Image capturing system

Abstract

To provide an image photographing system capable of suppressing a transmission data amount by efficiently controlling compression to a photographed image.SOLUTION: According to an aspect of the present invention, there is provided an image capturing system for capturing an object to be captured and outputting captured image data, including an image capturing apparatus and an image processing apparatus, wherein the image capturing apparatus includes an image capturing unit for capturing the object to be captured to generate a captured image, an image compressing unit for applying compression processing to the captured image to generate a compressed image, and a compressed image transmitting unit for transmitting the compressed image to the image processing apparatus.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image capture system. [Background technology]

[0002] 2. Description of the Related Art Conventionally, fixed-point observation is known in which an object is continuously observed from the same location with a fixed viewpoint, and the observed object is compared with previous observations to analyze the differences.

[0003] In this system that performs fixed-point observation, images acquired by cameras that take fixed-point and regular still images, such as surveillance cameras and security cameras, are effectively compressed to reduce the amount of data transmitted.

[0004] For example, when compressing the latest captured image from fixed-point images taken at time intervals of one to several seconds, the difference between the most recent captured image and the previous multiple captured images is calculated, and the image with the smallest difference is used for compression (Non-Patent Document 1, etc.). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] "Lossless Compression Method of Fixed-Point Images Using Image Differences," Yuka Kanno et al., Miyagi National College of Technology, 2003 Tohoku Branch Joint Conference of Institutes of Electrical Engineers, p.300, 2003 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when conventional technology is applied to cases where the shooting interval is several minutes to several tens of minutes, the difference amount increases and the compression rate decreases. This is because the longer the shooting interval, the greater the change in the surrounding environment of the subject over time, which in turn leads to greater changes in the captured image.

[0007] Examples of "changes in the surrounding environment of the subject being photographed over time" include changes in the brightness of the subject being photographed due to the movement of the sun or moon, changes in the position and shape of shadows, and changes in the lighting environment due to sunrise and sunset.

[0008] Therefore, there is a demand for an image capturing system that can reduce the amount of data to be transmitted by efficiently controlling the compression of captured images. [Means for solving the problem]

[0009] The present invention is an image capturing system that captures an image of a subject and outputs the captured image data, comprising: (1) an image capturing device that captures an image of the subject to be captured, applies a compression process to the captured image to generate a compressed image, and transmits the compressed image; and (2) an image processing device that applies a decompression process to the compressed image to generate an expanded image, wherein the image capturing device comprises: (1-1) an image capturing unit that captures an image of the subject to be captured and generates the captured image; (1-2) an image compression unit that applies a compression process to the captured image to generate the compressed image; and (1-3) a compressed image sending unit that transmits the compressed image to the image processing device, wherein the image processing device comprises: (2-1) a compressed image receiving unit that receives the compressed image; (2-2) an image expansion unit that applies a decompression process to the compressed image to generate the expanded image; and (2-3) an image output unit that outputs the expanded image to a device external to the image processing device. [Effects of the Invention]

[0010] According to the present invention, the amount of data to be transmitted can be reduced by efficiently controlling the compression of captured images. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing a configuration of an image capturing system according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing a configuration of an image compression unit according to the embodiment. [Figure 3]FIG. 2 is a block diagram showing the configuration of an image development unit according to the embodiment. [Figure 4] 3 is a flowchart showing the overall operation of the image capturing system (image capturing device and image processing device) according to the embodiment. [Figure 5] 10 is a flowchart showing detailed processing of an image compression unit according to the embodiment. [Figure 6] 10 is a flowchart illustrating detailed processing of an image development processing unit according to the embodiment. [Figure 7] 10A and 10B are diagrams showing an image of the relationship between a reference image and image capturing timing in the embodiment and modified embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (A) Main embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image capturing system according to the present invention will be described in detail below with reference to the drawings.

[0013] (A-1) Configuration of the embodiment <Overall structure> FIG. 1 is a block diagram showing the configuration of an image capturing system according to an embodiment.

[0014] In FIG. 1, an image capturing system 1 includes an image capturing device 10 and an image processing device 20.

[0015] The image capturing device 10 is a device that receives input from a person or a program, captures an image of a subject, compresses the captured image data, and outputs a compressed image.

[0016] The image processing device 20 is a device that performs decompression processing on the compressed image output by the image capturing device 10 and outputs a final output image.

[0017] The image capturing device 10 and the image processing device 20 are physically separate devices, and are connected to each other by any communication method, whether wired or wireless.

[0018] <Image capture device> As shown in FIG. 1, the image capturing device 10 includes an image capturing unit 11, an image compressing unit 12, and a compressed image transmitting unit 13.

[0019] The image capturing device 10 can be realized by a circuit device having a CPU, ROM, RAM, EEPROM, etc. The ROM stores programs that can be read by the CPU. The functions of the image capturing device 10 are realized by the CPU executing the programs stored in the ROM.

[0020] The image capturing unit 11 is configured, for example, with an image sensor, a lens, an aperture, a shutter, and a photography operation input device, etc. The photography operation input device controls the components of the image capturing unit 11, such as the image sensor, lens, aperture, and shutter, by manual operation input or commands from a program, etc. The image sensor, lens, aperture, and shutter may be those that are commonly available.

[0021] The image compression unit 12 performs compression processing on the captured image output from the image capturing unit 11 to generate a compressed image.

[0022] FIG. 2 is a block diagram showing the configuration of the image compression unit according to the embodiment.

[0023] The image compression unit 12 has a captured image input unit 121 that inputs a captured image, an image compression processing unit 122 that applies compression processing to the captured image to generate a compressed image, a compressed image output unit 123 that outputs the compressed image to the compressed image transmission unit 13, a reference image input / output unit 124 that manages the input and output of reference images, and a reference image storage unit 125 that stores reference images. Detailed processing of each functional block that constitutes the image compression unit 12 will be described in the section on operation.

[0024] The compressed image transmission unit 13 outputs the compressed image calculated by the image compression unit 12 to the image processing device 20. For example, the compressed image transmission unit 13 may be a communication unit that forms a packet including compressed image data and transmits it to the image processing device 20 in accordance with a communication protocol of a network (not shown).

[0025] <Image processing device 20> As shown in FIG. 1, the image processing device 20 includes a compressed image receiving unit 21, an image developing unit 22, and an image output unit .

[0026] The image processing device 20 can be realized by a circuit device having a CPU, ROM, RAM, EEPROM, etc. The ROM stores programs that can be read by the CPU. The functions of the image processing device 20 are realized by the CPU executing the programs stored in the ROM.

[0027] The compressed image receiving unit 21 inputs the compressed image output from the image capturing device 10 to the image processing device 20. For example, the compressed image receiving unit 21 may be a communication unit that receives a packet including compressed image data in accordance with a communication protocol of a network (not shown) and inputs the packet to the image processing device 20.

[0028] The image development unit 22 performs calculations on the input compressed image to calculate a developed image.

[0029] FIG. 3 is a block diagram showing the configuration of the image development unit according to the embodiment.

[0030] The image decompression unit 22 has a compressed image input unit 221 that inputs a compressed image, an image decompression processing unit 222 that applies decompression processing to the compressed image to generate an decompressed image, an decompressed image output unit 223 that outputs the decompressed image to the image output unit 23, a reference image input / output unit 224 that manages input and output of a reference image, and a reference image storage unit 225 that stores the reference image. Detailed processing of each functional block that constitutes the image decompression unit 22 will be described in the section on operation.

[0031] The image output unit 23 outputs the expanded image output from the image expansion unit 22 to the outside of the image processing device 20. The image output unit 23 may output the image data to an SD card or the like, or to a display device such as a liquid crystal display, for example.

[0032] (A-2) Operation of the embodiment Next, the operation of the image capturing system 1 according to the embodiment having the above configuration will be described.

[0033] (A-2-1) Overall movement FIG. 4 is a flowchart showing the overall operation of the image capturing system (image capturing device and image processing device) according to the embodiment.

[0034] <Step S11> In the image capturing device 10, the image capturing unit 11 receives operational inputs and capture execution commands from a person or a program, captures an image of a subject, and outputs the captured image. The captured image may be in a commonly used file format such as bitmap or JPEG, but is preferably uncompressed data or losslessly compressed data.

[0035] <Step S12> The image compression unit 12 performs image compression processing on the captured image input from the image capturing unit 11 to generate a compressed image. Details of the compression processing performed in step S12 will be described later.

[0036] <Step S13> The compressed image transmission unit 13 outputs the compressed image to the outside of the image capturing device 10. In this example, the output destination is the image processing device 20.

[0037] <Step S14> The compressed image receiving unit 21 stores the compressed image input from the image capturing device 10 inside the image processing device 20 (storage means such as a memory, not shown).

[0038] <Step S15> The image decompression unit 22 performs decompression processing on the compressed image to calculate a decompressed image. The decompression processing performed in step S15 will be described in detail later.

[0039] <Step S16> The image output unit 23 outputs the expanded image to the outside of the image processing device 20. The output destination may be any device, such as a storage device such as a hard disk drive (HDD) or a display device such as a liquid crystal display.

[0040] (A-2-2) Details of the process in step S12 (compression process) FIG. 5 is a flowchart showing detailed processing of the image compression unit according to the embodiment.

[0041] <Step S121> The photographed image input unit 121 stores the photographed image inside the image compression unit 12 (storage means such as a memory, not shown).

[0042] <Step S122> The reference image input / output unit 124 and the reference image storage unit 125 store the captured image as a subsequent reference image. The subsequent reference image is an image that is used as a reference image for the next and subsequent captures, and is used in a subsequent step.

[0043] <Step S123> The reference image input / output unit 124 and the reference image storage unit 125 determine whether or not a previous reference image exists. The previous reference image is image data used in the compression process (step S125, described later) for each shot. If a previous reference image exists, the process proceeds to the next step S124. On the other hand, if a previous reference image does not exist (for example, in the case of the first fixed-point observation), the process proceeds to step S127, described later.

[0044] <Step S124> The image compression processing unit 122 acquires the previous reference image from the reference image storage unit 125 via the reference image input / output unit 124 .

[0045] <Step S125> The image compression processing unit 122 calculates the difference between the captured image and the previous reference image, and generates a difference image.

[0046] <Step S126> The image compression processing unit 122 compresses the difference image to generate a compressed image. The compressed image is configured, for example, to include (1) compressed image data, (2) shooting time, and (3) reference image shooting time. A commonly known compression method may be used, but a lossless compression method is preferably used. Step S126 is followed by step S128.

[0047] <Step S128> The reference image input / output unit 124 and the reference image storage unit 125 update the previous reference image with the next reference image (the image internally stored in step S122 described above). In other words, the next reference image is the captured image that is the target of a series of compression processes. In the next and subsequent compression processes, the current captured image will be used as the previous reference image.

[0048] <Step S129> The compressed image output unit 123 outputs the compressed image to the outside of the image compression unit 12 .

[0049] <Step S127> On the other hand, if it is determined in step S123 that there is no previous reference image, the image compression processing unit 122 compresses the captured image to generate a compressed image. When the process proceeds to step S127, there is no previous reference image, and in this case the reference image capture time is set to null data. Whether or not to perform difference development processing in the subsequent development processing is determined depending on whether or not there is data on the reference image capture time. After step S127, the processes from step S128 onwards are executed.

[0050] (A-2-3) Details of the process (expansion process) in step S15 FIG. 6 is a flowchart showing detailed processing of the image development processing unit according to the embodiment.

[0051] <Step S151> The compressed image input unit 221 stores the compressed image inside the image expansion unit 22 (storage means such as a memory, not shown).

[0052] <Step S152> The image decompression processing unit 222 decompresses the compressed image and generates a decompressed differential image. If the previous compression process was performed using a lossless compression method, the decompressed differential image and the differential image will be equivalent. If a lossy compression method was used, the two images will not be equivalent.

[0053] <Step S153> The image decompression processing unit 222 determines whether a reference image is used in the compressed data. Specifically, the image decompression processing unit 222 determines whether reference image shooting time data is present (whether a reference image is used). If a reference image is used, the process proceeds to the next step S154, and if a reference image is not used, the process proceeds to step S156, which will be described later.

[0054] <Step S154> The image unfolding processing unit 222 acquires the previous reference image (the unfolded image stored in the previous step S156) from the reference image storage unit 225 via the reference image input / output unit 224 using the reference image photographing time data as a key.

[0055] <Step S155> The image unfolding processing unit 222 calculates an unfolded image from the unfolded differential image and the previous reference image. Since the unfolded differential image is the difference between the previous reference image and the captured image, the captured image is obtained by adding the unfolded differential image to the previous reference image. After step S155, the next step S156 is executed.

[0056] <Step S156> The reference image input / output unit 224 and the reference image storage unit 225 update the previous reference image with the unfolded image. In the next and subsequent unfolding processes, the currently captured image will be used as the previous reference image.

[0057] <Step S157> The developed image output unit 223 outputs the developed image to the outside of the image development unit 22.

[0058] (A-2-4) How to select a reference image In this embodiment, a difference image is created using an image taken at the same time one day earlier as a reference image. The present invention is assumed to be applied to a camera that takes images at a fixed point periodically at intervals of several minutes to several tens of minutes. With such a camera, it is expected that the difference between the image taken at the same time on the previous day will be smaller than the difference between the image taken immediately before.

[0059] (A-3) Effects of the embodiment As described above, according to this embodiment, the amount of data to be transmitted can be reduced by keeping the absolute amount of difference data small, and the amount of power consumed to transmit data from the image capturing device 10 to the image processing device 20 can be reduced.

[0060] (B) Although various modified embodiments have been mentioned in the above-described embodiment, the following modified embodiments can also be applied.

[0061] (B-1) In the above-described embodiment, the method of selecting a reference image was to select an image from the same time one day earlier as the reference image, but as a variant, an image from the same time period one day earlier may be selected as the reference image to generate a difference image.

[0062] This is based on the assumption that the image does not change significantly over the course of several minutes or several tens of minutes. The same time period can be determined in any way. For example, it can be determined as daytime in the morning, daytime in the afternoon, or nighttime, or intervals of several tens of minutes to several hours.

[0063] (B-2) FIG. 7 is a diagram showing an image of the relationship between the reference image and the timing of photographing in the embodiment and modified embodiment.

[0064] 7A shows a method for selecting a reference image according to the embodiment, where at each timing T (T101 to T105), reference images R (R11 to R15) from the same time one day earlier are referenced. Meanwhile, FIG. 7B shows a method for selecting a reference image according to a modified embodiment, where at each time period (between T101 and T102, between T103 and T105), reference images R (R21, R22) from the same time period one day earlier are referenced.

[0065] That is, in the modified embodiment, the amount of reference image data stored in the image capturing device 10 and the image processing device 20 can be further reduced than in the above-described embodiment. That is, the required storage capacity of each device can be reduced, and a reduction in equipment costs can be expected. [Explanation of symbols]

[0066] 1...image capturing system, 10...image capturing device, 11...image capturing section, 12...image compression section, 13...compressed image transmitting section, 20...image processing device, 21...compressed image receiving section, 22...image expansion section, 23...image output section, 121...captured image input section, 122...image compression processing section, 123...compressed image output section, 124...reference image input / output section, 125...reference image storage section, 221...compressed image input section, 222...image expansion processing section, 223...expanded image output section, 224...reference image input / output section, 225...reference image storage section, R...reference image, T...timing.

Claims

1. An image capturing system that captures an image of a subject and outputs the captured image data, an image capturing device that captures an image of the object to be captured, applies a compression process to the captured image to generate a compressed image, and transmits the compressed image; an image processing device that applies a decompression process to the compressed image to generate a decompressed image, The image capturing device is an image capturing unit that captures an image of the object to be captured and generates the captured image; an image compression unit that applies a compression process to the captured image to generate the compressed image; a compressed image transmitting unit that transmits the compressed image to the image processing device; The image processing device includes: a compressed image receiving unit that receives the compressed image; an image expansion unit that applies expansion processing to the compressed image to generate the expanded image; an image output unit that outputs the expanded image to an external device of the image processing device; An image capturing system comprising:

2. The image compression unit a photographed image input unit for inputting the photographed image; an image compression processing unit that applies compression processing to the captured image to generate the compressed image; a reference image input / output unit that manages input and output of the reference image; a reference image storage unit that stores the reference image; a compressed image output unit that outputs the compressed image to the compressed image transmission unit; 2. The image capturing system according to claim 1, further comprising:

3. The image development unit a compressed image input unit for inputting the compressed image; an image decompression processing unit that applies a decompression process to the compressed image to generate the decompressed image; a reference image input / output unit that manages input and output of the reference image; a reference image storage unit that stores the reference image; an exfoliated image output unit that outputs the exfoliated image to the image output unit; 2. The image capturing system according to claim 1, further comprising:

4. 3. The image capturing system according to claim 2, wherein the image compression processing executed on the captured image by the image compression unit includes processing for calculating a difference between the captured image and the reference image and generating a difference image.

5. 5. The image capturing system according to claim 2, wherein the reference image is an image captured on the day before the capture time of the captured image at the same time.

6. The image capturing system according to any one of claims 2 to 4, wherein the reference image is any image captured during the same time period on the day before the time period that includes the time of capturing the captured image.

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