Tof camera capable of automatic exposure

Abstract

The application provides a TOF camera capable of automatic exposure, comprising the following modules: a light projector for projecting infrared light to a target; an infrared camera for receiving the infrared light reflected by the target to generate an infrared image; a processor module for calculating a first exposure index according to the proportion of pixel values in each infrared image exceeding a preset first pixel value threshold, calculating a second exposure index according to the mean value of the amplitude value of each infrared image, and judging the exposure state of each infrared image according to the first exposure index, the upper limit pixel threshold corresponding to the first exposure index, the lower limit pixel threshold, the second exposure index and the amplitude threshold corresponding to the second exposure index, and adjusting the exposure time of the TOF camera according to the exposure state. The application can quickly adjust the exposure time to a suitable range, prevent overexposure and underexposure of the picture, and improve the accuracy of the depth map and the working distance range.

Description

TECHNICAL FIELD

[0001] The present application relates to a depth camera, in particular to a TOF camera capable of automatic exposure. BACKGROUND

[0002] A time of flight (TOF) depth camera calculates the distance by emitting a floodlight beam of a specific wave band, receiving the reflected light beam of the object in the measured space by a sensor and measuring the flight time of the light beam in the space, thereby obtaining the depth image of the measured space. The TOF depth camera can obtain the gray scale image and the depth image simultaneously, and is widely applied in the technical fields of 3D depth vision related gesture recognition, face recognition, 3D modeling, body sensing game, machine vision, auxiliary focusing, security, automatic driving and the like.

[0003] The TOF camera as a device capable of outputting a depth map has also been widely studied. The principle of the TOF camera is to calculate the distance of the photographed object from the camera by calculating the phase difference between the emitted infrared light and the received infrared light. In order to improve the accuracy, four different phase sine waves are usually used to correlate with the received light, and then the depth value is calculated. The correlation operation is essentially an integral operation in the circuit, and the integral time is called the exposure time.

[0004] Most of the TOF cameras on the market do not have the function of automatic exposure, so that when the environmental light is abnormally strong or close-range imaging, a large range of overexposure occurs in the picture, causing abnormal depth; and when long-distance imaging, the picture is underexposed, resulting in a serious decrease in signal-to-noise ratio, and even the depth value is directly missing. SUMMARY

[0005] In view of the defects in the prior art, the present application aims to provide a TOF camera capable of automatic exposure.

[0006] The TOF camera capable of automatic exposure provided by the present application comprises the following steps:

[0007] The TOF camera capable of automatic exposure provided by the present application comprises the following modules:

[0008] A light projector for projecting infrared light to a target;

[0009] An infrared camera for receiving infrared light reflected by the target to generate an infrared image;

[0010] a processor module configured to calculate a first exposure indicator according to a proportion of pixel values in each of the infrared images exceeding a pre-set first pixel value threshold, calculate a second exposure indicator according to a mean value of amplitude values of each of the infrared images, and determine an exposure state of each of the infrared images according to the first exposure indicator, an upper limit pixel threshold corresponding to the first exposure indicator, a lower limit pixel threshold, the second exposure indicator, and an amplitude threshold corresponding to the second exposure indicator, and adjust an exposure time of the TOF camera according to the exposure state.

[0011] Preferably, the processor module calculating the first exposure indicator comprises the following steps:

[0012] Step M1: obtaining a pixel value of each pixel in each of the infrared images;

[0013] Step M2: determining whether the pixel value of each pixel exceeds a pre-set first pixel value threshold to determine a number of overexposed pixels in each of the infrared images;

[0014] Step M3: obtaining a total number of pixels in each of the infrared images, and generating the first exposure indicator according to the number of overexposed pixels and the total number of pixels.

[0015] Preferably, the processor module calculating the second exposure indicator comprises the following steps:

[0016] Step N1: obtaining an amplitude value of each pixel in each of the infrared images;

[0017] Step N2: accumulating the amplitude values of the pixels in the infrared images to generate an amplitude value sum;

[0018] Step N3: obtaining a total number of pixels in each of the infrared images, and generating the second exposure indicator according to the amplitude value sum and the total number of pixels.

[0019] Preferably, determining the exposure state of the infrared images and adjusting the exposure time of the TOF camera according to the exposure state comprises the following steps:

[0020] Step S1: obtaining a pre-set upper limit pixel threshold and a lower limit pixel threshold;

[0021] Step S2: determining that the infrared image is overexposed when the first exposure indicator is greater than the upper limit pixel threshold, and determining that the infrared image is underexposed when the first exposure indicator is less than the lower limit pixel threshold and the second exposure indicator is less than the amplitude threshold;

[0022] Step S3: decreasing the exposure time of the infrared image in the next frame when the infrared image is overexposed, and increasing the exposure time when the infrared image is underexposed.

[0023] Preferably, in step S3, the exposure time t" of the next frame of the infrared image is determined according to the following formula: int

[0024]

[0025] wherein w is 0.9, t is the exposure time of the current frame, th2 is the upper pixel threshold, OEI2 is the first exposure index, and OEI2 is the second exposure index. int Δt1 is the exposure variation time when overexposure occurs, and Δt2 is the exposure variation time when underexposure occurs.

[0026] Δt1 = -OEI2 / k2

[0027] wherein k2 is the slope of the straight line fitted by the first exposure index OEI2 and Δt1, and k2 is calculated in advance.

[0028]

[0029] wherein k1 is the slope of the straight line fitted by the second exposure index and Δt2, and k1 is calculated in advance.

[0030] Preferably, the first exposure index is generated according to the proportion of the pixel values of the ROI region in each infrared image exceeding a pre-set first pixel threshold.

[0031] The second exposure index is generated according to the average value of the amplitude values of the ROI region in each infrared image.

[0032] Preferably, the infrared camera comprises a lens, a filter and an image sensor arranged along an optical path, and the image sensor is provided with at least four receiving windows.

[0033] The image sensor is configured to receive optical signals of at least four infrared lights through the at least four receiving windows, and the at least four receiving windows are sequentially arranged in time sequence, and each infrared image is generated according to the optical signals received by each receiving window.

[0034] Preferably, the upper pixel threshold is set to 0.04, the lower pixel threshold is set to 0.001, and the amplitude threshold is set to 255.

[0035] Preferably, the light detector can be a CMOS light sensor, a CCD light sensor or a SPAD light sensor.

[0036] The TOF camera capable of automatic exposure provided by the present application comprises the following steps:

[0037] The light projector is configured to project infrared light to the target.​​

[0038] an infrared camera for receiving infrared light reflected by the target to generate an infrared image;

[0039] a processor module for calculating a first exposure index according to pixel values in each of the infrared images, calculating a second exposure index according to amplitude values of each of the infrared images, judging an exposure state of each of the infrared images according to the first exposure index, a first upper limit pixel threshold corresponding to the first exposure index, a first lower limit pixel threshold, the second exposure index and a second amplitude threshold corresponding to the second exposure index, and adjusting an exposure time of the TOF camera according to the exposure state.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] In the present application, an exposure index is generated according to the average of pixel values and amplitude values in each of the infrared images, the exposure state is determined according to the exposure index, and the exposure time of the TOF camera is adjusted according to the exposure state, which can quickly adjust the exposure time to a suitable range, prevent overexposure and underexposure of the picture, and improve the accuracy of the depth map and the working distance range.

[0042] In the present application, the ROI region can be determined in the infrared image, and an exposure index is generated according to the average of pixel values and amplitude values of the ROI region, which can improve the accuracy of the ROI region of the depth map. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on the provided drawings. Other features, objects and advantages of the present application will become more apparent through reading the following detailed description of the non-limiting embodiments with reference to the following drawings:

[0044] Figure 1 A module schematic diagram of the TOF camera capable of automatic exposure in the embodiments of the present application;

[0045] Figure 2 A step flowchart for generating the first exposure index in the embodiments of the present application;

[0046] Figure 3 A step flowchart for generating the second exposure index in the embodiments of the present application;

[0047] Figure 4 A step flowchart for adjusting the exposure time according to the exposure state in the embodiments of the present application;

[0048] Figure 5 Module diagram of the light projector in the embodiment of the present application;

[0049] Figure 6 Module diagram of the infrared camera in the embodiment of the present application;

[0050] Figure 7 (a), (b), (c) are schematic diagrams of non-periodic arrangement of dot matrix light in the embodiment of the present application. DETAILED DESCRIPTION

[0051] The present application will be described in detail below with specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be pointed out that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made. These are within the scope of the present application.

[0052] The terms "first", "second", "third", "fourth" and the like in the description, claims, and drawings of the present application, and the above-mentioned drawings (if any) are used to distinguish like objects, and do not necessarily have to describe a particular order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein, for example, can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0053] The technical solutions of the present application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in some embodiments.

[0054] The TOF camera capable of automatic exposure provided by the present application aims to solve the problems existing in the prior art.

[0055] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in some embodiments. The embodiments of the present application will be described below with reference to the drawings.

[0056] Figure 1 Module diagram of the TOF camera capable of automatic exposure in the embodiment of the present application, such asFigure 1 As shown in the figure, the method comprises the following modules:

[0057] an optical projector configured to project infrared light towards a target;

[0058] an infrared camera configured to receive the infrared light reflected by the target and generate an infrared image;

[0059] a processor module configured to calculate a first exposure index according to a proportion of pixel values in each of the infrared images exceeding a preset first pixel value threshold, calculate a second exposure index according to a mean value of amplitude values of each of the infrared images, determine an exposure state of each of the infrared images according to the first exposure index, an upper limit pixel threshold corresponding to the first exposure index, a lower limit pixel threshold, the second exposure index, and an amplitude threshold corresponding to the second exposure index, and adjust an exposure time of the TOF camera according to the exposure state.

[0060] In the embodiment of the present application, the infrared camera comprises an infrared detector, and the infrared detector is configured to receive the infrared light reflected by the target. The infrared light can be infrared flood light or dot array light.

[0061] The infrared image can be an infrared speckle image or an infrared flood light image.

[0062] The infrared image is collected when the distance between the TOF camera and the target person is 30-300 cm.

[0063] The TOF camera is a 4-phase TOF camera, and four pairs of infrared speckle images are obtained through four exposures, and then a depth map is obtained through calculation.

[0064] Figure 2 The first exposure index is generated in the embodiment of the present application, and the flow chart of the step is as shown in the figure Figure 2 The processor module calculates the first exposure index, which comprises the following steps:

[0065] Step M1: obtaining a pixel value of each pixel in each of the infrared images;

[0066] Step M2: determining whether the pixel value of each pixel exceeds a preset first pixel value threshold to determine the number of overexposed pixels in each of the infrared images;

[0067] Step M3: obtaining a total number of pixels in each of the infrared images, and generating the first exposure index according to the number of overexposed pixels and the total number of pixels.

[0068] In the embodiment of the present application, the first exposure index can be set as a ratio of the number of overexposed pixels to the total number of pixels.

[0069] In the embodiment of the present application, the first pixel value is represented by 11-bit binary number in the range of 0 to 1024, thus the first pixel value threshold can be set as 1023.

[0070] Figure 3 The flow chart of the step of generating the second exposure index in the embodiment of the present application is shown in FIG. 4, wherein the processor module calculating the second exposure index comprises the following steps: Figure 3

[0071] Step N1: obtaining the amplitude value of each pixel in each of the infrared images;

[0072] Step N2: accumulating the amplitude values of the pixels in the infrared images to generate an amplitude sum;

[0073] Step N3: obtaining the total number of pixels in each of the infrared images, and generating the second exposure index according to the amplitude sum and the total number of pixels.

[0074] In the embodiment of the present application, the amplitude can also be represented by any of the physical quantities such as gray value, pixel value, illumination, luminous flux and radiant power.

[0075] In the embodiment of the present application, the second exposure index can be set as the ratio of the amplitude sum to the total number of pixels.

[0076] Figure 4 The flow chart of the step of adjusting the exposure time according to the exposure state in the embodiment of the present application is shown in FIG. 5, wherein judging the exposure state of the infrared image and adjusting the exposure time of the TOF camera according to the exposure state comprises the following steps: Figure 4

[0077] Step S1: obtaining the pre-set upper limit pixel threshold and lower limit pixel threshold;

[0078] Step S2: determining that the infrared image is overexposed when the first exposure index is greater than the upper limit pixel threshold, and determining that the infrared image is underexposed when the first exposure index is less than the lower limit pixel threshold and the second exposure index is less than the amplitude threshold;

[0079] Step S3: decreasing the exposure time of the next frame of the infrared image when the infrared image is overexposed, and increasing the exposure time when the infrared image is underexposed.

[0080] In the embodiment of the present application, the upper limit pixel threshold can be set as 0.04, the lower limit pixel threshold can be set as 0.001, and the amplitude threshold can be set as 255.

[0081] ​​In the embodiment of the present application, in step S3, the exposure time t" of the next frame of the infrared image is int is:

[0082]

[0083] wherein w is 0.9, t int is the exposure time of the current frame, th2 is the upper limit pixel threshold, OEI2 is the first exposure index, is the second exposure index; Δt1 is the exposure variation time when overexposure, Δt2 is the exposure variation time when underexposure,

[0084] Δt1 = -OEI2 / k2

[0085] wherein k2 is the slope of the straight line fitted by the first exposure index OEI2 and Δt1, and k2 can be calculated in advance,

[0086]

[0087] wherein k1 is the slope of the straight line fitted by the second exposure index and Δt2, and k1 can be calculated in advance.

[0088] In the embodiment of the present application, the first exposure index is generated according to the proportion of the pixel value of the ROI region in each infrared image exceeding the pre-set first pixel value threshold;

[0089] The second exposure index is generated according to the mean value of the amplitude value of the ROI region in each infrared image.

[0090] Figure 6 is a schematic diagram of the module of the TOF camera in the embodiment of the present application, as Figure 6 shown, when using the TOF camera provided by the present application, the infrared floodlight is projected to the target through the dot matrix light projector, and then the infrared image is generated by receiving the infrared floodlight reflected by the target through the infrared camera; the processor module calculates the first exposure index and the second exposure index, determines that the infrared image is overexposed when the first exposure index is greater than the upper limit pixel threshold, determines that the infrared image is underexposed when the first exposure index is less than the lower limit pixel threshold and the second exposure index is less than the amplitude threshold, and decreases the exposure time of the next frame of the infrared image when the infrared image is overexposed, and increases the exposure time when the infrared image is underexposed.

[0091] Figure 5 is a schematic diagram of the module of the structured light projector in the embodiment of the present application, as Figure 5 shown, the light projector includes a light source, a light source driver and a light modulator;

[0092] The light source driver is connected to the light source and is used to drive the light source to emit infrared light;

[0093] The light modulator is used to modulate the light projected by the light source and then project it toward a target.

[0094] In an embodiment of the present invention, the optical modulator can adopt a time modulator to adjust the waveform of the infrared light. The optical modulator can also adopt a spatial modulator to modulate the infrared light into a dot matrix light. The spatial modulator can adopt a diffraction grating (DOE) or a spatial light modulator (SLM).

[0095] Figure 6 FIG. 1 is a schematic diagram of a module of an infrared camera according to an embodiment of the present invention. Figure 6 As shown, the infrared camera includes a lens, a filter and an image sensor arranged along the optical path, and the image sensor is provided with at least four receiving windows;

[0096] The image sensor is used to receive at least four infrared light signals through at least four receiving windows; the at least four receiving windows are arranged sequentially in time sequence, and then each infrared image is generated according to the light signal received by each receiving window, and a depth image is calculated based on the four infrared images.

[0097] The image sensor includes a plurality of light detectors distributed in an array;

[0098] The lens is an optical imaging lens, which is used to ensure that the direction vector of the collimated light beam passing through the lens and entering the light detector array is in a one-to-one correspondence with the light detector;

[0099] The light detector is used to receive the collimated light beam reflected by the target object.

[0100] In an embodiment of the present invention, in order to filter background noise, a narrowband filter is usually installed in the optical imaging lens so that the light detector array can only pass the incident collimated light beam of a preset wavelength. The preset wavelength can be the wavelength of the incident collimated light beam, such as 950 nanometers, or it can be between 50 nanometers less than the incident collimated light beam and 50 nanometers greater than the incident collimated light beam. The light detector array can be arranged periodically or non-periodically. Depending on the number of discrete dot matrix lights required, the light detector array can be a combination of multiple single-point light detectors or a sensor chip that integrates multiple light detectors. In order to further optimize the sensitivity of the light detector, the illumination spot of a discrete dot matrix light on the target person can correspond to one or more light detectors. When multiple light detectors correspond to the same illumination spot, the signal of each detector can be connected through a circuit, so that they can be merged into a light detector with a larger detection area.

[0101] In the embodiment of the present application, the light detector can adopt a CMOS light sensor, a CCD light sensor or a SPAD light sensor.

[0102] In the embodiment of the present application, the structured light is dot array light; the dot array light is distributed in a preset shape as follows: a straight line, a triangle, a quadrilateral, a circle, a hexagon, a pentagon, a random arrangement, a spatial coding arrangement and a quasi-lattice arrangement.

[0103] Figure 7 (a), (b) and (c) are schematic diagrams of the non-periodic arrangement of the dot array light in the embodiment of the present application, as shown in Figure 7 (a), the spatial coding arrangement is specifically that in the periodic arrangement, a part of the light beams is omitted, so that the spatial coding of the arrangement position is realized, and in practice, the coding that can be adopted is not limited to Figure 7 the example in (a); as shown in Figure 7 (b), the random arrangement is specifically that the arrangement of the collimated light beams is randomly distributed, so that the similarity of the arrangement modes at different positions is very small or close to zero, as shown in Figure 7 (c), the quasi-lattice arrangement is specifically that the collimated light beams are non-periodically arranged at adjacent positions in a short distance and are periodically arranged at a long distance. Since the present application is limited by the optical system in implementation, the arrangement of the collimated light beams in a cross section may, in practice, be distorted, such as stretching, twisting and the like. The energy distribution of each collimated light beam in the cross section can be circular, circular ring or elliptical and other shapes. In the arrangement mode as shown in (7), this arrangement is beneficial to the uniform sampling of the non-deterministic target and optimizes the effect of the final 3D depth map.

[0104] In the deformation example of the present application, the TOF camera capable of automatic exposure provided by the present application includes the following steps:

[0105] a light projector for projecting infrared light to a target;

[0106] an infrared camera for receiving infrared light reflected by the target to generate an infrared image;

[0107] a processor module for calculating a first exposure index according to the pixel value of each infrared image, calculating a second exposure index according to the amplitude value of each infrared image according to the second exposure index, judging the exposure state of each infrared image according to the first exposure index, the upper limit pixel threshold corresponding to the first exposure index, the lower limit pixel threshold and the second exposure index, the amplitude threshold corresponding to the second exposure index, and adjusting the exposure time of the TOF camera according to the exposure state.

[0108] In an embodiment of the present invention, an exposure index is generated based on the average of the pixel values ​​and amplitude values ​​in each of the infrared images, the exposure state is determined based on the exposure index, and the exposure time of the TOF camera is adjusted based on the exposure state. This allows the exposure time to be quickly adjusted to an appropriate range, preventing overexposure and underexposure of the image, and improving the accuracy of the depth map and the working distance range.

[0109] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. The above description of the disclosed embodiments enables professionals and technicians in this field to implement or use the present invention. Various modifications to these embodiments will be apparent to professionals and technicians in this field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

[0110] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A TOF camera capable of automatic exposure, characterized in that: Includes the following modules: a light projector for projecting infrared light toward a target; an infrared camera, configured to receive infrared light reflected by the target and generate an infrared image; a processor module, configured to calculate a first exposure index based on a proportion of pixel values ​​in each of the infrared images exceeding a preset first pixel value threshold, calculate a second exposure index based on an average amplitude value of each of the infrared images according to the second exposure index, determine an exposure state of each of the infrared images based on the first exposure index, an upper pixel threshold and a lower pixel threshold corresponding to the first exposure index, and the second exposure index and an amplitude threshold corresponding to the second exposure index, and adjust the exposure time of the TOF camera according to the exposure state; Determining the exposure state of the infrared image and adjusting the exposure time of the TOF camera according to the exposure state includes the following steps: Step S1: Obtaining a preset upper pixel threshold and a lower pixel threshold; Step S2: determining that the infrared image is overexposed when the first exposure index is greater than the upper pixel threshold, and determining that the infrared image is underexposed when the first exposure index is less than the lower pixel threshold and the second exposure index is less than the amplitude threshold; Step S3: reducing the exposure time of the next frame of the infrared image when the infrared image is overexposed, and increasing the exposure time when the infrared image is underexposed; In step S3, the exposure time of the next frame of the infrared image is for: ； in, The value is 0.9, is the exposure time of the current frame, is the upper pixel threshold, is the first exposure indicator, The exposure change time when overexposure occurs. Exposure change time for underexposure; ； in, The first exposure indicator and The slope of the fitted straight line is Pre-calculated; ； in, is the second exposure index and The slope of the fitted straight line is Pre-calculated.

2. The TOF camera capable of automatic exposure according to claim 1, wherein: The processor module calculates the first exposure index including the following steps: Step M1: obtaining the pixel value of each pixel in each of the infrared images; Step M2: determining whether the pixel value of each pixel exceeds a preset first pixel value threshold, so as to determine the number of overexposed pixels in each infrared image; Step M3: Obtain the total number of pixels in each of the infrared images, and generate the first exposure index according to the number of overexposed pixels and the total number of pixels.

3. The TOF camera capable of automatic exposure according to claim 1, wherein: The processor module calculates the second exposure index including the following steps: Step N1: obtaining the amplitude value of each pixel in each of the infrared images; Step N2: Accumulating and determining the amplitude values ​​of the pixels in the infrared image to generate an amplitude value sum; Step N3: Obtain the total number of pixels in each of the infrared images, and generate the second exposure index according to the amplitude value and the total number of pixels.

4. The TOF camera capable of automatic exposure according to claim 1, wherein: The first exposure index is generated according to the ratio of the pixel value of the ROI area in each of the infrared images exceeding a preset first pixel value threshold; The second exposure index is generated according to an average amplitude value of the ROI region in each of the infrared images.

5. The TOF camera capable of automatic exposure according to claim 1, wherein: The infrared camera includes a lens, a filter and an image sensor arranged along the light path. The image sensor is provided with at least four receiving windows; The image sensor is used to receive at least four infrared light signals through at least four receiving windows; the at least four receiving windows are arranged sequentially in time sequence, and then each infrared image is generated according to the light signal received by each receiving window.

6. The TOF camera capable of automatic exposure according to claim 1, wherein: The upper pixel threshold is set to 0.04, the lower pixel threshold is set to 0.001, and the amplitude threshold is set to 255.

7. The TOF camera capable of automatic exposure according to claim 1, wherein: The light detector uses a CMOS light sensor, a CCD light sensor, or a SPAD light sensor.

8. A TOF camera capable of automatic exposure, characterized in that: The steps include: a light projector for projecting infrared light toward a target; an infrared camera, configured to receive infrared light reflected by the target and generate an infrared image; a processor module, configured to calculate a first exposure index based on pixel values ​​in each of the infrared images, calculate a second exposure index based on an amplitude value of each of the infrared images, determine an exposure state of each of the infrared images based on the first exposure index, an upper pixel threshold and a lower pixel threshold corresponding to the first exposure index, and the second exposure index and an amplitude threshold corresponding to the second exposure index, and adjust the exposure time of the TOF camera based on the exposure state; Determining the exposure state of the infrared image and adjusting the exposure time of the TOF camera according to the exposure state includes the following steps: Step S1: Obtaining a preset upper pixel threshold and a lower pixel threshold; Step S2: determining that the infrared image is overexposed when the first exposure index is greater than the upper pixel threshold, and determining that the infrared image is underexposed when the first exposure index is less than the lower pixel threshold and the second exposure index is less than the amplitude threshold; Step S3: reducing the exposure time of the next frame of the infrared image when the infrared image is overexposed, and increasing the exposure time when the infrared image is underexposed; In step S3, the exposure time of the next frame of the infrared image is for: ； in, The value is 0.9, is the exposure time of the current frame, is the upper pixel threshold, is the first exposure indicator, The exposure change time when overexposure occurs. Exposure change time for underexposure; ； in, The first exposure indicator and The slope of the fitted straight line is Pre-calculated; ； in, is the second exposure index and The slope of the fitted straight line is Pre-calculated.

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