JPH08249464A - Device for extracting area - Google Patents

Abstract

PURPOSE: To realize the moving area extraction by combining more than two binary means so as to accurately extract the area of the object with less noise regardless of the fluctuation in the illumination and external light in extracting the moving area from a moving picture. CONSTITUTION: The original picture outputted from a sampling means 101 is binarized by the 1st binarizing means 102, 103, 106, 108, and 110 with the lower threshold value and the 2nd binarizing means 104, 105, 107, 109, and 111 with the higher threshold value. A obtd. point decision means 112 judges how many binary pictures with a higher threshold value are included in the binary picture with a lower threshold value and selects the part with higher obtd. points. A 3rd binarizing means 113 binarizes the part concerned finally and extracts the moving area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an area extracting device included in a surveillance camera for performing moving image recognition.

[0002]

2. Description of the Related Art In a surveillance camera system based on moving image recognition, a moving image is detected by binarizing a differential image between frame images that are temporally preceding and succeeding or a differential image with a background image formed by an appropriate method. Is commonly practiced. However, if there are fluctuations or unevenness in the illumination conditions in the monitoring area, the moving region cannot be correctly detected by binarization using a single binarization threshold value. As an example of using a plurality of binarized threshold values, there is Japanese Patent Application Laid-Open No. 4-196993 shown in FIG. 2, in which a video signal from the ITV camera 1 is sampled by a sampling pulse generation circuit 10 and an A / D converter. The digital image data is converted into digital video data by 11 and stored in the image memory 12, and binarized by the differential binarization circuits 14 and 16 having different threshold values, and stored in the differential binarized image memories 15 and 17, respectively. One of them is selected by the CPU 13 to be output to the display device 5 and the alarm device 6, and it is essentially not capable of coping with fluctuations or unevenness of illumination conditions.

[0003]

In the prior art, when there are fluctuations or unevenness in lighting conditions, a difference in brightness appears in a region other than the actual moving object, and the binarization threshold is set low. Then, this is excessively detected as noise, and conversely, if the binarization threshold value is set high, there is a problem that leakage occurs in the target area.

The present invention solves such a conventional problem, and an object of the present invention is to provide an area extraction device capable of removing the influence of noise appearing in a difference image due to fluctuations and unevenness of illumination conditions. To do.

[0005]

In order to achieve the above object, the area extracting apparatus of the present invention comprises two or more two areas.
A plurality of binarizing means for binarizing the input image signal by the binarizing method and the respective binarized images are superposed, and in the area detected by one of the binarizing means, the other one A binarizing unit that selects a region including a certain ratio or more of the region detected by the binarizing unit and outputs a final binary image based on the selected region.

[0006]

According to the present invention, according to the above configuration, for example, to what extent the area detected by the binarizing means having a large threshold value is included in the area detected by the binarizing means having a small threshold value. By determining whether or not there is a large number of included areas as the true moving area and binarizing it,
Less affected by fluctuations and unevenness of lighting conditions, less noise,
In addition, it is possible to extract a moving area that can capture the target area without omission.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. First, the principle of the present invention will be described. When detecting a moving area from a moving image for the purpose of extracting a moving object, the moving area is generated when a difference image is created with a certain threshold due to the presence of uneven lighting in the monitoring area or fluctuations in external light. Parts that are not
On the contrary, a situation may occur in which the moving area is missed. Therefore, the present invention intends to solve this problem by using, for example, two large and small threshold values. Here, the principle will be described with reference to an example using two thresholds of large and small, but the fact that there are two thresholds and the thresholds of large and small limits the scope of the present invention. Not a thing.

Now, assuming that the difference image is binarized by using two large and small threshold values and a moving area is detected, a moving area binary image with a larger threshold value (hereinafter, moving area binary image A
Call. In), since more severe binarization is performed, only the area where a large difference occurs is detected. This moving area 2
In the value image A, it is expected that a phenomenon such as a partial omission of the moving object to be extracted will occur. On the other hand, a moving area binary image with a smaller threshold value (hereinafter, moving area binary image B
Call. In (), since looser binarization is performed, even a region in which only a small difference is generated is detected, and it is expected that a lot of noise such as external light and changes in illumination will be picked up.

The essence of the present invention is to superimpose these two moving area binary images, and among the areas detected in the moving area binary image B, the pixels also detected in the moving area binary image A inside. This is a point in which an area including a certain ratio or more is regarded as a true moving area and left, and other areas are regarded as noise and removed.

This is because external light fluctuations and the like are generally gradual in time, and when the difference between the frame and the background image adaptively formed in the time direction is taken, only a small difference signal is detected. On the other hand, the brightness value of a moving object and that of the background generally have a large difference, and a phenomenon that a large difference signal is generated due to the movement of the object is used. Due to this phenomenon, it is considered that the actual moving object is present in the moving area detected in the moving area binary image B, and the moving object is not present in the area not detected. However, since the moving area detected in the moving area binary image A may be missing at a portion of the actual moving object whose luminance value is similar to the background, the moving area binary image B Then, the area detected so as not to have such a dropout is used to output the final moving area. The above is the principle of the present invention.

In FIG. 1, 101 is a sampling means for sampling an input image signal to output an original image, and 102 is a first difference means for receiving the original image and outputting a first difference image, Reference numeral 103 is a first threshold value determining unit that determines a first threshold value, 104 is a second difference unit that receives the original image and outputs a second difference image, and 105 is a second difference unit. Is a second threshold value deciding means for deciding a threshold value of the first differential image signal, and outputs a first binary image by binarizing the first differential image signal by the first threshold value. Numeral 107 is one binarizing means, and 107 is second binarizing means for binarizing the second differential image signal by the second threshold value and outputting a second binary image, Reference numeral 108 denotes a first moving area that detects a moving area based on the first binary image. Reference numeral 109 is a first moving area detecting means for outputting a value image, and 109 is a second moving area detecting means for detecting a moving area based on the second binary image and outputting a second moving area binary image. 110 is a first labeling unit that labels the first moving area binary image for each connected area and outputs a first label image, and 111 is the second moving area binary image. Reference numeral 112 denotes a second labeling unit that outputs a second label image by labeling an image for each connected region, and 112 is the essence of the present invention, the first label image and the second label image. Numeral 113 is a score determination means for comparing the image with each label area of the first label image to determine a score and outputting the score for each label area. Binarization processing based on the score for each label area A third of 2 for
It is a valuation means.

The operation of the embodiment thus constructed will be described below. The sampling means 101 samples the input image signal. The first difference means 102 is
The first difference image is output in response to the output signal of the sampling means 101. As a difference method, a method of obtaining a difference between two or more frames before and after, a method of obtaining a difference with a background image which is measured in advance or formed from an input image, and difference images obtained by these methods are further described. A method of accumulating over a plurality of frames, a composite method of these methods, and the like can be considered. This also applies to the second difference means 104 described later, and will not be repeated.

The first threshold value determining means 103 determines a threshold value for binarizing the first difference image. As a threshold value determining method, a method of using a fixed threshold value in advance, a method of determining from a statistical value of an input image signal traced back for a certain time, or the like can be considered. This also applies to the second threshold value determining means 105, which will be described later, and will not be repeated.

The second difference means 104 receives the output signal of the sampling means 101 and outputs a second difference image. As the difference method, the same one as the first difference means may be used, or a different one may be used.

The second threshold value determining means 105 determines a threshold value for binarizing the second difference image. When the first difference means 102 and the second difference means 104 adopt the same difference method, it is necessary to use a threshold value higher than that of the first threshold value determination means 103. Otherwise, this is not the case.

The first binarizing means 106 receives the first difference image output by the first difference means 102 and the first threshold value output by the first threshold value determining means 103. , The first difference image is binarized.

The second binarizing means 107 receives the second difference image output by the second difference means 104 and the second threshold value output by the second threshold value determining means 105. , The second difference image is binarized.

The first moving area detecting means 108 includes a first moving area detecting means 108.
The moving area is detected based on the first binary image output by the value conversion unit 106. For example, the following may be considered as the moving area detection processing. When the difference method based on the inter-frame difference is used in the first difference means 102, it is considered that the binarized difference image shows the contour of the moving area, and therefore the processing of filling the closed area is adopted. May be. Further, in the case where the difference method based on the difference from the background image is used in the first difference means 102,
Since it is considered that the binarized difference image itself already shows a moving area, there are cases where no special moving area detection processing is required. Since these circumstances are the same in the second moving area detecting means 109 described later, they will not be repeated.

The second moving area detecting means 109 has a second
The moving area is detected based on the second binary image output by the digitizing means 107.

The first labeling means 110 receives the first moving area binary image output from the first moving area detecting means 108 and subjects it to connected component labeling processing. Note that, in addition to this process, a process of deleting a label having an excessively small area as noise may be performed. This is the same in the second labeling means 111 described later,
Do not repeat.

The second labeling means 111 receives the second moving area binary image output from the second moving area detecting means 109 and subjects it to the connected component labeling process.

The score determination means 112, which is the main feature of the present invention,
Receives the first label image output by the first labeling unit 110 and the second label image output by the second labeling unit 111, and scores for each label of the first label image. Is performed. As the score, for example, for each label of the first label image, the number of pixels of the second label image contained therein is counted, and it is divided by the number of pixels of the label. You may use.

The third binarizing means 113 outputs the first label image output by the first labeling means 110 and the score output by the score determining means 112 for each label of the first label image. In response to this, a third binarization unit is provided which sets a threshold value for the score and binarizes the first label image again according to the score of each label. The area remaining by this binarization processing is output as a moving area that correctly corresponds to the moving object.

[0024]

As described above, according to the present invention, a plurality of binarizing means for binarizing an input image signal by two or more binarizing methods and respective binarized images are provided. Overlaying, of the regions detected by one of the binarizing means, a region containing the region detected by the other binarizing device in a certain ratio or more is selected, and the final binarization is performed based on the selected region. Since the image forming device is provided with a binarizing unit that outputs an image, it is possible to extract a moving area that is not affected by fluctuations and unevenness of illumination conditions, has little noise, and can capture a target area without omission.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a region extraction device of the present invention.

FIG. 2 is a block diagram showing an example of a conventional moving image recognition apparatus.

[Explanation of symbols]

 101 Sampling Means 102 First Difference Means 103 First Threshold Value Means 104 Second Difference Means 105 Second Threshold Value Means 106 First Binarization Means 107 Second Binarization Means 108 First moving area detecting means 109 Second moving area detecting means 110 First labeling means 111 Second labeling means 112 Score deciding means 113 Third binarizing means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Kitamura Kenji Kitamura 3-10-1 Higashisanda, Tama-ku, Kawasaki-shi, Kanagawa Matsushita Giken Co., Ltd. (72) Takehisa Tanaka Tama-ku, Kawasaki-shi, Kanagawa 3-10-10 Higashisanda Matsushita Giken Co., Ltd. (72) Inventor Kazufumi Mizusawa 3-10-1 Higashisita 3-10-1 Higashimita, Tama-ku, Kawasaki City, Kanagawa (72) Inventor Masato Mori Kanagawa 4-1, Egasaki-cho, Tsurumi-ku, Yokohama-shi, Tokyo Prefecture

Claims (5)

[Claims] 1. A plurality of binarizing means for binarizing an input image signal by two or more binarizing methods and the obtained respective binarized images are overlapped,
Of the areas detected by one of the binarizing means, an area containing the area detected by the other binarizing means in a certain ratio or more is selected, and a final binary image is output based on the selected area. Area extracting device having a binarizing means for 2. A sampling means for sampling an input image signal to output an original image, a first difference means for receiving the original image and outputting a first difference image, and a first threshold value. First threshold value determining means, first binarizing means for binarizing the first difference image signal by the first threshold value, and outputting a first binary image; The moving area is detected based on the first binary image and the first moving area 2 is detected.
A first moving area detecting means for outputting a value image, a second difference means for receiving the original image and outputting a second difference image,
Second threshold value determining means for determining the second threshold value,
Second binarizing means for binarizing the second differential image signal by the second threshold value and outputting a second binary image; and a moving region based on the second binary image. Second moving area detecting means for detecting the second moving area binary image and outputting a second moving area binary image,
First labeling means for labeling the first moving area binary image for each connected area and outputting a first label image; and labeling the second moving area binary image for each connected area Then, a second labeling means for outputting a second label image and comparing the first label image and the second label image to determine a score for each label area of the first label image. A score determination means for outputting a score for each label area and a third binarization means for performing a binarization process on the first label image based on the score for each label area. Region extraction device. 3. The score determining means is obtained by dividing the number of pixels of the area of the second label image included in each label area of the first label image by the number of pixels of each label area. The area extraction device according to claim 2, which is a means for returning a numerical value. 4. The method according to claim 2, wherein either or both of the first difference means and the second difference means are means for providing a difference image between the background image and the sampled input image. Area extraction device. 5. The first difference means and / or the second difference means are means for providing a difference image between an input image sampled one frame time ago and a sampled input image. The area extraction device according to claim 2 or 3.