JP2005080047A - Image storage system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately store an image picked up by, e.g., a fixedly installed camera, etc., over a long period of time. <P>SOLUTION: An image storage system for storing an imaged pickup image is provided with an image storing part for storing a compressed pickup image, and a compression rate changing part for enhancing the compression rate of a first pickup image after the image storing part stores a second pickup image imaged after a first pickup image stored in the image storing part. The compression rate changing part may enhance the compression rate of the first pickup image by lowering the gradation or resolution of the first pickup image. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image storage system that stores captured images.

In recent years, an irreversible compression technique such as MPEG4 has been used as a technique for compressing images at a high compression rate (see, for example, Non-Patent Document 1). In these image compression techniques, an image is compressed by quantizing image data that has been subjected to discrete cosine transform, for example.
Hidematsu Kasano “Introduction MPEG-4” Technical Review, January 25, 2000

  However, in the lossy compression technique, when an image is compressed at a high compression rate, the image quality may deteriorate. In addition, when an image is compressed at a low compression rate, a moving image for a sufficient time may not be recorded on the storage medium. For this reason, conventionally, for example, it has been difficult to appropriately store an image captured for a long time by a fixed installation camera or the like.

  That is, according to the first aspect of the present invention, there is provided an image storage system for storing a captured image that is a captured moving image, the image storage unit storing a compressed captured image, and the image storage unit storing the compressed captured image. And a compression rate changing unit that increases the compression rate of the first captured image after the image storage unit stores the second captured image captured after the first captured image.

  Further, the compression rate changing unit may increase the compression rate of the first captured image by reducing the frame rate of the first captured image. The image storage unit stores image data decomposed for each spatial frequency component as a captured image, and the compression rate changing unit replaces at least a part of the spatial frequency component in the first captured image with a smaller value. The compression rate of the first captured image may be increased. The image storage unit stores a moving image compression-encoded based on the MPEG4 standard as a compressed captured image, and the compression rate changing unit decodes the first captured image and then at least a part of the spatial frequency The compression rate of the first captured image may be increased by compressing and encoding the first captured image again using a quantization coefficient larger than the quantization coefficient used before decoding for the component. . The image storage unit stores a plurality of captured images captured before the second captured image. After the image storage unit stores the second captured image, the compression rate changing unit includes the plurality of captured images. Among them, the compression rate of the captured image having the longest period after being stored in the image storage unit may be increased.

  In addition, when the person in the subject captured in the second captured image and the person in the subject captured in the first captured image are the same person, the compression ratio changing unit compresses the first captured image. You may increase the rate. When the person of the subject shown in the second captured image and the person of the subject shown in the first captured image are different people, the compression rate changing unit changes the compression rate of the first captured image. May be raised.

  Further, when the free capacity of the image storage unit becomes smaller than a predetermined size, the compression rate changing unit may increase the compression rate of the first captured image. The compression rate changing unit detects a time from when the first captured image is captured, and increases the compression rate of the first captured image when the time since the captured image has exceeded a predetermined time. It's okay.

  Further, the image processing apparatus further includes a template storage unit that stores the image template, and the compression rate changing unit increases the compression rate of an object that does not match the image template among the objects included in the first captured image. The image compression rate may be increased. The image processing apparatus further includes a template storage unit that stores the image template, and the compression rate changing unit increases the compression rate of an object that matches the image template among the objects included in the first captured image, thereby correcting the first captured image. The compression rate may be increased.

  In addition, the image storage unit stores the captured image in association with the object specified at the time of imaging by the user, and the compression rate changing unit is an object other than the object specified at the time of imaging among the objects included in the captured image. The compression rate of the first captured image may be increased by increasing the compression rate. The compression rate changing unit may increase the compression rate of the first captured image by increasing the compression rate of the background in the captured image.

  The image storage unit further stores a third captured image captured after the second captured image, and after the second captured image is stored by the image storage unit, the third captured image. Before the image storage unit stores the compression rate change unit, the compression rate of the first captured image is increased to the first changed compression rate, and after the third captured image is stored by the image storage unit, the compression rate The changing unit may increase the compression rate of the first captured image to a second changed compression rate that is higher than the first changed compression rate.

  The image storage unit further stores a third captured image captured after the second captured image, and after the second captured image is stored by the image storage unit, the third captured image. Before the image storage unit stores the compression rate change unit, the compression rate of the first captured image is increased to the first changed compression rate, and after the third captured image is stored by the image storage unit, the compression rate The changing unit may delete the first captured image.

  Further, the compression rate changing unit may increase the compression rate of the first captured image by reducing the gradation or resolution of the first captured image. Before the compression rate changing unit increases the compression rate of the first captured image, the image storage unit stores the first captured image that is a color image, and the compression rate changing unit stores the first captured image. By changing to a grayscale image, the compression rate of the first captured image may be increased.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 shows an example of the configuration of an image storage system 100 according to an embodiment of the present invention. The image storage system 100 of this example is a fixed installation camera such as a surveillance camera, for example, and stores a captured image that is a captured moving image with an increased compression rate in accordance with an elapsed time since the imaging. The image storage system 100 includes an imaging unit 102, a reception unit 114, a moving image generation unit 104, a template storage unit 110, an image storage unit 106, a capacity management unit 108, and a high compression processing unit 112.

  The imaging unit 102 generates a captured image captured by, for example, a CCD imaging device and supplies the captured image to the moving image generation unit 104. The imaging unit 102 may generate a captured image by continuously capturing fixed points such as in a store or an arcade, for example. The accepting unit 114 accepts an instruction from a user such as an operator who operates the image storage system 100, for example. The accepting unit 114 accepts, for example, an instruction for designating any subject from the user. When receiving this instruction, the reception unit 114 notifies the moving image generation unit 104 of the designated subject. In this example, the reception unit 114 receives an instruction for designating any subject from the user at the time of imaging when the captured image is captured. For example, the reception unit 114 may receive an instruction to specify a subject by detecting the subject that the operator is viewing based on the line of sight of the operator who operates the image storage system 100.

  The moving image generation unit 104 generates a compressed captured image by compressing the captured image received from the imaging unit 102, and supplies the compressed captured image to the image storage unit 106. In this example, the moving image generation unit 104 outputs a moving image that has been compression-encoded based on the MPEG4 standard as a compressed captured image.

  In addition, the moving image generation unit 104 generates a moving image including a plurality of objects as a compressed captured image. Here, an object is an image showing a specific subject, such as a specific person, building, or background object, for example, and is generated by extracting a portion showing the subject from a captured image captured by the imaging unit 102 Is done. The object may be a video object defined in the MPEG4 standard. The moving image generation unit 104 extracts each subject in the captured image received from the moving image generation unit 104, and generates an object corresponding to each subject.

  Then, when an instruction to specify any object that has been converted into an object is received from the reception unit 114, the moving image generation unit 104 further generates an image template for specifying the object. The moving image generation unit 104 supplies the generated image template to the template storage unit 110 in association with the captured image. The template storage unit 110 stores the image template generated by the moving image generation unit 104.

  The image storage unit 106 stores the captured image compressed by the moving image generation unit 104. In this example, the image storage unit 106 stores the captured image in association with the image template stored in the template storage unit 110. Thereby, the image storage unit 106 stores the captured image in association with the object designated at the time of imaging by the user. Note that the object designated at the time of imaging is, for example, an object indicating a subject designated by the user at the time of imaging. In another example, the image storage unit 106 may store a compressed still image as a compressed captured image.

  The capacity management unit 108 manages the free capacity of the image storage unit 106. When the free space becomes smaller than a predetermined size, the capacity management unit 108 notifies the high compression processing unit 112 to that effect.

  The high compression processing unit 112 is an example of a compression rate changing unit, and increases the compression rate of the captured image stored in the image storage unit 106 in response to a notification from the capacity management unit 108. In this case, for example, the high compression processing unit 112 selects the oldest captured image from a plurality of captured images stored in the image storage unit 106, and increases the compression rate of the selected captured image. The high compression processing unit 112 may select the captured image having the longest elapsed time since being stored in the image storage unit 106 as the oldest captured image. The high compression processing unit 112 reduces the data amount of the captured image by increasing the compression rate of the captured image. The high compression processing unit 112 detects the captured image when the free space of the image storage unit 106 is smaller than a predetermined size and the time since the captured image has been captured has exceeded a predetermined time. The compression ratio may be increased.

  In addition, after decoding the selected captured image, the high compression processing unit 112 compresses the captured image at a higher compression rate than before decoding. As described above, the high compression processing unit 112 increases the free capacity of the image storage unit 106 by increasing the compression rate of the old captured image. Therefore, according to the present example, a newly captured image can be compressed and stored at an appropriate compression rate.

Here, when increasing the compression rate of the selected captured image, the high compression processing unit 112 acquires an image template associated with the captured image from the template storage unit 110. And the high compression process part 112 raises the compression rate of this captured image by raising the compression rate of the object which does not correspond with an image template among the objects contained in the selected captured image. Thereby, the high compression process part 112 raises the compression rate of objects other than the object designated at the time of imaging among the objects contained in a captured image. For example, when an object indicating a person is specified in a captured image including objects indicating the foreground person and the background, the high compression processing unit 112 increases the compression ratio of the background in the selected captured image. The compression rate of this captured image is increased. According to this example, it is possible to appropriately increase the compression rate of an old captured image while appropriately maintaining the compression rate of an important object indicating a main subject or the like.

  In another example, the high compression processing unit 112 may extract the background of the captured image using a background extraction technique widely used in image processing, and reduce the amount of extracted background data. Also in this case, the compression rate of the old captured image can be appropriately increased.

  In another example, the high compression processing unit 112 may increase the compression rate of an object that matches the image template among the objects included in the selected captured image. The template storage unit 110 may store, for example, an image template of a person who appears frequently in a captured image, such as a store clerk in a store captured by the imaging unit 102. In this case, the compression rate of the old captured image can be appropriately increased by increasing the compression rate of the object indicating the known person that appears frequently in the captured image.

  The image storage system 100 may be a hard disk recording device that stores captured images in the image storage unit 106 that is, for example, a hard disk. In this case, the moving image generation unit 104 may receive a captured image captured at, for example, a broadcasting station from, for example, a television video receiving device instead of the imaging unit 102.

  FIG. 2 is a flowchart showing an example of the operation of the image storage system 100. First, the imaging unit 102 generates a captured image (S102). Next, the moving image generation unit 104 generates a moving image by compressing the captured image received from the imaging unit 102 (S104). Then, the image storage unit 106 stores the generated moving image (S106). In this case, the image storage unit 106 stores, for example, the compressed first captured image.

  In S102, the reception unit 114 may receive an instruction to specify any subject from the user. In S <b> 104, the moving image generation unit 104 may further generate an image template corresponding to the designated subject and supply it to the template storage unit 110. In S106, the template storage unit 110 may store the image template in association with the first captured image.

Next, the capacity management unit 108 detects the free capacity Vx of the image storage unit 106 (S108). If the free space Vx is larger than the predetermined size V ₀ (S110 Yes), the image storage system 100 repeats the operations after S102. In this case, in the next S106, the image storage unit 106 stores, for example, the compressed second captured image. The second captured image is an example of a captured image captured after the first captured image stored in the image storage unit 106.

Further, when the free space Vx is equal to or less than the predetermined size V ₀ (S110 No), if the free space Vx is larger than the predetermined size V ₁ smaller than V ₀ (S112 Yes), the high compression processing unit 112. Selects the oldest captured image (S114) and increases the compression rate of the captured image to a predetermined high compression rate (S116). For example, when the free space Vx becomes smaller than a predetermined size after the image storage unit 106 stores the second captured image, the high compression processing unit 112 is the first captured image that is the oldest captured image. Increase the compression ratio of the captured image. According to this example, the free space of the image storage unit 106 can be increased appropriately. In addition, this makes it possible to compress a newly captured image at an appropriate compression rate.

  In S114, the high compression processing unit 112 may select the oldest captured image among captured images compressed at a compression rate lower than a predetermined high compression rate. Further, the high compression processing unit 112 may select a plurality of captured images and increase their compression rate. The compression rate of the captured image may be a compression rate defined based on MPEG1, 2, 4, etc., for example. The high compression rate used in S116 is an example of a first modified compression rate.

  When the image storage unit 106 stores a plurality of captured images captured before the second captured image, after the image storage unit 106 stores the second captured image, the high compression processing unit 112 Of the plurality of captured images, the compression rate of the captured image having the longest period after being stored in the image storage unit 106 may be increased.

  Following S116, the image storage system 100 repeats the operations after S102. In this case, in the next S106, the image storage unit 106 stores, for example, a compressed third captured image. The third captured image is an example of a captured image captured after the second captured image.

Here, when the free space Vx reaches a predetermined magnitude _{V 1} or less (S112 No), the high compression processing unit 112 selects the oldest captured image (S118), the compression ratio of the captured image Then, it is increased to a predetermined maximum compression rate (S120). This maximum compression rate is an example of a second changed compression rate that is higher than the first changed compression rate. The high compression processing unit 112 may select the oldest captured image among captured images compressed at a compression rate lower than a predetermined maximum compression rate.

  As a result, the high compression processing unit 112 increases the compression rate of the captured image in a stepwise manner in accordance with the amount of free space in the image storage unit 106. For example, after the second captured image is stored in the image storage unit 106 and before the third captured image is stored in the image storage unit 106, the high compression processing unit 112 performs the first captured image in S <b> 116. The compression rate is increased to a predetermined high compression rate. After the third captured image is stored in the image storage unit 106, in S120, the high compression processing unit 112 increases the compression rate of the first captured image to a predetermined maximum compression rate.

  According to this example, the information amount of the old captured image can be sequentially reduced while maintaining the information amount of the new captured image by changing the compression rate stepwise according to the elapsed time from the time of imaging. . In addition, this makes it possible to appropriately recompress old captured images. Thereby, a newly captured image can be stored appropriately. Therefore, according to this example, many captured images can be appropriately stored in the image storage unit 106 having a limited capacity.

  Note that the high compression processing unit 112 may sequentially increase the compression rate of the captured image in a plurality of stages of three or more stages. Further, the high compression processing unit 112 may delete the captured image instead of increasing the compression rate of the captured image to the maximum compression rate. For example, after the image storage unit 106 stores the third captured image, the high compression processing unit 112 may delete the first captured image. Also in these cases, many captured images can be appropriately stored in the image storage unit 106 having a limited capacity.

  Further, in this example, the high compression processing unit 112 increases the compression rate of the old captured image using a decrease in the free space of the image storage unit 106 as a trigger. In another example, the high compression processing unit 112 may increase the compression rate of the old captured image using a time after the captured image is captured as a trigger. For example, the high compression processing unit 112 detects a time after the captured image is captured, and increases the compression rate of the captured image when the time since the captured image has elapsed for a predetermined time or more.

  FIG. 3 is a flowchart showing an example of detailed operation of the high compression processing unit 112 in S116 (see FIG. 2). First, the high compression processing unit 112 decodes the captured image selected in S114 (S202). Then, the high compression processing unit 112 reads an image template associated with the captured image from the template storage unit 110, and selects an object that does not match the image template from among the objects included in the decoded captured image. (S204). The object that matches the image template is, for example, an object that has a matching degree with the image template that is equal to or higher than a predetermined value.

  Then, the high compression processing unit 112 increases the compression rate of the selected object, and compresses and encodes this captured image again (S206). The high compression processing unit 112 may increase the compression rate of the selected object so that the compression rate of the entire captured image becomes a predetermined high compression rate. Further, the high compression processing unit 112 may increase the compression rate of the selected object to a predetermined high compression rate. According to this example, the compression rate of the captured image can be increased appropriately.

  Note that the high compression processing unit 112 may increase the compression rate of the captured image by reducing the gradation or resolution of the captured image whose compression rate should be increased. Further, the high compression processing unit 112 may increase the compression rate of the captured image by thinning out some frames, for example, and reducing the frame rate of the captured image. The high compression processing unit 112 may increase the compression rate of the captured image by changing the captured image to a grayscale image. In this case, before the high compression processing unit 112 increases the compression rate of the captured image, the image storage unit 106 stores a color image as the captured image.

  In this example, the image storage unit 106 stores image data decomposed for each spatial frequency component as a captured image based on the MPEG4 standard. Therefore, the high compression processing unit 112 may increase the compression rate of the captured image by replacing at least a part of the spatial frequency components in the captured image whose compression rate should be increased with a smaller value. For example, after decoding this captured image, the high compression processing unit 112 quantizes each spatial frequency component by using a quantization coefficient larger than the quantization coefficient used before decoding. The image is compressed and encoded again to increase the compression rate of the captured image.

  FIG. 4 shows another example of the configuration of the image storage system 100. In this example, the image storage system 100 accumulates captured images of a captured person. The image storage system 100 includes an imaging unit 102, a moving image generation unit 104, an image storage unit 106, a capacity management unit 108, a high compression processing unit 112, an index storage unit 116, and a person identification unit 118. Except for the points described below, in FIG. 4, the components denoted by the same reference numerals as those in FIG. 1 have the same or similar functions as those in FIG.

  In this example, the moving image generation unit 104 extracts a person shown in the captured image and creates an index representing the person. For example, the moving image generation unit 104 creates an image template indicating the person. Then, the moving image generation unit 104 supplies this index to the index storage unit 116 and the person identification unit 118.

  The index storage unit 116 stores the received index in association with the captured image. In addition, the person identifying unit 118 searches the other index stored in the index storing unit 116 for an index representing the same person as the received index. As a result, the person identifying unit 118 identifies whether the person represented by the received index is the same as the person represented by another index already stored in the index storage unit 116. When another index representing the same person is found, the person identifying unit 118 notifies the high compression processing unit 112 of a captured image corresponding to the other index.

  When the free space of the image storage unit 106 is reduced, the high compression processing unit 112 increases the compression rate of the captured image notified from the person identification unit 118 in response to the notification from the capacity management unit 108. Thereby, for example, when the person in the subject captured in the new captured image and the person in the subject captured in the old captured image are the same person, the high compression processing unit 112 increases the compression rate of the old captured image. For example, it is increased to a predetermined high compression rate.

  Thereby, when the image storage unit 106 stores the captured images of the same person in duplicate, the high compression processing unit 112 increases the compression rate of the old captured images. Therefore, according to this example, many captured images can be appropriately stored in the image storage unit 106 having a limited capacity.

  In addition, after the 1st and 2nd captured image in which the person of the same subject is imaged, the 3rd captured image in which the same person as the subject person in these captured images is further captured When captured, the high compression processing unit 112 may increase the compression rate of the second captured image to a predetermined high compression rate. In this case, the high compression processing unit 112 may increase the compression rate of the first captured image to a predetermined maximum compression rate. Further, the high compression processing unit 112 may delete the first captured image. According to this example, the captured image can be stored appropriately.

  In another example, when the person in the subject captured in the new captured image is different from the person in the subject captured in the old captured image, the high-compression processing unit 112 selects the old captured image. The compression rate may be increased. In this case, for example, the compression rate of a captured image in which a specific person is captured can be kept low.

  For example, in another example, when the image storage system 100 is a hard disk recording device and a favorite talent or the like appears in a plurality of captured images, these captured images are kept at a low compression rate and high image quality. Can be saved. For example, the high compression processing unit 112 may keep the compression rate of the captured image in which the same person as the person in the captured image designated by the user is captured low. Also in this case, the captured image can be stored appropriately.

  Note that the image storage unit 106 may store the captured images showing the same person in association with each other. In this case, for example, as the free space of the image storage unit 106 further decreases, the image storage unit 106 may increase the compression rate of a plurality of captured images associated with each other due to the same person being captured. The high compression processing unit 112 may select any captured image and increase the compression rate. At the same time as increasing the compression rate of the selected captured image, the high compression processing unit 112 is associated with the selected captured image in the image storage unit 106 and is older than the selected captured image, for example. The compression rate of the captured image may be increased. Also in this case, the captured image can be stored appropriately.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

It is a figure which shows an example of a structure of the image storage system 100 which concerns on one Embodiment of this invention. 4 is a flowchart illustrating an example of the operation of the image storage system 100. 5 is a flowchart illustrating an example of detailed operation of a high compression processing unit 112. 3 is a diagram illustrating another example of the configuration of the image storage system 100. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Image storage system, 102 ... Imaging part, 104 ... Moving image production | generation part, 106 ... Image storage part, 108 ... Capacity management part, 110 ... Template storage part, 112 ...・ High compression processing unit, 114... Accepting unit, 116... Index storage unit, 118.

Claims (17)

An image storage system for storing a captured image that is a captured moving image,
An image storage unit for storing the compressed captured image;
Compression that increases the compression rate of the first captured image after the image storage unit stores the second captured image captured after the first captured image stored in the image storage unit An image storage system comprising a rate changing unit.   The image storage system according to claim 1, wherein the compression rate changing unit increases the compression rate of the first captured image by reducing a frame rate of the first captured image. The image storage unit stores image data decomposed for each spatial frequency component as the captured image,
The image storage system according to claim 1, wherein the compression rate changing unit increases the compression rate of the first captured image by replacing at least a part of the spatial frequency component in the first captured image with a smaller value. . The image storage unit stores a moving image compressed and encoded based on the MPEG4 standard as the compressed captured image,
The compression rate changing unit uses the quantization coefficient larger than the quantization coefficient used before decoding for at least a part of the spatial frequency components after decoding the first captured image. The image storage system according to claim 1, wherein the compression rate of the first captured image is increased by compressing and encoding one captured image again. The image storage unit stores a plurality of the captured images captured before the second captured image,
After the image storage unit stores the second captured image, the compression rate changing unit compresses the captured image having the longest period since the image storage unit stores the second captured image. The image storage system according to claim 1, wherein the rate is increased.   In a case where the person of the subject shown in the second captured image and the person of the subject shown in the first captured image are the same person, the compression ratio changing unit is configured to use the first captured image. The image storage system according to claim 1, wherein the compression rate of the image storage system is increased.   When the person of the subject shown in the second captured image and the person of the subject shown in the first captured image are different people, the compression ratio changing unit is configured to use the first captured image. The image storage system according to claim 1, wherein the compression rate of the image storage system is increased.   The image storage system according to claim 1, wherein the compression rate changing unit increases the compression rate of the first captured image when a free space of the image storage unit becomes smaller than a predetermined size.   The compression ratio changing unit detects a time from when the first captured image is captured, and compresses the first captured image when the time since the captured image has exceeded a predetermined time. The image storage system according to claim 1, wherein the rate is increased. A template storage unit for storing image templates;
The compression rate changing unit increases the compression rate of the first captured image by increasing the compression rate of an object that does not match the image template among the objects included in the first captured image. The image storage system described. A template storage unit for storing image templates;
The compression rate changing unit increases the compression rate of the first captured image by increasing the compression rate of an object that matches the image template among the objects included in the first captured image. The image storage system described. The image storage unit stores the captured image in association with the object specified at the time of imaging by the user,
The compression rate changing unit increases the compression rate of the first captured image by increasing the compression rate of an object other than the object specified at the time of imaging among the objects included in the captured image. The image storage system described.   The image storage system according to claim 1, wherein the compression rate changing unit increases a compression rate of the first captured image by increasing a compression rate of a background in the captured image. The image storage unit further stores a third captured image captured after the second captured image,
The compression ratio changing unit compresses the first captured image after the second captured image is stored in the image storage unit and before the third captured image is stored in the image storage unit. Increase the rate to the first modified compression rate,
After the image storage unit stores the third captured image, the compression rate changing unit increases the compression rate of the first captured image to a second changed compression rate that is higher than the first changed compression rate. The image storage system according to claim 1. The image storage unit further stores a third captured image captured after the second captured image,
The compression ratio changing unit compresses the first captured image after the second captured image is stored in the image storage unit and before the third captured image is stored in the image storage unit. Increase the rate to the first modified compression rate,
The image storage system according to claim 1, wherein the compression ratio changing unit deletes the first captured image after the third captured image is stored in the image storage unit.   The image storage system according to claim 1, wherein the compression rate changing unit increases the compression rate of the first captured image by reducing the gradation or resolution of the first captured image. Before the compression rate changing unit increases the compression rate of the first captured image, the image storage unit stores the first captured image that is a color image,
The image storage system according to claim 1, wherein the compression rate changing unit increases the compression rate of the first captured image by changing the first captured image to a grayscale image.

Images