KR102580362B1 - Method for body temperature by using temperature measuring apparatus with thermal camera - Google Patents

Abstract

According to one embodiment of the present invention, there is a method of measuring body temperature using a body temperature measuring device, comprising: photographing a real or thermal image with a first camera in a standby state for body temperature measurement; Performing non-uniformity correction of the second thermal camera based on whether a subject is detected in the captured image of the first camera; When a subject is detected in an image captured by a first camera, determining whether it is a human face; and measuring the body temperature of the face using a second camera when the subject is a human face.

Description

Method for measuring body temperature by using temperature measuring apparatus with thermal camera}

The present invention relates to a method of measuring body temperature, and more specifically, when measuring body temperature using a thermal camera, by adjusting the timing of execution of non-uniformity correction (NUC) for the thermal camera, body temperature can be measured smoothly without interfering with the operation of the NUC. This is about a method of measuring body temperature that can be performed.

Recently, respiratory infectious diseases such as SARS (Severe Acute Respiratory Syndrome), new flu, MERS, and coronavirus have been occurring frequently, and equipment that measures body temperature using a thermal camera is being developed to detect and track people with symptoms of these infectious diseases. It is widely used.

A conventional method of measuring body temperature using a thermal camera includes installing a thermal camera in a passageway and measuring the body temperature of passengers passing through the passageway to identify people with high fever. In addition, a real camera and a thermal camera are used simultaneously to photograph passersby and the real image and/or thermal image are displayed on the screen to easily display and identify each passerby and their body temperature.

In order to accurately measure body temperature using a thermal camera, it is necessary to output an accurate temperature value corresponding to the amount of infrared light emitted from the measurement object. To this end, non-uniformity correction (NUC) is performed at a certain time period or whenever a certain event occurs. Perform. However, in general, it takes approximately 0.2 to 1 second to correct unevenness with the shutter of the thermal camera lowered. At this time, even if the person (subject) trying to measure body temperature stands in front of the camera, the subject cannot be displayed in real time and the body temperature cannot be measured in real time. There is a problem that the measurement operation is temporarily delayed.

Patent Document 1: Korean Patent Publication No. 10-2018-0123900 (published on November 20, 2018) Patent Document 2: Korean Patent No. 10-1729327 (announced on April 17, 2017)

The purpose of the present invention is to solve the above problems, and to provide a body temperature measurement method that allows smooth body temperature measurement by adjusting the uneven correction timing so that the uneven correction operation of the thermal camera does not interfere with the body temperature measurement operation. do.

According to one embodiment of the present invention, there is a method of measuring body temperature using a body temperature measuring device, comprising: photographing a real or thermal image with a first camera in a standby state for body temperature measurement; Performing non-uniformity correction of the second thermal camera based on whether a subject is detected in the captured image of the first camera; When a subject is detected in an image captured by a first camera, determining whether it is a human face; and measuring the body temperature of the face using a second camera when the subject is a human face.

According to an embodiment of the present invention, a method of measuring body temperature using a body temperature measuring device equipped with a thermal camera and a real-time camera includes the steps of determining whether a subject is a human face when a subject is detected in an image captured by the real-time camera; If the subject is determined to be a human face, determining whether the human face is located within a preset frame of the image captured by the real camera; And when the face is located in a preset frame of the image captured by the real camera, measuring the body temperature of the face using a thermal camera; and when the subject is determined to be a human face, non-uniformity correction of the thermal camera. Disclosed is a method of measuring body temperature using a body temperature measuring device, which further includes the step of executing.

According to one embodiment of the present invention, the NUC of the thermal camera is executed according to a preset time period or event until the subject appears in the image, but when the subject is recognized, the NUC is configured to stop from then until the body temperature measurement is completed. This has the advantage of allowing the NUC to perform body temperature measurement smoothly by preventing it from interfering with the body temperature measurement operation.

In addition, according to an embodiment of the present invention, the NUC of the thermal camera is executed according to a preset time period or event until the subject appears in the image, but when the subject is detected in the image or a face is detected in the subject, non-uniformity correction is performed immediately thereafter. Since the temperature measurement is performed immediately afterward, the NUC not only does not interfere with the temperature measurement operation, but also has the advantage of performing a more accurate temperature measurement because the NUC can be performed immediately before the temperature measurement.

1 is a diagram for explaining a body temperature measuring device according to an embodiment of the present invention;
Figure 2 is a block diagram of a body temperature measuring device according to an embodiment;
Figure 3 is a block diagram of a thermal camera according to one embodiment;
4 is a flowchart of a method for measuring body temperature according to the first embodiment;
Figure 5 is a diagram explaining the operation of the body temperature measuring device according to the movement of the subject;
Figure 6 is a flow chart of the body temperature measurement method according to the second embodiment;
Figure 7 is a flowchart of a method for measuring body temperature according to a third embodiment.

The above objects, other objects, features and advantages of the present invention will be easily understood through the following preferred embodiments related to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure will be thorough and complete and so that the spirit of the invention can be sufficiently conveyed to those skilled in the art.

In this specification, when an element is referred to as being on another element, it means that it may be formed directly on the other element or that a third element may be interposed between them. Similarly, when this specification refers to a component being connected (or coupled, fastened, attached, etc.) to another component, it is either directly connected (or coupled, fastened, attached, etc.) to the other component, or between them. This means that it can be indirectly connected (or combined, fastened, attached, etc.) through a third component. Additionally, the thickness of components in the drawings of this specification are exaggerated for effective explanation of technical content. Additionally, in the drawings of this specification, the length, width, volume, size, or thickness of components are exaggerated for effective explanation of technical content.

In this specification, when terms such as first, second, etc. are used to describe components, these components should not be limited by these terms. These terms are merely used to distinguish one component from another. Embodiments described and illustrated herein also include complementary embodiments thereof.

As used herein, singular forms also include plural forms, unless specifically stated otherwise in the context. The expressions 'including', 'consisting of', and 'consisting of' used in the specification do not exclude the presence or addition of one or more other components in addition to the mentioned components.

In this specification, the term 'software' refers to technology that moves hardware in a computer, and the term 'hardware' refers to the tangible devices or devices that make up a computer (CPU, memory, input device, output device, peripheral device, etc.) , the term 'step' refers to a series of processing or manipulation connected in time series to achieve a predetermined goal, the term 'computer program' or 'program' refers to a set of instructions combined to be processed by a computer, and the term ' ‘Program recording medium’ refers to a computer-readable recording medium that records programs used to install, run, or distribute programs.

Terms such as '~unit', '~module', '~unit', '~block', and '~board' used in this specification to refer to the components of the invention refer to processing at least one function or operation. may mean a physical, functional, or logical unit, which may be implemented as one or more hardware, software, or firmware, or as a combination of one or more hardware, software, and/or firmware.

As used herein, 'processing unit', 'computer', or 'computing device' refers to an operating system such as Windows, Mac, or Linux, a computer processor, memory, applications, storage devices (e.g., HDD, SDD), and It can be implemented as a device equipped with a monitor. The computer may be, for example, a desktop computer or a laptop, but these are examples and the present invention is not limited to the desktop computer or laptop. The mobile terminal may be one of mobile wireless communication devices such as a smartphone, tablet PC, or PDA.

The present invention will be described in detail below with reference to the drawings. In describing the specific embodiments below, various specific details have been written to explain the invention in more detail and to aid understanding. However, a reader with sufficient knowledge in the field to understand the present invention can recognize that it can be used without these various specific details. In some cases, it is mentioned in advance that parts that are commonly known but are not significantly related to the invention are not described in order to prevent confusion in describing the invention.

Figure 1 schematically shows a body temperature measuring device 100 according to an embodiment of the present invention. Referring to Figure 1, the body temperature measuring device 100 according to one embodiment is a device that can measure and display a person's body temperature and includes a camera module 10 installed on a support 40 at a predetermined height, an image processing device ( 20), and a display 30.

In one embodiment, the camera module 10 includes a real camera 11 and a thermal camera 12. In an alternative embodiment, camera module 10 may include only a thermal camera. The real camera 11 is a camera that generates image data by capturing images in the visible light range of the subject, and the thermal camera 12 detects infrared rays naturally emitted from the subject and converts the amount of infrared rays into heat to determine the temperature of the subject. It is a camera that generates data. In the drawing, both the real camera 11 and the thermal camera 12 are shown as being provided in the camera module 10, but the real camera 11 and the thermal camera 12 may be installed independently.

The image processing device 20 processes image data captured by the camera module 10. For example, the image processing device 20 performs preprocessing (e.g., noise removal, filtering, synchronization, registration, etc.) on the real image and/or thermal image received from the camera module 10 and performs one or more of the real image or thermal image. Image processing such as detecting the face of a subject (S) and overlapping temperature information for each subject (S) with a real or thermal image may be performed, and the processed real image data, thermal data, and/or real image may be performed. Synthetic data of overheating can be output to the display 30.

The display 30 is a device that displays image data processed by the image processing device 20 to the user, and may be implemented as any image output device, such as an LCD display or an LED display. In one embodiment, the image processing device 20 may output real images and thermal images to the display 30 in various ways. In the illustrated embodiment, a part of the subject, including the face, can be displayed as a real image through the display 30, and body temperature information (for example, body temperature displayed as a number and phrases such as “normal body temperature”) can be displayed in a predetermined area of the screen. there is. Additionally, in an alternative embodiment, when the image processing device 20 performs facial recognition of the face, it may additionally display whether the subject S is an insider belonging to a predetermined group or an unregistered outsider. Also, at this time, a preset frame 35 area may be displayed on the screen of the display 30, and the face of a person standing in front of the camera module 10 to measure body temperature can be guided to be located within this frame 35. there is. That is, in this case, it can be configured to perform body temperature measurement and face recognition operations when the subject's face is located within this frame 35.

In an alternative embodiment, only one of the real image or the thermal image may be output to the display 30, or a composite image in which the real image and the thermal image overlap each other may be output, for example, PIP (Picture Image). Like the -In-Picture) function, the screen can be divided and real images and thermal images can be output in parallel.

Meanwhile, the image captured with a thermal camera above is referred to as a 'thermal image', but in this specification, it is also called a 'thermal image', 'thermal image', or 'infrared image' with the same meaning. Additionally, in this specification, 'image data' is simply called 'video' or 'image'. In addition, in this specification, 'subject' is an object that is subject to photography by the cameras 11 and 12, and is not limited to people but is used as a concept to include any object photographed by the cameras 11 and 12. In other words, the subject may be a person positioned in front of the cameras 11 and 12 to measure body temperature, but while the cameras 11 and 12 are taking pictures in a standby state for body temperature measurement, any object (such as an object or It could also be a person passing by, etc.)

Figure 2 is a block diagram of a body temperature measuring device 100 according to an embodiment. In FIG. 2, the camera module 10, the image processing device 20, and the display 30 correspond to the camera module 10, the image processing device 20, and the display 30 in FIG. 1, respectively.

The camera module 10 may include a real camera 11 and a thermal camera 12. The real camera 11 can generate image data by capturing an image of the subject S in the visible light region. In one embodiment, the real camera 11 is implemented with hardware and/or software, such as a lens, a CCD, and an analog-to-digital (A/D) converter. The light coming through the lens is converted into an electrical signal by the CCD, and this signal is converted into image data, a digital signal, by the A/D converter. Since the configuration and operation of the real camera 11 are known technologies, detailed description will be omitted below.

The thermal camera 12 can detect infrared rays naturally emitted from the subject S and convert the amount of infrared rays into heat to generate temperature data of the subject. In one embodiment, the thermal camera 12 includes an infrared lens that passes infrared rays, a detector (detection element array) that detects infrared rays incident on the infrared lens and converts them into electrical signals, and a device that converts the electrical signals into temperature data, which is a digital signal. It may include an analog-to-digital (A/D) converter, etc. The specific configuration of the thermal camera 12 will be described later with reference to FIG. 3. In addition, the thermal camera 12 can additionally perform temperature correction, non-uniformity correction (NUC), dead pixel processing, etc. on the temperature data converted from the A/D converter.

Real images and thermal images generated by the real camera 11 and the thermal camera 12 of the camera module 10 are transmitted to the image processing device 20 and processed. In one embodiment, the image processing device 20 may include an image processing unit 21, a face detection unit 22, and a temperature correction unit 23.

The image processing unit 21 performs image processing operations such as noise removal, filtering, synchronization, image registration and synthesis on the real image and/or thermal image received from the camera module 10, and includes the following functions, for example: It may include one or more of the following.

(1) Noise removal and image improvement: The image processing unit 21 may perform processing for image improvement, such as image quality improvement and contrast improvement of real images and/or thermal images. For example, the image processing unit 21 may remove noise or unevenness by performing processes such as low-pass filtering, image blurring, and image smoothing.

Additionally, the image processing unit 21 can also perform high-pass filtering on the image. For example, high-pass filtering can be performed on a real image using a spatial filter to extract high spatial frequency components of the real image (i.e., the outline or borderline portion of the subject). As another method of extracting high spatial frequency components from an image, the image processing unit 21 may use a method of extracting the difference between two temporally consecutive images. That is, by obtaining the difference between the image at the first time and the image at the second time in the continuous image sequence, high spatial frequency components representing the edge or outline of the subject can be extracted.

(2) Image synchronization: The image processing unit 21 temporally synchronizes the real images and thermal images taken at the same time by the real image camera 11 and the thermal camera 12, respectively, so that the real image and thermal image corresponding to the same time can be obtained. In general, the real image camera 11 and the thermal image camera 12 have different image capture speeds due to differences in hardware/software such as CCD, detection element array, and A/D converter, so it is necessary to obtain real images and thermal images at the same time. Synchronization of the output of the camera 11 and the thermal camera 12 may be necessary.

(3) Image registration: The image processing unit 21 can match the real image and the thermal image so that the real image camera 11 and the thermal image camera 12 photograph the same subject at the same viewing angle and output the image in the same size. Additionally, in order to match the real image and the thermal image, the image processing unit 21 may change the resolution of one of the two images to have the same resolution.

(4) Color thermal image conversion: The image processing unit 21 can convert each pixel of the thermal image into a color according to the temperature data of the corresponding pixel and output it. In other words, the temperature data of each pixel is converted into a color matched according to the temperature band to generate colored thermal image data. For example, the image processing unit 21 generates a color thermal image by applying RGB values matched to each temperature value of the temperature data of each pixel. Accordingly, for example, a color thermal image can be generated in which high temperatures are displayed in red and low temperatures are displayed in blue.

Additionally, the image processing unit 21 can detect the temperature of a specific pixel and perform application processing accordingly. For example, a pixel with the highest temperature among all pixels can be detected, or pixels with a temperature within a preset temperature range can be detected.

(5) Image synthesis: The image processing unit 21 can generate one composite image by combining real and thermal images taken by the real camera 11 and the thermal camera 12 for the same subject. For image synthesis, the above-described image synchronization and matching processing may first be performed, and then, for example, a composite image may be generated by overlapping part or all of the thermal image with the real image. Alternatively, a composite image can be created by overlapping information indicating the temperature of a specific pixel or specific pixel area on a real image or thermal image.

In the image processing device 20, the face detection unit 22 may detect a face area of a subject in a real image and/or a thermal image and calculate detection area information including coordinates of the detected face area. In one embodiment, the face detection unit 22 may detect a face using predefined facial features. For example, a face can be detected using the size, shape, and correlation of facial feature components (e.g., eyes, nose, mouth, outline, brightness, etc.), and facial color and texture information. Alternatively, the face detection unit 22 may use not only facial feature points but also non-face feature points. For example, in response to a case where the subject is wearing a hat, sunglasses, or a mask, specific points about various types and sizes of hats, sunglasses, and masks can be defined in advance and used. Additionally, to first detect a person in an image and then detect the face area, feature points on the entire human body or upper body (for example, each joint and skeleton of the human body, etc.) can be used. The face detection unit 22 can detect faces from thermal and/or real images using various known methods and algorithms in addition to the above-described face detection method using feature points.

In one embodiment, the face detection unit 22 may be configured to first detect whether a subject exists in an image captured by the real camera 11 and/or the thermal camera 12, and to detect a face if the subject exists. That is, when a random subject begins to appear within the camera's viewing angle, the face detection unit 22 first determines whether the subject exists, and when it determines that the subject exists, it can determine whether the subject is a face through a face detection operation. . At this time, when detecting the presence of a subject, the 'subject' does not necessarily have to be a person, but may be any object moving within the viewing angle of the cameras 11 and 12.

The temperature correction unit 23 is a functional unit that corrects the thermal camera so that the temperature value of the subject photographed and output by the thermal camera 12 matches the actual temperature of the subject. In one embodiment, the temperature correction unit 23 performs corrections such as temperature correction and non-uniformity correction (NUC) so that the output value of each pixel of the detector (detection element array) of the thermal camera 12 represents the accurate temperature of the subject. can do.

In one embodiment, the image processing unit 21, face detection unit 22, and temperature correction unit 23, which are each functional unit of the image processing device 20 described above, include software programmed to perform the corresponding function and support it as necessary. It may be composed of hardware that In addition, these functional units 21, 22, and 23 may each be implemented as independent software or may be implemented as one integrated software, and at least some of these functional units may be implemented in any processing device outside the image processing device 20. It can also be installed and run.

Figure 3 is a block diagram of the thermal camera 12 according to one embodiment. In one embodiment, the thermal camera 12 may include an infrared lens 121, a shutter 122, a detector 123, and an analog-to-digital converter (ADC) 124. The infrared lens 121 is a lens that passes infrared rays, and the shutter 122 blocks light coming in from the outside as needed, such as performing temperature correction or non-uniformity correction (NUC). In one embodiment, the shutter 122 is used to block infrared rays incident on the detector 123 when performing non-uniformity correction (NUC) of temperature data. Therefore, if non-uniformity correction is performed in a shutterless manner, the shutter 123 may not be needed.

The detector 123 is a detection element array that detects infrared rays that have passed through the lens 121 and converts them into electrical signals. For example, it has a focal plane array (FPA) structure composed of a two-dimensional array of multiple pixels. It may have a structure, but is not limited to this structure. The ADC 124 is a converter that converts an electrical signal into a digital signal, and converts the electrical signal, which is an analog signal generated by the detector 123, into a digital signal. The digital signal converted in this way is transmitted to the image processing device 20 and processed as an image in the image processing device 20.

For example, the temperature correction unit 23 of the image processing device 20 performs correction processing such as non-uniformity correction (NUC), temperature correction, and/or dead pixel processing on the detector signal received from the thermal camera 12. And the detector signal can be converted into temperature data.

In one embodiment, non-uniformity correction (NUC) corrects all detection elements of the detector of the thermal camera 12 so that they can produce the same output under the same conditions. Even when all detection elements in the detection element array receive the same infrared rays, they inherently exhibit slightly different outputs due to differences in the sensitivity of each detection element, resulting in spatial non-uniformity in the thermal image. In order to correct the non-uniformity between these pixels, a correction table is prepared in advance to correct the output value for each pixel in order to output with uniform sensitivity in all pixels, and the correction value of the correction table is applied to each pixel of the thermal image. By printing, unevenness is eliminated.

However, since these response characteristics of the detection element change over time due to various factors such as temperature drift, non-uniformity correction (NUC) is performed every predetermined period or when non-uniformity (noise) accumulates above a certain amount. For example, in the case of a shutter-type NUC, the shutter 122 is lowered and the shutter 122 is photographed in a state in which the inflow of external light is blocked. Since the shutter 122 can be assumed to be an object with a constant temperature, the gain and/or offset for each detection element in the correction table is corrected and updated so that the output values of the detection elements that photograph the shutter 122 are all the same. Non-uniformity correction (NUC) can be completed.

However, even if non-uniformity correction is performed in this way, the temperature of the subject is often not accurately measured due to various factors such as the external or internal temperature of the thermal camera, the infrared emissivity of the subject, and atmospheric conditions. In one embodiment, temperature correction is performed in this way. Temperature errors due to at least some of several factors are corrected so that the thermal camera 12 can output the accurate temperature of the subject.

In the art, various methods for non-uniformity correction (NUC) and temperature correction, which correct only the offset of the correction table or correct the gain and offset, are known, so detailed descriptions will be omitted in this specification. Additionally, when performing non-uniformity correction or temperature correction in the body temperature measurement method of the present invention, any of these known non-uniformity correction and/or temperature correction methods may be used, and the scope of the present invention is not limited or restricted to any specific correction method. You will understand that it is not.

The image processing unit 21 of the image processing device 20 may receive temperature data corrected by the temperature correction unit 23 and convert it into thermal image (or “thermal image” or “thermal image”) data. For example, temperature data that has been temperature-corrected, non-uniformity-corrected, and/or dead-pixel-processed is converted into colors matched to each temperature band to generate thermal image data. For example, a thermal image is generated by applying RGB values matched to each temperature value of the temperature data, thereby generating a color thermal image that displays high temperatures in red and low temperatures in blue, or displays high temperatures in blue. It can produce black-and-white thermal images that display close to white and low temperatures appear close to black.

Meanwhile, conventional thermal cameras are generally set to perform non-uniformity correction using a shutter at predetermined intervals or when a certain amount of noise accumulates. However, when a thermal camera is used to measure body temperature, the non-uniformity correction occurs when the person whose body temperature is to be measured stands in front of the camera. When calibration is performed, the temperature measurement operation is delayed, causing user inconvenience. Therefore, by default, it is set to perform uneven correction when a certain event occurs, such as a preset cycle or noise exceeding the threshold, but when the person (subject) whose body temperature is to be measured is located in front of the camera, the uneven correction is temporarily stopped by detecting the subject. It may be desirable to configure it to stop (or delay) or perform non-uniformity correction at a specific time after detecting the subject.

Hereinafter, various embodiments of stopping the non-uniform correction of the thermal camera or executing it at a specific time based on the detection of the subject will be described with reference to FIGS. 4 to 7.

Figure 4 is a flowchart of a method for measuring body temperature according to the first embodiment, and Figure 5 is a diagram for explaining the operation of the body temperature measuring device according to the movement of the subject. In one embodiment, it is assumed that the body temperature measuring device 100 is installed at the entrance of a building or a passageway through which people pass. First, in step S110, the camera is in a standby state. That is, at this stage, the real camera 11 and the thermal camera 12 are turned on and shooting toward the front. For example, the image captured by either the real camera 11 or the thermal camera 12 is displayed on the display 30. It may continue to be displayed.

In this state, the image processing device 20 performs non-uniformity correction (NUC) of the thermal camera 12 based on whether the subject moves in the captured image of either the real camera 11 or the thermal camera 12. (S115). In the illustrated embodiment, when there is no change in the captured image of the real camera 11, that is, while the subject does not appear within the viewing angle of the camera, the image processing device 20 performs the NUC at every preset time period or whenever a preset event occurs. You can run . For example, the preset time period may be preset to a predetermined time such as 1 minute, 3 minutes, or 5 minutes, and the preset event may occur when the noise of the image exceeds a predetermined range (e.g., inside or outside the body temperature measuring device 100). (when a temperature sensor is installed) may include events such as when the temperature change inside or outside the thermal camera 12 is more than a predetermined range.

When a person (subject) approaches the body temperature measuring device 100 to measure body temperature, the image processing device 20 detects the subject (S120). In this regard, Figure 5 schematically shows the movement of the subject S in front of the body temperature measuring device 100, in which the subject S is photographed by the real camera 11 of the camera module 10 and displayed on the display 30. Indicates real-time output status. When the subject S whose body temperature is to be measured approaches the body temperature measuring device 100, a portion of the subject S that falls within the viewing angle of the real camera 11 is photographed and displayed on the display 30, as shown in FIG. 5(a). displayed in At this time, the image processing device 20 can recognize and detect the existence of the subject in the image captured by the real camera 11.

As an example of a method for detecting a subject in an image (i.e., recognizing its presence), the amount of pixel change is calculated by comparing the current image frame with the image frame just before a predetermined time in an image captured in real time by the real camera 11. A first step, a second step of repeating the first step for a predetermined time, and a third step of determining that the subject has been detected when the amount of pixel change calculated while repeating the second step gradually increases is performed to detect the subject. Existence can be determined. That is, as the subject S gradually enters the viewing angle of the camera 11, the pixel occupied by the subject S in the image increases, and the amount of pixel change increases. Based on this, it is possible to determine whether the subject exists. In addition, of course, the step of recognizing a subject in an image can be performed according to other methods known in the image processing field.

In this way, if the subject S is detected in step S120, the image processing device 20 temporarily stops non-uniformity correction for the thermal camera 12. That is, the image processing device 200 is initially set to execute the NUC at every preset time period or whenever a preset event occurs, but when the subject S is detected in step S120, the NUC is executed for a predetermined time or until the event occurs. For example, the NUC can be controlled not to run until the body temperature measurement step (S150) is completed. That is, the NUC is not running until the body temperature of the subject (S) is measured using the thermal camera 12. Do not run it, and after measuring the body temperature, run the NUC again at a preset time period or when a preset event occurs.

When the subject S is detected in step S120, it is determined whether the subject S is a human face, and if it is a human face, it is determined whether the face is located within the preset frame area 35 on the display 30 ( S130). For example, as shown in FIG. 5(b), when the face area is within the display 30 enough to detect the face of the subject S, the image processing device 20 detects a human face in the image of the subject S. can be detected. Since known face detection technologies can be used to detect faces, detailed descriptions are omitted. In addition, in step S130, for face recognition and accurate measurement of body temperature, it is determined whether the face is located within the frame 35 of the screen, and if the face is not accurately located within the frame 35, for example, a guidance message is transmitted to the speaker or the display 30 is displayed. You can induce the movement of the subject (S) by displaying it on the screen.

Then, as shown in FIG. 5(c), when the face of the subject S enters the frame 35 of the display 30, the image processing device 20 recognizes the face from this image (S140) and measures the body temperature. After measuring, the results can be displayed (S150). Face recognition (S140) is a step to identify the detected face and can use known face recognition technology. If the body temperature measurement device 100 is installed, for example, at the entrance to a company building, this face recognition step (S140) can be performed. However, if it is installed in a passageway where unspecified people pass by, the face recognition step (S140) can be omitted.

Body temperature measurement is performed using a thermal camera (12). For example, the temperature of a predetermined location on the face (for example, between the eyebrows or the forehead, etc.) can be measured from a thermal image captured by the thermal camera 12 and output as body temperature.

According to the first embodiment described above, the NUC of the thermal camera 12 is executed according to a preset time period or event until the subject appears in the image, but when the subject is recognized, from then until the body temperature measurement is completed. The NUC is configured to stop, and as a result, the NUC does not interfere with the body temperature measurement operation, so body temperature measurement can be performed smoothly.

Meanwhile, in the illustrated embodiment, it is assumed that real images captured by the real camera 11 are used for subject detection (S120), face detection (S130), and face recognition (S140). However, in an alternative embodiment, subject detection At least one of (S120), face detection (S130), and face recognition (S140) may be performed using a thermal image captured by the thermal camera 12.

Figure 6 is a flowchart of a method for measuring body temperature according to a second embodiment. Compared to the first embodiment of FIG. 4, the second embodiment of FIG. 6 differs in that the non-uniformity correction (NUC) step (S215) is performed after detecting the subject (S120), and the remaining steps are the same. Or, since they are similar, the same member numbers were used.

First, in step S110, the camera is in a standby state. At this stage, the real camera 11 and the thermal camera 12 are turned on and are taking pictures of the front. While this step (S110) continues, the image processing device 20 may perform non-uniformity correction on the thermal camera at a preset time period or whenever a preset event occurs.

Afterwards, when the subject S approaches the body temperature measuring device 100 to measure body temperature and appears in the image of the real camera 11 as shown in FIG. 5(a), the image processing device 20 detects the subject ( S120). In this way, when the subject S is detected in step S120, the image processing device 20 performs non-uniformity correction for the thermal camera 12 (S125) and immediately thereafter until the end of the body temperature measurement step (S150). Stop uneven correction until. That is, the unevenness correction is performed once as soon as the subject is detected, and after that, the unevenness correction is not performed even if the preset time period or a certain event occurs.

Also preferably, at the same time as executing the step (S125) of performing non-uniformity correction in the temperature correction unit 23 of the image processing device 20, the image processing unit 21 and the face detection unit ( In 22), a step (S130) of detecting a face and determining whether the detected face is located within the frame 35 may be performed. In this step (S130), if the face is not exactly located within the frame 35 as shown in FIG. 5(b), a guidance message may be output to a speaker or display screen to induce movement of the subject S.

Then, as shown in FIG. 5(c), when the face of the subject S enters the frame 35 of the display 30, the image processing device 20 recognizes the face from this image (S140) and measures the body temperature. After measuring, the results can be displayed (S150). And when the body temperature measurement is completed in step S150, the image processing device 20 may perform non-uniformity correction again for the thermal camera 12 at a preset time period or whenever a preset event occurs.

According to the second embodiment described above, the NUC of the thermal camera 12 is executed according to a preset time period or event until the subject appears in the image, but when the subject is recognized, non-uniformity correction is performed immediately thereafter and body temperature measurement is completed from then on. The NUC is configured to stop until

Figure 7 is a flowchart of a method for measuring body temperature according to a third embodiment. Compared to the first embodiment of FIG. 4, the third embodiment of FIG. 7 is different in that the non-uniformity correction (NUC) step (S315) is performed after detecting the face in the subject (S130), and the remaining steps are Since they are the same or similar, the same member numbers were used.

In step S110, the camera is in a standby state. At this stage, the real camera 11 and the thermal camera 12 are turned on and are taking pictures of the front. While this step (S110) continues, the image processing device 20 may perform non-uniformity correction on the thermal camera at a preset time period or whenever a preset event occurs.

Afterwards, when the subject S approaches the body temperature measuring device 100 to measure body temperature and appears in the image of the real camera 11 as shown in FIG. 5(a), the image processing device 20 detects the subject ( S120). When the subject S is detected, a step S130 of detecting a face by the image processing unit 21 and the face detection unit 22 of the image processing device 20 and determining whether the detected face is located within the frame 35 is performed (S130). You can. In this step (S130), if the face is not exactly located within the frame 35 as shown in FIG. 5(b), a guidance message may be output to a speaker or display screen to induce movement of the subject S.

Thereafter, as shown in FIG. 5(c), when the face of the subject S enters the frame 35 of the display 30, the image processing device 20 may perform a face recognition step (S140). At this time, in the third embodiment of the present invention, the non-uniformity correction step (S135) may be performed simultaneously with the face recognition step (S140) or at least partially overlapped in time. At this time, the face recognition step (S140) is performed in the image processing unit 21 and/or the face detection unit 22 based on the real image, and the uneven correction step (S135) is performed in the temperature correction unit 23, so there are two steps (S135) ,S140) can be performed simultaneously, and uneven correction can be performed immediately before body temperature measurement (S150), which has the advantage of allowing more accurate body temperature measurement. Additionally, if there is no face recognition step (S140), the unevenness correction step (S135) can be performed immediately after the face is detected in step (S130). In this case, the unevenness correction step (S135) is performed when the face is not in the frame (35). It may be executed at the same time as performing the operation of determining the location and sending a guidance message to the subject (i.e., S130).

According to the third embodiment described above, the NUC of the thermal camera 12 is executed according to a preset time period or event until the subject appears in the image, but when a face is detected in the subject, non-uniformity correction is performed immediately thereafter and body temperature is measured immediately thereafter. Because it is running, NUC not only does not interfere with the temperature measurement operation, but also allows NUC to be performed right before body temperature measurement, allowing for more accurate body temperature measurement.

As described above, those of ordinary skill in the field to which the present invention pertains can understand that various modifications and variations are possible from the description of this specification. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the claims and equivalents thereof as well as the claims described later.

10: camera module 11: real camera
12: thermal camera 20: image processing device
30: Display 40: Temperature calibrator
41: case 42: infrared emitter
100: Body temperature measuring device 111: Lens
112: shutter 113: detector
114: ADC

Claims (7)

A method of measuring body temperature using a body temperature measuring device equipped with a thermal camera and a real image camera,
Performing non-uniformity correction of the thermal camera according to a preset time period;
When a subject is detected in an image captured by a real camera, stopping non-uniformity correction according to the time period and determining whether the subject is a human face;
If the subject is determined to be a human face, determining whether the human face is located within a preset frame of the image captured by the real camera;
Simultaneously with the step of determining whether a human face is located within the preset frame, performing non-uniformity correction of the thermal camera; and
When a person's face is located in the preset frame, measuring the body temperature of the face using a thermal camera,
Body temperature measurement by a body temperature measuring device, characterized in that it is configured to not perform unevenness correction according to the time period while performing the step of measuring facial body temperature and to resume unevenness correction according to the time period after facial body temperature measurement is completed. method. According to claim 1,
After the step of measuring the facial body temperature, the method further includes outputting body temperature information and whether or not the body temperature is normal to a display based on the measured body temperature. delete The method of claim 1, wherein when a subject is detected in an image captured by a real camera, the step of determining whether it is a human face comprises:
A first step of comparing the current image frame of a real-time camera with the image frame just before a predetermined time and calculating the amount of pixel change,
a second step of repeating the first step for a predetermined time, and
If the amount of pixel change calculated while repeating the second step gradually increases, a third step is performed to determine that the subject has been detected, thereby further comprising a third step of detecting the subject in the image captured by the real camera. , Method of measuring body temperature using a body temperature measuring device.
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