Image processing system and image processing method

Abstract

To provide an image processing system capable of acquiring a photographed image of a subject with good quality.SOLUTION: Transmittance control means changes the transmittance of light reaching an imaging portion of a photographing device over time, and detects a subject while repeatedly controlling the change in the transmittance of light. Image data showing the subject generated by the imaging portion at different light transmittances is output.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an image processing system and an image processing method. [Background technology]

[0002] There is a demand for a technology that can output a captured image of a subject in a short time with good quality. In such a technology, it is required to generate image data that is more suitable for the intended use as an image of the subject, such as reducing the phenomenon that halation occurs due to a large amount of light incident on the imaging section of the imaging device. A related technology is disclosed in Patent Document 1.

[0003] Patent Document 1 discloses a technology for a license plate reader that suppresses a decrease in the recognition rate of the registration number written on the license plate from an image of a vehicle. Patent Document 1 describes that two images captured consecutively in time are stored in correspondence with each other. Patent Document 1 also describes that one of the two images is an image captured with a first exposure amount, and the other is an image captured with a second exposure amount. Patent Document 1 also describes that if the registration number written on the license plate of the vehicle captured by image processing cannot be recognized, the other image is captured, and image processing is performed to recognize the registration number written on the license plate of the vehicle captured in this captured image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-15478 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is a demand for technology that can capture images of subjects that are as good as possible even when the subject is moving fast, such as a vehicle equipped with the license plate described above.

[0006] An object of this disclosure is to provide an image processing system and an image processing method that solve the above problems. [Means for solving the problem]

[0007] According to a first aspect of this disclosure, an image processing system includes a transmittance control means for changing the transmittance of light reaching an imaging section of a photographing device over time, a detection means for detecting a subject, and an image data output means for outputting image data of the subject generated by the imaging section at different transmittances of the light.

[0008] According to a first aspect of this disclosure, an image processing method varies the transmittance of light reaching an imaging unit of a photographing device over time, detects a subject, and outputs image data depicting the subject generated by the imaging unit at different transmittances of light. Effect of the Invention

[0009] When the moving speed of the subject is fast, it is possible to obtain a photographed image of the subject that is as good as possible at the timing when the subject is located within a predetermined photographing range. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of an image processing system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a functional block diagram of each device constituting the image processing system according to the embodiment of the present disclosure. [Diagram 3] FIG. 1 is a diagram illustrating a hardware configuration of an image processing device according to an embodiment of the present disclosure. [Figure 4] FIG. 13 illustrates the state of image data as a function of transmittance according to one embodiment of the present disclosure. [Diagram 5] FIG. 2 is a diagram showing a processing flow of an image processing system according to an embodiment of the present disclosure. [Figure 6] FIG. 11 is a functional block diagram illustrating an image processing system according to another embodiment of the present disclosure. [Figure 7] FIG. 13 is a functional block diagram illustrating a filter device according to another embodiment of the present disclosure. [Figure 8] FIG. 11 is a diagram showing a processing flow by an image processing system according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First Embodiment FIG. 1 is a schematic configuration diagram of an image processing system according to an embodiment of the present disclosure. 1, the image processing system 100 includes a filter device 1, a camera 2, an image processing device 3, and a vehicle detector 4. The filter device 1 is a device that changes the transmittance of light incident on the camera 2. In this embodiment, the filter device 1 operates independently of the camera 2. However, the filter device 1 may be a device that is provided inside the camera 2 and on the path of light incident on an imaging element (imaging unit 23 described below).

[0012] The camera 2 generates a plurality of image data depicting a subject. In the present disclosure, the camera 2 captures the license plate of the subject vehicle 50 as the main subject. The image data depicting the subject generated by the camera 2 is image data corresponding to different light transmittances controlled by the filter device 1. As a result, the average brightness of the entire image range of each image data is different. The filter device 1 changes the transmittance at short intervals such as several tens of milliseconds, and the camera 2 is set in advance to release the shutter in synchronization with the timing corresponding to the different transmittances. For this synchronization, the filter device 1 and the camera 2 may be connected to communicate with each other to perform synchronization control.

[0013] The image processing device 3 outputs image data that is least affected by halation among the multiple image data. The vehicle detector 4 detects the subject vehicle 50 when the subject vehicle 50 reaches a predetermined position. The vehicle detector 4 may detect the vehicle 50 by emitting infrared light, for example, and receiving the reflected light.

[0014] FIG. 2 is a functional block diagram of each device constituting the image processing system according to an embodiment of the present disclosure. The filter device 1 includes a filter mechanism 11 and a transmittance control unit 12. As an example, the filter mechanism 11 has a mechanism in which a disk on which a plurality of filters with different light transmittances are arranged in a circular shape rotates. The filter mechanism 11 may be of any type as long as it has a mechanism for sequentially changing the light transmittance so that the amount of light incident on the camera 2 varies.

[0015] When the filter mechanism 11 has the above configuration, the transmittance control unit 12 controls the rotation of the disk. The transmittance control unit 12 may control the speed at which the disk is rotated. The filter device 1 operates independently of the camera 2, and controls the amount of light incident on the camera 2 by filters with different transmittances. In the present disclosure, the filter device 1 operates before the vehicle detector 4 detects the vehicle 50 and before the camera 2 releases the shutter, and changes the amount of light incident on the camera 2 at intervals of several tens of milliseconds. The transmittance control unit 12 may change the transmittance of each filter by changing the value of the voltage applied to each filter of the filter mechanism 11 arranged on the path of light incident on the imaging unit. A filter whose transmittance changes due to the application of a voltage is called a light adjustment filter. The transmittance control unit 12 may change the transmittance by controlling the filter mechanism 11, which sequentially switches between multiple filters with different transmittances arranged on the path of light incident on the imaging unit 23 of the camera 2.

[0016] Camera 2 includes a detection unit 21, a control unit 22, and an imaging unit 23. Detection unit 21 detects the start of imaging of a subject based on receipt of a vehicle detection signal from vehicle detector 4. Control unit 22 performs control such as releasing the shutter of camera 2 based on detection by detection unit 21 of the start of imaging of a subject. Imaging unit 23 images vehicle 50, which is a subject, using light transmitted through the filter of filter device 1, and generates image data.

[0017] The image processing device 3 includes an image processing unit 31. The image processing unit 31 selects and outputs image data with the lowest degree of halation among image data of a subject generated by the imaging unit 23 at different light transmittances. The vehicle detector 4 includes a signal output unit 41. The signal output unit 41 outputs to the camera 2 a vehicle detection signal indicating that a vehicle 50 has been detected.

[0018] FIG. 3 is a diagram illustrating a hardware configuration of the image processing device. 3, the image processing device 3 is a computer including various hardware components such as a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a HDD (Hard Disk Drive) 104, and a communication module 105. The filter device 1, the camera 2, and the vehicle detector 4 may also include a part or all of a similar hardware configuration.

[0019] FIG. 4 is a diagram showing the state of image data according to the transmittance. As shown in FIG. 4, the camera 2 generates image data according to the amount of incident light by controlling the transmittance of the filter device 1. As a result, the image data generated when the camera 2 photographs an object during the day becomes a plurality of image data according to the transmittance, ranging from image data with low transmittance to image data with high transmittance. Similarly, the image data generated when the camera 2 photographs an object at night becomes a plurality of image data according to the transmittance, ranging from image data with low transmittance to image data with high transmittance. In the daytime, when the amount of light incident on the camera 2 is large and halation occurs in the image, the license plate information is captured with good visibility in image data with low transmittance. In the nighttime, when the amount of light incident on the camera 2 is small and the image is dark, and the visibility of the license plate information is poor, the license plate information is captured with better visibility in an image with high transmittance. The image processing device 3 selects and outputs image data in which the license plate information (character strings such as numbers) is captured with good visibility.

[0020] FIG. 5 is a diagram showing a processing flow of the image processing system. Next, the processing flow of the image processing system will be explained step by step. First, the filter device 1 is in operation in advance, and the filter mechanism 11 is driven under the control of the transmittance control unit 12 (step S101). The filter device 1 changes the amount of light incident on the imaging unit 23 of the camera 2 by driving the filter mechanism 11.

[0021] With the filter mechanism 11 of the filter device 1 in operation, the vehicle detector 4 waits to detect the vehicle 50. When the vehicle 50 approaches the vehicle detector 4, the infrared light emitted by the vehicle detector 4 is reflected by the vehicle 50. The vehicle detector 4 receives the reflected light and thereby detects the vehicle 50. The signal output unit 41 of the vehicle detector 4 outputs a vehicle detection signal to the camera 2 (step S102).

[0022] The detection unit 21 of the camera 2 receives the vehicle detection signal. Based on the vehicle detection signal, the detection unit 21 detects the start of photographing the vehicle 50 (step S103). The detection unit 21 instructs the control unit 22 to start photographing. Based on the detection by the detection unit 21 that the photographing of the subject has started, the control unit 22 controls the camera 2 to release the shutter (step S104). The imaging unit 23 images the vehicle 50 using light that has passed through the filter of the filter device 1, and generates image data (step S105). The imaging unit 23 repeats photographing the vehicle 50. The imaging unit 23 outputs multiple image data to the image processing device 3 (step S106).

[0023] The image processing unit 3 acquires image data. The image processing unit 31 compares a plurality of image data showing the vehicle 50 from the camera 2. The image processing unit 31 identifies the image data with the best visibility (step S107). In this process, the image processing unit 31, in the daytime processing, identifies, for example, the image data with the lowest average luminance of each pixel included in the image data. This process is an example of the process in which the image processing unit 3 selects the image data with the lowest degree of halation among the image data showing the subject generated by the imaging unit 23 at different light transmittances. Alternatively, in the nighttime processing, the image processing unit 31 identifies, for example, the image data with the highest average luminance of each pixel included in the image data. The image processing unit 31 may use any process as long as it can identify the image data with the appropriate luminance that shows the license plate information with the best visibility according to the conditions such as the time, weather, and illuminance. As a result, the image processing unit 31 identifies the image data with the best visibility of the license plate information among the plurality of image data. The image processing unit 31 outputs the identified image data (step S108). The image processing unit 31 may calculate a score for the license plate information and identify image data in which the license plate information is highly visible based on the score. For example, the license plate is read from a plurality of images, and a score indicating the likelihood (high visibility) of each is calculated based on the sharpness, pattern recognition, etc. The image processing unit 31 identifies image data in which the license plate information with a high score is highly visible based on the results. In this case, the image processing unit 31 may calculate a score for each character on the license plate, and combine image areas with high scores for each character to identify them as one image data.

[0024] According to the above-mentioned process, the filter device 1 detects the subject while it is driven first, and the camera 2 generates image data of the subject according to different incident light amounts. Therefore, compared to the case where the filter device 1 is driven to vary the transmittance of light incident on the camera 2 after detecting the subject, image data according to multiple different incident light amounts can be generated instantaneously after the subject is detected. As a result, even if the subject moves quickly or the focal depth is not large, multiple image data of the subject can be generated in a short time while varying the incident light amount on the camera 2. Since image data based on multiple different incident light amounts generated in a short time can be generated, image data that provides a desired subject situation, such as the selection of image data with the lowest degree of halation, can be selected. As a result, when the subject is the license plate of the vehicle 50, the visibility of the license plate information can be improved, and the detection accuracy of the license plate information can be improved.

[0025] (Another embodiment 1) In the above-described image processing system 100, the image processing device 3 may detect the character string on the license plate using the image data specified in step S107. The image processing device 3 may also detect the vehicle model and color using the image data specified in step S107.

[0026] (Another embodiment 2) FIG. 6 is a functional block diagram showing an image processing system according to another embodiment of the present disclosure. FIG. 7 is a functional block diagram illustrating a filter device according to another embodiment of the present disclosure. FIG. 8 is a diagram showing a processing flow by an image processing system according to another embodiment of the present disclosure.

[0027] The image processing system 100 includes at least a transmittance control unit 61 , a detection unit 62 , and an image data output unit 63 . The transmittance control means 61 included in the filter device 1 controls the filter mechanism 71. The filter mechanism 71 changes the transmittance of light that reaches the imaging section of the imaging device over time (step S701). The detection means 62 detects the subject (step S702). The image data output means 63 outputs image data showing the subject generated by the imaging section at different light transmittances (step S703).

[0028] The program of the image processing device 3 may be a program for implementing some of the above-mentioned functions, or may be a so-called differential file (differential program) that can implement the above-mentioned functions in combination with a program already recorded in the computer system.

[0029] Although the image processing system 100 of this disclosure has been described above, this disclosure is not limited to the above-mentioned embodiment. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of this disclosure within the scope of this disclosure. Furthermore, each embodiment can be appropriately combined with other embodiments.

[0030] Note that some or all of the above-described embodiments can be described as, but are not limited to, the following supplementary notes.

[0031] (Appendix 1) a transmittance control means for changing the transmittance of light reaching an imaging unit of the imaging device over time; A detection means for detecting a subject; an image data output unit that outputs image data of the subject generated by the imaging unit at different light transmittances; An image processing system comprising:

[0032] (Appendix 2) The transmittance control means changes the transmittance by changing a value of a voltage applied to a filter disposed in a path of light incident on the imaging unit. 2. An image processing system as described in claim 1.

[0033] (Appendix 3) The transmittance control means changes the transmittance by sequentially switching among a plurality of filters having different transmittances that are arranged on a path of light incident on the imaging unit. 2. An image processing system as described in claim 1.

[0034] (Appendix 4) The transmittance control means controls the rotation of a disk on which the plurality of filters having different transmittances are arranged in a circular shape. 4. An image processing system as described in claim 3.

[0035] (Appendix 5) an image processing unit that selects image data that has a lowest degree of halation from among image data of the subject that are generated by the imaging unit at different light transmittances; 5. The image processing system according to claim 1, further comprising:

[0036] (Appendix 6) The transmittance of light reaching the imaging unit of the imaging device is changed over time, Detect the subject, The image data representing the subject generated by the imaging unit at different light transmittances is output. Image processing methods.

[0037] (Appendix 7) The transmittance is changed by changing a value of a voltage applied to a filter disposed in a path of light incident on the imaging unit. 7. An image processing method according to claim 6.

[0038] (Appendix 8) A plurality of filters having different transmittances are arranged on a path of light incident on the imaging unit, and the transmittance is changed by sequentially switching the filters. 7. An image processing method according to claim 6.

[0039] (Appendix 9) The rotation of a disk on which the plurality of filters having different transmittances are arranged in a circular shape is controlled. 9. An image processing method according to claim 8.

[0040] (Appendix 10) an image processing unit that selects image data that has a lowest degree of halation from among image data of the subject that are generated by the imaging unit at different light transmittances; 10. The image processing method according to any one of claims 6 to 9, comprising:

[0041] (Appendix 11) Located in front of the lens of the imaging device, The transmittance of light reaching the imaging unit of the imaging device is changed over time. Filter device.

[0042] (Appendix 12) A filter device provided in front of the lens of the imaging device, The transmittance of light reaching the imaging unit of the imaging device is changed over time. Filter method.

[0043] (Appendix 13) A computer of a filter device provided in front of a lens of an imaging device, A means for changing the transmittance of light reaching the imaging section of the imaging device over time. A program that functions as a [Explanation of symbols]

[0044] 1. Filter device (transmittance control means 61) 2. Camera (image data output means 63) 3. Image Processing Device 4. Vehicle detector (detection means 62) 5. Vehicle 100 Image Processing System 11. Filter mechanism 12 Transmittance control section 21. Detection unit 22 Control section 23 Imaging unit 31 Image processing section 41 Signal output section

Claims

1. a transmittance control means for changing the transmittance of light reaching an imaging unit of the imaging device over time; A detection means for detecting a subject; an image data output unit that outputs image data of the subject generated by the imaging unit at different light transmittances; An image processing system comprising:

2. The transmittance control means changes the transmittance by changing a value of a voltage applied to a filter disposed in a path of light incident on the imaging unit. The image processing system according to claim 1 .

3. The transmittance control means changes the transmittance by sequentially switching among a plurality of filters having different transmittances that are arranged on a path of light incident on the imaging unit. The image processing system according to claim 1 .

4. The transmittance control means controls the rotation of a disk on which the plurality of filters having different transmittances are arranged in a circular shape. The image processing system according to claim 3 .

5. an image processing unit that selects image data that has a lowest degree of halation from among image data of the subject that are generated by the imaging unit at different light transmittances; The image processing system according to claim 1 , further comprising:

6. The transmittance of light reaching the imaging unit of the imaging device is changed over time, Detect the subject, The image data representing the subject generated by the imaging unit at different light transmittances is output. Image processing methods.

Images