JP2007300462A - Device and method for recording image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recording device and method capable of suppressing the limit of a storage capacity to the minimum while efficiently securing a camera image to be required as alarm information, even when a storage medium with less storage capacity such as a flash ROM or a RAM buffer is used for storing the camera image. <P>SOLUTION: A prescribed number of frame of camera images are temporarily stored in a ring shape image buffer 12. While an alarm detecting part 13 does not detect an abnormality, the camera image from the image buffer 12 is not stored. When the alarm detecting part 13 detects the abnormality, the camera images from the image buffer 12 are selected in response to a preservation frame rate, which becomes highest around an alarm generation time and becomes lower as separated from the alarm generation time, and then, stored in an alarm image storage part 16. Consequently, the capacity of the alarm image storage part 16 is saved while sufficiently storing the camera images to be required as the alarm information. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image recording apparatus used for measures against shoplifting, theft, mischief and the like in a bank, a convenience store, and the like, and an image recording method for storing an image obtained by imaging a monitoring target.

  2. Description of the Related Art Conventionally, as the above-described image recording apparatus, there is an apparatus that stores images before and after an alarm is generated in accordance with a prespecified frame rate (see, for example, Patent Document 1). The image recording apparatus disclosed in Patent Document 1 includes a ring-shaped image buffer capable of storing several frames of camera images in order to store camera images (called pre-alarm images) before the occurrence of an alarm. Using this image buffer, the camera image is stored in accordance with a predetermined storage frame rate (a ratio of storing the camera image with respect to the storage means for storing the camera image) that is designated in advance, and when an alarm occurs, The latest number of camera images specified in advance are stored as pre-alarm images (ie, images before occurrence of an alarm), and then the predetermined number of camera images are stored as post-alarm images (ie, images after occurrence of an alarm). . The state of the processing is shown in FIG. In the figure, a solid vertical line indicates a one-frame camera image. A camera image before the occurrence of an alarm is a pre-alarm image, and a camera image after the occurrence of an alarm is a post-alarm image. As shown in the figure, the storage frame rate is constant.

JP 2000-278672 A

  However, in the conventional image recording apparatus, the camera image is stored at a predetermined storage frame rate for a predetermined time, and a storage medium having a small storage capacity such as a flash ROM or a RAM buffer may be used for the storage. Therefore, there is a problem that the storage time, the frame rate, the image size, and the like are limited to be small due to the limitation of the storage capacity.

  The present invention has been made in view of such circumstances, and even if a storage medium having a small storage capacity such as a flash ROM or a RAM buffer is used for storing a camera image, a camera image necessary as alarm information can be efficiently secured. However, an object of the present invention is to provide an image recording apparatus and an image recording method capable of minimizing the storage capacity limitation.

The object is achieved by the following configuration or method.
The image recording apparatus according to the present invention is an image recording apparatus for storing a camera image obtained by imaging a monitoring target area with a camera, and an image input unit that creates a camera image in units of frames from a video signal input from the camera. And an image buffer for storing a predetermined number of frames of camera images created by the image input means, and when an abnormality is detected in the monitoring target area, an abnormality detection is performed on the camera image stored in the image buffer. Camera image storage control means for increasing the storage frame rate indicating the ratio of storing in the vicinity of the hour and lowering the storage frame rate as the distance from the abnormality detection time increases.

  With this configuration, camera images of a predetermined number of frames are stored in the image buffer, and when there is an abnormality in the monitoring target area, the image buffer is stored at a storage frame rate that is highest around the time of abnormality detection and decreases as the distance from the abnormality detection increases. Select and save the camera images. Thereby, it is possible to save the capacity of a storage device (flash ROM, RAM buffer, etc.) for storing the camera image while sufficiently storing an image necessary as alarm information.

  Further, in the image recording apparatus of the present invention, when the camera image storage control unit detects a plurality of abnormalities within the monitoring target area, the camera image storage unit is configured so that the storage frame rate at the time of detecting each abnormality is the highest. Save the file.

  With this configuration, even if there are a plurality of abnormalities in the monitoring target area, the camera image can be stored at a storage frame rate at which each abnormality is detected at a maximum value.

  In the image recording apparatus of the present invention, the camera image storage control unit uses the image buffer as a list connected by a pointer, and stores the camera image in the entire storage capacity of the image buffer. A predetermined amount is deleted from the oldest camera image among the stored camera images, and a new camera image is stored in the storage area obtained by the deletion.

  With this configuration, even when there are a plurality of abnormalities using an image buffer having a small storage capacity, a step in the total storage rate curve obtained by adding the storage rate curves of the storage frame rates for each of them can be reduced. That is, for example, if two abnormalities occur, the old camera image does not remain in the image buffer when the subsequent abnormalities occur, so the total storage is performed by adding the storage frame rate storage rate curves for each of the two abnormalities. A step occurs in the rate curve. For such problems, use the image buffer as a list linked by a pointer, save the camera image in the entire storage capacity of the image buffer, and then start with the oldest camera image saved in the image buffer. A predetermined amount was deleted, and a new camera image was saved in the free storage area. As a result, it is possible to store a pre-alarm image (camera image before the occurrence of an alarm) for a longer time, and to reduce a step in the total storage rate curve.

  In the image recording apparatus of the present invention, the image storage control means stores all of the I frame, the P frame, and the B frame from the time when the abnormality is detected, The storage frame rate is changed in the order of storage of P frame, storage of I frame, and storage.

  With this configuration, the MPEG moving image format can be efficiently stored.

  Also, the image recording method of the present invention is an image recording method for storing a camera image obtained by imaging a monitoring target area with a camera, wherein a camera image is generated in units of frames from a video signal input from the camera. The camera images for a predetermined number of frames are temporarily stored in the image buffer, and when there is an abnormality in the monitoring target area, when the camera image stored in the image buffer is stored, The storage frame rate indicating the storage ratio of the camera image is maximized, and the storage frame rate is decreased as the distance from the abnormality detection time is increased.

  By this method, camera images of a predetermined number of frames are stored in the image buffer, and when there is an abnormality in the monitoring target area, the image buffer is stored at a storage frame rate that is highest around an abnormality detection and lowers as the distance from the abnormality detection increases. Select and save the camera images. Thereby, it is possible to save the capacity of a storage device (flash ROM, RAM buffer, etc.) for storing the camera image while sufficiently storing an image necessary as alarm information.

  According to the image recording apparatus of the present invention, a predetermined number of frames of camera images are stored in the image buffer, and when there is an abnormality in the monitoring target area, it is highest around the abnormality detection and becomes lower as it goes away from the abnormality detection. The camera image in the image buffer is selected and stored at the storage frame rate. Thereby, it is possible to save the capacity of a storage device (flash ROM, RAM buffer, etc.) for storing the camera image while sufficiently storing an image necessary as alarm information.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a schematic configuration of an image recording apparatus according to Embodiment 1 of the present invention. In the figure, an image recording apparatus 1 according to the present embodiment includes an image input unit 10, an image encoding unit 11, an image buffer 12, an alarm detection unit 13, a storage frame calculation unit 14, and an alarm image accumulation process. Unit 15 and an alarm image storage unit 16. The image input unit 10 takes in a video signal output from a camera (not shown), creates a frame-unit camera image, and inputs it to the image encoding unit 11. A camera (not shown) captures an image of a subject entering the monitored area, and includes an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The subject is, for example, a person, an object, a car in a parking lot, or the like.

  The image encoding unit 11 encodes and outputs each time a frame-unit camera image is input from the image input unit 10. The image buffer 12 is a ring buffer that can store several frames of camera images in order to store pre-alarm images and post-alarm images. Incidentally, the ring-shaped buffer is a FIFO (First In First Out) memory. When a predetermined number of frames of camera images are stored, the camera images are read in the stored order. Then, a new camera image is overwritten on the camera image that has been read out. The alarm detection unit 13 detects abnormalities such as shoplifting, theft, mischief, and the like, and notifies the storage frame calculation unit 14 of the abnormality when the abnormality is detected. The storage frame calculation unit 14 calculates a rate at which the camera image is stored in the alarm image storage unit 16, that is, a storage frame rate. That is, when an alarm notification is given, the storage frame rate is calculated so as to be highest around the time of alarm occurrence and lower as the distance from the alarm occurrence time increases. While the alarm notification is not performed, the storage frame rate is not calculated and its value becomes zero.

  The alarm image storage processing unit 15 selects the camera images to be stored in the alarm image storage unit 16 according to the storage frame rate obtained by the storage frame calculation unit 14 for the predetermined number of frames of camera images stored in the image buffer 12. . As shown in FIG. 2, the storage frame rate is the highest in the vicinity around the time of the alarm occurrence, and becomes a mountain shape that becomes lower as the distance from the time of the alarm occurrence. Decrease gradually as you leave. In FIG. 2, a solid vertical line indicates a camera image to be saved, and a dotted vertical line indicates a thinned camera image. The camera image before the alarm occurrence is a pre-alarm image, and the camera image after the alarm occurrence is a post-alarm image. The alarm image accumulation processing unit 15 detects the camera image corresponding to the occurrence of the alarm by grasping the timing of capturing the camera image from the image buffer 12. Thus, when an alarm occurs, the camera image is stored according to a high storage frame rate, and as the distance from the alarm occurs, the camera image is stored according to a low storage frame rate.

  The alarm image storage unit 16 stores the camera image from the alarm image storage processing unit 15. The alarm image storage unit 16 uses a storage medium having a small storage capacity such as a flash ROM or a RAM buffer. In the present invention, as described above, the storage frame rate of the camera image is variable so as to be the highest around the time of the alarm occurrence and lower as the distance from the alarm occurrence time increases. The capacity of the alarm image storage unit 16 can be saved. That is, an image can be efficiently stored even in an image recording apparatus that does not have a large-capacity recording apparatus that uses a large-capacity recording medium such as a hard disk, an optical disk, or a magneto-optical disk.

  Here, storage of images in a moving image format having correlation between frames such as MPEG (Moving Picture Expert Group) will be described with reference to FIG. 3A is an image stored in the image buffer 12, and FIG. 3B is an image stored in the alarm image storage unit 16. In an MPEG movie file, an I frame created by compressing data in units of frames, a P frame created by converting only the difference that has changed with reference to the previous I frame, and the previous and subsequent frames There is a B frame that also uses the difference between. A group of one or more I frames and a plurality of P frames and B frames is called a GOP (Group of Pictures). The selection of the images stored in the alarm image storage unit 16 is as follows: (1) All IBPs → (2) IP (thinning B) → (3) All I (thinning P) → (4) I thinning out. It is only necessary to determine the curve of the storage frame rate in advance to determine the timing at which the thinning rate is changed, that is, how long each of (1) to (4) continues.

  The image input unit 10 corresponds to an image input unit. The storage frame calculation unit 14 and the alarm image accumulation processing unit 15 constitute a camera image storage control unit. The alarm image storage unit 16 corresponds to a storage device (flash ROM, RAM buffer, etc.).

  Next, the operation of the image recording apparatus 1 of the present embodiment will be described. A video signal from a camera (not shown) is input to the image input unit 10 to create a camera image in units of frames. The camera image created for each frame is encoded by the image encoding unit 11 and temporarily stored in the image buffer 12. In this case, a predetermined number of camera images are stored in the image buffer 12. When a predetermined number of frames of camera images are stored in the image buffer 12, they are read out in the writing order and input to the alarm image accumulation processing unit 15. The alarm image storage processing unit 15 does not select the camera image from the image buffer 12 because the value of the storage frame rate is zero while no abnormality is detected by the alarm detection unit 13. That is, the camera image while no abnormality is detected by the alarm detection unit 13 is not stored in the alarm image storage unit 16. On the other hand, when an abnormality is detected by the alarm detection unit 13, the camera image from the image buffer 12 is selected according to the storage frame rate that is highest around the time of occurrence of the alarm and lowers as the distance from the time of occurrence of the alarm, and accumulates the alarm image. Stored in section 16.

  As described above, according to the image recording apparatus 1 of the present embodiment, a predetermined number of camera images are temporarily stored in the ring-shaped image buffer 12, and while no abnormality is detected by the alarm detection unit 13, When an alarm is detected by the alarm detection unit 13 without saving the camera image from the image buffer 12, the camera from the image buffer 12 is highest according to the storage frame rate that is highest in the vicinity of the alarm occurrence and lower as the distance from the alarm occurrence. Since the images are sorted and stored in the alarm image storage unit 16, it is possible to save the capacity of the alarm image storage unit 16 while sufficiently storing the camera images necessary as alarm information. That is, an image can be efficiently stored even in an image recording apparatus that does not have a large-capacity recording apparatus that uses a large-capacity recording medium such as a hard disk, an optical disk, or a magneto-optical disk.

  In the above embodiment, only one alarm is generated. However, when two alarms (Alarm 1 and Alarm 2) are generated, for example, as shown in FIG. It is preferable to store the camera image by forming a total storage frame rate curve so that the storage frame rate at the time becomes the maximum value.

(Embodiment 2)
FIG. 5 is a block diagram showing a schematic configuration of an image recording apparatus according to Embodiment 2 of the present invention. In the figure, the image recording apparatus 1A according to the present embodiment prevents the step D from occurring in the storage frame rate as shown in FIG. 6 even when an image buffer 12 having a small storage capacity is used. is there. In other words, when an image buffer 12 having a small storage capacity is used, for example, when two alarms (alarm 1 and alarm 2) occur at short time intervals, an old camera image remains in the image buffer 12 when the alarm 2 occurs. Therefore, a step D may occur in the storage frame rate.

  In the image recording apparatus 1A of the present embodiment, when the image buffer 12 is made into a list connected by pointers and the camera images are stored in the entire storage capacity of the image buffer 12, the storage frame calculation unit 14A A predetermined amount of the older camera image stored in the image buffer 12 is deleted, and a new camera image can be stored in the obtained storage area. Specifically, when the alarm 2 is assumed to have occurred, the maximum value of the storage frame rate of each of the alarm 1 and the alarm 2 is calculated, and the older camera image in the image buffer 12 is deleted until the calculation formula is satisfied. . The empty area of the image buffer 12 obtained by deletion is reused to store the next camera image. As a result, it is possible to store a pre-alarm image for a longer time, and to reduce a step in the total storage frame rate curve.

  Note that the storage frame calculation unit 14A and the alarm image storage processing unit 15 constitute a camera image storage control unit.

  Even if a storage medium with a small storage capacity such as a flash ROM or a RAM buffer is used for storing camera images, the present invention efficiently secures the camera images necessary as alarm information and minimizes the storage capacity. It can be suppressed, and can be applied to a system for taking measures against shoplifting, theft, mischief and the like in a bank or a convenience store.

1 is a block diagram showing a schematic configuration of an image recording apparatus according to Embodiment 1 of the present invention. The figure for demonstrating the preservation | save operation | movement of the camera image at the time of abnormality of the image recording device which concerns on Embodiment 1 of this invention. The figure for demonstrating the preservation | save of the image of the moving image format with correlation between frames like MPEG in the image recording device which concerns on Embodiment 1 of this invention. The figure for demonstrating the preservation | save operation | movement of a camera image when the several alarm generate | occur | produces in the image recording device which concerns on Embodiment 1 of this invention. FIG. 3 is a block diagram showing a schematic configuration of an image recording apparatus according to Embodiment 2 of the present invention. The figure for demonstrating the characteristic of the preservation | save operation | movement of the camera image in the image recording device which concerns on Embodiment 2 of this invention. The figure for demonstrating the preservation | save operation | movement of the camera image in the conventional image recording device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A image recording device 10 Image input part 11 Image encoding part 12 Image buffer 13 Alarm detection part 14, 14A Storage frame calculation part 15 Alarm image accumulation | storage process part 16 Alarm image accumulation | storage part

Claims (5)

In an image recording apparatus for storing a camera image obtained by imaging a monitoring target area with a camera,
Image input means for creating a camera image in frame units from a video signal input from the camera;
An image buffer for storing a predetermined number of frames of camera images created by the image input means;
When an abnormality is detected in the monitoring target area, for the camera image stored in the image buffer, the storage frame rate indicating the ratio of storing in the vicinity at the time of abnormality detection is the highest, and as the distance from the abnormality detection time increases, Camera image storage control means for lowering the storage frame rate;
An image recording apparatus comprising:   The said camera image preservation | save control means preserve | saves a camera image so that the preservation | save frame rate at the time of each abnormality detection may become the highest, when several abnormality is detected in the said monitoring object area | region. Image recording device.   The camera image storage control means uses the image buffer as a list connected by a pointer, and stores the camera image in the entire storage capacity of the image buffer, so that the oldest camera among the camera images stored in the image buffer is stored. The image recording apparatus according to claim 1 or 2, wherein a new camera image is stored in a storage area obtained by deleting a predetermined amount from the image and deleting the image.   The image storage control means saves all of the I frame, P frame, and B frame, saves the I frame and P frame, and saves the I frame from the time when the abnormality is detected, when saving the image in the MPEG moving image format. 4. The image recording apparatus according to claim 1, wherein the storage frame rate is changed in the order of no storage. In an image recording method for storing a camera image obtained by imaging a monitoring target area with a camera,
A camera image is created in units of frames from a video signal input from the camera, and camera images for a predetermined number of frames are temporarily stored in an image buffer. An image recording method in which when a camera image stored in an image buffer is stored, a storage frame rate indicating a storage ratio of peripheral camera images at the time of abnormality detection is maximized, and the storage frame rate is decreased as the distance from the abnormality detection time is increased.

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