour signal generating means for generating a contour signal corresponding to the contour of one rectangular region whose contour has been corrected by the contour correcting means;
And a display unit that receives the contour signal as an input together with the decoded image signal decoded by the decoding unit, and displays the contour signal as a frame in an image of the decoded image signal. A maximum value / minimum value detecting means for detecting a maximum value and a minimum value of luminance of one or more image regions in one rectangular region whose contour is corrected by the contour correcting unit;
The information of the one rectangular region whose contour has been corrected, the maximum value and the minimum value of the luminance are received as an input together with the decoded image signal decoded by the decoding means, and the decoding in the one rectangular region whose contour has been corrected Contrast enhancement means for performing contrast enhancement processing on the image signal based on the maximum value and the minimum value of the brightness to increase the dynamic range of the image contour portion, and the display means includes the contrast A frame based on the contour signal is received around an image in which the contrast of one rectangular region subjected to the contour correction is enhanced by receiving the decoded image signal and the contour signal subjected to the contrast enhancement processing by the enhancement unit. The monitoring system according to claim 1, wherein the monitoring system is displayed.

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