Passing person counting device

Abstract

To provide a passing people number measuring device that can properly extract information related to a movement of people from an image related to a detection area.SOLUTION: A passing people number measuring device 10A comprises: a first difference image creation unit 22 that creates a first difference image by changing, of pixels constituting an original difference image that is a difference image between two thermal images, pixels indicating that a thermal change is less than a first change amount to pixels indicating that no thermal change occurs; a second difference image creation unit 23 that creates a second difference image by changing pixels indicating that the thermal change is less than a second change amount (second change amount>first change amount) to pixels indicating that no thermal change occurs; and a final difference image creation unit 24 that creates a final difference image by changing pixels indicating that no thermal change occurs and adjacent to the pixels constituting the second difference image and indicating that the thermal change occurs, to pixels indicating the occurrence of the same thermal change as the thermal change indicated by pixels corresponding to the pixels constituting the first difference image.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a passing - person counting device that measures the number of people passing through a detection area provided near entrances and exits of various facilities and various vehicles.

Background Art

[0002] Conventionally, an entrance - exit monitoring device described in Patent Document 1 is known. This device includes a pair of thermal - sensing sensors (an outdoor - side thermopile sensor and an indoor - side thermopile sensor) provided above an entrance and exit, an amplifier that amplifies the difference between the output signals of each sensor, and a CPU processing unit that discriminates human movement based on the output signal of the amplifier. According to this device, not only the entry and exit of people but also the fact that a person trying to enter made a U - turn without entering and a person trying to exit made a U - turn without exiting can be discriminated.

[0003] However, this device cannot accurately identify the number of people who entered or exited when multiple entries or exits occur simultaneously. The same is true when entry and exit occur simultaneously.

[0004] [[ID=]20]To solve this problem, a type of device has also been proposed that includes a thermal - image sensor that generates a thermal image of a detection area provided near an entrance and exit at regular intervals, and a discrimination unit that discriminates human movement based on a difference image between two thermal images generated at different times. According to this device, the number of people passing through the detection area and the passing direction can be discriminated. For example, according to this device, it can be discriminated that two people entered from the entrance and three people exited from the entrance.

[0005] Incidentally, in the latter type of device, pixels that indicate a thermal change exceeding a predetermined threshold are often designated as valid pixels (pixels used for discrimination), while other pixels are designated as invalid pixels (pixels not used for discrimination). This method is expected to remove unnecessary information unrelated to human movement, allowing for more accurate discrimination of human movement.

[0006] However, the above method had a problem: setting the threshold was difficult. If the threshold was too low, unnecessary information would not be sufficiently removed, and the desired effect would not be achieved. Conversely, if the threshold was too high, not only unnecessary information but also necessary information would be removed, making it difficult to adequately distinguish human movement. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 9-113355 [Overview of the project] [Problems that the invention aims to solve]

[0008] This invention has been made in view of the above circumstances, and aims to provide a pass-by person counting device that can extract information related to human movement from images of a detection area without any excess or deficiency. [Means for solving the problem]

[0009] To solve the above problems, the first person-passing measurement device according to the present invention is a device for measuring the number of people who have passed through a predetermined detection area, comprising: a thermal image generation unit that generates a thermal image relating to the detection area each time time Δt has elapsed; a difference image generation unit that generates a difference image which is the difference between the thermal image generated at time t and the thermal image generated at time t+Δt; a first difference image generation unit that generates a first difference image by changing pixels among the pixels constituting the difference image that indicate that the thermal change was less than a preset first change amount to pixels that indicate that there was no thermal change; and among the pixels constituting the difference image, if the thermal change is less than a preset second change amount (however, the second change amount > The system includes a second difference image generation unit that generates a second difference image by changing pixels indicating that the thermal change was less than the first change to pixels indicating that there was no thermal change; a final difference image generation unit that generates a final difference image from the first difference image and the second difference image; and a measurement unit that measures the number of people who have passed through the detection area based on the final difference image. The final difference image generation unit generates the final difference image by changing pixels indicating that there was no thermal change adjacent to pixels indicating that there was a thermal change in the second difference image to pixels indicating that there was a thermal change, if the pixel corresponding to that pixel in the first difference image is a pixel indicating that there was a thermal change.

[0010] Furthermore, in order to solve the above problems, the second pass-through person measuring device according to the present invention is a device for measuring the number of people who have passed through a predetermined detection area, and comprises: a raw image generation unit that generates a raw image relating to the thermal change of the detection area that occurred during a predetermined time; a first difference image generation unit that generates a first difference image by changing pixels that show a thermal change of less than a predetermined first amount among the pixels constituting the raw image to pixels that show no thermal change; a second difference image generation unit that generates a second difference image by changing pixels that show a thermal change of less than a predetermined second amount (however, second amount > first amount) among the pixels constituting the raw image to pixels that show no thermal change; a final difference image generation unit that generates a final difference image from the first difference image and the second difference image; and a measuring unit that measures the number of people who have passed through the detection area based on the final difference image, wherein the final difference image generation unit generates the final difference image by changing pixels that show no thermal change adjacent to pixels that show thermal change in the second difference image to pixels that show thermal change when the pixel corresponding to that pixel in the first difference image shows thermal change.

[0011] The final difference image generation unit described above may have the following configuration: it generates a third difference image by changing a pixel indicating no thermal change adjacent to a pixel indicating a thermal change that constitutes the second difference image, to a pixel indicating a thermal change that constitutes the first difference image, if the corresponding pixel in the first difference image is a pixel indicating a thermal change; and then generates a final difference image by changing a pixel indicating no thermal change adjacent to a pixel indicating a thermal change that constitutes the third difference image, to a pixel indicating a thermal change that constitutes the first difference image, if the corresponding pixel in the first difference image is a pixel indicating a thermal change.

[0012] Herein, in this specification, a pixel α and a pixel β are considered "adjacent" if any of the following conditions [1] to [4] are met. If condition [1] is adopted, the number of pixels β adjacent to pixel α is 4, and if condition [2] is adopted, the number of pixels β adjacent to pixel α is 8. [1] When pixels α and β overlap each other at an edge. [2] When pixels α and β overlap each other at an edge or angle. [3] When the Euclidean distance between pixel α and pixel β falls below a predetermined threshold. [4] When the Manhattan distance between pixel α and pixel β falls below a predetermined threshold. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a pass-through counting device that can extract information related to human movement from images of a detection area without any excess or deficiency. [Brief explanation of the drawing]

[0014] [Figure 1] This is a block diagram of a pass-by counting device according to the first embodiment of the present invention. [Figure 2] This figure shows an example of a difference image generated by the passerby counting device according to the first embodiment. [Figure 3] This figure shows an example of a first difference image generated by the passerby counting device according to the first embodiment. [Figure 4] This figure shows an example of a second difference image generated by the passerby counting device according to the first embodiment. [Figure 5] This figure shows an example of a final difference image generated by the passerby counting device according to the first embodiment. [Figure 6] This figure shows the procedure for generating the final difference image using the passerby counting device according to the first embodiment. [Figure 7] This is an operation flowchart of the pedestrian counting device according to the first embodiment. [Figure 8] This is a block diagram of a pass-by counting device according to a second embodiment of the present invention. [Figure 9] This figure shows the procedure for generating a final difference image using a passerby counting device according to a modified version of the present invention. [Modes for carrying out the invention]

[0015] Hereinafter, an embodiment of the passing person counting device according to the present invention will be described with reference to the accompanying drawings.

[0016] [First Embodiment] FIG. 1 shows a passing person counting device 10A according to a first embodiment of the present invention. The passing person counting device 10A is for measuring the number of pedestrians W1 passing in the M1 direction and the number of pedestrians W2 passing in the M2 direction in a detection area A provided on the floor 200 near the entrance / exit of a commercial facility. As shown in the figure, it includes a thermal image generation unit 11A, a storage unit 12, a control unit 20A, a setting unit 13, an external interface unit 14, an audio output unit 15, a light emitting unit 16, and a housing that houses these components. The passing person counting device 10A is attached to the ceiling 100 such that the thermal image generation unit 11A faces the detection area A.

[0017] In this embodiment, the mounting height H is 4 m. Also, the detection area A in this embodiment is a rectangle with a side length of 4 m perpendicular to the assumed passing directions M1 and M2 and a side length of 3 m parallel to the passing directions M1 and M2. When the mounting height H changes, the size of the detection area A changes accordingly.

[0018] The thermal image generation unit 11A is composed of a two-dimensional thermal image sensor. The thermal image generation unit 11A detects far-infrared rays radiated from the detection area A (floor 200) or the pedestrians W1 and W2 within the area A, and generates a thermal image of 60 pixels × 45 pixels (more precisely, data related to the thermal image) corresponding to the detection result. The generation of the thermal image is performed every 1 / 10 s. The generated thermal images are sequentially sent to the storage unit 12.

[0019] The storage unit 12 is composed of a volatile or non-volatile memory. The storage unit 12 stores at least the latest thermal image and the one before it among the thermal images sent from the thermal image generation unit 11A every 1 / 10 s. In other words, the storage unit 12 stores the last generated thermal image (hereinafter referred to as the "second thermal image") and the thermal image generated 1 / 10 s before it (hereinafter referred to as the "first thermal image").

[0020] The control unit 20A consists of a microprocessor (MPU) and a computer program executed on the MPU. In this embodiment, the original difference image generation unit 21, the first difference image generation unit 22, the second difference image generation unit 23, the final difference image generation unit 24, and the measurement unit 25 are formed within the control unit 20A by the execution of the computer program.

[0021] The difference image generation unit 21 generates a 60-pixel × 45-pixel difference image P0 (more precisely, data related to the difference image P0) as shown in Figure 2, based on the first and second thermal images stored in the memory unit 12. For example, the difference image generation unit 21 determines the thermal change that the pixel at coordinate (0,0) in the difference image P0 should indicate by subtracting the temperature indicated by the pixel at coordinate (0,0) in the first thermal image from the temperature indicated by the pixel at coordinate (0,0) in the second thermal image. The difference image P0 can be said to indicate what kind of thermal change occurred in 1 / 10 s.

[0022] In Figure 2, pixels indicating that the absolute value of the thermal change was greater than 0°C and less than 2°C (the "first change" described later) are hatched, pixels indicating that the absolute value of the thermal change was between 2°C and 5°C (the "second change" described later) are filled in gray, pixels indicating that the absolute value of the thermal change was 5°C or greater are filled in black, and pixels indicating that the absolute value of the thermal change was 0°C are white. The same applies to Figures 3, 4, and 5.

[0023] The first difference image generation unit 22 generates a first difference image P1 (more precisely, data relating to the first difference image P1) as shown in Figure 3 by changing pixels that indicate the absolute value of the thermal change was less than a preset first change amount (i.e., hatched pixels) among the pixels constituting the original difference image P0 to pixels that indicate there was no thermal change (i.e., white pixels). The first difference image P1 can be said to be an extraction of pixels that indicate the absolute value of the thermal change was greater than or equal to the first change amount.

[0024] The second difference image generation unit 23 generates a second difference image P2 (more precisely, data related to the second difference image P2) as shown in Figure 4 by changing pixels that indicate the absolute value of the thermal change was less than a preset second change amount (i.e., hatched pixels and gray pixels) among the pixels that make up the original difference image P0 to pixels that indicate there was no thermal change (i.e., white pixels). The second difference image P2 can be said to be an extraction of pixels that indicate the absolute value of the thermal change was equal to or greater than the second change amount.

[0025] The final difference image generation unit 24 generates a final difference image PF (more precisely, data relating to the final difference image PF) from the first difference image P1 and the second difference image P2, as shown in Figure 5. More specifically, the final difference image generation unit 24 generates the final difference image PF by changing a pixel indicating no thermal change adjacent to a pixel indicating that there was a thermal change (i.e., a black pixel) in the second difference image P2 to a pixel indicating the same thermal change as the corresponding pixel in the first difference image P1. In this embodiment and the second embodiment described later, two pixels that overlap each other at an edge or corner are considered "adjacent" pixels.

[0026] The generation of the final difference image PF will be explained in detail with reference to Figure 6.

[0027] The final difference image generation unit 24 first focuses on pixel (4,3), one of the two pixels that constitute the second difference image P2 that indicate a thermal change, and which is close to coordinate (0,0) and indicates a thermal change of +6°C. Of the eight pixels adjacent to pixel (4,3), (3,2), (4,2), (5,2), (3,3), (5,3), (3,4), (4,4), (5,4), pixels (3,2), (4,2), (5,2), (3,3), (3,4), (4,4), and (5,4) indicate that there was no thermal change. Therefore, the final difference image generation unit 24 refers to pixels (3,2), (4,2), (5,2), (3,3), (3,4), (4,4), and (5,4) of the first difference image P1.

[0028] The pixel (3,2) in the first difference image P1 indicates that there was no change in temperature. Therefore, the final difference image generation unit 24 does not make any changes to the pixel (3,2) in the second difference image P2.

[0029] The pixel (4,2) in the first difference image P1 indicates a temperature change of +4°C. Therefore, the final difference image generation unit 24 changes the pixel (4,2) in the second difference image P2 to an indicator of a temperature change of +4°C.

[0030] The pixel (5,2) in the first difference image P1 indicates a temperature change of +3°C. Therefore, the final difference image generation unit 24 changes the pixel (5,2) in the second difference image P2 to a pixel indicating a temperature change of +3°C.

[0031] The final difference image generation unit 24 performs the same processing on pixels (3,3), (3,4), (4,4), and (5,4).

[0032] Next, the final difference image generation unit 24 focuses on pixel (5,3), which indicates that there was another thermal change in the second difference image P2. Of the eight pixels adjacent to pixel (5,3) (4,2), (5,2), (6,2), (4,3), (6,3), (4,4), (5,4), (6,4), pixels (6,2), (6,3), and (6,4) indicate that there was no thermal change at this point. Therefore, the final difference image generation unit 24 refers to pixels (6,2), (6,3), and (6,4) of the first difference image P1.

[0033] The pixel (6,2) in the first difference image P1 indicates that there was no change in temperature. Therefore, the final difference image generation unit 24 does not make any changes to the pixel (6,2) in the second difference image P2.

[0034] The pixel (6,3) in the first difference image P1 indicates a temperature change of +2°C. Therefore, the final difference image generation unit 24 changes the pixel (6,3) in the second difference image P2 to a pixel indicating a temperature change of +2°C.

[0035] The pixel (6,4) in the first difference image P1 indicates a temperature change of +3°C. Therefore, the final difference image generation unit 24 changes the pixel (6,4) in the second difference image P2 to a pixel indicating a temperature change of +3°C.

[0036] The final difference image generation unit 24 generates the final difference image PF by making the above-described changes to the second difference image P2. As can be seen from Figures 3, 4, and 5, the final difference image PF can be said to be an extension of the region where the thermal change was greater than or equal to the second change amount by up to one pixel, within the range that does not exceed the region where the thermal change was greater than or equal to the first change amount.

[0037] The measurement unit 25 measures the number of pedestrians W1 that passed through detection area A in the M1 direction and the number of pedestrians W2 that passed through in the M2 direction, based on the final difference image PF. Various known methods can be used for this measurement.

[0038] The external interface unit 14 is connected to a suitable external device. The external interface unit 14 can transmit the measurement results from the measurement unit 25 to the external device at predetermined timings and in predetermined formats.

[0039] The audio output unit 15 consists of a buzzer or a speaker. The audio output unit 15 can inform people in the vicinity of the measurement results by outputting audio corresponding to the measurement results from the measurement unit 25.

[0040] The light-emitting unit 16 is composed of at least one light-emitting diode. The light-emitting unit 16 can notify people in the vicinity of the measurement results by lighting up or flashing in a manner (color, brightness, etc.) corresponding to the measurement results from the measurement unit 25.

[0041] The setting unit 13 consists of DIP switches. The user can set the aforementioned first and second change amounts via the setting unit 13. The user can also individually switch the external interface unit 14, the audio output unit 15, and the light-emitting unit 16 on or off via the setting unit 13.

[0042] Figure 7 is an operation flowchart of the pedestrian traffic measuring device 10A according to this embodiment, which describes the movements of each part described above in chronological order.

[0043] In step S1, the storage unit 12 stores the first thermal image generated by the thermal image generation unit 11A.

[0044] In step S2, which is executed 1 / 10 s after step S1, the storage unit 12 stores the second thermal image generated by the thermal image generation unit 11A.

[0045] In step S3, which is performed after step S2, the difference image generation unit 21 generates a difference image P0 from the first thermal image and the second thermal image.

[0046] In step S4, which is performed after step S3, the first difference image generation unit 22 generates a first difference image P1 from the original difference image P0, and the second difference image generation unit 23 generates a second difference image P2 from the original difference image P0. The generation of the first difference image P1 and the second difference image P2 may be performed simultaneously, or one may be performed first.

[0047] In step S5, which is performed after step S4, the final difference image generation unit 24 generates a final difference image PF from the first difference image P1 and the second difference image P2.

[0048] In step S6, which is performed after step S5, the measurement unit 25 measures the number of people passing through based on the final difference image PF.

[0049] The person-counting device 10A in this embodiment operates repeatedly according to this operation flow every 1 / 10 second. In the second cycle of the flow, the second thermal image generated and stored in the first cycle becomes the first thermal image. The same applies to the third cycle and beyond.

[0050] Thus, the pedestrian counting device 10A according to this embodiment measures the number of pedestrians W1 and W2 based on a final difference image PF, which can be said to be a combination of the best aspects of the first difference image P1 generated using a first change amount as a threshold and the second difference image P2 generated using a second change amount as a threshold. In other words, the pedestrian counting device 10A measures the number of pedestrians W1 and W2 based on a final difference image PF, which is an image that extracts information related to the movement of pedestrians W1 and W2 without any excess or deficiency from the original difference image P0 relating to the detection area A. For this reason, the pedestrian counting device 10A can measure the number of pedestrians W1 and W2 more accurately than conventional devices.

[0051] [Second Example] Figure 8 shows a passerby counting device 10B according to a second embodiment of the present invention. The passerby counting device 10B differs from the passerby counting device 10A in that it has a thermal image generation unit 11B instead of a thermal image generation unit 11A, a control unit 20B instead of a control unit 20A, and does not have a storage unit 12, but is otherwise common to the passerby counting device 10A.

[0052] The thermal image generation unit 11B is composed of a two-dimensional thermal image sensor capable of generating an image relating to the thermal change of detection area A that occurred during a predetermined time (for example, 1 / 10 s), that is, an image corresponding to the original difference image P0 of the first embodiment.

[0053] The control unit 20B, like the control unit 20A, is composed of a microprocessor and a computer program executed on that processor. In this embodiment, the first difference image generation unit 22, the second difference image generation unit 23, the final difference image generation unit 24, and the measurement unit 25 are formed within the control unit 20B by the execution of the computer program.

[0054] The first difference image generation unit 22 generates the first difference image P1 from the image (original difference image P0) generated by the thermal image generation unit 11B.

[0055] The second difference image generation unit 23 generates a second difference image P2 from the image (original difference image P0) generated by the thermal image generation unit 11B.

[0056] According to this embodiment, the passerby counting device 10B can reduce manufacturing costs by eliminating the memory unit 12, and the computer program can be simplified by eliminating the original image generation unit 21. Naturally, the passerby counting device 10B can also achieve the same effects as the passerby counting device 10A.

[0057] [Differentiation] Although the first and second embodiments of the person-counting device according to the present invention have been described above, the configuration of the present invention is not limited to these.

[0058] For example, the people passing through detection area A, which is set up near the entrances and exits of various facilities other than commercial facilities or various vehicles, may be used to measure people passing through the detection area A.

[0059] Furthermore, the mounting location for the people-passing measurement devices 10A and 10B may be on a wall.

[0060] Furthermore, the people passing through measuring devices 10A and 10B do not necessarily have to include all or part of the setting unit 13, the external interface unit 14, the audio output unit 15, and the light-emitting unit 16.

[0061] Furthermore, the final image generation unit 24 of the people passing through the devices 10A and 10B may generate the final difference image PF by changing a pixel indicating no thermal change adjacent to a pixel indicating a thermal change that constitutes the second difference image P2, to a pixel indicating a thermal change that corresponds to that pixel in the first difference image P1, if that pixel is a pixel indicating a thermal change. In other words, when the final image generation unit 24 changes a pixel indicating no thermal change adjacent to a pixel indicating a thermal change that constitutes the second difference image P2 to a pixel indicating a thermal change that corresponds to a pixel indicating a thermal change, it does not need to inherit the amount of thermal change from the first difference image P1.

[0062] Furthermore, the final image generation unit 24 of the people passing through the devices 10A and 10B may generate a third difference image by changing a pixel indicating no thermal change adjacent to a pixel indicating a thermal change that constitutes the second difference image P2, if the corresponding pixel in the first difference image P1 is a pixel indicating a thermal change, then generate the final difference image PF by changing a pixel indicating no thermal change adjacent to a pixel indicating a thermal change that constitutes the third difference image, if the corresponding pixel in the first difference image P1 is a pixel indicating a thermal change. As shown in Figure 9(C), the final difference image PF of this modified example can be said to be an extension of the region where the thermal change was 2 or greater by up to 2 pixels, within the range that does not exceed the region where the thermal change was 1 or greater.

[0063] Furthermore, the original difference image P0, the first difference image P1, the second difference image P2, the third difference image, and the final difference image PF generated by the people passing through measuring devices 10A and 10B may consist only of coordinate information of pixels indicating that a thermal change has occurred. For example, the second difference image P2 shown in Figure 6(B) may consist of coordinate information "(4,3),(5,3)", and the final difference image PF shown in Figure 6(C) may consist of coordinate information "(4,2),(5,2),(3,3),(4,3),(5,3),(6,3),(3,4),(4,4),(5,4),(6,4)". It should be noted that something consisting only of coordinate information may no longer be called an "image", but in this specification, such things will also be referred to as "images".

[0064] Furthermore, the number of pixels constituting each difference image P0, P1, and P2 in the first and second embodiments (60 × 45 = 2700 pixels) is merely an example. The first change amount (2°C) and the second change amount (5°C) in the first and second embodiments are also merely examples. However, the second change amount must be greater than the first change amount. [Explanation of symbols]

[0065] 10A, 10B Passing Person Counting Device 11A,11B Thermal image generation section 12 Storage section 13. Settings Section 14 External Interface Section 15 Audio output section 16 Light-emitting part 20A, 20B Control Unit 21 Difference Image Generation Unit 22 First Difference Image Generation Unit 23 Second Difference Image Generation Unit 24 Final difference image generation unit 25 Measurement section 100 ceiling 200 beds P0 Original Image P1 First difference image P2 Second difference image PF Final Difference Image W1, W2 Pedestrians

Claims

1. A passerby counting device that measures the number of people passing through a predetermined detection area, A thermal image generation unit generates a thermal image of the detection area each time time Δt elapses, A difference image generation unit generates a difference image which is the difference between the thermal image generated at time t and the thermal image generated at time t + Δt, A first difference image generation unit generates a first difference image by changing pixels that indicate that the thermal change was less than a preset first change amount among the pixels constituting the original difference image to pixels that indicate that there was no thermal change, A second difference image generation unit generates a second difference image by changing pixels that indicate that the thermal change was less than a preset second amount of change (where the second amount of change > the first amount of change) among the pixels constituting the original difference image to pixels that indicate that there was no thermal change, A final difference image generation unit generates a final difference image from the first difference image and the second difference image, A measurement unit that measures the number of people who have passed through the detection area based on the final difference image, Equipped with, The final difference image generation unit generates the final difference image by changing a pixel that indicates no thermal change adjacent to a pixel that indicates a thermal change in the second difference image, to a pixel that indicates a thermal change if the corresponding pixel in the first difference image is a pixel that indicates a thermal change. A device for measuring the number of people passing through, characterized by the following features.

2. A passerby counting device that measures the number of people passing through a predetermined detection area, A raw image generation unit generates a raw image relating to the thermal changes of the detection area that occurred during a predetermined period of time, A first difference image generation unit generates a first difference image by changing pixels that show a thermal change of less than a preset first change amount among the pixels constituting the original image to pixels that show no thermal change. A second difference image generation unit generates a second difference image by changing pixels that show a thermal change of less than a preset second amount of change (where the second amount of change > the first amount of change) among the pixels constituting the original image to pixels that show no thermal change. A final difference image generation unit generates a final difference image from the first difference image and the second difference image, A measurement unit that measures the number of people who have passed through the detection area based on the final difference image, Equipped with, The final difference image generation unit generates the final difference image by changing a pixel that indicates no thermal change adjacent to a pixel that indicates a thermal change in the second difference image, to a pixel that indicates a thermal change if the corresponding pixel in the first difference image is a pixel that indicates a thermal change. A device for measuring the number of people passing through, characterized by the following features.

3. The final difference image generation unit generates a third difference image by changing a pixel indicating no thermal change adjacent to a pixel indicating a thermal change in the second difference image, if the corresponding pixel in the first difference image is a pixel indicating a thermal change, then generates the final difference image by changing a pixel indicating no thermal change adjacent to a pixel indicating a thermal change in the third difference image, if the corresponding pixel in the first difference image is a pixel indicating a thermal change. A device for measuring the number of people passing through, as described in claim 1 or 2.

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