Camera system, camera control method and program

A camera system for capturing an image of a predetermined scope, having a plurality of monitoring cameras operable to change a monitoring area respectively, comprises a camera controller, when changing its monitoring area of one of the monitoring cameras, operable to control the other monitoring cameras to monitor a dead area that is outside of the monitoring area of the monitoring camera. When the camera controller controls the monitoring camera to zoom into a subject, the camera controller may control the other monitoring cameras to monitor the dead area of the monitoring area by zooming out the subject.

This patent application claims priority from Japanese Patent Application No. 2004-256209 filed on Sep. 2, 2003, the content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a camera system and a camera control method, including a plurality of monitoring camera, and relates to a program for the camera system and the camera control method. More particularly, the present invention relates to the camera system and the camera control method for monitoring a predetermined scope by the plurality of monitoring cameras, and the computer program for controlling the plurality of the monitoring cameras.

2. Description of the Related Art

Conventionally, the monitoring system for capturing a face image of a person as an intruder with a magnified image by controlling the monitoring camera to pan and zoom in the intruder who invades into the monitoring scope has been in practical use. (For example, see the article from the J-Net Corporation's web site “http://www.gazou.co.jp/Products/index.html”; entitled “Image Monitoring System”)

However, there is a problem that in the monitoring scope a dead area is generated, when capturing a specific area in more detail by controlling the camera to pan and zoom in.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a displaying apparatus and a control method for the displaying apparatus, which are capable of overcoming the above drawbacks accompanying the conventional art. The above and other objects can be achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.

According to the first aspect of the present invention, a camera system for capturing an image of a predetermined scope, having a plurality of monitoring cameras operable to change a monitoring area respectively, comprises a camera controller, when changing its monitoring area of one of the monitoring cameras, the camera controller controls the other monitoring cameras to monitor a dead area that is outside of the monitoring area of the monitoring camera.

When the camera controller controls the monitoring camera to zoom into a subject, the camera controller may control the other monitoring cameras to monitor the dead area of the monitoring area by zooming out the subject.

The camera controller may regard recognition of a new subject as a trigger, and controls the monitoring camera to zoom into the new subject.

According to the second aspect of the present invention, a camera control method for monitoring a predetermined scope by a plurality of monitoring cameras operable to change its monitoring area respectively, comprises a step of: when changing a monitoring area of one of the monitoring cameras, controlling the other monitoring cameras to monitor a dead area that is outside of the monitoring area of the monitoring camera.

According to the third aspect of the present invention, a computer program medium storing thereon a program for a camera system, in order to monitor a predetermined scope by a plurality of monitoring cameras operable to change its monitoring area, the program comprises a camera controlling module, when changing its monitoring area of one of the monitoring cameras, the camera controlling module controls the other monitoring cameras to monitor a dead area that is outside of the monitoring area of the monitoring camera.

The camera controller may adjust both an exposure of one monitoring camera and an exposure of the other monitoring cameras differently, when a region of which luminance is beyond a dynamic range of the monitoring cameras is lager than a predetermined area in the predetermined scope.

The camera controller may adjust the exposure of the monitoring camera in accordance with a high luminance region, of which average luminance is the highest in the predetermined scope, and adjusts the exposures of the other monitoring cameras in accordance with a region except the high luminance region in the predetermined scope.

The camera controller may adjust each of focuses of the monitoring camera and the other monitoring cameras, in accordance with the regions, which are captured with the adjusted exposures respectively.

The summary of the invention does not necessarily describe all necessary features of the present invention. The present invention may also be a subcombination of the features described above. The above and other features and advantages of the present invention will become more apparent from the following description of the embodiments taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a block diagram exemplary showing a functional configuration of a camera system10. According to the camera system10of the present invention, it is an object to capture a specific area in more detail without any dead area. In addition, the monitoring scope is an example of a predetermined scope according to the present invention.

The camera system10includes a plurality of monitoring cameras12, a camera controller14, and an image recording section16. The plurality of monitoring cameras12is operable to change a monitoring area respectively. When changing a monitoring area of one of the monitoring cameras12, the camera controller14controls the other monitoring cameras12to monitor a dead area where the monitoring camera12does not capture. The image recording section16stores each of the image data1-ncaptured by each of the plurality of monitoring cameras12.

Each of the monitoring cameras12has a predetermined monitoring area respectively, and all of the monitoring cameras12capture a predetermined monitoring scope as a whole. The camera controller14obtains each of the image data1-nconsecutively and then decides whether an abnormality occurs. Any method for detecting the abnormality may be used as long as a position of the abnormality is detected.

For example, the camera controller14stores an image in which any abnormality was not captured as a reference image in advance, and then obtains binary images by comparing a difference between each of the captured images and the reference image with a predetermined threshold. Next, if the area of the binary image is larger than a predetermined reference value, the camera controller14decides that some abnormalities have occurred in the corresponding part of the binary image.

If the camera controller14detects the abnormality in the images captured by monitoring the monitoring scope, the camera controller14controls both the direction and the scaling factor of the monitoring camera12that is monitoring the abnormal position so that the abnormal position is zoomed in. At the same time, the camera controller14controls each of the directions and scaling factors of the other monitoring cameras12that are monitoring the next area of the abnormal position, in order to capture the dead area that is generated as an area outside of the monitoring area of the monitoring camera14because of the operation of zooming into the abnormality.

The recording medium60stores a program for realizing each of the functions of the monitoring camera12, the camera controller14, and the image recording section16in the camera system10. The camera system10may obtain the program through a network, and then execute the program.

FIG. 2is a first example showing the functional diagram of the camera controller14. The camera controller14includes an abnormality detector141, a zooming method deciding section142, a dead area deciding section143, a monitoring area storing section144, a dead area compensation section145and a control signal output section146. The abnormality detector141acquires each of the image data1-nfrom the monitoring cameras12, and decides whether an abnormality has occurred, and decides the position of the abnormality. The zooming method deciding section142selects the monitoring camera12in order to capture the abnormal position in more detail when the abnormality has occurred, and then decides the monitoring area to be zoomed in by the selected monitoring camera12. The monitoring area storing section144stores the monitoring scope to be monitored by all the monitoring cameras12, and each of the monitoring areas that is assigned to each of the monitoring cameras12. The dead area deciding section143decides a dead area, i.e., an area which is not captured as the monitoring scope because one of the monitoring cameras12has changed its monitoring area by zooming in the abnormal position. The dead area compensation section145decides a method for capturing the dead area that is decided by the monitoring area storing section144, by using the other monitoring cameras12except the monitoring camera12which is monitoring the abnormality. The control signal output section146outputs a control signal for controlling each of the positions and each of the scaling factors of the monitoring cameras12, based on the method that is decided by the dead area compensation section145. Moreover, the changing of the scaling factor of the monitoring camera12, i.e., the mechanism for zooming, may be an optical zoom or a digital zoom.

According to the configuration described above, the camera system10can capture the specific area without the dead area.

FIG. 3is an example of the monitoring scope in the camera system10. In this embodiment, the camera system10monitors the monitoring scope that is shown inFIG. 3by using four monitoring cameras12(cameras1-4). Normally, the camera1monitors Area1, the camera2monitors Area2, the camera3monitors Area3, and the camera4monitors Area4. The above described monitoring area storing section144stores the monitoring scope and each of the monitoring areas as shown in this figure. The abnormality detector141decides whether the abnormality has occurred based on some changes in the images captured by the cameras1-4.

FIG. 4is a drawing exemplary illustrating an operation of the camera system10when the abnormality detector141detects an abnormality in Area2inFIG. 3. In this example, an intruder enters a room from a door, which is included in the area2. At first, the abnormality detector141detects the abnormality based on the change of the images in camera2that is monitoring Area2. Next, the zooming method deciding section142selects the camera2among the four cameras, in which the abnormality in the image has occurred, and then decides a monitoring area to be captured by zooming into the intruder.

The dead area deciding section143decides a dead area, i.e., an area which is not captured as the monitoring scope because the camera2has changed its monitoring area for the purpose of zooming into the intruder. In this case, the dead area deciding section143decides that a tableau, upper part of the door, and lower part of the door are in the dead area.

The dead area compensation section145selects one of the monitoring cameras from the cameras1,3, and4, in order to capture the dead area that is decided by the dead area deciding section143, and then decides each of the new monitoring areas of the cameras1,2, and4. For example, in this case, the dead area compensation section145selects the camera4as the monitoring camera to capture the dead area in Area2, and then, magnifies the monitoring area of the camera4so that the dead area of Area2is included in the monitoring area of the camera4.

Next, the control signal output section146outputs each of the control signals for controlling the positions and scaling factors of the monitoring cameras12to each of the monitoring cameras12based on the each of new monitoring areas of the monitoring cameras12, where the areas are decided by the zooming method deciding section142and the dead area compensation section145.

Each of the monitoring cameras12changes its positions and scaling factor according to each of the control signals. For example, the camera2zooms into the subject and the camera4zooms out so that Area2and Area4are included in an image.

In this case, the dead area compensation section145may change each of the monitoring areas of the plural monitoring cameras in order to capture the dead area of the camera2. For example, we assume that Area2is divided into four equal parts. If the camera2zooms into the top right area, it is necessary to magnify the monitoring area of the camera4by a factor of 2 along the top direction and left direction in order to cover the dead area only by using the camera4. On the contrary, if both the camera1and camera4are used to cover the dead area, the camera1has only to magnify its monitoring area along the right direction by a factor of 1.5, and the camera4has only to magnify its monitoring area along the top direction by a factor of 1.5.

In other words, the dead area, which occurs when one of the cameras zooms in, is captured by other cameras, by the operations of zooming out. Therefore, operations of zooming out of each camera can be minimized. Accordingly, it is possible to eliminate the dead area in the monitoring area with minimum deterioration in accuracy of the image captured by each camera.

In addition, the camera controller14may regard recognition of a new subject as a trigger, and control one monitoring camera to zoom into the new subject. In this case, the camera controller14controls the other monitoring cameras to zoom out the new subject, thereby capturing the dead area. For example, the camera controller14distinguishes between an abnormality caused by an appearance of a new subject and an abnormality caused by the movement well-known subject when detecting the abnormality in the monitoring scope. Then, the camera controller14regards the abnormality of the appearance of the new subject as a trigger, and then controls the cameras to zoom into the new subject.

Moreover, the camera controller14may distinguish between an abnormality caused by an appearance of persons and an abnormality caused by subjects other than persons, and then, control the cameras to zoom into the persons preferentially. The camera controller14decides whether the abnormality is caused by persons or not based on whether the image has some appropriate colors as a person's skin. In addition, the camera controller14decides whether the abnormality is caused by persons or not based on the size of the subject. If the camera is capable of detecting the infrared radiation, the camera controller14may decide whether the abnormality is caused by persons or not based on the temperature of the subject detected from the image.

A second example of the camera controller14will be explained below. Components having the same or similar functions as those in the first example are assigned with the same reference numerals and will not be described. According to this example, the camera controller14adjusts both an exposure of one monitoring camera12and an exposure of the other monitoring cameras12differently when a region of which luminance exceeds a dynamic range of the monitoring cameras12is lager than a predetermined area out of the monitoring scope. Thus, the whole dynamic range of the camera system10is increased, and consequently, it is possible to obtain clear monitoring images without overexposure or underexposure.

FIG. 5is a functional diagram showing the camera controller14in this example. The camera controller14includes an error region deciding section150, an exposure allotment deciding section152, the control signal output section146and a focus deciding section154. The error region deciding section150detects an error region in which the overexposed region or the underexposed region is included in the images corresponding to the predetermined monitoring scope. The error region is the region, of which luminance is beyond a dynamic range of the monitoring cameras12and the region is larger than a predetermined area. Although the region is saturated with light, or the region is lacking of light, if these regions are too small, the error region deciding section150excludes these such small regions from the subject to be detected. The predetermined area used when deciding whether a region should be excluded or not may be provided as a region having at least a pixel. The predetermined area may be arbitrarily provided by pixel measure.

The exposure allotment deciding section152allots each range of the luminance to each monitoring camera12. Specifically, the exposure allotment deciding section152selects an appropriate monitoring camera12in order to capture the error region detected by the error area deciding section150. For example, the appropriate monitoring camera12is a monitoring camera12including the error region within its image of the monitoring area. The exposure allotment deciding section152controls the selected monitoring camera12in order to adjust the exposure in accordance with the error region optimally. Next the exposure allotment deciding section152adjusts the exposures of the other monitoring cameras12in accordance with a region except the error region in the images of the monitoring scope. The control signal output section146may output a control signal for changing at least one of the positions and scaling factor, so that the error region is positioned at the center of the image and the error region occupies a greater part of the image. In addition, the control signal output section146may output a control signal for controlling each of the positions and scaling factors of the plural monitoring cameras12, so that the other monitoring cameras12capture the region except the error region. In addition, the error region is an example of the high luminance region in the present invention.

The focus deciding section154adjusts focuses of each of the plural monitoring cameras12in accordance with the regions, which are captured with the exposures adjusted by the exposure allotment deciding section152, respectively. For example, the focus deciding section154outputs a control signal for adjusting the focus of the monitoring camera12in accordance with the error region in the image, and outputs control signals for adjusting the focuses of each of the other monitoring cameras12in accordance with a region except the error region.

FIG. 6is an example of the monitoring image when the degree of the contrasting in monitoring scope is large. In the monitoring scope, the region A in the monitoring scope is a bright region, in which outside light shines. On the contrary, the region B is darker than the region A. The contrast between the region A and the region B exceeds the dynamic range of one monitoring camera12. In this case, the error region deciding section150decides that the luminance of the region B is not within the dynamic range of the monitoring camera12if the exposure of the monitoring camera12is adjusted in accordance with the region A. Similarly, the error region deciding section150decides that the luminance of the region A is not within the dynamic range of the monitoring camera12if the exposure of the monitoring camera is adjusted in accordance with the region B. When a region being not within the dynamic range is larger than a predetermined area, the error region deciding section150detects this region as the error region. For example, in this case, the error region deciding section150detects the bright region A as the error region. The exposure allotment deciding section152outputs a control signal in order to adjust the exposure of the camera1in accordance with the region A, and the most part of the region A detected as the error region is included in the images captured by the camera1. The control signal output section146outputs the signal to control at least one of the position and scaling factor of the camera1so that the camera1captures all of the region A.

The exposure allotment deciding section152optimizes exposures of the camera1, the camera2, and the camera4respectively in the region B excluding the region A in the monitoring scope. The exposure allotment deciding section152outputs a control signal for optimizing each of the exposures of the cameras2-4in accordance with each of the monitoring areas when there is a contrast within the region B. The control signal output section146outputs the signal for controlling at least one of the positions and scaling factor of the cameras2-4so that the cameras2-4capture the whole of the region B. The control signal output section146outputs the signal for controlling at least one of the position and scaling factor of the of the cameras2-4so that the cameras2-4capture the dead area which occurs as the result of the changing of at least one of the positions and the scaling factors of the cameras2-4.

The focus deciding section154adjusts the focus of the camera1in accordance with the area captured with the exposure decided by the exposure allotment deciding section152, i.e., the region A. Each of the focuses of the cameras2-4is adjusted in accordance with each of the areas captured with each of the exposures decided by the exposure allotment deciding section152.

As apparent from the explanations above, according to the camera system10in this example, the dynamic range of the camera system10is magnified when a region, of which luminance is beyond a dynamic range of the monitoring cameras12, is larger than a predetermined area in the monitoring scope because each of the exposures of the monitoring cameras12are adjusted differently. Thus, a clear image without white region caused by excess of the light intensity or a black region caused by lack of the light intensity can be acquired. According to the present invention, a camera system that monitors a specific scope in detail without dead area can be provided.