Face recognition device and face recognition method

Abstract

The application provides a face recognition device and a face recognition method, and the face recognition device comprises a fixed frame, a structured light projector, an infrared image acquisition module and a control processing module. The structured light projector comprises a projector frame, a laser and a diffractive optical element. The laser emits infrared laser, and the diffractive optical element is arranged downstream of the light path of the laser and is used for dispersing the infrared laser into multiple blocks. Each block has randomly distributed laser spots, and the light intensity distribution in each laser spot is approximately equal. The infrared image acquisition module acquires reflected light of the laser and generates an infrared speckle image, and the control processing module generates face feature data. The embodiment of the application uses the infrared image acquisition module to acquire the infrared speckle image for living body recognition, does not need to generate a depth map, simplifies the structure of the face recognition device, reduces the production and installation cost, saves the operation resource, and can be popularized in application environments such as access control and attendance.

Description

Technical Field

[0001] This invention relates to the field of facial recognition technology, and in particular to a facial recognition device and a facial recognition method. Background Technology

[0002] Facial recognition devices, used in access control, attendance systems, and turnstiles, have significantly improved efficiency and reduced manpower requirements at various checkpoints due to their advantages such as rapid recognition, seamless passage, and high accuracy, making them widely popular in the market. Their core technology is a visual AI application based on facial biometrics. It extracts and compares facial features to achieve accurate identification of individuals. In terms of hardware, facial recognition devices rely on visual sensors to capture facial images. Common facial recognition devices typically employ a binocular module solution based on "color + infrared," where a color camera captures color images and an infrared camera captures infrared images. By utilizing the different interactions of infrared light with various materials such as photographs, masks, and skin, as well as the differences in optical properties such as reflection / scattering, it distinguishes between live and spoofed individuals, achieving a liveness detection function.

[0003] However, the infrared reflection / scattering characteristics of some flat paper are similar to those of skin. Therefore, photos printed using this material are relatively easy to attack binocular facial recognition devices. The rampant buying and selling of facial photos and the ease of printing them pose a significant security risk to facial recognition applications due to this inexpensive attack method. Currently, there are facial recognition devices that use depth modules to acquire color and infrared images and generate depth images. These devices add a depth image to the color and infrared facial images for liveness detection, achieving high accuracy and are used in scenarios such as financial payments. However, depth modules have high integration, require stable structures and heat dissipation, and have complex manufacturing processes. They require precise and stable production and assembly processes. Furthermore, depth calculations by the depth module consume computing power, typically requiring dedicated chips to meet or consume the computing power of the host computer. Therefore, depth modules with dedicated chips are expensive, while those consuming host computer computing power cannot be used in low- to mid-range access control machines with insufficient computing power, hindering their widespread application in access control and attendance scenarios. Therefore, there is an urgent need to improve traditional facial recognition devices and methods.

[0004] The content of the background section is merely the technology known to the inventor and does not necessarily represent the prior art in this field. Summary of the Invention

[0005] To address one or more deficiencies in existing technologies, this invention provides a face recognition device for detecting and recognizing faces, wherein the face recognition device includes:

[0006] Fixed frame;

[0007] A structured light projector, the structured light projector comprising:

[0008] Projector frame;

[0009] A laser, which is a single-point or multi-point light source, is disposed within the projector frame and configured to emit infrared laser light within a specific wavelength range; and

[0010] A diffractive optical element is disposed within the projector frame and downstream of the laser's optical path. This element is used to modulate the light field distribution of the infrared laser emitted by the laser, thereby forming a preset spot pattern with a certain field of view. The spot pattern is formed by staggered splicing of multiple small blocks into the projection pattern of the certain field of view. Each small block contains randomly distributed infrared laser spots, and the light intensity distribution within each laser spot is approximately uniform.

[0011] An infrared image acquisition module, installed within the fixed frame, is configured to acquire reflected laser light and generate an infrared speckle image; and

[0012] The control processing module communicates with both the structured light projector and the infrared image acquisition module, and generates facial feature data based on the reflected light acquired by the infrared image acquisition module.

[0013] According to one aspect of the invention, the structured light projector further includes a first lens disposed within the projector frame and located upstream of the optical path of the diffractive optical element, the first lens being used to collimate infrared laser light before modulation by the diffractive optical element.

[0014] According to one aspect of the invention, the structured light projector further includes a second lens disposed within the projector frame and located downstream of the optical path of the diffractive optical element, the second lens being used to adjust the size of the defined field of view.

[0015] According to one aspect of the invention, the structured light projector forms a light spot at a projection distance of 10 centimeters or more.

[0016] According to one aspect of the invention, the wavelength range of the infrared laser is 808-1550 nanometers.

[0017] According to one aspect of the invention, the facial feature data includes facial depth features.

[0018] According to one aspect of the present invention, the face recognition device further includes an RGB (red, green, blue) color image acquisition module, which is installed within the fixed frame. The RGB color image acquisition module is controlled by the control processing module and configured to acquire a color image of a face in a predetermined area in front of the user for face comparison and identity recognition.

[0019] According to one aspect of the present invention, the face recognition device further includes an infrared light-emitting diode, which is fixed on the fixed frame and is controlled to be turned on or off by the control processing module.

[0020] According to one aspect of the present invention, the face recognition device further includes a second infrared image acquisition module, which is installed within the fixed frame and configured to acquire reflected light from the infrared light emitted by the infrared light-emitting diode and generate an infrared image.

[0021] According to one aspect of the invention, the control processing module is configured to control the structured light projector and the infrared light-emitting diode to alternately turn on and off, and to control the infrared image acquisition module to alternately acquire the reflected light of the infrared laser emitted by the structured light projector and the reflected light of the infrared light emitted by the infrared light-emitting diode.

[0022] According to one aspect of the invention, the infrared light emitted by the infrared light-emitting diode is substantially the same as the infrared laser wavelength emitted by the structured light projector.

[0023] The present invention also includes a face recognition method, which uses the face recognition device as described above to perform face recognition, the face recognition method comprising:

[0024] Control the structured light projector to project infrared lasers with a preset arrangement onto a face target within a set area;

[0025] The reflected light from the infrared laser is collected, and an infrared speckle image is generated;

[0026] Facial feature data is generated based on the infrared speckle image and compared with a facial database.

[0027] According to one aspect of the present invention, the face recognition device further includes an RGB color image acquisition module, and the face recognition method further includes controlling the RGB color image acquisition module to acquire color images of the same target face.

[0028] According to one aspect of the present invention, the face recognition device further includes an infrared light-emitting diode, and the face recognition method further includes turning on the infrared light-emitting diode and acquiring an infrared image of the same target face.

[0029] According to one aspect of the present invention, the face recognition device further includes a second infrared image acquisition module, and the face recognition method further includes acquiring infrared images of the same target face using the second infrared image acquisition module.

[0030] According to one aspect of the present invention, the face recognition method further includes alternately turning the structured light projector and the infrared light-emitting diode on and off, and controlling the infrared image acquisition module to alternately acquire the reflected light of the infrared laser emitted by the structured light projector and the reflected light of the infrared light emitted by the infrared light-emitting diode, thereby generating an infrared speckle image and an infrared image of the same target face.

[0031] Compared with existing technologies, embodiments of the present invention provide a face recognition device that utilizes a structured light projector to emit a special laser pattern with a preset arrangement, and uses an infrared image acquisition module to acquire an infrared speckle image of the target. Facial feature data from this image is used for liveness detection, improving security performance. Furthermore, it eliminates the need to generate a depth map, simplifying the structure of the face recognition device, reducing production and installation costs, and saving computing power. This allows for wider application in access control and attendance systems. Embodiments of the present invention also include a face recognition method that utilizes the aforementioned face recognition device for both face recognition and liveness detection. Attached Figure Description

[0032] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0033] Figure 1 This is an exploded view of a face recognition device in one embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of a face recognition device in one embodiment of the present invention;

[0035] Figure 3A This is a schematic diagram of the structure of a structured light projector in one embodiment of the present invention;

[0036] Figure 3B This is a schematic diagram of a structured light projector including a first lens in one embodiment of the present invention;

[0037] Figure 3C This is a schematic diagram of a structured light projector including a second lens in one embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the optical path when the first lens and the diffractive optical element are combined in one embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of the light field of a structured light projector in one embodiment of the present invention;

[0040] Figure 6 This is an exploded view of a face recognition device according to another embodiment of the present invention;

[0041] Figure 7 This is a structural block diagram of a face recognition device in one embodiment of the present invention;

[0042] Figure 8 This is an infrared speckle image of a face recognition device in one embodiment of the present invention;

[0043] Figure 9 This is a flowchart illustrating a face recognition method in one embodiment of the present invention.

[0044] Reference numerals: 1. Face recognition device; 10. Fixed frame; 20. Structured light projector; 21. Projector frame; 22. Laser; 23. Diffractive optical element; 24. First lens; 25. Second lens; 30. Infrared image acquisition module; 40. Control and processing module; 50. RGB color image acquisition module; 60. Infrared light-emitting diode; 70. Second infrared image acquisition module. Detailed Implementation

[0045] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0046] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0047] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0049] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0050] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0051] like Figure 1 and Figure 2 As shown, according to an embodiment of the present invention, a face recognition device 1 includes a fixed frame 10, a structured light projector 20, an infrared image acquisition module 30, and a control processing module 40. The fixed frame 10 is used to fix the structured light projector 20 and the infrared image acquisition module 30 in the face recognition device 1. The fixed frame 10 has through holes or light-transmitting structures to emit and receive light of corresponding wavelengths. Furthermore, in specific application scenarios, the fixed frame 10 is fixedly connected to the application device, such as being fixedly installed on access control equipment, attendance equipment, etc. The fixed frame 10 can also be processed into a specific shape, with the outer top ends of the structured light projector 20 and the infrared image acquisition module 30 approximately in the same plane, so that the overall appearance of the application device is consistent. The control processing module 40 communicates with both the structured light projector 20 and the infrared image acquisition module 30. It can be installed within the fixed frame 10 and connected to both via data cables. Alternatively, it can be installed in other locations, such as inside access control or attendance equipment, or in other remote devices, communicating with both via data cables or wireless transmission. The control processing module 40 can control the specific operating modes of the structured light projector 20 and the infrared image acquisition module 30, such as turning them on, off, or switching them at a specific frequency. Furthermore, the control processing module 40 can also acquire data collected by the infrared image acquisition module 30.

[0052] like Figure 3AAs shown, the structured light projector 20 includes a structured light frame 21, a laser 22, and a diffractive optical element 23. The laser 22 and the diffractive optical element 23 are disposed within the structured light frame 21. The laser 22 can emit infrared laser light within a specific wavelength range. The diffractive optical element 23 is disposed downstream of the optical path of the laser 22 and is used to modulate the light field distribution of the infrared laser light emitted by the laser 22 to form a preset spot pattern with a certain field of view. The spot pattern is formed by multiple small blocks being staggered and spliced ​​together to form a projection pattern with a certain field of view. Each small block has randomly distributed infrared laser spots, and the light intensity distribution within each laser spot is approximately uniform.

[0053] In this embodiment, the structured light projector 20 emits a laser pattern composed of multiple segments. According to a preferred embodiment of the present invention, the light field distribution of the structured light projector 20 is as follows: Figure 5 As shown, multiple blocks are arranged according to a preset distribution pattern. For example, in this embodiment, the face recognition device 1 is used on an access control device. Within the space directly in front of the access control device, the central area is better able to reflect facial features during face information acquisition. The infrared laser blocks have no stretching distortion and high spot density, which can accurately acquire facial feature data. Conversely, the infrared laser blocks distributed at the edges have greater stretching distortion and lower spot density, resulting in poorer accuracy in acquiring facial feature data. The preset blocks of infrared lasers can be set according to specific application scenarios, application devices, and application requirements to make full use of infrared lasers and reduce energy consumption. For example, for a device performing face recognition while moving, the infrared laser blocks can be concentrated on the movement trajectory. Multiple dense or sparse infrared laser blocks form a projection map with a large field of view, i.e., the scanning range of the structured light projector 20. Each infrared laser block has randomly distributed laser spots. That is, after each infrared laser block is defined, the laser spots are randomly distributed within the block to reflect the facial features within the infrared laser block as accurately as possible.

[0054] like Figure 3B As shown, according to a preferred embodiment of the present invention, the structured light projector 20 further includes a first lens 24. The first lens 24 is disposed within the projector frame 21 and located upstream of the optical path of the diffractive optical element 23. It is used to collimate the infrared laser emitted by the laser 22, and then modulate it through the diffractive optical element. The first lens 24 is not limited to a single lens, but can also be a lens group. The light field distribution of the first lens 24 and the diffractive optical element 23 in cooperation is as follows: Figure 4 As shown, the laser 22 can be provided with multiple light-emitting points, which illuminate the first lens 24. After refraction by the first lens 24, a parallel beam is formed and illuminates the diffractive optical element 23.

[0055] Furthermore, according to a preferred embodiment of the present invention, such as Figure 3CAs shown, the structured light projector 20 also includes a second lens 25, which is disposed within the projector frame 21 and downstream of the optical path of the diffractive optical element 23. The second lens 25 is used to adjust the size of the field of view of the structured light projector 20, change the position of the concentrated segments in the field of view, or the distance of the laser spots projected, to meet specific application requirements. For example, in a specific application scenario, if the distance between the structured light projector 20 and the target (face) is relatively far, the field of view of the structured light projector 20 can be changed by adjusting the second lens 25 to ensure that a sufficient number of laser spots can be projected onto the face.

[0056] Unlike passive binocular depth calculation, structured light depth calculation utilizes structured light projected onto a target. The depth of the target is calculated based on the distortion of the structured light pattern caused by the target, essentially marking the target with structured light. Current depth modules using structured light principles aim for high-precision depth calculations by employing sharp laser spots emitted from the structured light projector. A more concentrated light intensity distribution, such as an approximately conical distribution, improves depth calculation accuracy. In this embodiment, the light intensity within each laser spot is approximately uniformly distributed, exhibiting an approximately flat-topped pattern. The uniformly diffused light intensity within the laser spot, when projected onto the target, still allows for depth marking and includes the target's depth features. Furthermore, the uniform light spot effectively reflects the infrared reflection characteristics of different target materials. Therefore, based on this infrared speckle map, the target's depth features and infrared reflection characteristics can be obtained, directly applicable to liveness detection. The module structure in this embodiment is simpler than traditional depth modules. Moreover, this embodiment directly acquires target depth features by collecting structured light maps, eliminating the need for depth map calculations. This results in a more efficient algorithm, faster and more accurate face liveness recognition, and lower computational resource consumption.

[0057] like Figure 1 and Figure 6As shown, the face recognition device 1 in this embodiment also includes an infrared image acquisition module 30. The infrared image acquisition module 30 is installed inside the fixed frame 10, and its function is to acquire the reflected light after the laser emitted by the structured light projector 20 illuminates the target, generating an infrared speckle image. Taking a planar face photograph as an example, the reflective surface of a planar face photograph is flat and has no depth variation, while structured light can mark the depth of the target. Therefore, the image acquired by the structured light projected onto a planar face photograph has no depth features, while the image acquired after projecting onto a face contains depth features and better infrared recognition features, enabling excellent liveness detection. In existing technologies, depth modules output depth maps. Depth features are acquired based on the target's depth map, and depth calculation is performed using geometric principles based on parallax. This requires the infrared acquisition module and structured light projector to have a fixed and stable geometric relationship, resulting in higher requirements for structural stability and heat dissipation. Furthermore, to increase parallax and facilitate depth calculation, the baseline distance between the infrared image acquisition module and the structured light projector is usually increased. Therefore, the structured light projector and infrared image acquisition module are typically positioned at both ends of the face recognition device, placing high demands on the structural stability of the face recognition device and resulting in poor arrangement flexibility and customizability. In this embodiment, the face recognition device 1 does not need to output a depth map. Instead, it directly acquires facial depth features using the infrared speckle image acquired by the infrared image acquisition module 30. Therefore, in this embodiment, the structured light projector 20 and the infrared image acquisition module 30 in the face recognition device 1 are not constrained by positional relationship and can be flexibly arranged within the fixed frame 10, offering greater flexibility and customizability. For example… Figure 6 As shown, the structured light projector 20 and the infrared image acquisition module 30 can be arranged adjacent to each other or even attached to each other, making the face recognition device 1 more compact, greatly reducing the size of the face recognition device 1 and improving the structural adaptability of the face recognition device 1.

[0058] According to a preferred embodiment of the present invention, the structured light projector 20 projects infrared laser light into a forward region and forms light spots at a projection distance of 10 cm or more from the structured light projector 20. In applications such as access control and attendance, the range of face recognition is 10 cm or more. To improve the accuracy of the infrared speckle image acquired by the infrared image acquisition module 30, the structured light projector 20 can be adjusted to form a laser projection pattern with the aforementioned characteristics at a projection distance of 10 cm or more. Depending on the specific application requirements, it is preferred to form the laser projection pattern within a range of 30-150 cm. For example, according to a preferred embodiment of the present invention, the structured light projector 20 projects 30,000 laser spots in a specific field of view using the aforementioned projection method, thereby ensuring that there are sufficient laser spots illuminating the face within the specified distance. The center wavelength of the laser is 940 nanometers. The infrared speckle image containing facial feature data can be obtained by acquiring the reflected light using the infrared image acquisition module 30. Figure 8As shown, planar objects cannot cause the laser spot to shift (no depth feature), while three-dimensional objects will cause the laser spot to shift (with depth feature), showing a clear distinction.

[0059] Face recognition device 1 is usually installed outdoors or indoors near windows where ambient light is strong. To avoid the influence of ambient light on the recognition results of face recognition device 1, it is necessary to increase the luminous intensity of structured light projector 20. At the same time, in order to avoid the stimulation of human eyes by strong visible light and to prevent damage to human eyes and skin by ultraviolet light, infrared light is selected as the light source for structured light projector 20 in the embodiments of the present invention. According to some preferred embodiments of the present invention, the wavelength range of the infrared laser projected by structured light projector 20 can be 808-1550 nanometers, such as 808 nanometers, 850 nanometers, 940 nanometers, etc. Compared with mid- and far-infrared light, near-infrared light can better reflect the infrared reflection characteristics of different materials, which is beneficial for its application in face liveness detection.

[0060] like Figure 6 and Figure 7 As shown, the face recognition device 1 also includes an RGB color image acquisition module 50. The RGB color image acquisition module 50 is installed in the fixed frame 10. The RGB color image acquisition module 50 is controlled by the control processing module 40 and can acquire color images of faces in a predetermined area in front for face comparison and identity recognition.

[0061] The RGB color image acquisition module 50 can select a color camera or other device with the same function to acquire a planar color image of a face under visible light. Based on the facial feature data contained therein, and with the assistance of other devices, face recognition is performed to improve the accuracy of the face recognition device 1.

[0062] According to a preferred embodiment of the present invention, such as Figure 1 and Figure 7As shown, the face recognition device 1 also includes an infrared light-emitting diode 60, which is fixedly mounted on the fixed frame 10 and can be controlled to be turned on or off by the control processing module 40. In this embodiment, the infrared light-emitting diode 60 emits infrared light. In low-light environments, the infrared image acquisition module 30 acquires the reflected light after the infrared light emitted by the infrared light-emitting diode 60 illuminates the target, generating an infrared image for face recognition applications in low-light environments. In strong light environments, the laser spot emitted by the structured light projector 20 will be submerged in ambient light after a certain distance. Unlike the depth module, which fails to perform depth calculations and thus cannot perform liveness detection in this situation, the infrared image after the laser spot is submerged is used to perform liveness detection on different materials, improving the applicability of the face recognition device 1 for liveness detection in strong light environments. In some preferred embodiments of the present invention, to further simplify and optimize the scheme architecture, the RGB color image acquisition module 50 is omitted, and the infrared light emitted by the structured light projector 20 and the infrared light-emitting diode 60 has the same or similar wavelength band. Specifically, the control processing module 40 can control the structured light projector 20 and the infrared light-emitting diode 60 to alternately turn on and off, and control the same infrared image acquisition module 30 to alternately acquire the reflected light generated after the laser emitted by the structured light projector 20 illuminates the target to generate an image for face liveness detection, and the reflected light generated after the infrared light emitted by the infrared light-emitting diode 60 illuminates the target to generate an image for face recognition applications.

[0063] According to a preferred embodiment of the present invention, such as Figure 7 As shown, the face recognition device 1 also includes a second infrared image acquisition module 70. The second infrared image acquisition module 70 is used to acquire the reflected light after the infrared light emitted by the infrared LED illuminates the target and generate an infrared image for face recognition applications. The infrared acquisition module 30 is used to acquire the reflected light after the laser emitted by the structured light projector 20 illuminates the target and generate an infrared speckle map for face liveness detection. The structured light projector 20 and the infrared LED 60 select infrared light of different wavelengths. The second infrared image acquisition module 70 and the infrared acquisition module 30 are independent of each other and their working states do not affect each other.

[0064] Figure 9 The following illustrates the flow of a face recognition method 100 using the aforementioned face recognition device according to an embodiment of the present invention. Figure 9 Detailed description.

[0065] like Figure 9As shown, in S101, the structured light projector is controlled to project a laser pattern with a preset arrangement to a face target within a set area. The set area is the face recognition range in front of the face recognition device, for example, 10 centimeters or more. Within this range, the laser emitted by the structured light projector has a preset arrangement. According to the aforementioned embodiment, the laser emitted by the structured light projector is composed of multiple blocks spliced ​​into a projection image with a large field of view, which is projected onto the target object. Each block has randomly distributed laser spots, and the light intensity in each laser spot is approximately uniformly distributed and has an approximately flat top distribution.

[0066] In step S102, the reflected light after the laser emitted by the structured light projector illuminates the target is collected, and an infrared speckle image is generated. In this embodiment, the infrared image acquisition module in the face recognition device is used to collect the reflected light after the laser emitted by the structured light projector illuminates the target. As mentioned above, the structured light with a preset arrangement pattern will make depth marks on the three-dimensional object, and the depth features of the face can be reflected through the infrared speckle image for face liveness detection. Compared with the existing depth module face liveness anti-spoofing scheme, this embodiment does not need to calculate the depth map and then obtain the face depth features, but directly obtains the face depth features in the infrared speckle image. It can also be used for liveness detection, and the calculation process is greatly simplified. At the same time, there are no strict requirements for structural stability and heat dissipation of the depth module.

[0067] In step S103, the control and processing module in the face recognition device generates target feature data based on the infrared speckle image and compares it with the liveness feature database to complete the face liveness detection process and obtain the liveness detection result.

[0068] In a preferred embodiment of the present invention, the face recognition device further includes an RGB color image acquisition module, and the face recognition method further includes controlling the RGB color image acquisition module to acquire color images of the same target face for use in face recognition applications.

[0069] A face recognition device may consist only of a structured light projector, an infrared LED, and an infrared image acquisition module. The infrared LED is turned on, and the infrared image acquisition module acquires infrared images of the same target face. This process alternates with the acquisition of reflected light from the structured light and the generation of an infrared speckle image to avoid interference between the infrared light emitted by the infrared LED and the laser emitted by the structured light projector. Specifically, according to a preferred embodiment of the invention, the face recognition method further includes alternately turning the structured light projector and the infrared LED on and off, and controlling the infrared image acquisition module to alternately acquire reflected light from the laser emitted by the structured light projector and reflected light from the infrared light emitted by the infrared LED, generating infrared speckle images and infrared images of the same target face. Furthermore, this process can be repeated multiple times to obtain multiple sets of data. The acquired infrared speckle images are used for liveness detection, and the infrared images are used for face recognition applications.

[0070] Of course, in a face recognition device that simultaneously possesses an RGB color image acquisition module, an infrared light-emitting diode, a structured light projector, and an infrared image acquisition module, it is possible to acquire infrared speckle images, color images, and infrared images of the same target face, and combine them to generate face feature data, thereby improving the accuracy of face liveness detection.

[0071] In some embodiments of the present invention, the face recognition device may also have a second infrared image acquisition module, which is used to acquire the reflected light after the infrared light emitted by the infrared LED illuminates the target and generate an infrared image. When the infrared light emitted by the infrared LED is different from the laser band emitted by the structured light projector, the infrared LED and the structured light projector can be turned on at the same time. The infrared image and the infrared speckle image of the same target task can be acquired simultaneously by two independent infrared image acquisition modules. The infrared image is used for face recognition applications, and the infrared speckle image is used for face liveness detection.

[0072] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A face recognition device for detecting and recognizing faces, wherein the face recognition device comprises: Fixed frame; A structured light projector, the structured light projector comprising: Projector frame; A laser, which is a single-point or multi-point light source, is disposed within the projector frame and configured to emit infrared laser light within a specific wavelength range; and A diffractive optical element is disposed within the projector frame and downstream of the laser's optical path. It is used to modulate the light field distribution of the infrared laser emitted by the laser to form a preset spot pattern with a certain field of view. The spot pattern is formed by staggered splicing of multiple small blocks into the projection pattern with the certain field of view. Each small block has randomly distributed infrared laser spots. An infrared image acquisition module is installed within the fixed frame and is configured to acquire reflected light from the laser and generate an infrared speckle image. and The control processing module communicates with the structured light projector and the infrared image acquisition module respectively, and generates facial feature data based on the reflected light acquired by the infrared image acquisition module. Each laser spot has an approximately flat-top distribution, and the light intensity within the laser spot is uniformly diffused to obtain the depth characteristics and infrared reflection properties of the target.

2. The face recognition device according to claim 1, wherein the structured light projector further includes a first lens, the first lens being disposed within the projector frame and located upstream of the optical path of the diffractive optical element, the first lens being used to collimate the infrared laser and then modulate it through the diffractive optical element.

3. The face recognition device according to claim 1 or 2, wherein the structured light projector further includes a second lens, the second lens being disposed within the projector frame and located downstream of the optical path of the diffractive optical element, the second lens being used to adjust the size of the certain field of view.

4. The face recognition device according to claim 1, wherein the structured light projector forms a light spot at a projection distance of 10 cm or more.

5. The face recognition device according to claim 1, wherein the wavelength range of the infrared laser is 808-1550 nanometers.

6. The face recognition device according to claim 1, wherein the face feature data includes face depth features.

7. The face recognition device according to claim 1 further includes an RGB color image acquisition module, wherein the RGB color image acquisition module is installed within the fixed frame, the RGB color image acquisition module is controlled by the control processing module, and is configured to acquire color images of faces in a predetermined area in front for face comparison and identity recognition.

8. The face recognition device according to claim 1 further includes an infrared light-emitting diode, the infrared light-emitting diode being fixed on the fixed frame, and the infrared light-emitting diode being controlled to be turned on or off by the control processing module.

9. The face recognition device according to claim 8 further includes a second infrared image acquisition module, the second infrared image acquisition module being installed within the fixed frame, the second infrared image acquisition module being configured to acquire the reflected light of the infrared light emitted by the infrared light-emitting diode and generate an infrared image.

10. The face recognition device according to claim 8, wherein the control processing module is configured to control the structured light projector and the infrared light-emitting diode to alternately turn on and off, and to control the infrared image acquisition module to alternately acquire the reflected light of the laser emitted by the structured light projector and the reflected light of the infrared light emitted by the infrared light-emitting diode.

11. A face recognition method, comprising performing face recognition using a face recognition device as described in any one of claims 1-10, the face recognition method comprising: Control the structured light projector to project lasers with a preset arrangement onto a face target within a set area; The reflected light from the infrared laser is collected, and an infrared speckle image is generated; Facial feature data is generated based on the infrared speckle image and compared with a facial database.

12. The face recognition method according to claim 11, wherein the face recognition device further includes an RGB color image acquisition module, and the face recognition method further includes controlling the RGB color image acquisition module to acquire color images of the same target face.

13. The face recognition method according to claim 11 or 12, wherein the face recognition device further includes an infrared light-emitting diode, and the face recognition method further includes turning on the infrared light-emitting diode and acquiring an infrared image of the same target face.

14. The face recognition method according to claim 13, wherein the face recognition device further includes a second infrared image acquisition module, and the face recognition method further includes acquiring infrared images of the same target face using the second infrared image acquisition module.

15. The face recognition method according to claim 13 further includes alternately turning the structured light projector and the infrared light-emitting diode on and off, and controlling the infrared image acquisition module to alternately acquire the reflected light of the laser emitted by the structured light projector and the reflected light of the infrared light emitted by the infrared light-emitting diode, to generate an infrared speckle image and an infrared image of the same target face.

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