Monitoring system, monitoring method and program

In order to appropriately detect abnormalities for the purpose of surveillance with it being possible to prevent an unnecessary increase in data amount of the monitoring images, a monitoring system includes an image capturing section that captures a moving image of a monitored area, a variation reduced image generating section that generates a variation reduced image by reducing a temporal variation in an image, based on a plurality of moving-image making-up images included in the moving image captured by the image capturing section, a condition storing section that stores thereon a condition which is required to be satisfied by a variation reduced image which is generated by using a plurality of moving-image making-up images included in a moving image which is judged to show an abnormality, a satisfaction judging section that judges whether the variation reduced image generated by the variation reduced image generating section satisfies the condition, an output moving image generating section that, when the satisfaction judging section judges negatively, generates an output moving image which has a lower image quality than when the satisfaction judging section judges positively, based on the moving image captured by the image capturing section, and an output section that outputs the output moving image generated by the output moving image generating section.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of PCT/JP2007/074773 filed on Dec. 18, 2007, and claims priority under 35 U.S.C. §119(a) on Patent Application Nos. 2006-340532, 2006-347075, and 2007-318977 filed in Japan on Dec. 18, 2006, Dec. 25, 2006, and Dec. 10, 2007, respectively, all of which are hereby expressly incorporated by reference into the present application.

BACKGROUND

1. Technical Field

The present invention relates to a monitoring system, a monitoring method, and a program. More particularly the present invention relates to a monitoring system and a monitoring method for realizing surveillance by way of images, and a program for use with a monitoring system.

2. Description of the Related Art

According to a known image capturing apparatus, a moving image compressing section detects a motion vector. During a period in which the detected motion vector indicates a value less than a predetermined value, the image capturing apparatus decreases the frame rate for the image capturing performed by an image capturing section by designating a relatively long time period as the period of the synchronous signal supplied to the image capturing section. On the other hand, during a period in which the detected motion vector indicates a value equal to or higher than the predetermined value, the image capturing apparatus increases the frame rate for the image capturing by designating a relatively short time period as the period of the synchronous signal. See Patent Document 1, for example. In this image capturing apparatus, the resolution set for the image capturing performed by the image capturing section is lowered during the period in which the motion vector indicates a value less than the predetermined value.[Patent Document 1] Unexamined Japanese Patent Application Publication No. 2004-200989

According to the disclosure of Patent Document 1, when not detecting a movement represented by the predetermined value or higher in images it is capturing, the image capturing apparatus captures images of a low resolution at a low frame rate. Here, these lower-resolution images may make it difficult to determine whether a person who appears in the images is suspicious or not. However, if the image capturing apparatus captures and outputs high-resolution images, the data amount of the images increases. In this case, the image capturing apparatus requires a larger storage or transmission capacity. There are different problems. The image capturing apparatus may be fixed to, for example, a ceiling. Here, a short-cycle slight tremble of the ceiling may cause the image capturing apparatus to mistakenly detect that there is a movement in the monitored area even when there is nobody moving in the monitored area. Apart from this, if the frame rate for the image capturing is increased to such a point that the image capturing apparatus can detect a quick suspicious behavior, the image capturing apparatus may even detect a slow movement which does not need to be monitored. As stated, the increase in the frame rate for the image capturing is unnecessary. Therefore, the increase in the data amount of the captured moving images may be more than necessary.

SUMMARY

In view of this, the object of the present invention is to provide a monitoring system, a monitoring method and a program which are capable of solving the above-mentioned problems. This object is achieved by combining the features recited in the independent claims. The dependent claims define further effective specific example of the present invention.

To solve the above-mentioned problem, a first embodiment of the present invention provides a monitoring system including an image capturing section that captures a moving image of a monitored area, a variation reduced image generating section that generates a variation reduced image by reducing a temporal variation in an image, based on a plurality of moving-image making-up images included in the moving image captured by the image capturing section, a condition storing section that stores thereon a condition which is required to be satisfied by a variation reduced image which is generated by using a plurality of moving-image making-up images included in a moving image which is judged to show an abnormality, a satisfaction judging section that judges whether the variation reduced image generated by the variation reduced image generating section satisfies the condition, an output moving image generating section that, when the satisfaction judging section judges negatively, generates an output moving image which has a lower image quality than when the satisfaction judging section judges positively, based on the moving image captured by the image capturing section, and an output section that outputs the output moving image generated by the output moving image generating section.

The variation reduced image generating section may generate the variation reduced image by averaging a plurality of moving-image making-up images included in the moving image captured by the image capturing section. When the satisfaction judging section judges negatively, the output moving image generating section may generate an output moving image including the variation reduced image generated by the variation reduced image generating section, and when the satisfaction judging section judges positively, the output moving image generating section may use the moving image captured by the image capturing section as an output moving image.

A second embodiment of the present invention provides a monitoring method including capturing a moving image of a monitored area, generating a variation reduced image by reducing a temporal variation in an image, based on a plurality of moving-image making-up images included in the moving image captured in the image capturing, storing a condition which is required to be satisfied by a variation reduced image which is generated by using a plurality of moving-image making-up images included in a moving image which is judged to show an abnormality, judging whether the variation reduced image generated in the variation reduced image generating satisfies the condition, when the variation reduced image is judged not to satisfy the condition in the judging, generating an output moving image which has a lower image quality than when the variation reduced image is judged to satisfy the condition in the judging, based on the moving image captured in the image capturing, and outputting the output moving image generated in the output moving image generating.

A third embodiment of the present invention provides a program for use with a monitoring system. The program causes the monitoring system to function as an image capturing section that captures a moving image of a monitored area, a variation reduced image generating section that generates a variation reduced image by reducing a temporal variation in an image, based on a plurality of moving-image making-up images included in the moving image captured by the image capturing section, a condition storing section that stores thereon a condition which is required to be satisfied by a variation reduced image which is generated by using a plurality of moving-image making-up images included in a moving image which is judged to show an abnormality, a satisfaction judging section that judges whether the variation reduced image generated by the variation reduced image generating section satisfies the condition, an output moving image generating section that, when the satisfaction judging section judges negatively, generates an output moving image which has a lower image quality than when the satisfaction judging section judges positively, based on the moving image captured by the image capturing section, and an output section that outputs the output moving image generated by the output moving image generating section.

Here, all the necessary features of the present invention are not listed in the summary. The sub-combinations of the features may become the invention.

The present invention is capable of providing a monitoring system which can appropriately detect abnormalities for the purpose of surveillance with it being possible to prevent an unnecessary increase in data amount of the monitoring images.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described. The embodiment does not limit the invention according to the claims, and all the combinations of the features described in the embodiment are not necessarily essential to means provided by aspects of the invention.

FIG. 1illustrates an exemplary environment in which a monitoring system110relating to an embodiment is used. The monitoring system110includes therein a plurality of image capturing apparatuses100ato100c, a transmission path140, a server170, and a plurality of display apparatuses180,181,182, . . . . The server170and plurality of display apparatases180,181,182, . . . are provided in a monitoring room160distant from monitored areas150,151,152, . . . . Here, the set of image capturing apparatuses100ato100cis provided in each of the plurality of monitored areas150,151,152, . . . to capture the images of a corresponding one of the plurality of monitored areas150,151,152, . . . . Hereinafter, the set of image capturing apparatuses100ato100cprovided in each of the plurality of monitored areas150,151,152, . . . is collectively referred to as the image capturing apparatuses100.

The image capturing apparatuses100capture the moving images of the monitored areas150,151,152, . . . and transmit the captured moving images to the server170via the transmission path140. The server170receives the moving images from the image capturing apparatuses100, and causes the display apparatuses180,181,182, . . . to display the received moving images thereon. The display apparatuses180,181,182, . . . respectively display thereon the moving images of the monitored areas150,151,152, . . . .

Here, the image capturing apparatuses100capture frame images which have a resolution higher than the monitor resolution at which the display apparatuses180,181,182, . . . can display frame images. Also, the image capturing apparatuses100capture moving images at a frame rate higher than the monitor display rate at which the display apparatuses180,181,182, . . . can display moving images. During a period in which no person or change is detected in a moving image captured, each image capturing apparatus100captures a moving image, converts the captured moving image into a moving image in which frame images of a resolution equal to or lower than the monitor resolution are displayed at a rate equal to or lower than the monitor display rate, and continues to transmit the moving image obtained by the conversion to the server170.

When detecting a person or change in the moving image captured, the image capturing apparatus100starts and continues to transmit, to the server170, the captured moving image with a high resolution and a high frame rate until such a time point that the image capturing apparatus100no longer detects a person or change in the moving image. The server170records thereon the moving image received from the image capturing apparatus100, and causes a corresponding one of the display apparatuses180,181,182, . . . to display thereon the received moving image in such a manner as to conform to the monitor resolution and monitor display rate.

For example, the image capturing apparatus100temporally averages a plurality of captured frame images so as to obtain an averaged image, and detects a change by using the obtained averaged image or detects a person in the averaged image. For example, the image capturing apparatus100determines that a change is detected in the moving image when detecting a change between temporally successive averaged images in a region thereof having an area equal to or larger than a predetermined threshold value. When detecting a person or change in the moving image, the image capturing apparatus100generates frame images which have, at least in the region in which the person or change is detected, the original resolution at the time of the image capturing, and transmits a moving image including the generated frame images to the server170. When detecting a movement of a person, the image capturing apparatus100generates frame images which have, at least in a region in which a section ahead of the person in terms of the moving direction is adjusted to be larger, the original resolution at the time of the image capturing, and transmits a moving image including the generated frame images to the server170.

The image capturing apparatus100may transmit, to the server170, a moving image which is made up by frame images showing the region in which the person or change is detected. If this is the case, the image capturing apparatus100stores thereon the partial images showing the region other than the region in which the person or change is detected. Here, as mentioned above, the image capturing apparatus100starts to transmit, to the server170, frame images with a lowered image quality once the person or change becomes no longer detected. Therefore, the amount of data transmitted via the transmission path140decreases once the person or change becomes no longer detected. Considering this, the image capturing apparatus100may transmit to the server170the partial images which have been stored thereon once the person or change becomes no longer detected.

The server170causes the image capturing apparatus100to increase the threshold value as the difference between the amount of data which can be transmitted per unit time via the transmission path140and the amount of data which is transmitted per unit time from the image capturing apparatus100decreases. Such a configuration can prevent the amount of data transmitted via the transmission path140from increasing, thereby preventing the moving image data from arriving late.

The monitored areas150,151,152, . . . may be respectively spaces within different buildings or different spaces within the same building. For example, the monitored areas150,151,152, . . . may be aisles between the shelves in a shop. The monitored areas150,151,152, . . . are not limited to the spaces within one or more buildings, but may be open spaces which are not enclosed.

FIG. 2illustrates an exemplary block configuration of the image capturing apparatus100. The image capturing apparatus100includes therein an image capturing section200, a variation reduced image generating section201, an image capturing control section210, an object region identifying section212, an image storing section214, a differential image generating section216, an image characteristic extracting section220, a satisfaction judging section230, a condition storing section240, a condition designating section242, a permissible data amount obtaining section250, an image quality selecting section260, an image quality storing section262, an output control section270, an image generating section280, and an output section290. The satisfaction judging section230includes therein a match calculating section232. The image generating section280includes therein an output moving image generating section282.FIG. 3illustrates an exemplary block configuration of the image characteristic extracting section220. The image characteristic extracting section220includes therein a change amount calculating section221, a movement amount calculating section222, a moving direction identifying section223, a particular color area calculating section224, and an object extracting section225. The variation reduced image generating section201includes therein an averaged image generating section202.

The image capturing section200captures an image of a monitored area. Specifically speaking, the image capturing section200captures a moving image of the monitored area. The variation reduced image generating section201generates a variation reduced image by reducing a temporal variation in an image, based on a plurality of moving-image making-up images included in the moving image captured by the image capturing section200. To be specific, the averaged image generating section202generates an averaged image by averaging a plurality of moving-image making-up images included in the moving image captured by the image capturing section200. For example, the averaged image generating section202generates an averaged image by averaging, in units of a pixel a plurality of moving-image making-up images. Note that the averaged image may be referred to only as an example of a variation reduced image relating to the present invention. As another example, the variation reduced image may be an image generated by selecting, in units of a pixel a median or largest value among the pixel values of the plurality of moving-image making-up images. As a further different example, the variation reduced image may be an image generated by adding, in units of a pixel, the pixel values of the plurality of moving-image making-up images (an overlap image).

The condition storing section240stores thereon a condition which is required to be satisfied by a variation reduced image that is generated by using a plurality of moving-image making-up images included in a moving image. To be specific, the condition storing section240stores thereon a condition which is required to be satisfied by a variation reduced image that is generated by using a plurality of moving-image making-up images included in a moving image satisfying a predetermined condition. For example, the condition storing section240stores thereon a condition used to judge whether abnormalities are present in the monitored region. Therefore, the condition storing section240stores thereon a condition which is required to be satisfied by a variation reduced image that is generated based on a plurality of moving-image making-up images included in a moving image that is judged to show abnormalities. To be specific, the condition storing section240stores thereon a condition which is required to be satisfied by an averaged image which is generated by averaging a plurality of moving-image making-up images included in a moving image that is judged to show abnormalities.

The following introduces some examples of the moving image that is judged to show abnormalities. Such abnormal moving images include a moving image in which a person is captured, a moving image in which the face of a person is captured, a moving image in which a predetermined person is captured, a moving image in which a person other than a predetermined person is captured, a moving image in which a physical object having a predetermined shape is captured, a moving image in which a predetermined physical object is taken away, a moving image in which a predetermined phenomenon such as flame and smoke is captured, a moving image in which a moving physical object is captured, a moving image in which a physical object moving in a predetermined direction is captured, a moving image in which a physical object moving at a speed higher than a predetermined value is captured, a moving image in which a moving physical object with a speed varying amount higher than a predetermined value is captured, a moving image in which people or physical objects collide with each other at a predetermined speed or higher, a moving image in which a person or physical object enters into a predetermined position, a moving image in which a person or physical object stays at a predetermined position for a predetermined time period or longer, and a moving image in which no physical objects are captured. Therefore, when the variation reduced image generated based on the moving image of the monitored area satisfies the condition stored on the condition storing section240, it can be judged that abnormalities are present in the monitored region.

The satisfaction judging section230judges whether the variation reduced image generated by the variation reduced image generating section201satisfies a predetermined condition. For example, the satisfaction judging section230judges whether the variation reduced image generated by the variation reduced image generating section201satisfies the condition. To be specific, the satisfaction judging section230judges whether the averaged image generated by the averaged image generating section202satisfies the condition. When the satisfaction judging section230judges that the variation reduced image does not satisfy the condition, the output moving image generating section282generates, based on the moving image captured by the image capturing section200, an output moving image having a lower image quality than when the satisfaction judging section230judges that the variation reduced image satisfies the condition. To be specific, when the satisfaction judging section230judges that the averaged image does not satisfy the condition, the output moving image generating section282generates an output moving image by using the moving-image making-up images included in the moving image captured by the image capturing section200. The generated output moving image includes moving-image making-up images which have a lower image quality than when the satisfaction judging section230judges that the averaged image satisfies the condition.

The output section290outputs the output moving image generated by the output moving image generating section282. For example, the output section290outputs the output moving image generated by the output moving image generating section282to the transmission path140which is provided to transmit moving images of monitored areas which are captured by a plurality of image capturing sections200. Alternatively, the output section290may output the moving image of the monitored area which is captured by the image capturing section200. For example, the output section290may output the moving image captured by the image capturing section200when the satisfaction judging section230judges that the averaged image satisfies the condition.

The variation reduced image generating section201may generate the variation reduced image based on a predetermined number of moving-image making-up images included in the moving image captured by the image capturing section200. When the satisfaction judging section230judges that the variation reduced image does not satisfy the condition, the output moving image generating section282may generate, based on the moving image captured by the image capturing section200, an output moving image which has a lower image quality during at least part of a period in which the predetermined number of moving-image making-up images are captured, than when the satisfaction judging section230judges that the variation reduced image satisfies the condition.

Specifically speaking, when the satisfaction judging section230judges that the variation reduced image does not satisfy the condition, the output moving image generating section282generates an output moving image including moving-image making-up images having a lower resolution than when the satisfaction judging section230judges that the variation reduced image satisfies the condition. To be specific, when the satisfaction judging section230judges that the averaged image does not satisfy the condition, the output moving image generating section282generates an output moving image including moving-image making-up images which have a lower resolution than when the satisfaction judging section230judges that the averaged image satisfies the condition. Alternatively, when the satisfaction judging section230judges that the variation reduced image does not satisfy the condition, the output moving image generating section282may generate an output moving image including moving-image making-up images which are expressed by using a smaller number of gray levels than when the satisfaction judging section230judges that the variation reduced image satisfies the condition. To be specific, when the satisfaction judging section230judges that the averaged image does not satisfy the condition, the output moving image generating section282may generate an output moving image including a moving-image making-up images which are expressed by using a smaller number of gray levels than when the satisfaction judging section230judges that the averaged image satisfies the condition.

As a further alternative example, when the satisfaction judging section230judges that the variation reduced image does not satisfy the condition, the output moving image generating section282may generate, by using the moving image captured by the image capturing section200, an output moving image which has a lower display rate than when the satisfaction judging section230judges that the variation reduced image satisfies the condition. To be specific, when the satisfaction judging section230judges that the averaged image does not satisfy the condition, the output moving image generating section282may generate, by using the moving image captured by the image capturing section200, an output moving image which has a lower display rate than when the satisfaction judging section230judges that the averaged image satisfies the condition.

When the satisfaction judging section230judges that the variation reduced image does not satisfy the condition, the output moving image generating section282may generate an output moving image including variation reduced images generated by the variation reduced image generating section201. When the satisfaction judging section230judges that the variation reduced image satisfies the condition, the output moving image generating section282may use the moving image captured by the image capturing section200as an output moving image. To be specific, when the satisfaction judging section230judges that the averaged image does not satisfy the condition, the output moving image generating section282may generate an output moving image including averaged images generated by the averaged image generating section202. When the satisfaction judging section230judges that the averaged image satisfies the condition, the output moving image generating section282may use the moving image captured by the image capturing section200as the output moving image.

The differential image generating section216generates a differential image between a first variation reduced image and a second variation reduced image which are both generated by the variation reduced image generating section201. Here, the second variation reduced image is generated by using moving-image making-up images which are captured after any of the moving-image making-up images used to generate the first variation reduced image. To be specific, the differential image generating section216generates a differential image between a first averaged image and a second averaged image which are both generated by the averaged image generating section202. It should be noted here that the second averaged image is generated by using moving-image making-up images which are captured after any of the moving-image making-up images which are used for generating the first averaged image. When the satisfaction judging section230judges that the variation reduced image does not satisfy the condition, the output moving image generating section282generates an output moving image including differential images generated by the differential image generating section216. When the satisfaction judging section230judges that the variation reduced image satisfies the condition, the output moving image generating section282uses the moving image captured by the image capturing section200as an output moving image. To be specific, when the satisfaction judging section230judges that the averaged image does not satisfy the condition, the output moving image generating section282may generate an output moving image including differential images generated by the differential image generating section216. When the satisfaction judging section230judges that the averaged image satisfies the condition, the output moving image generating section282may use the moving image captured by the image capturing section200as the output moving image.

The permissible data amount obtaining section250obtains the data amount per unit time which is permitted to be output from the output section290. For example, the permissible data amount obtaining section250may obtain the amount of data which can be transmitted per unit time via the transmission path140, or the amount of data which an output control device172can process per unit time. When the satisfaction judging section230judges that the variation reduced image does not satisfy the condition, the output moving image generating section282generates the output moving image including the differential images generated by the differential image generating section216under the condition that the data amount obtained by the permissible data amount obtaining section250is smaller than a predetermined value. To be specific, when the satisfaction judging section230judges that the averaged image does not satisfy the condition, the output moving image generating section282generates an output moving image including differential images generated by the differential image generating section216under the condition that the data amount which is obtained by the permissible data amount obtaining section250is smaller than a predetermined value.

Here, the satisfaction judging section230may judge whether each of the partial regions in the variation reduced image satisfies the condition. To be specific, the satisfaction judging section230may judge whether each of the partial regions in the averaged image satisfies the condition. The output moving image generating section282may generate an output moving image in which the image quality is lower in a region which is different from a satisfying region that is judged by the satisfaction judging section230to satisfy the condition than in the satisfying region. To be specific, the output moving image generating section282may generate an output moving image including moving-image making-up images in which the image quality is lower in a region which is not a satisfying region that is judged by the satisfaction judging section230to satisfy the condition than in the satisfying region.

The object extracting section225extracts an object from the variation reduced image generated by the variation reduced image generating section201. To be specific, the object extracting section225extracts an object which satisfies a predetermined condition from the moving image captured by the image capturing section200. Specifically speaking, the object extracting section225extracts an object which satisfies the condition stored on the condition storing section240, from the moving-image making-up images included in the moving image captured by the image capturing section200. The image quality of the moving image obtained by the conversion performed by the image generating section280on the moving image captured by the image capturing section200decreases as the size of the object extracted by the object extracting section225increases. The output section290outputs the moving image obtained by the conversion performed by the image generating section280. In this case, the resolution of the moving image obtained by the conversion performed by the image generating section280on the moving image captured by the image capturing section200decreases as the size of the object extracted by the object extracting section225increases.

The movement amount calculating section222calculates the amount of the movement made by the object extract by the object extracting section225between the moving-image making-up images included in the moving image captured by the image capturing section200. The condition storing section240stores thereon a lower limit value for the amount of a movement which is required to be made by an object required to be extracted. For example, the condition storing section240stores thereon a lower limit value for the amount of a movement, between successive frames, which is required to be made by the object required to be extracted. The object extracting section225extracts, from the moving-image making-up images included in the moving image captured by the image capturing section200, an object which makes a movement the amount of which is calculated by the movement amount calculating section222and is equal to or higher than the lower limit value for the amount of the movement which is stored on the condition storing section240. Here, the resolution of the moving image obtained by the conversion performed by the image generating section280on the moving image captured by the image capturing section200decreases as the size of the object extracted by the object extracting section225increases. To be specific, the display rate of the moving image obtained by the conversion performed by the image generating section280on the moving image captured by the image capturing section200decreases as the amount of the movement made by the object which is calculated by the movement amount calculating section222increases.

The image quality storing section262stores thereon, in association with the size of the object and the amount of the movement made by the object, combinations of the display rate of a moving image and the image quality of the moving-image making-up images included in the moving image. The image quality selecting section260selects a combination of the image quality and display rate which is stored on the image quality storing section262in association with the size of the object extracted by the object extracting section225and the amount of the movement made by the object which is calculated by the movement amount calculating section222. The image generating section280converts the moving image captured by the image capturing section200into a moving image in which moving-image making-up images having the image quality selected by the image quality selecting section260are displayed at the display rate selected by the image quality selecting section260.

The moving direction identifying section223identifies the direction in which the object extracted by the object extracting section225moves, based on what is shown by the moving image captured by the image capturing section200. The image generating section280generates, by using the cropping technique and the moving-image making-up images included in the moving image captured by the image capturing section200, moving-image making-up images each of which contains therein the object and the width of which is larger in the moving direction than in the direction vertical to the moving direction. The output section290outputs a moving image including the moving-image making-up images generated by the image generating section280. The movement amount calculating section222calculates the amount of the movement made by the object, in the direction identified by the moving direction identifying section223, between the moving-image making-up images included in the moving image captured by the image capturing section200. The width, in the moving direction which is identified by the moving direction identifying section223, of the moving-image making-up images generated by the image generating section280by using the cropping technique and the moving-image making-up images included in the moving image captured by the image capturing section200increases as the amount of the movement which is calculated by the movement amount calculating section222increases. Therefore, the image capturing apparatus100can provide a monitoring image which enables a user to appropriately monitor a region towards which a suspicious person moves, with it being possible to prevent an unnecessary increase in the amount of data transmitted via the transmission path140.

The condition storing section240stores thereon a lower limit value for the amount of a change, from a reference image, which is required to be detected in moving-image making-up images included in a moving image which is judged to show abnormalities. The change amount calculating section221calculates the amount of a change, from a reference image, which is found in the variation reduced image generated by the variation reduced image generating section201. To be specific, the change amount calculating section221calculates the amount of a change, from a predetermined reference image, which is found in the moving image captured by the image capturing section200. For example, the change amount calculating section221calculates the amount of a change found in a first moving-image making-up image contained in the moving image captured by the image capturing section200, from a second moving-image making-up image which is captured prior to the first moving-image making-up image. Note that the change amount calculating section221calculates the amount of a change, from the reference image, in the averaged image generated by the averaged image generating section202. Here, the reference image may be an image of the monitored area which is provided in advance, a moving-image making-up image which is captured by the image capturing section200at a preceding timing, or an averaged image which is generated at a preceding timing.

The satisfaction judging section230judges that the variation reduced image satisfies the condition when the amount of the change which is calculated by the change amount calculating section221is equal to or higher than the lower limit value for the amount of the change which is stored on the condition storing section240. To be specific, the satisfaction judging section230judges that the averaged image satisfies the condition when the amount of the change which is calculated by the change amount calculating section221is equal to or higher than the lower limit value for the amount of the change which is stored on the condition storing section240.

When the amount of the change which is calculated by the change amount calculating section221is lower than a predetermined lower limit value for the amount of the change, the output control section270converts the moving image captured by the image capturing section200into a moving image which has a smaller amount of data than when the amount of the change which is calculated by the change amount calculating section221is equal to or higher than the lower limit value, and causes the output section290to output the moving image obtained by the conversion. To be specific, when the amount of the change from the reference image is smaller than the lower limit value, the output control section270converts the moving image captured by the image capturing section200into a moving image which has a lower resolution than when the amount of the change from the reference image is equal to or higher than the lower limit value, and causes the output section290to output the moving image obtained by the conversion. Alternatively, when the amount of the change from the reference image is lower than the lower limit value, the output control section270may convert the moving image captured by the image capturing section200into a moving image which is expressed by using a smaller number of gray levels than when the amount of the change from the reference image is equal to or higher than the lower limit value, and cause the output section290to output the moving image obtained by the conversion. As another alternative example, when the amount of the change from the reference image is smaller than the lower limit value, the output control section270converts the moving image captured by the image capturing section200into a moving image which has a lower display rate than when the amount of the change from the reference image is equal to or higher than the lower limit value, and causes the output section290to output the moving image obtained by the conversion. Here, the condition designating section242increases the lower limit value stored on the condition storing section240as the data amount obtained by the permissible data amount obtaining section250decreases.

The change amount calculating section221may calculate the amount of the movement made by the object which shows a given subject, between the first and second moving-image making-up images included in the moving image captured by the image capturing section200. When the amount of the movement made by the object which is calculated by the change amount calculating section221is lower than a predetermined lower limit value for the amount of the movement, the output control section270converts the moving image captured by the image capturing section200into a moving image which has a smaller amount of data than when the amount of the movement which is calculated by the change amount calculating section221is equal to or higher than the lower limit value for the amount of the movement, and causes the output section290to output the moving image obtained by the conversion. Here, the condition designating section242may increase the lower limit value for the amount of the movement as the data amount obtained by the permissible data amount obtaining section250decreases.

The condition storing section240stores thereon a lower limit value for the degree of match which is required to be detected between a predetermined object and an object in a variation reduced image generated by using moving-image making-up images included in a moving image which is judged to show abnormalities. To be specific, the condition storing section240stores thereon a lower limit value for the degree of match which is required to be detected between a predetermined object and an object in an averaged image generated by averaging moving-image making-up images included in a moving image which is judged to show abnormalities. The object extracting section225extracts an object from the averaged image generated by the averaged image generating section202.

When the degree of match between the object extracted by the object extracting section225and the predetermined object is equal to or higher than the lower limit value stored on the condition storing section240, the satisfaction judging section230judges that the variation reduced image satisfies the condition. To be specific, when the degree of match between the object extracted by the object extracting section225and the predetermined object is equal to or higher than the lower limit value stored on the condition storing section240, the satisfaction judging section230judges that the averaged image satisfies the condition. To be further specific, the match calculating section232calculates the degree of match between the shape of the object included in the moving image captured by the image capturing section200and the shape of a predetermined reference object. When the degree of match calculated by the match calculating section232is equal to or higher than the lower limit value stored on the condition storing section240, the satisfaction judging section230judges that the averaged image satisfies the condition.

When the degree of match calculated by the match calculating section232is lower than a predetermined lower limit value for the degree of match, the output control section270may convert the moving image captured by the image capturing section200into a moving image which has a smaller amount of data than when the degree of match calculated by the match calculating section232is equal to or higher than the lower limit value, and cause the output section290to output the moving image obtained by the conversion. To be specific, when the degree of match calculated by the match calculating section232is lower than a predetermined lower limit value for the degree of match in terms of shape, the output control section270converts the moving image captured by the image capturing section200into a moving image which has a smaller amount of data than when the degree of match calculated by the match calculating section232is equal to or higher than the lower limit value for the degree of match in terms of shape, and causes the output section290to output the moving image obtained by the conversion. Here, the condition designating section242may increase the lower limit value for the degree of match in terms of shape as the data amount obtained by the permissible data amount obtaining section250decreases.

The condition storing section240stores thereon a lower limit value for the area occupied by colors included in a predetermined color range, which is required to be detected in a variation reduced image generated by using moving-image making-up images included in a moving image which is judged to show abnormalities. To be specific, the condition storing section240stores thereon a lower limit value for the area occupied by colors included in a predetermined color range, which is required to be detected in an averaged image generated by averaging moving-image making-up images included in a moving image which is judged to show abnormalities. For example, the condition storing section240may store thereon a lower limit value for the area occupied by colors included in a color range which has colors characteristic to a person. The particular color area calculating section224calculates the area occupied by the colors included in the predetermined color range, in the variation reduced image generated by the variation reduced image generating section201. To be specific, the particular color area calculating section224calculates the area occupied by the colors included in the predetermined color range, in the averaged image generated by the averaged image generating section202.

When the area calculated by the particular color area calculating section224is equal to or higher than the lower limit value for the area which is stored on the condition storing section240, the satisfaction judging section230judges that the variation reduced image satisfies the condition. To be specific, when the area calculated by the particular color area calculating section224is equal to or higher than the lower limit value for the area which is stored on the condition storing section240, the satisfaction judging section230judges that the averaged image satisfies the condition. To be further specific, the match calculating section232calculates the degree of match between the colors included in the object contained in the moving image captured by the image capturing section200and the colors included in a predetermined reference object. When the degree of match calculated by the match calculating section232is equal to or higher than the lower limit value stored on the condition storing section240, the satisfaction judging section230judges that the averaged image satisfies the condition.

The condition storing section240stores thereon a lower limit value for the degree of match which is required to be detected in a variation reduced image which is generated by using moving-image making-up images included in a moving image which is judged to show abnormalities, between the direction from the position of the subject contained in the variation reduced image to the image capturing section200and the direction in which the subject moves. To be specific, the condition storing section240stores thereon a lower limit value for the degree of match which is required to be detected in an averaged image generated by averaging moving-image making-up images included in a moving image which is judged to show abnormalities, between the direction from the position of the subject contained in the averaged image to the image capturing section200and the direction in which the subject moves.

The moving direction identifying section223identifies the direction in which the subject moves in the monitored area based on what is shown by a plurality of variation reduced images generated by the variation reduced image generating section201. To be specific, the moving direction identifying section223identifies the direction in which the subject moves in the monitored area based on what is shown by a plurality of averaged images generated by the averaged image generating section202. When the degree of match between the direction in which the subject moves and the direction from the position of the subject to the image capturing section200is equal to or higher than the lower limit value for the degree of match which is stored on the condition storing section240, the satisfaction judging section230judges that the variation reduced image satisfies the condition. To be specific, when the degree of match between the direction in which the subject moves and the direction from the position of the subject to the image capturing section200is equal to or higher than the lower limit value for the degree of match which is stored on the condition storing section240, the satisfaction judging section230judges that the averaged image satisfies the condition.

When the satisfaction judging section230judges that there is an object satisfying the condition, the object region identifying section212identifies an object region including the object satisfying the condition. When the satisfaction judging section230judges that there is an object satisfying the condition, the output section290outputs the image of the object region. When the satisfaction judging section230judges that there is an object satisfying the condition, the image storing section214stores thereon the image of the region other than the object region. When the satisfaction judging section230judges that there is no object satisfying the condition in the moving image of the monitored area after the image storing section214stores thereon the image of the region other than the object region, the output control section270causes the output section290to output the image of the region other than the object region which is stored on the image storing section214.

When the satisfaction judging section230judges that there is an object satisfying the condition, the image quality of the image of the object region which is output from the output section290may increase as the data amount obtained by the permissible data amount obtaining section250increases. When the satisfaction judging section230judges that there is an object satisfying the condition, the size of the object region including the object satisfying the condition which is identified by the object region identifying section212may increase as the data amount obtained by the permissible data amount obtaining section250increases.

When the satisfaction judging section230judges that there is no object satisfying the condition in the moving image of the monitored area after the image storing section214stores thereon the image of the region other than the object region, the output control section270causes the output section290to output the image of the region other than the object region which is stored on the image storing section214under the condition that the data amount which is obtained by the permissible data amount obtaining section250is higher than a predetermined value.

When the satisfaction judging section230judges that there is no object satisfying the condition in the moving image of the monitored area after the image storing section214stores thereon the image of the region other than the object region, the output control section270may cause the output section290to output the image of the region other than the object region which is stored on the image storing section214, with the image quality corresponding to the data amount which is obtained by the permissible data amount obtaining section250.

The object region identifying section212may identify, as the object region, a region including an object which makes a movement, between a plurality of moving-image making-up images included in the moving image captured by the image capturing section200, the amount of which is equal to or higher than the lower limit value for the amount of the movement which is stored on the condition storing section240.

The condition storing section240may store thereon a lower limit value for the degree of match between an object which is required to be extracted from a moving image and a predetermined object. The object region identifying section212may extract, as the object region, a region including an object which matches the predetermined object at a degree of match equal to or higher than the lower limit value for the degree of match which is stored on the condition storing section240. The condition storing section240may store thereon a lower limit value for the area occupied by colors included in a predetermined color range, which is required to be found in an object which is required to be extracted from a moving image. The object region identifying section212extracts, as the object region, a region including an object in which the area occupied by the colors included in the predetermined color range is equal to or higher than the lower limit value for the area which is stored on the condition storing section240.

Here, the change amount calculating section221and condition designating section242may not necessarily be provided in each image capturing apparatus100. Alternatively, the monitoring system110may include therein a single change amount calculating section221and a single condition designating section242. In this case, the change amount calculating section221may calculate the amount of a change from a predetermined reference image in each of the moving images captured by a plurality of image capturing sections200. The output control section270may then convert a moving image in which the amount of the change which is calculated by the change amount calculating section221is lower than a predetermined lower limit value for the amount of the change into a moving image which has a smaller data amount than when the amount of the change calculated by the change amount calculating section221is equal to or higher than the lower limit value, and output the moving image obtained by the conversion to the transmission path140. The condition designating section242may increase the lower limit value which is stored on the condition storing section240as the difference between the amount of data which can be transmitted per unit time via the transmission path140and the amount of data which is output per unit time from each of the plurality of image capturing sections200decreases. The match calculating section232may calculate the degree of match between a predetermined reference object and an object included in each of the moving images captured by the plurality of image capturing sections200. The output control section270converts a moving image in which the degree of match which is calculated by the match calculating section232is lower than a predetermined lower limit value for the degree of match into a moving image which has a smaller data amount than when the degree of match which is calculated by the match calculating section232is equal to or higher than the lower limit value, and outputs the moving image obtained by the conversion to the transmission path140. The condition designating section242increases the lower limit value as the difference between the amount of data which can be transmitted per unit time via the transmission path140and the amount of data which is output per unit time from each of the plurality of image capturing sections200decreases.

The image capturing control section210designates the image capturing range of the image capturing section200in such a manner that the image capturing section200captures a moving image including moving-image making-up images which contain therein an object and the width of which is larger in the moving direction than in the direction vertical to the moving direction, and then causes the image capturing section200to capture the moving image of the monitored area. The output section290outputs the moving image which is captured by the image capturing section200in such a state that the image capturing range is designated by the image capturing control section210. Here, the image capturing control section210may adjust the image capturing conditions imposed on the image capturing section200so as to appropriately capture images of a subject included in the image capturing range which enables the image capturing section200to capture moving-image making-up images which contain an object and the width of which is larger in the moving direction than in the direction vertical to the moving direction. The output section290may output the moving image captured by the image capturing section200in such a state that the image capturing conditions have been adjusted by the image capturing control section210.

The image capturing control section210may designate the image capturing range of the image capturing section200in such a manner that the image capturing section200captures moving-image making-up images which contain an object and in which a region positioned ahead of the object in the moving direction is larger than a region positioned behind the object in the moving direction, and cause the image capturing section200to capture the images. The image capturing control section210may adjust the image capturing conditions imposed on the image capturing section200so as to appropriately capture images of a subject which is included in the image capturing range which enables the image capturing section200to capture moving-image making-up images which contain an object and in which a region positioned ahead of the object in the moving direction is larger than a region positioned behind the object in the moving direction is captured.

The image capturing rate for the moving image captured by the image capturing section200may be higher than the monitor display rate. The data amount per unit time which is required for transmitting the moving images captured by all image capturing apparatuses100may be higher than the amount of data which can be transmitted per unit time via the transmission path140. Note that the moving-image making-up images in the present embodiment are, for example frame images or field images. The image capturing section200may capture the image of the entire monitored area through a fish-eye lens.

According to the above description, the image capturing apparatus100captures a moving image, and transmits the captured moving image to the server170. According to a different embodiment, however, the server170may have some of the functions of the image capturing apparatus100. For example, the image capturing apparatus100may capture the moving image of the monitored area, and output the captured moving image without a change to the transmission path140, and the server170may control the image quality of the moving image to be recorded thereon, or may control the image quality of the moving images to be displayed on the display apparatuses180,181, and182. If this is the case, the server170may include therein the object region identifying section212, image storing section214, differential image generating section216, image characteristic extracting section220, satisfaction judging section230, condition storing section240, condition designating section242, permissible data amount obtaining section250, image quality selecting section260, image quality storing section262, output control section270, image generating section280, and output section290. In this case, the output section290may record the moving images generated by the output moving image generating section282onto a recording medium, or may cause the moving images generated by the output moving image generating section282to be displayed on the display apparatuses180,181and182.

FIGS. 4A and 4Billustrate an exemplary flow of operations performed by the image capturing apparatus100. The image capturing section200captures a moving image of the monitored area, by successively capturing frame images which have a resolution higher than the monitor resolution of the display apparatuses180to182at a frame rate which is higher than the monitor display rate of the display apparatuses180to182(step S400). Here, the averaged image generating section202increments the averaging counter each time the image capturing section200captures a frame image. Based on the value shown by the averaging counter, the averaged image generating section202judges whether the image capturing section200has captured a predetermined number of frame images (step S401). When judging positively in the step S401, the averaged image generating section202generates an averaged image by averaging in units of a pixel the predetermined number of frame images captured by the image capturing section200(step S402), and sets the value of the averaging counter at zero.

After this, the satisfaction judging section230judges whether an object corresponding to a person is detected (step S404). To be specific, the object extracting section225extracts the outline of the object from the averaged image by using a technique such as edge reinforcement. The match calculating section232then calculates the degree of match, in terms of shape, between the region within the outline of the object which is extracted by the object extracting section225and a predetermined pattern of a person, by comparing the region within the outline of the object which is extracted by the object extracting section225and the predetermined pattern of a person to each other. For example, the match calculating section232may calculate the degree of match in terms of shape, by dividing the area of a portion within the outline of the object which overlaps a pattern of a person which has the same area as the object by the area of the region enclosed by the outline of the object. When the degree of match in terms of shape which is calculated by the match calculating section232is equal to or higher than the lower limit value for the degree of match in terms of shape which is stored on the condition storing section240, the satisfaction judging section230judges that an object corresponding to a person is detected.

Here, the movement amount calculating section222calculates the speed at which the object which is extracted by the object extracting section225moves. When the satisfaction judging section230judges that an object corresponding to a person is detected in the step S404, the image quality selecting section260obtains the moving speed of the object corresponding to the person which is calculated by the movement amount calculating section222(step S406).

Subsequently, the image capturing apparatus100determines the display rate of the output moving image to be output to the transmission path140and the resolution of the frame images to be output to the transmission path140(step S408). To be specific, the image quality selecting section260selects a combination of the resolution and the display rate which is stored on the image quality storing section262in association with the area of the object corresponding to the person and the moving speed of the object corresponding to the person. For example, the resolution selected by the image quality selecting section260in the step S408increases (however does not exceed the resolution of the frame images captured by the image capturing section200) as the size of the object decreases, and the display rate selected by the image quality selecting section260in the step S408increases (however, does not exceed the image capturing rate of the frame images captured by the image capturing section200) as the moving speed of the object increases.

In accordance with the display rate selected in the step S408, the output moving image generating section282judges whether to generate an output moving image including output frame images which are generated based on the frame images captured by the image capturing section200(step S410). For example, the output moving image generating section282has therein a counter which is incremented each time the image capturing section200captures a frame image and which is initialized to zero every time a moving image is generated based on captured frame images. Here, the output moving image generating section282judges that the output moving image including the output frame images is generated, when the product of the value shown by the counter and the interval between the timings at which the frame images are captured by the image capturing section200is equal to or higher than the time interval between the output frame images included in the output moving image which is displayed at the display rate selected in the step S408.

When the output moving image generating section282judges positively in the step S410, the permissible data amount obtaining section250detects the amount of data which is transmitted per unit time via the transmission path140(step S412). The permissible data amount obtaining section250calculates a permissible data amount which corresponds to the difference between the amount of data which can be transmitted per unit time via the transmission path140and the amount of data which is transmitted per unit time via the transmission path140. Alternatively, the permissible data amount obtaining section250may obtain the permissible data amount from the server170.

The output moving image generating section282then judges whether to be capable of generating a moving image having the image quality selected in the step S408(step S414). To be specific, the output moving image generating section282judges positively when the permissible data amount is equal to or higher than the amount of data which needs to be transmitted per unit time in order to transit moving image data which has the resolution and display rate selected in the step S408.

When judging positively in the step S414, the output moving image generating section282generates output frame images having the resolution selected in the step S408by discarding some of the pixels forming the frame images captured by the image capturing section200. The output moving image generating section282then generates a moving image including the generated output frame images, and supplies the generated moving image to the output section290(step S416). Subsequently, the image capturing apparatus100judges whether an image capturing end instruction has been received (step S418). When judging negatively in the step S418, the image capturing apparatus100next performs the operation in the step S400. When judging positively in the step S418, the image capturing apparatus100ends the operations.

After the image capturing apparatus100moves on to the operation in the step S400subsequently to the judgment of ending the image capturing in the step S418, it may be judged in the step S401that the predetermined number of frame images have not been captured. If such is the case, the output moving image generating section282judges whether to generate an output moving image including output frame images (step S440). In the step S440, the output moving image generating section282judges whether to generate an output moving image including output frame images, in accordance with the display rate which has already been determined, as in the step S410. When the output moving image generating section282judges positively in the step S440, the image capturing apparatus100next performs the operation in the step S412. When the output moving image generating section282judges negatively in the step S440, the image capturing apparatus100next performs the operation in the step S400.

When judging negatively in the step S414, the output moving image generating section282obtains the movement direction of the object corresponding to the person (step S420). To be specific, the output moving image generating section282obtains the moving direction which is identified by the moving direction identifying section223for the object corresponding to the person, as the movement direction of the object.

Following this, the output moving image generating section282determines the cropping range for the frame images captured by the image capturing section200(step S422). To be specific, the output moving image generating section282determines the cropping range in such a manner as to obtain a cropped image which includes the object corresponding to the person and the width of which is larger in the movement direction of the object than in the direction vertical to the movement direction. Hereinafter, the region within the cropping range is referred to as a person region. The output moving image generating section282generates cropped images showing the person region by cropping the frame images in accordance with the cropping range determined in the step S422(step S424). Here, the image storing section214stores thereon the images showing the removed region as a result of the cropping (the images of the region other than the person region) (step S426). The output moving image generating section282then generates a moving image including the cropped images obtained in the step S424, and supplies the generated moving image to the output section290(step S428). The image capturing apparatus100next performs the operation in the step S418.

When the satisfaction judging section230does not detect the object corresponding to the person in the step S404, the output moving image generating section282generates a moving image based on the averaged images, and supplies the moving image to the output section290(step S430). Here, the output moving image generating section282may generate a moving image including output frame images which are generated by appropriately discarding some of the pixels of the averaged images and thus have a reduced amount of data, and supply the generated moving image to the output section290. Alternatively, the output moving image generating section282may generate a moving image including output frame images which are generated by appropriately discarding some of the pixels forming the frame images captured by the image capturing section200and thus have a reduced amount of data, and supply the generated moving image to the output section290.

Subsequently, the output control section270supplies, to the output section290, a moving image including the images of the region other than the person region which are stored on the image storing section214in the step S426(step S432). Also, when the output moving image generating section282judges that the output moving image is generated based on the frame images in the step S410, the image capturing apparatus100proceeds to the operation in the step S432, and the output control section270supplies, to the output section290, the moving image including the images of the region other than the person region which are stored in the step S426onto the image storing section214. In the step S432, the output control section270may cause the output section290to output the individual images of the region other than the person region, instead of generating the moving image including the images of the region other than the person region and supplying the generated moving image to the output section290.

As described above, when detecting movement made by a person, the image capturing apparatus100transmits to the server170a moving image which has a higher resolution and a higher display rate than when not detecting such a movement of a person. Here, when the transmission path140is heavily burdened, the image capturing apparatus100transmits to the server170a moving image including frame images that only show at a high resolution the region of the original frame images in which the movement of the person is detected and are obtained by removing the remaining region by the cropping. After this, when the movement of the person becomes no longer detected, the image capturing apparatus100transmits the images showing the region other than the person region which has been removed by the cropping. As a result, the image capturing apparatus100can reduce the time period required for the transmission of the moving image data to the server170, even when the transmission path140is heavily burdened.

FIG. 5illustrates, as an example, image quality information stored on the image quality storing section262by using a table. The image quality storing section262stores thereon the resolution PR of output frame images included in a moving image to be output and the display rate FR of the moving image to be output, in association with the area S occupied by a person and the speed V of a movement. For example, when the area S of the person is no less than S1and less than S2and the speed V of the movement is less than V1, the resolution PR of the output frame images is PR3and the display rate FR of the moving image to be output is FR1, according to the image quality storing section262.

The resolutions PR1, PR2, PR3and PR4are defined as PR4>PR3>PR2>PR1, and the display rates FR1, FR2, FR3and FR4are defined as FR4>FR3>FR2>FR1. In other words, the display rate FR stored on the image quality storing section262increases as the speed of the movement increases, and the resolution PR stored on the image quality storing section262increases as the area of the person decreases. With such a configuration, the image capturing apparatus100decreases the resolution of the frame images as the dimensions of the person in the frame images increase. In this way, the image capturing apparatus100can prevent the data amount of the moving image to transmit from unnecessarily increasing. In addition, the image capturing apparatus100increases the display rate as the speed of the movement made by the person increases. In this way, the image capturing apparatus100can provide a moving image which enables a monitoring person to easily realize what the person is doing.

According to the above description, the image quality storing section262stores thereon the resolution PR of the output frame images and the display date FR of the moving image to be output in association with the area S of the person and the speed V of the movement. Alternatively, the image quality storing section262may store thereon, in association with the area S of the person and the speed V of the movement, the resolution PR of the output frame images, the number of gray levels, and the display rate FR of the moving image to be output. For example, the number of gray levels stored on the image quality storing section262may decrease as the area of the person increases. As the area of the person increases, the number of gray levels for the output frame images which are used by the output moving image generating section282to generate the output moving image may decrease.

As described above, the condition storing section240stores thereon condition to be satisfied by an object which is required to be extracted from the images captured by the image capturing section200. The object extracting section225extracts an object which satisfies the condition from the image captured by the image capturing section200. The image quality of the images generated by the image generating section280based on the images captured by the image capturing section200decreases as the size of the object extracted by the object extracting section225increases. The output section290outputs the image generated by the images generating section280.

For example, the condition storing section240stores thereon a lower limit value for the degree of match between an object required to be extracted and a predetermined object. The object extracting section225extracts, from the moving image captured by the image capturing section200, an object which matches the predetermined object with the degree of the match being higher than the lower limit value which is stored on the condition storing section240. The image quality of the images generated by the image generating section280based on the images captured by the image capturing section200decreases as the size of the object extracted by the object extracting section225increases.

The condition storing section240stores thereon a lower limit value for the area occupied by colors included in a predetermined color range, which is required to be found in an object to be extracted. The object extracting section225extracts, from the moving image captured by the image capturing section200, an object in which the area occupied by the colors included in the predetermined color range is equal to or higher than the lower limit value for the area which is stored on the condition storing section240. The image quality of the images generated by the image generating section280based on the images captured by the image capturing section200decreases as the size of the object extracted by the object extracting section225increases.

To be specific, as the size of the object extracted by the object extracting section225increases, the resolution of the images generated by the image generating section280based on the images captured by the image capturing section200decreases. Alternatively, as the size of the object extracted by the object extracting section225increases, the number of gray levels of the images generated by the image generating section280based on the images captured by the image capturing section200decreases.

FIG. 6illustrates an example of the cropped image generated by the output moving image generating section282. The output moving image generating section282generates, based on an image600, a cropped image A which is to be included in the moving image to be output from the output section290. Here, the image600may be one of the frame images making up the moving image captured by the image capturing section200, or the averaged image generated by the averaged image generating section202. The moving direction identifying section223and movement amount calculating section222respectively calculate a moving direction660of a person650in the image600and the speed V of the movement made by the person650, based on the change in the position of the same person650which is extracted by the object extracting section225, between a plurality of successive images.

Subsequently, the output moving image generating section282determines a cropping box610(the step S422inFIG. 4B). In the cropping box610, the person650is contained and the width x of the cropping box610in the moving direction which is identified by the moving direction identifying section223is larger than the width y of the cropping box610in the direction vertical to the moving direction. According to the example shown inFIG. 6, the output moving image generating section282determines the cropping box610in which the region ahead of the person650in the moving direction which is identified by the moving direction identifying section223is larger than the region behind the person650in the moving direction.

After this, the output moving image generating section282generates a moving image which has the cropped image A within the cropping box610as an output frame image associated with the timing at which the image600is captured, and supplies the generated moving image to the output section290(the step S428inFIG. 4B). Here, the image storing section214stores thereon an image B showing the region outside the cropping box610(the step S426inFIG. 4B). The output section290transmits the image B which is stored on the image storing section214when the permissible data amount becomes larger than the amount of the moving image data output from the output section290(the step S432inFIG. 4B).

As described above, the image generating section280generates, by using the cropping technique and based on the moving-image making-up images included in the moving image captured by the image capturing section200, moving-image making-up images which include an object and in which the region ahead of the object in the moving direction is larger than the region behind the object in the moving direction. With such a configuration, the image capturing apparatus100can transmit, to the server170, images which are cropped so as to include not only the person650but also the region towards which the person650moves. Therefore, the image capturing apparatus100can provide a moving image which shows a subject desired by the monitoring person with it being possible to reduce the amount of data transmitted when compared with a case where the captured images showing the entire region are transmitted. As a result the image capturing apparatus100can swiftly supply, to the server170, a moving image whose contents enable the monitoring person to satisfactorily monitor the person650, even when the transmission path140is congested and has no room for transmitting the moving image showing the entire region.

FIG. 7illustrates a different example of the cropped image which is generated by the output moving image generating section282. According to the example shown inFIG. 7, the speed of the movement which is calculated by the movement amount calculating section222is higher than in the example shown inFIG. 6. In this case, the output moving image generating section282designates a cropping box710in order that the cropped image A has a larger width in the direction760identified by the moving direction identifying section223than in the exemplary case described with reference toFIG. 6. With such a configuration, the image capturing apparatus100can supply to the server170images which enable the monitoring person to accurately know for what purpose the person makes the movement even when the person moves fast.

FIG. 8illustrates a further different example of the cropped image which is generated by the output moving image generating section282. According to the example shown inFIG. 8, the output moving image generating section282determines a cropping box810in which a person850is positioned in substantially the center. Here, the image generating section280generates, by using the cropping technique and based on the moving-image making-up images included in the moving image captured by the image capturing section200, moving-image making-up images which include the object extracted by the object extracting section225and in which the region ahead of the object in the moving direction is larger than the region behind the object in the moving direction. Which is to say, the output moving image generating section282determines the cropping box810in order to obtain the cropped image A in which the region ahead of the person850in the moving direction and the region behind the person850in the moving direction are substantially the same. With such a configuration, the image capturing apparatus100can supply to the server170images which enable the monitoring person to appropriately monitor the regions ahead and behind the person850.

According to the above description with reference toFIGS. 6 to 8, the image capturing apparatus100crops the frame images captured or averaged images, for example. Alternatively to a case where the images are cropped by using the cropping boxes610,710and810, however, the image capturing control section210may adjust the image capturing conditions for the subjects within the cropping boxes610,710and810, and then cause the image capturing section200to capture images of the subjects. For example, the image capturing control section210may control the image capturing direction and zoom setting of the image capturing section200in such a manner that the ranges within the cropping boxes610,710and810are the ranges to be image-captured by the image capturing section200.

FIG. 9illustrates, in a chronological order, exemplary frame images included in the moving image output from the output section290. The averaged image generating section202generates each of averaged images910,920,930,940, . . . ,980,990, . . . by averaging four frame images which are successively captured by the image capturing section200. When no change is found between successive averaged images, the output moving image generating section282supplies to the output section290a moving image made up by output frame images which are displayed at an interval which is n times (n is a predetermined number and, for example, four) as long as the interval at which the image capturing section200captures frame images. For example, the output moving image generating section282supplies to the output section290a moving image which includes, as the output frame images, averaged images each of which is obtained by averaging a predetermined number of successive frame images (for example, the averaged images910,920and930). Here, the output moving image generating section282may supply to the output section290a moving image which includes, as the output frame images, images each of which is generated by appropriately discarding some of the pixels making up an averaged image, or may supply to the output section290a moving image which includes differential images which are generated by the differential image generating section216based on successive averaged images. Alternatively, the output moving image generating section282may identify a time period during which the moving-image making-up images which are averaged to generate the averaged image are captured, and may supply to the output section290a moving image which includes, as the output frame images, the images each of which is obtained by discarding some of the pixels of a corresponding one of the moving-image making-up images captured during the identified time period. As another alternative example, the output moving image generating section282may supply, to the output section290, a moving image which includes, as the output frame images, only part of the moving-image making-up images captured during the identified time period.

When (for example, at times t12and t16) a change is detected between successive averaged images (for example, between the averaged images920and930and between the averaged images930and940) and the satisfaction judging section230judges that there is an object corresponding to a person in an averaged image (for example, the averaged images930and940), the output moving image generating section282supplies to the output section290a moving image which includes the frame images captured by the image capturing section200after the time t12.

Here, as described with reference to the steps S420to S428inFIG. 4B, the output moving image generating section282may supply to the output section290a moving image which includes, as the output frame image, a cropped image941which is cropped by using the cropping box described with reference toFIGS. 6 to 8. The image storing section214stores thereon an image945which shows a region removed as a result of the cropping. Until a time t80at which the movement of the person becomes no longer detected, the output moving image generating section282generates a moving image including the output frame images arranged at the interval equal to the interval at which the image capturing section200captures frame images, and supplies the generated moving image to the output section290. Although it is not shown inFIG. 9for the purpose of intelligibility, the image storing section214may store thereon the images which show the region removed as a result of the cropping also from the time t14to the time t80.

When the change becomes no longer detected between successive averaged images, for example, between the averaged images980and990, the output moving image generating section282restarts supplying to the output section290the moving image which includes an averaged image as one output frame image. Here, the output control section270causes the output section290to output the image945stored on the image storing section214. The output control section270may divide the image945into a plurality of regions and cause the output section290to sequentially output the images showing the plurality of regions, in order to satisfy such a condition that the amount of data which is output per unit time from the output section290is equal to or lower than the permissible data amount which is obtained by the permissible data amount obtaining section250.

The image storing section214may store thereon all of the frame images captured by the image capturing section200from the time t13to the time t80, and cause the output section290to output a moving image which has, as one output frame image, each of the frame images stored on the image storing section214on or after the time t81at which the change becomes no longer detected. Here, the output control section270may determine the size, resolution or number of gray levels of the images to be transmitted from the output section290, in such a manner that the total amount of data which is output per unit time from the output section290is equal to or lower than the permissible data amount which is obtained by the permissible data amount obtaining section250. Note that the output control section270causes the output section290to output timing information indicating the timing at which each image is captured, in addition to the frame images (or the image945) stored on the image storing section214.

As described above, the variation reduced image generating section201generates a variation reduced image at an interval equal to a predetermined time duration by using a plurality of moving-image making-up images included in a moving image captured by the image capturing section200during a time period having the predetermined time duration. Assume a case where the variation reduced image generating section201generates a first variation reduced image by using a plurality of moving-image making-up images included in the moving image captured by the image capturing section200during a first period. When the satisfaction judging section230judges that the first variation reduced image does not satisfy the condition, the output moving image generating section282uses the first variation reduced image as the moving-image making-up image of the output moving image corresponding to the first period. When the satisfaction judging section230judges that the first variation reduced image satisfies the condition, the output moving image generating section282uses the moving image captured by the image capturing section200during the first period as the output moving image corresponding to the first period. To be specific, the averaged image generating section202averages a plurality of moving-image making-up images included in a moving image captured by the image capturing section200during a period having a predetermined time duration, to generate averaged images at an interval equal to the predetermined time duration. Assume a case where the averaged image generating section202generates a first averaged image by averaging a plurality of moving-image making-up images included in the moving image captured by the image capturing section200during a first period. When the satisfaction judging section230judges that the first averaged image does not satisfy the condition, the output moving image generating section282uses the first averaged image as the moving-image making-up image of the output moving image corresponding to the first period. When the satisfaction judging section230judges that the first averaged image satisfies the condition, the output moving image generating section282uses the moving image captured by the image capturing section200during the first period as the output moving image corresponding to the first period.

The variation reduced image generating section201may generate a variation reduced image at an interval equal to a predetermined time duration by using a plurality of moving-image making-up images included in a moving image which is captured by the image capturing section200during a time period having the predetermined time duration. Assume a case where the variation reduced image generating section201generates a first variation reduced image by using a plurality of moving-image making-up images included in the moving image captured by the image capturing section200during a first period. When the satisfaction judging section230judges that the first variation reduced image does not satisfy the condition, the output moving image generating section282may use a variation reduced image which is generated by the variation reduced image generating section201by using a plurality of moving-image making-up images captured by the image capturing section200during a second period which follows the first period, as the moving-image making-up image of the output moving image corresponding to the second period. When the satisfaction judging section230judges that the first variation reduced image satisfies the condition, the output moving image generating section282may use the moving image captured by the image capturing section200during the second period as the output moving image corresponding to the second period. To be specific, the averaged image generating section202may average a plurality of moving-image making-up images included in a moving image which is captured by the image capturing section200during a period having a predetermined time duration, to generate averaged images at an interval equal to the predetermined time duration. Assume a case where the averaged image generating section202generates a first averaged image by averaging a plurality of moving-image making-up images included in the moving image captured by the image capturing section200during a first period. When the satisfaction judging section230judges that the first averaged image does not satisfy the condition, the output moving image generating section282may use an averaged image which is generated by the averaged image generating section202by averaging a plurality of moving-image making-up images captured by the image capturing section200during a second period which follows the first period, as the moving-image making-up image of the output moving image corresponding to the second period. When the satisfaction judging section230judges that the first averaged image satisfies the condition, the output moving image generating section282may use the moving image captured by the image capturing section200during the second period as the output moving image corresponding to the second period.

Note that the variation reduced image generating section201may determine the time duration during which a plurality of moving-image making-up images are captured to generate a single variation reduced image, in such a manner that the display rate of the moving image which is made up by a plurality of variation reduced images becomes lower than the display rate of the moving image which can be transmitted at the rate equal to the data amount obtained by the permissible data amount obtaining section250. Based on the determined time duration, the variation reduced image generating section201may generate a variation reduced image at an interval equal to the determined time duration by using the moving-image making-up images included in the moving image captured by the image capturing section200during a time period having the determined time duration. To be specific, the averaged image generating section202may determine the time duration during which a plurality of moving-image making-up images are captured to generate a single averaged image, in such a manner that the display rate of the moving image which is made up by a plurality of averaged images becomes lower than the display rate of the moving image which can be transmitted at the rate equal to the data amount obtained by the permissible data amount obtaining section250. Based on the determined time duration, the averaged image generating section202may average the moving-image making-up images included in the moving image captured by the image capturing section200during a period having the determined time duration, so as to generate averaged images at an interval equal to the determined time duration.

FIG. 10illustrates an example of the output frame image generated by the output moving image generating section282. To be more specific,FIG. 10illustrates a different example of the output frame image which is generated by the output moving image generating section282based on the frame image captured by the image capturing section200at the time t13inFIG. 9. According to the example shown inFIG. 9, the output moving image generating section282generates a moving image which has, as output frame images, cropped images including the region in which the person is present based on the frame images captured by the image capturing section200, and causes the output section290to output the generated moving image. According to the example shown inFIG. 10, the output moving image generating section282alternatively generates a moving image which includes an output frame image1010in which the resolution is higher in the region in which the person is present than in the region other than the region in which the person is present and causes the output section290to output the generated moving image.

The output moving image generating section282generates the output frame image1010, based on the frame image captured by the image capturing section200, by discarding more pixels in the region other than the region in which the person is present than in the region in which the person is present. Here, the output moving image generating section282may additionally cause the output section290to output resolution information indicating resolutions in the regions defined in the output frame image1010. The image storing section214may store thereon an image expressed by the pixels discarded by the output moving image generating section282. The output control section270may cause the output section290to output the image stored on the image storing section214after the time t81.

As described in the preceding section, the moving image captured by the image capturing section200has a larger data amount than the moving image whose number of pixels, number of gray levels, and display rate are compatible with the display apparatuses180to182. Also, the moving image captured by the image capturing section200has a data amount that is larger than the data amount which can be transmitted per unit time from each image capturing apparatus100via the transmission path140. The output moving image generating section282and output control section270reduce the amount of data which is output per unit time from the output section290, by controlling the image quality (for example, the resolution, number of gray levels and display rate) of the moving image output from the output section290.

FIG. 11illustrates, as an example, the variation over time in the amount of data which is required to be output from the output section290to the transmission path140. The permissible data amount obtaining section250obtains the amount of data which can be transmitted per unit time from each image capturing apparatus100via the transmission path140, as the permissible data amount which is the amount of data which can be transmitted per unit time via the transmission path140. As described with reference toFIGS. 1 to 10, the output moving image generating section282and output control section270control the resolution, number of gray levels, and display rate of the moving image to be output from the output section290, in order to prevent the amount of data which is output per unit time from the output section290from exceeding the permissible data amount.

For example, when a movement of a person is detected, the output moving image generating section282may attempt to transmit a moving image which is captured by the image capturing section200and thus has a high display rate or high resolution. In this case, the amount of data which is output per unit time from the output section290exceeds the permissible data amount, for example, as in the period from the time t1102to the time t1103. To deal with this problem, the output moving image generating section282generates a moving image having a lower data amount in order to lower the amount of data which is output per unit time from the output section290to the permissible data amount. For example, the output moving image generating section282crops the frame images captured by the image capturing section200in order to generate a moving image only showing a region in which a person is present, or appropriately discards some of the pixels making up the frame images in accordance with the speed of a movement made by a person. The output control section270causes the output section290to output the images removed as a result of the cropping during the period from the time t1102to the time t1103or the images expressed by the pixels discarded during the period from the time t1102to the time t1103, during a period in which the amount of data which is output per unit time from the output section290is smaller than the permissible data amount (for example, during the period from the time t1103to the time t1104). The above-described control produces an effect that the moving image transmitted from the image capturing apparatus100to the server170can have a data amount substantially equal to the permissible data amount. As a result, the monitoring system110can efficiently use the bandwidth of the transmission path140.

FIG. 12illustrates, as an example, the conditions stored on the condition storing section240. The condition storing section240stores thereon lower limit values (S1, V1, Sα, Sβ, sγ, and md) for the area occupied by the person, the speed of the movement made by the object, the area of the changed region, the area occupied by particular colors, the degree of match in terms of shape between the detected object and the reference object, and the degree of match between the movement direction and the reference direction. When an object is detected in the averaged image generated by the averaged image generating section202and, in terms of the detected object, one of the area of the person, the speed of the movement made by the object, the area of the changed region, the area occupied by particular colors, the degree of match in terms of shape between the detected object and the reference object, and the degree of match between the reference direction and the movement direction has a value equal to or higher than a corresponding one of the lower limit values stored on the condition storing section240, the satisfaction judging section230judges that the averaged image satisfies the conditions stored on the condition storing section240. If such positive judgment is made, the output moving image generating section282generates a moving image which has a higher image quality than when the satisfaction judging section230judges that the averaged image does not satisfy the conditions stored on the condition storing section240, based on the moving image captured by the image capturing section200, as described with reference toFIGS. 1 to 11.

The condition storing section240may store thereon, as the lower limit value for the area of the changed region, a lower limit value for the number of pixels whose pixel values change by an amount equal to or more than a predetermined value between frame images captured by the image capturing section200or between averaged images generated by the averaged image generating section202. Alternatively, the condition storing section240may store thereon, as the lower limit value for the area of the changed region, a lower limit value for the ratio between the number of pixels whose pixel values change by an amount equal to or more than a predetermined value and the number of all the pixels in the frame image or averaged image. Here, the pixel value may denote a luminance value.

The condition storing section240may store thereon, as the lower limit value for the area occupied by particular colors, a lower limit value for the number of pixels which have a color included in a predetermined color range in the frame image or averaged image. The condition storing section240may store thereon, as the lower limit value for the area occupied by particular colors, a lower limit value for the ratio between the number of pixels which have a color included in the predetermined color range and the number of all the pixels in the frame image or averaged image.

The condition storing section240may store thereon, as the lower limit value for the degree of match in terms of shape between the detected object and the reference object, a lower limit value for the area of the overlap between the object contained in the frame image or averaged image and the predetermined reference object of the same size. The condition storing section240may store thereon, as the lower limit value for the degree of match in terms of shape between the detected object and the reference object, a lower limit value for the ratio of the area of the overlap between the object contained in the frame image or averaged image and the predetermined reference object of the same size to the area of the object.

The condition storing section240may store thereon, as the lower limit value for the degree of match between the reference direction and the movement direction, a lower limit value for an indicator value which is inversely proportional to the angle formed between the movement direction of the object contained in the frame image or averaged image and the predetermined reference direction. Here, the reference direction may be a predetermined direction in the frame image or averaged image, or a predetermined direction in the real space. The condition storing section240may store thereon, as the lower limit value for the degree of match between the reference direction and the movement direction, a lower limit value for the indicator value which is inversely proportional to the angle formed between the direction in which a subject indicated by the object contained in the frame image or averaged image moves and the direction from the position of the subject to the image capturing section200.

FIG. 13illustrates, as an example, frame images1310,1320and1330which captures therein a subject approaching towards the image capturing section200. The moving direction identifying section223calculates the positions of barycenters1311,1321and1331of objects1315,1325and1335which are extracted by the object extracting section225from the frame images1310,1320and1330captured by the image capturing section200. Also, the moving direction identifying section223calculates the lengths l1312, l1322and l1332of the objects extracted by the object extracting section225from the frame images1310,1320and1330.

Subsequently, the moving direction identifying section223calculates the increasing rate at which the length of the object increases between the frame images1310,1320and1330and the changing rate at which the position of the barycenter of the object changes between the frame images1310,1320and1330. When the increasing rate of the length of the object is equal to or higher than a predetermined reference value, and the changing rate of the position of the barycenter of the object is lower than a predetermined reference value, the moving direction identifying section223judges that the subject indicated by the object is approaching towards the image capturing section200.

Here, the condition storing section240may store thereon a condition which is used to determine whether the barycenter of the object moves towards the center in the image. When the position of the barycenter moves towards the center in the image, the satisfaction judging section230judges that the image satisfies the condition stored on the condition storing section240. In addition to the condition which is used to determine whether the barycenter of the object moves towards the center in the image, the condition storing section240may store thereon a condition which is related to the change in the size of the object. For example, the condition storing section240may store thereon a condition used to judge whether, between the moving-image making-up images or averaged images, the increasing rate of the length of the object is higher than a predetermined increasing rate and the barycenter of the object moves towards the center in the image, or a condition used to judge whether, between the moving-image making-up images or averaged images, the increasing rate of the length of the object is higher than the predetermined increasing rate and the barycenter of the object is positioned in the vicinity of the center of the image.

As described above, the image capturing apparatus100can increase the image quality of the moving image to output, when detecting a subject moving towards the image capturing section200. With such a configuration, the image capturing apparatus100can appropriately monitor a person who approaches towards an object to be protected against theft, with the image capturing section200being provided in the object to be protected. Also, the image capturing apparatus100can appropriately monitor a person who attempts to obstruct the operation of the image capturing apparatus100, for example, by covering the image capturing section200with cloth.

FIG. 14illustrates, as an example, the variation over time in the lower limit value for the speed of the movement which is designated by the condition designating section242. The amount of moving image data transmitted via the transmission path140is substantially constant from the time t1400to the time t1401, from the time t1402to the time t1403, and from the time t1404to the time t1405. During these periods, none of the image capturing apparatuses100detects a movement of a person. Therefore, all the image capturing apparatuses100convert the moving images captured into moving images of lower image quality and output the moving images of lower image quality, so that the total data amount of the moving images output from the image capturing apparatuses is R0.

On the other hand, from the time t1401to the time t1402, from the time t1403to the time t1404, and from the time t1405to the time t1406, any one or more of the image capturing apparatuses100detect a movement of a person. Therefore, one or more of the image capturing apparatuses100output the captured moving images to the transmission path140without converting the captured moving images into moving images of lower image quality. This results in an increase in the amount of data transmitted per unit time via the transmission path140. Here, the permissible data amount obtaining section250obtains, as the permissible data amount which is permitted to be transmitted per unit time, the difference between the maximum amount Rmax of data which can be transmitted per unit time via the transmission path140and the amount of data which is transmitted per unit time via the transmission path140. Alternatively, the permissible data amount obtaining section250may obtain, as the permissible data amount, the resulting value of dividing the difference between the maximum amount Rmax of data which can be transmitted per unit time via the transmission path140and the amount of data which is transmitted per unit time via the transmission path140, by the number of image capturing apparatuses100which output the moving images to the transmission path140.

The condition designating section242causes the condition storing section240to store thereon a lower limit value for the speed of the movement which is inversely proportional to the permissible data amount which is obtained by the permissible data amount obtaining section250. With such a configuration, the lower limit value for the speed of the movement which is stored on the condition storing section240increases as the permissible data amount decreases.

Here, a priority order may be determined in advance among the image capturing apparatuses100. The condition designating section242may decrease the lower limit value for the speed of the movement which is stored on the condition storing section240as the priority of the image capturing apparatus100increases. The condition designating section242may store, onto the condition storing section240, the lower limit value for the speed of the movement which is determined in accordance with the permissible data amount, at predetermined intervals and in accordance with a predetermined order.

According to the above description, the condition designating section242designates the lower limit value for the speed of the movement which is stored on the condition storing section240in accordance with the permissible data amount. Similarly, the condition designating section242can designate, in accordance with the permissible data amount, the lower limit values stored on the condition storing section240for the area occupied by the person, the area of the changed region, the area occupied by particular colors, the degree of match in terms of shape between the detected object and the reference object, and the degree of match between the reference direction and the movement direction.

FIG. 15illustrates, as an example, how to define averaging periods during each of which moving-image making-up images averaged to generate a single averaged image are captured. According to the exemplary case shown inFIG. 9, each averaging period includes therein the timings at which successive four moving-image making-up images are captured, and the averaging periods do not overlap each other. As an alternative example, the averaging periods may overlap each other. As an example of the averaging periods of the latter type,FIG. 15illustrates averaging periods each of which includes therein the timings at which successive five moving-image making-up images are captured, and the averaging periods overlap each other. Here, the start timing of each of the successive averaging periods shown inFIG. 15is shifted from the start timing of an immediately preceding averaging period by a time equal to the image capturing interval at which the moving-image making-up images are captured. However, the difference in start timing between successive averaging periods is not limited to be equal to the image capturing interval.

As indicated by the above explanation, the averaged image generating section202generates averaged images by, so to say, successively averaging the moving-image making-up images. When the amount of a change between adjacent averaged images is smaller than a predetermined value, the output moving image generating section282may generate an output moving image which includes, as the output frame images, images obtained by reducing the resolution or the number of gray levels of the moving-image making-up images captured during the averaging periods. When the amount of a change between adjacent averaged images is smaller than a predetermined value, the output moving image generating section282may generate an output moving image which includes, as the output frame images, the images obtained by reducing the resolution or the number of gray levels of the moving-image making-up images which are captured at the timings corresponding to the middle of the respective averaging periods. When the amount of a change between adjacent averaged images is smaller than a predetermined value, the output moving image generating section282may generate an output moving image in which the display rate is lowered during at least part of the averaging periods.

FIG. 16illustrates another exemplary method to judge whether a condition is satisfied. According to the above description, the satisfaction judging section230judges whether a variation reduced image such as an averaged image satisfies a condition. As an alternative example, the satisfaction judging section230judges whether each moving-image making-up image shows abnormalities. When judging whether each moving-image making-up image satisfies a condition, the satisfaction judging section230can employ the same method as used to judge whether an averaged image satisfies a condition.

According to the exemplary case shown inFIG. 16, the satisfaction judging section230makes a judgment of “NO ABNORMALITIES” at the times t1601, t1602, t1604, and t1607, and makes a judgment of “ABNORMALITIES” at the times t1603, t1605, and t1606. When the satisfaction judging section230makes a judgment of “NO ABNORMALITIES”, the moving-image making-up image does not satisfy the condition stored on the condition storing section240. When the satisfaction judging section230makes a judgment of “ABNORMALITIES”, the moving-image making-up image satisfies the condition stored on the condition storing section240.

The satisfaction judging section230counts the number of judgments of “ABNORMALITES” and the number of judgments of “NO ABNORMALITIES”, which are made for the moving-image making-up images captured during each averaging period. When the number of judgments of “ABNORMALTIES” is larger than the number of judgments of “NO ABNORMALITIES”, the satisfaction judging section230judges that the condition is satisfied in the averaging period. According to the exemplary case shown inFIG. 16, the satisfaction judging section230makes the judgment of “NO ABNORMALITIES” (the condition is not satisfied) for the averaging period from the time t1601to the time t1605, and makes the judgment of “ABNORMALITIES” (the condition is satisfied) for the averaging period from the time t1602to the time t1606and for the averaging period from the time t1603to the time t1607.

According to the exemplary case shown inFIG. 16, the abnormalities are assessed by two values of “ABNORMALITIES” and “NO ABNORMALITIES”. However; the satisfaction judging section230may calculate the degree of abnormalities for each moving-image making-up image. When the average value among the calculated degrees of abnormalities (or the median value among the degrees of abnormalities, the largest value among the degrees of abnormalities, or the total value of the degrees of abnormalities) is higher than a predetermined value, the satisfaction judging section230may judge that the condition is satisfied for the averaging period. Here, the degree of abnormalities can be, for example, the degree of satisfying a predetermined condition, or the number, area or the like of the objects satisfying a predetermined condition. In more detail, the degree of abnormalities may be the degree of match between an object contained in a moving-image making-up image and a predetermined pattern for a person, the degree of match between the direction in which an object contained in a moving-image making-up image moves and a predetermined direction, or the like. The above part describes, with reference toFIG. 16, the alternative operation of the satisfaction judging section230under the assumption that the averaging periods overlap each other, for example, as shown inFIG. 15. However, the satisfaction judging section230can judge whether the condition is satisfied in the manner described above, even when the averaging periods do not overlap each other as illustrated inFIG. 9.

FIG. 17illustrates an exemplary hardware configuration of a computer1500relating to the monitoring system110. The computer1500is constituted by a CPU surrounding section, an input/output (I/O) section and a legacy I/O section. The CPU surrounding section includes a CPU1505, a RAM1520, a graphic controller1575, and a display device1580which are connected to each other by means of a host controller1582. The I/O section includes a communication interface1530, a hard disk drive1540, and a CD-ROM drive1560which are corrected to the host controller1582by means of an I/O controller1584. The legacy I/O section includes a ROM1510, a flexible disk drive1550, and an I/O chip1570which are connected to the I/O controller1584.

The host controller1582connects the RAM1520with the CPU1505and graphic controller1575which access the RAM1520at a high transfer rate. The CPU1505operates in accordance with programs stored on the ROM1510and RAM1520, to control the constituents. The graphic controller1575obtains image data which is generated by the CPU1505or the like on a frame buffer provided within the RAM1520, and causes the display device1580to display the obtained image data. Alternatively, the graphic controller1575may include therein a frame buffer for storing thereon image data generated by the CPU1505or the like.

The I/O controller1584connects, to the host controller1582, the hard disk drive1540, communication interface1530and CD-ROM drive1560which are I/O devices operating at a relatively high rate. The hard disk drive1540stores thereon programs and data to be used by the CPU1505provided in the computer1500. The communication interface1530communicates with the image capturing apparatuses100via a network, to provide programs and data to the image capturing apparatuses100. The CD-ROM drive1560reads programs or data from a CR-ROM1595, and supplies the read programs or data to the hard disk drive1540and communication interface1530via the RAM1520.

The I/O controller1584is also connected to the ROM1510, flexible disk drive1550and/O chip1570which are I/O devices operating at a relatively low rate. The ROM1510stores thereon a boot program executed by the computer1500at the start up, programs unique to the hardware of the computer1500, and the like. The flexible disk drive1550reads programs or data from a flexible disk1590, and supplies the read programs or data to the hard disk drive1540and communication interface1530via the RAM1520. The I/O chip1570is used to connect a variety of I/O devices such as the flexible disk drive1550via, for example, a parallel port, a serial port, a keyboard port a mouse port or the like.

A program to be supplied to the communication interface1530via the RAM1520is provided by a user in a state of being stored on a recording medium such as the flexible disk1590, CD-ROM1595and an IC card. The program is read from the recording medium, provided to the communication interface1530via the RAM1520, and transmitted to the image capturing apparatuses100via the network. The program transmitted to the image capturing apparatuses100is installed in and executed by the image capturing apparatuses100.

The program to be installed in and then executed by the image capturing apparatuses100causes each of the image capturing apparatuses100to function as the image capturing section200, variation reduced image generating section201, image capturing control section210, object region identifying section212, image storing section214, differential image generating section216, change amount calculating section221, movement amount calculating section222, moving direction identifying section223, particular color area calculating section224, object extracting section225, satisfaction judging section230, match calculating section232, condition storing section240, condition designating section242, permissible data amount obtaining section250, image quality selecting section260, image quality storing section262, output control section270, image generating section280, output moving image generating section282, and output section290described with reference toFIGS. 1 to 16.

The program mentioned above may be stored on an external recording medium. The recording medium is, for example, an optical recording medium such as DVD and PD, a magnet-optical recording medium such as MD, a tape medium, a semiconductor memory such as an IC card and the like, in addition to the flexible disk1590and CD-ROM1595. The recording medium may be a storage device such as a hard disk and RAM which is provided in a server system connected to a dedicated communication network or the Internet, and the program may be provided to the computer1500via the network.

While the embodiment of the present invention has been described, the technical scope of the invention is not limited to the above described embodiment. It is apparent to persons skilled in the art that various alternations and improvements can be added to the above-described embodiment. It is also apparent from the scope of the claims that the embodiments added with such alternations or improvements can be included in the technical scope of the invention.