Image acquisition method and device, equipment, storage medium and program product

Abstract

The invention discloses an image acquisition method and device, equipment, a storage medium and a program product, and relates to the technical field of image acquisition. The method is used for an image acquisition device, and the image acquisition device comprises a light supplement lamp, a master camera, a slave camera and a controller. The method comprises the following steps: the controller sends a first exposure control signal to the main camera; under the condition that the first exposure control signal is received, the main camera performs periodic exposure; under the condition that single exposure is completed, the master camera sends a frame synchronization signal to the slave camera; under the condition that the frame synchronization signal is received, the slave camera performs exposure; the controller controls the light supplementing lamp to perform periodic light supplementing based on the exposure time of the camera, and the light supplementing time period of the light supplementing lamp covers the exposure time period of the camera; and the master camera and the slave camera transmit acquired image data to the controller.

Description

Technical Field

[0001] Embodiments of the present application relate to the technical field of image acquisition, and in particular, to an image acquisition method, apparatus, device, storage medium, and program product. Background Art

[0002] Nowadays, the ways of performing identity verification are gradually increasing, including identity verification methods through image acquisition and image feature comparison, such as palmprint recognition and face recognition, etc.

[0003] In related technologies, during the process of image acquisition, at least two cameras are usually used simultaneously to respectively acquire identity verification images, and then the image features of the images acquired by the two cameras are combined to perform identity verification.

[0004] However, in the identity verification image acquisition scheme provided by related technologies, the two cameras are independently controlled by a main control chip and perform continuous exposure, resulting in a relatively high power consumption of the image acquisition device. Summary of the Invention

[0005] Embodiments of the present application provide an image acquisition method, apparatus, device, storage medium, and program product, and the technical solutions are as follows:

[0006] On the one hand, embodiments of the present application provide an image acquisition method, which is used for an image acquisition device, and the image acquisition device includes a fill light, a main camera, a slave camera, and a controller;

[0007] ' The method includes:

[0008] The controller sends a first exposure control signal to the main camera;

[0009] When receiving the first exposure control signal, the main camera performs periodic exposure;

[0010] When a single exposure is completed, the main camera sends a frame synchronization signal to the slave camera;

[0011] When receiving the frame synchronization signal, the slave camera performs exposure;

[0012] The controller controls the fill light to perform periodic fill light based on the exposure moment of the camera, and the fill light period of the fill light covers the exposure period of the camera;

[0013] The main camera and the slave camera transmit the acquired image data to the controller.

[0014] On the other hand, embodiments of the present application provide an image acquisition apparatus, and the apparatus includes:

[0015] A control module for sending a first exposure control signal to the main camera module;

[0016] The main camera module is configured to perform periodic exposure when receiving the first exposure control signal;

[0017] The main camera module is further configured to send a frame synchronization signal to the slave camera module when a single exposure is completed;

[0018] The slave camera module is configured to perform exposure when receiving the frame synchronization signal;

[0019] The control module is further configured to control the fill light module to perform periodic fill light based on the exposure time of the camera module, and the fill light period of the fill light module covers the exposure period of the camera module;

[0020] The main camera module is further configured to transmit the captured image data to the control module;

[0021] The slave camera module is further configured to transmit the captured image data to the control module.

[0022] In some embodiments, the control module is configured to receive a stroboscopic signal sent by the camera module, where the stroboscopic signal is used to indicate fill light; when detecting a target stroboscopic signal state, the control module controls the fill light module to perform periodic fill light, and the target stroboscopic signal state includes a signal rising edge and a signal falling edge, the signal rising edge corresponds to the exposure start time, and the signal falling edge corresponds to the exposure end time.

[0023] In some embodiments, the control module is configured to, when detecting the target stroboscopic signal state, control the fill light module to perform periodic fill light through a timer group based on a control strategy corresponding to the target stroboscopic signal state, and the timer group includes a lighting timer and a turning-off timer.

[0024] In some embodiments, the control module is configured to, when detecting the signal falling edge, activate the lighting timer in the timer group and control the fill light module to turn off; when the lighting timer reaches a first timer duration, activate the turning-off timer in the timer group and control the fill light module to turn on; when the turning-off timer reaches a second timer duration, activate the lighting timer in the timer group and control the fill light module to turn off.

[0025] In some embodiments, the control module is configured to activate the light-off timer in the timer group and control the light supplement module to turn on when a signal rising edge is detected; activate the light-on timer in the timer group and control the light supplement module to turn off when the light-off timer reaches a second timer duration; and activate the light-off timer in the timer group and control the light supplement module to turn on when the light-on timer reaches a first timer duration.

[0026] In some embodiments, the second timer duration is greater than or equal to the single exposure duration of the camera module, and the frame duration is an integer multiple of the sum of the first timer duration and the second timer duration.

[0027] In some embodiments, the control module is further configured to reset the light-on timer and the light-off timer when the target stroboscopic signal state is detected.

[0028] In some embodiments, the control module is configured to receive a first stroboscopic signal sent by the main camera module or a second stroboscopic signal sent by the slave camera module; control the main light supplement module corresponding to the main camera module to perform periodic light supplement when the target stroboscopic signal state of the first stroboscopic signal is detected; and control the slave light supplement module corresponding to the slave camera module to perform periodic light supplement when the target stroboscopic signal state of the second stroboscopic signal is detected, where the slave light supplement module is different from the main light supplement module.

[0029] In some embodiments, the frame synchronization interface of the main camera module is connected to the frame synchronization interface of the slave camera module, and the frame synchronization interface of the main camera module is configured to output a state, and the frame synchronization interface of the slave camera module is configured to input a state; the main camera module is configured to send the frame synchronization signal to the slave camera module through the frame synchronization interface when a single exposure is completed.

[0030] In some embodiments, the main camera module is configured to send the frame synchronization signal to the slave camera module through the frame synchronization interface when a signal falling edge of the stroboscopic signal is detected, where the stroboscopic signal is used to indicate light supplement, and the signal falling edge corresponds to the end moment of exposure.

[0031] In some embodiments, the main camera module is configured to perform periodic exposure based on an exposure frequency and a single exposure duration when the first exposure control signal is received, where the exposure frequency is configured by the control module.

[0032] In some embodiments, the control module is configured to send the first exposure control signal to the main imaging module when it is recognized that there is an object to be photographed within the photographing range; and send a second exposure control signal to the main imaging module when it is recognized that the object to be photographed has left the photographing range; the main imaging module is configured to stop periodic exposure when receiving the second exposure control signal.

[0033] On the other hand, an embodiment of the present application provides an image acquisition device. The image acquisition device includes a fill light, a main camera, a secondary camera, a controller, and a memory. At least one program is stored in the memory, and the at least one program is loaded and executed by the controller to implement the image acquisition method as described in the above aspect.

[0034] On the other hand, a computer-readable storage medium is provided. At least one program is stored in the readable storage medium, and the at least one program is loaded and executed by a controller to implement the image acquisition method as described in the above aspect.

[0035] On the other hand, an embodiment of the present application provides a computer program product or a computer program. The computer program product includes computer instructions. The computer instructions are stored in a computer-readable storage medium. A controller of an image acquisition device reads the computer instructions from the computer-readable storage medium, and the controller executes the computer instructions to implement the image acquisition method as described in the above aspect.

[0036] In an embodiment of the present application, the image acquisition device includes at least two cameras, and there is a main camera among them. The controller controls the main camera to perform periodic exposure by sending a first exposure control signal to the main camera, and the main camera sends a frame synchronization signal to the secondary camera after a single exposure, so as to control the secondary camera to perform exposure. During this process, the controller only needs to control the main camera to start exposure, and the frame synchronization signal sent by the main camera can control the secondary camera, which can avoid simultaneous exposure of the main camera and the secondary camera, reduce the power consumption of the image acquisition device during exposure, and moreover, send a frame synchronization signal to the secondary camera after the single exposure of the main camera, which can enable the secondary camera to perform periodic exposure at the same frame rate as the main camera. In addition, the controller also controls the fill light to perform periodic fill light, and the fill light period of the fill light covers the exposure period of the camera, that is, the fill light remains on during the exposure period of the camera, so as to avoid underexposure and ensure the quality of the acquired image. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0038] Figure 1 Shows a schematic diagram of a main control chip independently controlling two cameras;

[0039] Figure 2 Shows a schematic diagram of a camera control scheme;

[0040] Figure 3 Shows a schematic diagram of another camera control scheme;

[0041] Figure 4 Shows a timing diagram of the exposure of two cameras;

[0042] Figure 5 Shows a timing diagram of an exposure and fill light;

[0043] Figure 6 Shows a schematic diagram of a palmprint recognition device provided by an exemplary embodiment of the present application;

[0044] Figure 7 Shows a flowchart of an image acquisition method provided by an exemplary embodiment of the present application;

[0045] Figure 8 Shows a schematic diagram of an image acquisition device provided by an exemplary embodiment of the present application;

[0046] Figure 9 Shows a timing diagram of the exposure of a camera provided by an exemplary embodiment of the present application;

[0047] Figure 10 Shows a schematic diagram of an image acquisition device including two slave cameras provided by an exemplary embodiment of the present application;

[0048] Figure 11 Shows a schematic diagram of an image acquisition device including two slave cameras provided by another exemplary embodiment of the present application;

[0049] Figure 12 Shows a schematic diagram of a fill light period and an exposure period provided by an exemplary embodiment of the present application;

[0050] Figure 13 Shows a timing diagram of the fill light of a fill light and the exposure of a camera provided by an exemplary embodiment of the present application;

[0051] Figure 14 Shows the timing diagram of fill light supplement and camera exposure provided by another exemplary embodiment of the present application;

[0052] Figure 15 Shows the schematic structural diagram of an image acquisition device provided by an exemplary embodiment of the present application;

[0053] Figure 16 Shows the schematic diagram of the controller structure provided by an exemplary embodiment of the present application;

[0054] Figure 17 Shows the timing diagram of main fill light and slave fill light for light supplement provided by an exemplary embodiment of the present application;

[0055] Figure 18 Shows the schematic diagram of an image acquisition device provided by an exemplary embodiment of the present application;

[0056] Figure 19 Shows the structural diagram of an image acquisition device provided by an exemplary embodiment of the present application. Detailed implementation manners

[0057] To make the objectives, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0058] Nowadays, when performing identity verification, user identity feature images are often collected as samples, such as fingerprint images, face images, palmprint images, etc., and the features of the collected images are extracted to obtain image features, so as to compare with the identity image features saved in advance to determine whether the identity verification is passed. Moreover, to ensure that the obtained user image features are more comprehensive, multiple cameras may be used for image acquisition simultaneously, so as to obtain image features in different aspects. For example, when performing face recognition, an infrared camera can be used to capture infrared images for live detection to ensure that the object for face recognition is a live body, and at the same time an RGB camera is used to capture images, so as to perform face feature comparison and achieve face recognition.

[0059] When using multiple cameras for image acquisition, the following two camera exposure control schemes are proposed in the related art.

[0060] In related art solution one, the identity verification device independently controls two cameras. Schematically, please refer to Figure 1, which shows a schematic diagram of a main control chip independently controlling two cameras. The figure includes a main control chip 101, a camera A 102, and a camera B 103. The main control chip 101 is independently connected to and controls the camera A 102 and the camera B 103 respectively. The main control chip 101 includes an IIC (Inter-Integrated Circuit) controller (or I2C controller) for sending an initialization signal (II2 signal) to the camera A 102 or the camera B 103, which may include timing signals, exposure duration, etc. The main control chip 101 is connected to the camera A 102 and the camera B 103 respectively through GPIO (General Propose Input Output) for sending a reset signal and an enable signal to the camera A 102 and the camera B 103. The main control chip 101 also includes an MIPI (Mobile Industry Processor Interface) controller for sending a main clock signal (mclk signal) to the camera A 102 and the camera B 103 respectively, and receiving the image data collected by the camera A 102 and the camera B 103. And the main control chip 101 also includes a clock for sending an MIPI clock signal to the camera A 102 and the camera B 103 respectively. Among them, the main clock signal is the internal clock for driving the camera A 102, and the main clock signal determines the working speed of the camera. The MIPI clock signal refers to the clock signal of the MIPI interface, which is the clock signal for controlling the synchronous transmission of image data.

[0061] Schematically, please refer to Figure 2 , which shows a schematic diagram of a camera control scheme. It includes a main control chip 201, a first camera 202, and a second camera 203. The main control chip 201 controls the first camera 202 and the second camera 203 respectively. The main control chip sends an initialization signal, a main clock signal, etc. to the first camera 202 and the second camera 203 respectively. The first camera 202 and the second camera 203 will send a strobe signal (strobe signal) to the main control chip during the camera exposure process, and the strobe signal is in a high level state. And after a single exposure of the camera, the first camera 202 and the second camera 203 will send the collected image data to the main control chip. During the above process, the camera is in the Continue (continuous) mode, and the main control chip independently controls the first camera and the second camera, and various signals are respectively sent by the main control signal to the first camera and the second camera.

[0062] In the second related technical solution, in the main control chip of the identity authentication device, the camera A and the camera B are connected through PWM (Pulse Width Modulation) or GPIO to control the FSYNC (Frame SYNC) signal to achieve synchronous control of the camera A and the camera B. Schematically, please refer to Figure 3 , which shows a schematic diagram of a camera control solution of the present application. Among them, the main control chip 301 sends initialization information and a main clock signal to the first camera 302 and the second camera 303. And, both cameras return a stroboscopic signal and image data to the main control chip. In the main control chip, the frame synchronization signal is sent to the first camera 302 and the second camera 303 respectively through PWM or GPIO, so as to achieve synchronous control of the first camera 302 and the second camera 303. In the above process, the camera is in the Master-Slave mode, and the external host realizes synchronous control through PWM or GPIO.

[0063] In the first related technical solution above, the two cameras are respectively controlled by the main control chip, and continuous exposure can be achieved. Please refer to Figure 4 , which shows the exposure timing diagram of the two cameras. Among them, at the end of a single frame, the camera exposes. During the exposure process of the camera, the stroboscopic signal is at a high level, and at the end of the exposure, the sensor sends a frame synchronization signal. And in response to detecting the rising edge of the frame synchronization signal, the sensor sends the image data collected in a single frame to the main control chip, and the corresponding MIPI read signal is at a low level. After the image data is sent, the MIPI read signal becomes high level. In the figure, the exposure times of camera A and camera B overlap. Since the two cameras work simultaneously, the average current and peak power consumption are relatively high, that is, the overall power consumption is large.

[0064] Please refer to Table 1, which shows the comparison of the advantages and disadvantages of the first related technical solution and the second related technical solution above.

[0065] Table 1

[0066]

[0067] In the first related technical solution, the main control chip independently controls the two cameras respectively, and the implementation method is relatively simple and suitable for continuous shooting. However, since the two cameras may expose simultaneously, the peak power consumption during simultaneous exposure is relatively high.

[0068] In the second related technical solution, the time difference between the exposures of the first camera and the second camera can be preset to avoid high power consumption caused by simultaneous exposure of the two cameras. However, since the main control chip controls the camera to perform exposure through the FSIN (frame synchronization signal), the PWM drive and the camera drive need to be synchronized, which is of high complexity. Moreover, the synchronous control relies on a high-precision clock to ensure that the time difference between the main control chip sending the FSIN signal to the two cameras conforms to the set time difference. In addition, since system scheduling is required for camera exposure control by PWM, there will be a delay in system scheduling outside the set time difference, so it cannot be guaranteed that the time difference between the exposures of the two cameras conforms to the set time difference.

[0069] Therefore, to simultaneously solve the problems existing in the above-mentioned first related technical solution and the second related technical solution, that is, to achieve precise synchronous control while reducing the peak power consumption, the embodiment of the present application provides an image acquisition method. Only the controller is used to control the main camera to perform exposure, and then the frame synchronization signal sent by the main camera is used to control the slave camera to perform exposure, which can ensure that the exposure times of the main camera and the slave camera are staggered, reducing the peak power consumption. And it does not need to rely on a high-precision clock, and can ensure that the time difference between the exposures of the main camera and the slave camera is fixed. Since no system scheduling is required, no additional delay will be generated.

[0070] On the other hand, since the quality of the image captured by the camera will affect the result of identity verification, for example, if underexposure occurs during the exposure of the camera, the quality of the captured image will be low, resulting in inaccurate identity verification results.

[0071] Figure 5 Shows a timing diagram of exposure and fill light. Among them, the high level of the fill light is the lit state, the low level is the unlit state, and the high level of the stroboscopic signal indicates that the camera is performing exposure. In the first frame, the fill light is in the unlit state corresponding to the exposure period of the camera, so the camera has invalid exposure. In the third frame, the fill light first lights up and then dims during the exposure period, resulting in underexposure, so the quality of the obtained image is poor.

[0072] Therefore, the solution provided by the embodiment of the present application can align the fill light period with the exposure period, thereby avoiding invalid exposure and underexposure states while reducing power consumption as much as possible.

[0073] The image acquisition method provided by the embodiment of the present application can be applied to at least the following scenarios.

[0074] 1. Palmprint recognition scenario.

[0075] In the palmprint recognition scenario, a palmprint recognition device is required to capture the user's palmprint. Please refer to Figure 6, which shows a schematic diagram of a palmprint recognition device provided by an exemplary embodiment of the present application. In the figure, the palmprint recognition device 610 includes a first camera 611, a second camera 612, a fill light 613, an infrared emitting component 614, and a controller (not shown in the figure). The first camera 611 and the second camera 612 include an RGB (Red-Green-Blue) camera and an infrared camera, with the first camera 611 serving as the main camera. The infrared emitting component 614 is used to emit infrared light. The infrared light emitted by the infrared emitting component 614 illuminates an object and causes diffuse reflection. The reflected infrared light is received by the infrared camera, thereby obtaining image data. During the palmprint recognition process, the infrared camera can obtain the vein pattern of the palm as an identity feature for palmprint recognition. During the palmprint recognition process, the controller sends a first exposure control signal to the first camera 611 to control the first camera to perform periodic exposure. After a single exposure, the first camera 612 sends a frame synchronization signal to the second camera 613 to control the second camera 613 to perform exposure. Furthermore, during the exposure period, the controller controls the fill light 613 to provide fill light, and the main camera and the slave camera transmit the collected palm print image data to the controller.

[0076] 2. Face recognition scenario.

[0077] In a face recognition scenario, a face recognition device is required to capture a user's face image. The face recognition device includes a controller and at least two cameras. In this embodiment, a face recognition device including a first camera and a second camera is taken as an example. The first camera is a master camera and the second camera is a slave camera. In the process of capturing face images, the controller in the face recognition control device sends a first exposure signal to the first camera, thereby controlling the first camera to perform periodic exposure, and the first camera sends a frame synchronization signal to the second camera to control the slave camera to perform exposure. The controller controls the fill light to perform periodic fill light based on the camera's exposure period to avoid underexposure. The first camera and the second camera both transmit the captured face image data to the controller for the controller to perform facial feature comparison to obtain face recognition results.

[0078] In addition, the solution provided in the embodiments of the present application can also be applied to other identity authentication scenarios, or to multi-camera image acquisition devices that require image acquisition. The embodiments of the present application only use the above two application scenarios as examples to illustrate the camera exposure control and fill light control methods in the image acquisition device.

[0079] It should be noted that the information (including but not limited to user palmprint images, user face images, etc.), data (including but not limited to data for analysis, stored data, displayed data, etc.), and signals involved in this application are all authorized by the user or fully authorized by all parties, and the collection, use, and processing of relevant data need to comply with the relevant laws, regulations, and standards of relevant countries and regions.

[0080] Before and during the process of collecting relevant data of the user, this application can display a prompt interface, pop-up window, or output voice prompt information. The prompt interface, pop-up window, or voice prompt information is used to prompt the user that their relevant data is currently being collected, so that this application only starts to execute the relevant steps of obtaining the user's relevant data after obtaining the confirmation operation of the user on the prompt interface or pop-up window. Otherwise (that is, when the confirmation operation of the user on the prompt interface or pop-up window is not obtained), the relevant steps of obtaining the user's relevant data are ended, that is, the relevant data of the user is not obtained.

[0081] Please refer to Figure 7 , which shows a flowchart of an image acquisition method provided by an exemplary embodiment of this application. This method is used for an image acquisition device, and the image acquisition device includes a fill light, a main camera, a secondary camera, and a controller. This method includes the following steps.

[0082] Step 701, the controller sends a first exposure control signal to the main camera.

[0083] Before sending the first exposure control signal to the main camera, the controller will also send an initialization signal, a reset signal, a main clock signal, etc. to the main camera to ensure that the main camera can start to perform exposure.

[0084] Among them, in addition to controlling the camera to perform exposure, the main controller can also control the fill light to perform fill light, or perform image data processing on the image data returned by the received camera, etc. For example, in the case where the image acquisition device is a palmprint recognition device, the controller sends a first exposure control signal to the main camera to control the camera to perform exposure, and after the main camera performs exposure and sends the acquired image data to the controller, the controller performs image feature extraction on the received image data to determine the palmprint features to be recognized, and compares them with the pre-stored palmprint features to obtain the palmprint recognition result.

[0085] Optionally, the end of a single exposure of the main camera is regarded as the end of a frame, and then the camera sends the image data collected in the previous frame to the controller.

[0086] Optionally, the main camera includes a main sensor. The controller sends a first exposure control signal to the main sensor. The main sensor performs exposure when receiving the first exposure control signal, and sends a frame synchronization signal to the slave sensor in the slave camera, thereby controlling the slave sensor to perform exposure.

[0087] Step 702, when receiving the first exposure control signal, the main camera performs periodic exposure.

[0088] Among them, the frequency of the main camera performing periodic exposure is the same, and the exposure duration of each exposure of the camera is also the same. Exposure refers to the amount of light irradiating on the camera sensor, which determines the brightness of the image.

[0089] Optionally, after the controller is connected to the camera, the controller sends the exposure duration and exposure frequency to the main camera. During the subsequent process of the controller controlling the main camera to perform exposure, the exposure duration and exposure frequency do not change.

[0090] Optionally, in response to the user's modification operation, the controller sends the modified exposure duration and exposure frequency to the main camera. Before receiving the user's modification operation again, the exposure duration and exposure frequency do not change.

[0091] Optionally, when the controller sends the first exposure signal to the main camera, it also sends the exposure frequency to the main camera. When receiving the exposure frequency and the first exposure signal, the main camera performs periodic exposure according to the received exposure frequency.

[0092] The frame rate of the main camera for collecting images is related to the exposure frequency of the camera. Each time the camera performs an exposure, it can collect one frame of image. Therefore, the higher the exposure frequency of the camera, the greater the frame rate.

[0093] Step 703, when a single exposure is completed, the main camera sends a frame synchronization signal to the slave camera.

[0094] That is, every time the main camera completes an exposure, the main camera sends a frame synchronization signal to the slave camera. After the main camera is exposed, the frame synchronization signal switches to a high level. Then, in response to the rising edge of the frame synchronization signal, the camera sends the collected image signal to the controller. In addition, in the solution provided by the embodiments of the present application, the frame synchronization signal can also be used to control the exposure of the slave camera.

[0095] Since the main camera sends the frame synchronization signal when a single exposure is completed, the frequency of the slave camera receiving the frame synchronization signal is consistent with the exposure frequency of the main camera. Furthermore, the exposure frequency of the slave camera is consistent with that of the main camera, so the frame rate of the slave camera for collecting images is consistent with that of the main camera.

[0096] Step 704, in the case of receiving a frame synchronization signal, perform exposure from the camera.

[0097] In the case of receiving a frame synchronization signal once, perform one exposure from the camera. Since the main camera sends a frame synchronization signal to the slave camera when a single exposure is completed, the frequency of the frame synchronization signal received by the slave camera is the same as the exposure frequency of the main camera. Furthermore, the exposure frequency of the slave camera is the same as that of the main camera, so the frame rate of the images captured by the slave camera is the same as that of the main camera. For example, if the frame rate of the main camera is 25fps, that is, the camera captures 25 frames of images in one second, then the main camera performs 25 exposures in one second. After each exposure, a frame synchronization signal is sent to the slave camera, that is, 25 frame synchronization signals are sent in one second, so that the slave camera also performs 25 exposures in one second, and the frame rate is also 25fps.

[0098] Performing exposure when the slave camera receives the frame synchronization signal sent by the main camera can enable the slave camera and the main camera to perform exposure at staggered peaks, avoiding overheating of the image acquisition device caused by excessive peak power consumption. Moreover, without the need for the controller to have a high-precision clock, the time difference between the exposure of the main camera and the slave camera can be kept stable.

[0099] Step 705, the controller controls the fill light to perform periodic fill light based on the exposure moment of the camera, and the fill light period of the fill light covers the exposure period of the camera.

[0100] During the exposure period of the camera, the fill light needs to be in the on state to fill light the object to be photographed. Therefore, the controller controls the fill light to perform periodic fill light based on the exposure moment of the camera. The fill light frequency of the fill light is the same as the exposure frequency of the camera. Moreover, to avoid underexposure of the camera caused by the fill light turning on first and then off or off first and then on during the exposure period, the fill light period of the fill light should cover the exposure period of the camera.

[0101] For example, if the fill light duration of the fill light is 3ms and the exposure duration of the camera is 5ms, even if the fill light starts to fill light from the moment when the slave camera starts to expose, the fill light will still be in the off state during the last 2ms of the camera exposure, which will cause underexposure. Therefore, the fill light duration of the fill light should be greater than the exposure duration of the camera.

[0102] Step 706, the main camera and the slave camera transmit the captured image data to the controller.

[0103] After the capture of the last frame of the main camera and the slave camera after a single exposure is completed, the frame synchronization signal will turn to high level, which will trigger the main camera and the slave camera to send the image data captured in the previous frame to the controller.

[0104] Optionally, after the controller acquires the image data, it processes the image data to obtain image features for subsequent operations. For example, in a face recognition device, the controller extracts face features based on the received image data to obtain the face features to be recognized, and then compares the face features with the pre-stored face features to obtain the face recognition result.

[0105] In summary, in the embodiment of the present application, the image acquisition device includes at least two cameras, and there is a main camera among them. The controller controls the main camera to perform periodic exposure by sending a first exposure control signal to the main camera, and the main camera sends a frame synchronization signal to the slave camera after a single exposure, so as to control the slave camera to perform exposure. In this process, the controller only needs to control the main camera to start exposure, and the slave camera can be controlled by the frame synchronization signal sent by the main camera, which can avoid the main camera and the slave camera from performing exposure at the same time, reduce the power consumption of the image acquisition device for exposure, and moreover, sending a frame synchronization signal to the slave camera after a single exposure of the main camera can enable the slave camera to perform periodic exposure at the same frame rate as the main camera. In addition, the controller also controls the fill light to perform periodic fill light, and the fill light period of the fill light covers the exposure period of the camera, that is, the fill light remains on during the exposure period of the camera, so as to avoid underexposure and ensure the quality of the captured images.

[0106] In the embodiment of the present application, the controller only sends a first exposure signal to the main camera to control the main camera to perform exposure. The slave camera is controlled by the frame synchronization signal sent by the main camera. Therefore, the frame synchronization interface of the main camera is connected to the frame synchronization interface of the slave camera, and the frame synchronization interface of the main camera is configured to output status, and the frame synchronization interface of the slave camera is configured to input status. When the frame synchronization interface of the main camera is configured to output status, the main camera can only send signals externally through this interface and cannot receive signals through this interface. When the frame synchronization interface of the slave camera is configured to input status, the camera can only receive signals through this interface and cannot send signals externally through this interface.

[0107] Then, when a single exposure is completed, the main camera sends a frame synchronization signal to the slave camera through the frame synchronization interface. Correspondingly, the slave camera performs exposure in response to the frame synchronization signal received by the frame synchronization interface.

[0108] Optionally, a master-slave synchronization control relationship is formed between the main camera and the slave camera, and the main camera controls the slave camera to perform exposure.

[0109] Schematically, please refer to Figure 8, which shows a schematic diagram of an image acquisition device provided by an exemplary embodiment of the present application. It includes a controller 801, a main camera 802, and a slave camera 803. The controller 801 sends an initialization signal and a main clock signal to the main camera 802 and the slave camera 803 respectively. And, along with the exposure of the main camera 802 and the slave camera 803, the main camera 802 and the slave camera 803 send stroboscopic signals to the controller 801 respectively, and after the exposure, the main camera 802 and the slave camera 803 send the acquired image signals to the controller 801 respectively. Among them, the main camera 802 and the slave camera 803 are connected through a frame synchronization interface (FSYNC). The frame synchronization interface of the main camera 802 is configured to output the status, and the frame synchronization interface of the slave camera 803 is configured to input the status. The controller 801 sends a first exposure signal to the main camera through the IIC interface. Subsequently, the main camera 802 performs periodic exposure, and the main camera 802 sends a frame synchronization signal to the slave camera 803 through the frame synchronization interface to control the exposure of the slave camera 803.

[0110] The state of the camera during exposure can be reflected by the stroboscopic signal. During the exposure of the camera, the stroboscopic signal is in the high level state. During the period when the camera is not exposed, the stroboscopic signal is in the low level state. Therefore, when the main camera completes a single exposure, the stroboscopic signal will switch from high level to low level in a short time, that is, a signal falling edge is generated. Therefore, when the signal falling edge of the stroboscopic signal is detected, the main camera sends a frame synchronization signal to the slave camera through the frame synchronization interface.

[0111] Among them, the stroboscopic signal can also be used to indicate the fill light for filling light. And since the stroboscopic signal switches to high level at the end of the exposure of the main camera, the signal falling edge corresponds to the end of the exposure.

[0112] Please refer to Figure 9, which shows the timing diagram of the camera exposure provided by an exemplary embodiment of the present application. It includes the main camera exposure timing diagram and the slave camera exposure timing diagram. During the exposure process of the main camera, the first strobing signal is in the high level state, and at the end of the exposure, the first strobing signal switches to the low level state, generating a signal falling edge of the first strobing signal. When the signal falling edge of the first strobing signal is detected, the main camera sends a frame synchronization signal to the slave camera. When the slave camera receives the frame synchronization signal (i.e., the corresponding frame synchronization signal falling edge), the slave camera will start to expose. During the exposure period of the slave camera, the second strobing signal is in the high level state. At the end of the exposure of the slave camera, the second strobing signal also switches to the low level. When the signal falling edge of the second strobing signal is detected, the corresponding frame synchronization signal of the slave camera switches to the high level. In addition, the main camera and the slave camera send the collected image data to the controller in response to the signal rising edge of the frame synchronization signal, and the corresponding MIPI readout signal switches to the low level. After the image data is sent, the MIPI readout signal is switched back to the high level again. In the figure, both the main camera and the slave camera send the collected image data to the controller after each exposure ends.

[0113] In a possible implementation, there are multiple cameras in the image acquisition device. Then, there is one main camera and at least two slave cameras among the multiple cameras. There may be two connection methods for the frame synchronization interfaces between the main camera and the slave cameras. Here, taking the case where there are three cameras in the image acquisition device as an example, the connection methods of the frame synchronization interfaces will be described.

[0114] Method 1: The frame synchronization interfaces of the slave cameras are all connected to the frame synchronization interface of the main camera.

[0115] The frame synchronization interface of the main camera is configured in the output state, and the frame synchronization interface of each slave camera is configured in the input state. Then, when the main camera completes a single exposure, the main camera sends a frame synchronization signal to the slave cameras through the frame synchronization interface, which can stagger the exposure periods of the main camera and each slave camera, and can reduce the peak power consumption to a certain extent.

[0116] Please refer to Figure 10, which shows a schematic diagram of an image acquisition device including two slave cameras provided by an exemplary embodiment of the present application. It includes a controller 1001, a main camera 1002, a first slave camera 1003, and a second slave camera 1004. The controller 1001 sends initialization signals, main clock signals, etc. to multiple cameras respectively, and each camera sends a stroboscopic signal and the acquired image data to the controller 1101. When controlling the camera to perform exposure, the controller 1001 sends a first exposure control signal to the main camera 1002. After the main camera 1002 completes a single exposure, it sends frame synchronization signals to the first slave camera 1003 and the second slave camera 1004 respectively to control the first slave camera 1003 and the second slave camera 1004 to perform exposure.

[0117] Method 2: When the camera supports being both the receiver and sender of the frame synchronization signal, the frame synchronization interfaces of multiple slave cameras are connected in sequence.

[0118] Optionally, there are two frame synchronization interfaces in the first slave camera. One frame synchronization interface is set to the input state and connected to the main camera, and the other frame synchronization interface is set to the output state and connected to the second slave camera. Optionally, when the main camera completes a single exposure, the main camera sends a frame synchronization signal to the first slave camera through the frame synchronization interface. When the first slave camera receives the frame synchronization signal, it performs exposure. When the first slave camera completes a single exposure, the first slave camera sends a frame synchronization signal to the second slave camera through the frame synchronization interface to control the second slave camera to perform exposure.

[0119] Through this connection method, sequential exposure of multiple cameras can be achieved, thus avoiding excessive peak power consumption and causing device heating.

[0120] Please refer to Figure 11 , which shows a schematic diagram of an image acquisition device including two slave cameras provided by another exemplary embodiment of the present application. It includes a controller 1101, a main camera 1102, a first slave camera 1103, and a second slave camera 1104. The controller 1101 sends a first exposure control signal to the main camera 1102. After the main camera 1102 completes a single exposure, it sends a frame synchronization signal to the first slave camera 1103 to control the first slave camera 1103 to perform exposure, and when the first slave camera 1103 completes a single exposure, it sends a frame synchronization signal to the second slave camera 1104 to control the second slave camera 1104 to perform exposure. In addition, the IIC interface and GPIO interface, etc. between the controller and each camera are connected to achieve the transmission of other control signals and image data.

[0121] In the embodiments of the present application, the main camera sends a frame synchronization signal to the slave camera through a frame synchronization interface to control the slave camera to perform exposure, which can ensure that the exposure frame rate of the slave camera is consistent with that of the main camera, and perform staggered exposure to avoid high peak power consumption.

[0122] In a possible implementation manner, in order to avoid large power consumption caused by continuous exposure of the camera, the controller will identify the shooting range and control the camera to perform exposure only when a subject to be photographed is identified.

[0123] When it is identified that there is a subject to be photographed within the shooting range, the controller sends a first exposure control signal to the main camera.

[0124] When it is identified that there is a subject to be photographed within the shooting range, it indicates that the image acquisition device currently needs to perform shooting. Therefore, the controller sends a first exposure control signal to the main camera, and the main camera sends a frame synchronization signal to the slave camera to control the slave camera to perform exposure.

[0125] For example, in a palmprint recognition scenario, the image acquisition device is a palmprint recognition device. Usually, the palmprint recognition device should be fixed at a certain position for identity verification. Then, when there is no object to be verified currently, it is expected that the camera in the palmprint recognition device does not perform exposure. Therefore, when it is identified that there is a user or a palm within the shooting range, the controller sends a first exposure control signal to the main camera, so that after the main camera completes a single exposure, it sends a frame synchronization signal to the slave camera to control the slave camera to perform exposure.

[0126] After the palmprint recognition device starts periodic exposure, the subject to be photographed may leave the shooting range. Therefore, when it is identified that the subject to be photographed has left the shooting range, the controller sends a second exposure control signal to the main camera, and this second exposure control signal is used to control the main camera to stop periodic exposure. When receiving the second exposure control signal, the main camera stops periodic exposure.

[0127] Since the main camera stops performing periodic exposure, the main camera will no longer send a frame synchronization signal to the slave camera, so the slave camera no longer performs exposure. It can avoid excessive power consumption caused by the camera still performing exposure after the subject to be photographed leaves the shooting range, resulting in waste of device processing resources.

[0128] For example, in a palmprint recognition scenario, after the user performs palmprint recognition and the palm is a certain distance away from the device, continuous exposure is not required. Therefore, after detecting that the palm has left the shooting range, the controller sends a second exposure control signal to the main camera, so that the main camera stops periodic exposure, and then the slave camera stops exposure.

[0129] Optionally, the image capturing device includes an induction detector that can emit infrared signals or microwave signals, so as to be able to sense whether there is an object to be captured within the capturing range. In addition, other methods can also be used to identify whether there is an object to be captured within the capturing range. The specific method for identifying the object to be captured within the capturing range in this embodiment is not limited.

[0130] In the embodiment of the present application, by identifying whether there is an object to be captured within the capturing range to determine whether the controller sends an exposure control signal to the main camera, it is possible to avoid the camera still performing periodic exposure when there is no object to be captured within the current capturing range, thus avoiding waste of power consumption.

[0131] The stroboscopic signal sent by the camera can represent the exposure state of the current camera. When the stroboscopic signal is in the high level state, the camera is in the exposure state, and when the stroboscopic signal is in the low level state, the camera is in the non-exposure state. Therefore, the fill light can be controlled to perform fill light according to the state of the stroboscopic signal, so that the fill light stage covers the camera exposure stage.

[0132] First, the controller receives the stroboscopic signal sent by the camera, and the stroboscopic signal is used to indicate fill light.

[0133] The controller may detect four situations of the high level, low level, signal rising edge, and signal falling edge of the stroboscopic signal. When the stroboscopic signal is in the high level, the camera is in the exposure state, and when the stroboscopic signal is in the low level state, the camera is in the non-exposure state. At the moment when the camera starts to expose, the stroboscopic signal switches from the low level to the high level, generating a rising edge of the stroboscopic signal. At the moment when the camera stops exposing, the stroboscopic signal switches from the high level to the low level, generating a falling edge of the stroboscopic signal.

[0134] Subsequently, when the target stroboscopic signal state is detected, the controller controls the fill light to perform periodic fill light.

[0135] Among them, the target stroboscopic signal state includes the signal rising edge and the signal falling edge. The signal rising edge corresponds to the exposure start moment, and the signal falling edge corresponds to the exposure end moment.

[0136] Since fill light needs to be performed by the fill light during the exposure period, in order to avoid high power consumption caused by the fill light being constantly on, the exposure start moment and the exposure end moment can be used as the basis for controlling the turn-on and turn-off of the fill light, that is, the signal rising edge and the signal falling edge of the stroboscopic signal are used as the basis for controlling the turn-on and turn-off of the fill light.

[0137] In a possible implementation, different control strategies are configured in the controller for different target stroboscopic signal states. For example, when the falling edge of the stroboscopic signal is detected, it indicates the end of exposure, and then the controller needs to control the supplementary light to turn off. When the rising edge of the stroboscopic signal is detected, it indicates the start of exposure, and then the controller needs to control the supplementary light to turn on.

[0138] Therefore, when the target stroboscopic signal state is detected, the controller controls the supplementary light to perform periodic supplementary lighting based on the control strategy corresponding to the target stroboscopic signal state through the timer group, so that the supplementary lighting period covers the exposure period.

[0139] Schematically, please refer to Figure 12 which shows a schematic diagram of the supplementary lighting period and the exposure period provided by an exemplary embodiment of the present application. When the stroboscopic signal is at a high level, the camera performs exposure, and the supplementary lighting period of the supplementary light (at a high level) completely covers the exposure period of the camera, which can ensure that the supplementary light is in the on state throughout the exposure period.

[0140] Among them, the timer group includes a lighting timer and a turning-off timer. The controller controls the supplementary light to perform periodic supplementary lighting according to the timing states of different timers in the timer group.

[0141] The timer is set with a timer duration. After the timer is activated, the timer starts timing. When the timing duration reaches the timer duration, it triggers the controller to control the supplementary light according to the control strategy.

[0142] When the supplementary light is controlled to perform periodic supplementary lighting through the timer, it is necessary to set the timing durations of the lighting timer and the turning-off timer to ensure that the supplementary light is in the on state during the exposure period.

[0143] Optionally, the lighting timer corresponds to a first timer duration, and the turning-off timer corresponds to a second timer duration. During the timing of the turning-off timer, when the supplementary light is in the on state, it is necessary to make the on duration of the supplementary light greater than or equal to the exposure duration of the camera. Therefore, the second timer duration should be greater than or equal to the single exposure duration of the camera. On the other hand, since the lighting timer and the turning-off timer alternate in timing, and the exposure period is in the last period of a frame, therefore, while ensuring that the lighting duration is greater than the exposure duration, it is also necessary to ensure that the frame duration is an integer multiple of the sum of the first timer duration and the second timer duration, so as to ensure that the supplementary light remains lit during the exposure period of the camera.

[0144] For example, if the frame rate of the camera is 25fps, the frame duration is 40ms. Assuming the exposure duration is 5ms, since the duration of the second timer should be greater than or equal to the single exposure duration of the camera, the duration of the second timer can be set to 6ms, and it is required that the frame duration is an integer multiple of the sum of the duration of the first timer and the duration of the second timer, then the duration of the first timer can be 4ms.

[0145] Optionally, there may be the following two situations when the controller controls the fill light to perform periodic fill light through the timer group.

[0146] First, the target stroboscopic signal state is the signal falling edge.

[0147] Then, in the case of detecting the signal falling edge, the controller activates the lighting timer in the timer group and controls the fill light to turn off. Subsequently, when the lighting timer reaches the duration of the first timer, the controller activates the extinguishing timer in the timer group and controls the fill light to turn on. And when the extinguishing timer reaches the duration of the second timer, the controller activates the lighting timer in the timer group and controls the fill light to turn off.

[0148] Detecting the signal falling edge indicates that the current camera exposure is over, and at this time, the fill light is not required for fill light. Therefore, the fill light is controlled to turn off in the case of detecting the signal falling edge. At the same time, it is also necessary to activate the lighting timer in the timer group. During the process of the lighting timer starting to count, the fill light remains off. When the counting duration reaches the pre-set duration of the first timer, the controller controls the fill light to turn on and activates the extinguishing timer. During the counting process of the extinguishing timer, the fill light remains on. Subsequently, if the extinguishing timer reaches the pre-set duration of the second timer, it is necessary to control the fill light to turn off. Thus, by alternately activating the lighting timer and the extinguishing timer in the timer group, the fill light period can cover the camera exposure period.

[0149] Optionally, in the case of detecting the signal falling edge, the controller triggers an interrupt and activates the timer group to start counting. Then, it is necessary to configure the lighting timer and the extinguishing timer in advance. For example, set the first timer and the second timer through the ktime_set() function, and the timer can be initialized through the hrtimer_init() function.

[0150] Optionally, in the case of detecting the signal falling edge of the stroboscopic signal, the controller triggers an interrupt and calls the pre-set lighting timer and extinguishing timer in the interrupt function.

[0151] When a signal falling edge is detected, an interrupt is triggered and the interrupt function is executed. The controller first controls the supplementary light to turn off and activates the lighting timer for timing. When the lighting timer reaches the first timer duration, the controller controls the supplementary light to turn on, and at the same time activates the extinguishing light timer. When the timing duration of the extinguishing light timer reaches the second timer duration, the controller controls the supplementary light to turn off and activates the lighting timer for timing.

[0152] Schematically, please refer to Figure 13 , which shows the supplementary light and the camera supplementary light timing diagram provided by an exemplary embodiment of the present application. In the figure, when a signal falling edge of the stroboscopic signal is detected, the controller controls the supplementary light to turn off and activates the lighting timer in the timer group. After the lighting timer is activated, it starts timing. During the timing process, the supplementary light is in the off state (low level). When the first timer duration is reached, the controller controls the supplementary light to turn on and activates the extinguishing light timer. During the timing process of the extinguishing light timer, the supplementary light in the figure is in the on state (high level). When the second timer duration is reached, the controller activates the lighting timer in the timer group and controls the supplementary light to turn off. Then the lighting timer and the extinguishing light timer alternate in timing to control the supplementary light to be periodically lit. Then, when the stroboscopic signal switches to high level (i.e., the camera starts to expose), the supplementary light remains on until a signal falling edge of the stroboscopic signal is detected again.

[0153] For example, if the camera frame rate is set to 25fps, the frame duration is 40ms, the first timer duration set by the lighting timer is 4ms, and the second timer duration set by the extinguishing light timer is 6ms. Then, when a signal falling edge is detected, the controller activates the lighting timer in the timer group and controls the supplementary light to turn off. The lighting timer starts timing first. When the first timer duration is reached, the controller controls the supplementary light to turn on and activates the extinguishing light timer. The sum of the first timer duration and the second timer duration is 10ms. In one frame, the lighting timer and the extinguishing light timer are respectively activated 4 times. The exposure period is the last period in one frame. Then, when the extinguishing light timer is activated for the last time, the controller controls the supplementary light to turn on, so that it can be ensured that the supplementary light is in the on state during the exposure period.

[0154] Second, the target stroboscopic signal state is a signal rising and falling edge.

[0155] First, when a signal rising edge is detected, the controller activates the extinguishing light timer in the timer group and controls the supplementary light to turn on. Subsequently, when the extinguishing light timer reaches the second timer duration, the controller activates the lighting timer in the timer group and controls the supplementary light to turn off. Similarly, when the lighting timer reaches the first timer duration, the controller activates the extinguishing light timer in the timer group and controls the supplementary light to turn on.

[0156] When a signal rising edge is detected, it indicates that the current camera starts to expose. At this time, the fill light needs to be turned on for filling light. Therefore, when the signal rising edge is detected, the controller controls the fill light to turn on. In addition, it is also necessary to activate the light-off timer in the timer group. During the time when the light-off timer starts to count, the fill light remains on. When the counted time reaches the preset second timer duration, the controller controls the fill light to turn off and activates the light-on timer. During the time when the light-on timer is counting, the fill light remains off. Subsequently, when the light-on timer reaches the preset first timer duration, it is necessary to control the fill light to turn on. Thus, by alternately activating the light-off timer and the light-on timer in the timer group, the fill light can be kept on during the exposure period of the camera.

[0157] Optionally, when the controller detects a signal rising edge, it triggers an interrupt and activates the timer group to start counting. Then, it is necessary to configure the light-on timer and the light-off timer in advance, as well as configure the interrupt function. The specific configuration process can refer to the configuration process shown in the above embodiments, and this embodiment will not be elaborated.

[0158] Schematically, please refer to Figure 14 , which shows the fill light and the fill light timing diagram of the camera provided by another exemplary embodiment of the present application. In the figure, when the signal rising edge of the stroboscopic signal is detected, the controller controls the fill light to turn on and activates the light-off timer in the timer group. After the light-off timer is activated, it starts to count. During the counting process, the fill light is in the on state (high level). When the second timer duration is reached, the controller controls the fill light to turn off and activates the light-on timer. During the time when the light-on timer is counting, corresponding to the figure, the fill light is in the off state (low level). When the first timer duration is reached, the controller re-activates the light-off timer in the timer group and controls the fill light to turn on. Then, the light-on timer and the light-off timer alternate in counting, controlling the fill light to be periodically lit. When the stroboscopic signal switches to the high level, the fill light remains on until the signal rising edge of the stroboscopic signal is detected again.

[0159] For example, if the camera frame rate is set to 25fps, the frame duration is 40ms. The first timer duration set by the lighting timer is 4ms, and the second timer duration set by the lighting-off timer is 6ms. In the case of detecting a rising edge of a signal, the controller activates the lighting-off timer in the timer group and controls the fill light to turn on, which can ensure that the fill light is on during the exposure period. The lighting-off timer starts timing first. When the second timer duration is reached, the fill light is controlled to turn off, and the lighting timer is activated. The sum of the first timer duration and the second timer duration is 10ms. The lighting timer and the lighting-off timer are respectively activated 4 times between two adjacent signal rising edges detected. And when a signal rising edge is detected, the fill light is turned on and the lighting-off timer is activated, which can ensure that the fill light is on during the exposure period.

[0160] In a possible implementation manner, the lighting timer and the lighting-off timer alternate in timing. Due to factors such as function calls during the controller's execution of the control strategy, after the lighting timer and the lighting-off timer alternate in timing for a period of time, the timer timing may become inaccurate, resulting in an offset between the fill light period and the exposure period. Therefore, in the case of detecting the state of the target stroboscopic signal, the lighting timer and the lighting-off timer are reset, thereby avoiding deviation between the fill light period and the exposure period.

[0161] Optionally, before activating the lighting timer each time, the lighting timer is reset first, and before activating the lighting-off timer each time, the lighting-off timer is reset first, which can also ensure the accuracy of the timer timing.

[0162] In a possible implementation manner, different fill lights exist in the image acquisition device and are respectively used for filling light during the exposure periods of different cameras.

[0163] Schematically, please refer to Figure 15 , which shows a schematic structural diagram of an image acquisition device provided by an exemplary embodiment of the present application. It includes an infrared light-emitting diode 1501, an RGB light guide ring 1502, an IR camera 1503, an RGB camera 1504, a main fill light 1505, and a slave fill light 1506. The infrared light-emitting diode 1501 is used to emit infrared rays so that the IR camera 1503 can obtain infrared image data according to the infrared ray reflection situation. The RGB light guide ring 1502 is used to control the light reception amount of the image sensor when the RGB camera 1504 takes pictures. It includes a plurality of fill lights. The main fill light 1505 and the slave fill light 1506 are arranged in a cross pattern and are respectively used for filling light for the IR camera 1503 and the RGB camera 1504, and the main fill light 1505 and the slave fill light 1506 are independently controlled.

[0164] Both the main camera and the secondary camera send stroboscopic signals to the controller. The controller receives the first stroboscopic signal sent by the main camera, or receives the second stroboscopic signal sent by the secondary camera.

[0165] Since different fill lights are independently controlled, when the target stroboscopic signal state of the first stroboscopic signal is detected, the controller controls the main fill light corresponding to the main camera to perform periodic fill light. When the target stroboscopic signal state of the second stroboscopic signal is detected, the controller controls the secondary fill light corresponding to the secondary camera to perform periodic fill light, and the secondary fill light is different from the main fill light.

[0166] For the fill lights corresponding to different cameras, the controller controls them separately based on their respective corresponding stroboscopic signals, which can meet the exposure requirements of each of the two cameras.

[0167] Schematically, please refer to Figure 16 , which shows a schematic diagram of the controller structure provided by an exemplary embodiment of the present application. The controller includes a camera control component 1601 and a fill light alignment component 1602. The camera control component 1601 is used to control the main camera to perform periodic exposure, and the fill light alignment component 1602 is used to align the fill light periods of the fill lights corresponding to multiple cameras with their respective corresponding camera exposure periods.

[0168] Optionally, the target stroboscopic signal states corresponding to the main camera and the secondary camera may be the same or different. Taking the target stroboscopic signal states corresponding to the first stroboscopic signal and the second stroboscopic signal both being the signal falling edge as an example, the process of the controller controlling periodic fill light such as fill light will be described.

[0169] During the process of image acquisition, the controller sends a first exposure control signal to the main camera to control the main camera to perform periodic exposure. When the main camera completes a single exposure, if the falling edge of the first stroboscopic signal is detected, the controller controls the fill light corresponding to the main camera to perform periodic fill light. And, when the falling edge of the first stroboscopic signal is detected, the main camera sends a frame synchronization signal to the secondary camera. When the frame synchronization signal is received, the secondary camera starts to expose. When the exposure of the secondary camera ends, if the controller can detect the falling edge of the second stroboscopic signal, the controller controls the secondary fill light corresponding to the secondary camera to perform periodic fill light.

[0170] Schematically, please refer to Figure 17, which shows the timing diagram of the main fill light and the secondary fill light provided by an exemplary embodiment of the present application. When the falling edge of the first strobing signal corresponding to the main camera is detected, the controller controls the main fill light to perform periodic fill light. When the second strobing signal corresponding to the secondary camera is detected, the controller controls the secondary fill light to perform periodic fill light. The fill light period of the main fill light is aligned with the exposure period of the main camera, and the fill light period of the secondary fill light is aligned with the exposure period of the secondary camera.

[0171] In the embodiment of the present application, the controller controls according to the detected strobing signal state, and controls the fill light to perform periodic fill light through the timer group, which can ensure that the fill light time of the fill light is aligned with the exposure time of the camera by setting appropriate timing duration and control strategy. In addition, different cameras correspond to different fill lights, and the controller controls the fill lights separately to ensure that the exposure times of both the main camera and the secondary camera can be aligned with the fill light time, avoiding under-exposure or ineffective exposure.

[0172] In a possible implementation manner, when receiving the first exposure control signal, the main camera performs periodic exposure based on the exposure frequency and the single exposure duration, and the exposure frequency is configured by the controller.

[0173] Optionally, when the controller sends an initialization signal to the main camera, the exposure frequency is sent to the main camera synchronously. Or, before the controller sends the first exposure control signal to the main camera each time, the exposure frequency is sent to the main camera first.

[0174] In another possible implementation manner, when the image acquisition device performs image acquisition on the object to be photographed, since the object to be photographed may stay in the camera shooting range for a short time, the image quality that may be captured in a short time is poor, such as the image is blurred or there is occlusion of the object to be photographed in the image, etc., which is difficult to be used for subsequent processing. For example, in the palmprint recognition scenario, the user may not keep the palm in the shooting area of the camera all the time, so the poor image quality captured in a short time may lead to inaccurate palmprint recognition and a low success rate of palmprint recognition.

[0175] In order to obtain more high-quality images in a short time, when the number of valid images in the images captured by the camera is lower than the number threshold, the frame rate of the camera shooting can be increased, that is, the exposure frequency of the camera is increased. Wherein the valid image refers to an image with a clarity higher than the clarity threshold. Increasing the camera exposure frequency enables the image acquisition device to capture more images per unit time, so that the controller can select high-quality images from the captured more images for subsequent processing.

[0176] The adjusted camera exposure frequency is sent to the main camera by the controller. After receiving the adjusted exposure frequency and the first exposure control signal, the main camera performs periodic exposure according to the adjusted exposure frequency.

[0177] For example, in the palmprint recognition scenario, if the number of valid images collected during a palmprint recognition process is small, the shooting frame rate of the camera is increased, that is, the exposure frequency of the camera is increased, so that during a palmprint recognition process, the image acquisition device can collect more palmprint images, and then the controller can select higher-quality images from these palmprint images for further comparison of palmprint features. In the palmprint recognition scenario, a valid image is an image that can be used for palmprint recognition, that is, the palmprint features included in the valid image are relatively comprehensive.

[0178] Optionally, in order to obtain more high-quality images in a short time, when the number of valid images in the images collected by the camera is lower than the number threshold, the exposure time of the camera shooting can be increased, so as to shorten the time for the camera to obtain one frame of image, so that more images can be taken per unit time.

[0179] Similarly, after adjusting the exposure frequency of the camera, in order to enable the fill light to fill light during the exposure stage of the camera, that is, to enable the fill light period of the fill light to cover the exposure period of the camera. Therefore, the controller needs to adjust the first timer duration corresponding to the lighting timer and the second timer duration corresponding to the extinguishing timer according to the adjusted frame rate and the exposure duration of the camera.

[0180] In the embodiment of the present application, the frame rate of the main camera is configured by the controller, and when the quality of multiple captured images is poor, the controller adjusts the exposure frame rate of the camera in real time, which is beneficial to capturing more images in the same duration, so as to obtain higher-quality images. And the timer duration is adjusted in real time according to the adjusted shooting frame rate, which is beneficial to ensuring that the fill light period is aligned with the exposure period.

[0181] Please refer to Figure 18 , which shows a schematic diagram of an image acquisition device provided by an exemplary embodiment of the present application. The device includes:

[0182] A control module 1801, configured to send a first exposure control signal to the main camera module 1802;

[0183] The main camera module 1802 is configured to perform periodic exposure when receiving the first exposure control signal;

[0184] The main camera module 1802 is further configured to send a frame synchronization signal to the slave camera module 1803 when a single exposure is completed;

[0185] The slave imaging module 1803 is configured to perform exposure when receiving the frame synchronization signal;

[0186] The control module 1801 is further configured to control the fill light module to perform periodic fill light based on the exposure time of the imaging module, and the fill light period of the fill light module covers the exposure period of the imaging module;

[0187] The main imaging module 1802 is further configured to transmit the acquired image data to the control module 1801;

[0188] The slave imaging module 1803 is further configured to transmit the acquired image data to the control module 1801.

[0189] Optionally, the control module 1801 is configured to:

[0190] Receive the stroboscopic signal sent by the imaging module, where the stroboscopic signal is used to indicate fill light;

[0191] When detecting the target stroboscopic signal state, control the fill light module to perform periodic fill light, where the target stroboscopic signal state includes a signal rising edge and a signal falling edge, the signal rising edge corresponds to the exposure start time, and the signal falling edge corresponds to the exposure end time.

[0192] Optionally, the control module 1801 is configured to:

[0193] When detecting the target stroboscopic signal state, based on the control strategy corresponding to the target stroboscopic signal state, control the fill light module to perform periodic fill light through a timer group, where the timer group includes a lighting timer and a turning-off timer.

[0194] Optionally, the control module 1801 is configured to:

[0195] When detecting the signal falling edge, activate the lighting timer in the timer group and control the fill light module to turn off;

[0196] When the lighting timer reaches the first timer duration, activate the turning-off timer in the timer group and control the fill light module to turn on;

[0197] When the turning-off timer reaches the second timer duration, activate the lighting timer in the timer group and control the fill light module to turn off.

[0198] Optionally, the control module 1801 is configured to:

[0199] When the rising edge of the signal is detected, activate the light-off timer in the timer group and control the fill light module to turn on;

[0200] When the light-off timer reaches the second timer duration, activate the light-on timer in the timer group and control the fill light module to turn off;

[0201] When the light-on timer reaches the first timer duration, activate the light-off timer in the timer group and control the fill light module to turn on.

[0202] Optionally, the second timer duration is greater than or equal to the single exposure duration of the camera module, and the frame duration is an integer multiple of the sum of the first timer duration and the second timer duration.

[0203] Optionally, the control module 1801 is further configured to:

[0204] When the target stroboscopic signal state is detected, reset the light-on timer and the light-off timer.

[0205] Optionally, the control module 1801 is configured to:

[0206] Receive the first stroboscopic signal sent by the main camera module 1802, or receive the second stroboscopic signal sent by the slave camera module 1803;

[0207] When the target stroboscopic signal state of the first stroboscopic signal is detected, control the main fill light module corresponding to the main camera module 1802 to perform periodic fill light;

[0208] When the target stroboscopic signal state of the second stroboscopic signal is detected, control the slave fill light module corresponding to the slave camera module 1803 to perform periodic fill light, and the slave fill light module is different from the main fill light module.

[0209] Optionally, the frame synchronization interface of the main camera module 1802 is connected to the frame synchronization interface of the slave camera module 1803, and the frame synchronization interface of the main camera module 1802 is configured to output the status, and the frame synchronization interface of the slave camera module 1803 is configured to input the status;

[0210] The main camera module 1802 is configured to send the frame synchronization signal to the slave camera module 1803 through the frame synchronization interface when a single exposure is completed.

[0211] Optionally, the main camera module 1802 is configured to:

[0212] When a signal falling edge of the stroboscopic signal is detected, the frame synchronization signal is sent to the slave camera module 1803 through the frame synchronization interface. The stroboscopic signal is used to indicate fill light, and the signal falling edge corresponds to the end moment of exposure.

[0213] Optionally, the main camera module 1802 is configured to:

[0214] When receiving the first exposure control signal, perform periodic exposure based on the exposure frequency and the single-exposure duration, where the exposure frequency is configured by the control module 1801.

[0215] Optionally, the control module 1801 is configured to:

[0216] When it is recognized that there is a to-be-photographed object within the photographing range, send the first exposure control signal to the main camera module 1802;

[0217] When it is recognized that the to-be-photographed object leaves the photographing range, send a second exposure control signal to the main camera module 1802;

[0218] The main camera module 1802 is configured to stop periodic exposure when receiving the second exposure control signal.

[0219] In summary, in the embodiments of the present application, the image acquisition device includes at least two cameras, where there is a main camera. The controller controls the main camera to perform periodic exposure by sending a first exposure control signal to the main camera, and the main camera sends a frame synchronization signal to the slave camera after a single exposure, so as to control the slave camera to perform exposure. During this process, the controller only needs to control the main camera to start exposure, and the frame synchronization signal sent by the main camera can control the slave camera, which can avoid simultaneous exposure of the main camera and the slave camera, reduce the power consumption of the image acquisition device for exposure, and moreover, send a frame synchronization signal to the slave camera after the single exposure of the main camera, which can enable the slave camera to perform periodic exposure at the same frame rate as the main camera. In addition, the controller also controls the fill light to perform periodic fill light, and the fill light period of the fill light covers the exposure period of the camera, that is, the fill light remains on during the exposure period of the camera, so as to avoid underexposure and ensure the quality of the captured images.

[0220] It should be noted that: For the device provided in the above embodiments, only the division of the above functional modules is used for illustration. In actual applications, the above functions can be allocated to different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the device provided in the above embodiments and the method embodiments belong to the same concept. For the implementation process, please refer to the method embodiments and will not be elaborated here.

[0221] Please refer to Figure 19 , which shows a structural diagram of an image acquisition device 1900 provided by an exemplary embodiment of the present application. The image acquisition device may be a device with an image acquisition function such as a palmprint recognition device or a face recognition device.

[0222] Generally, the image acquisition device 1900 includes a controller 1901 and a memory 1902.

[0223] The controller 1901 may include one or more processing cores, such as a 4-core processor or an 8-core processor. The controller 1901 may be implemented in at least one of the following hardware forms: Digital Signal Processing (DSP), Field-Programmable Gate Array (FPGA), and Programmable Logic Array (PLA). The controller 1901 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the wake state, also known as the Central Processing Unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the controller 1901 may be integrated with a Graphics Processing Unit (GPU), and the GPU is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the controller 1901 may further include an Artificial Intelligence (AI) processor, which is used to process computational operations related to machine learning.

[0224] The memory 1902 may include one or more computer-readable storage media, which may be tangible and non-transitory. The memory 1902 may also include high-speed random access memory, as well as non-volatile memory, such as one or more disk storage devices and flash storage devices. In some embodiments, the non-transitory computer-readable storage media in the memory 1902 is used to store at least one instruction for being executed by the controller 1901 to implement the image acquisition method provided by the embodiments of the present application.

[0225] In some embodiments, the terminal 1900 may further optionally include: a peripheral device interface 1905 and peripheral devices, where the peripheral devices include a main camera 1903 and a secondary camera 1904.

[0226] The main camera 1903 and the secondary camera 1904 are used to capture a to-be-captured image within a shooting range and send the acquired image data to the controller. The secondary camera 1904 controls the exposure based on the frame synchronization signal sent by the main camera 1903.

[0227] The peripheral device interface 1905 can be used to connect at least one peripheral device related to input / output (I / O) to the controller 1901 and the memory 1902. In some embodiments, the controller 1901, the memory 1902, and the peripheral device interface 1905 are integrated on the same chip or circuit board; in some other embodiments, any one or two of the controller 1901, the memory 1902, and the peripheral device interface 1905 can be implemented on a separate chip or circuit board, and the present embodiment does not limit this.

[0228] Those skilled in the art can understand that Figure 19 the structure shown in does not constitute a limitation on the terminal 1900, and it may include more or fewer components than shown in the figure, or combine certain components, or adopt a different component layout.

[0229] The embodiments of the present application also provide a computer-readable storage medium, which stores at least one segment of program, and the at least one segment of program is loaded and executed by the controller to implement the image acquisition method described in the above various embodiments.

[0230] According to one aspect of the present application, there is provided a computer program product, which includes computer instructions stored in a computer-readable storage medium. The controller of the image acquisition device reads the computer instructions from the computer-readable storage medium, and the controller executes the computer instructions, so that the terminal executes the image acquisition method provided in various optional implementation manners of the above aspect.

[0231] Those skilled in the art should be able to realize that in one or more of the above examples, the functions described in the embodiments of the present application can be implemented by hardware, software, firmware, or any combination thereof. When implemented using software, these functions can be stored in a computer-readable storage medium or transmitted as one or more instructions or codes on a computer-readable storage medium. The computer-readable storage medium includes computer storage media and communication media, where the communication media includes any medium that facilitates the transfer of a computer program from one place to another. The storage media can be any available medium accessible by a general-purpose or special-purpose computer.

[0232] The above are only alternative embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included within the protection scope of the present application.

Claims

1. An image acquisition method, characterized in that, The method is used for an image acquisition device, which includes a fill light, a main camera, a slave camera, and a controller; The method includes: The controller sends a first exposure control signal to the main camera; When receiving the first exposure control signal, the main camera performs periodic exposure; When a single exposure is completed, the main camera sends a frame synchronization signal to the slave camera; When receiving the frame synchronization signal, the slave camera performs exposure; The controller controls the fill light to perform periodic fill light based on the exposure time of the camera, and the fill light period of the fill light covers the exposure period of the camera; The main camera and the slave camera transmit the acquired image data to the controller.

2. The method according to claim 1, wherein The controller controls the fill light to perform periodic fill light based on the exposure time of the camera, including: The controller receives a stroboscopic signal sent by the camera, and the stroboscopic signal is used to indicate fill light; When a target stroboscopic signal state is detected, the controller controls the fill light to perform periodic fill light. The target stroboscopic signal state includes a signal rising edge and a signal falling edge. The signal rising edge corresponds to the exposure start time, and the signal falling edge corresponds to the exposure end time.

3. The method according to claim 2, wherein When a target stroboscopic signal state is detected, the controller controls the fill light to perform periodic fill light, including: When a target stroboscopic signal state is detected, the controller controls the fill light to perform periodic fill light based on a control strategy corresponding to the target stroboscopic signal state through a timer group. The timer group includes a lighting timer and a light-off timer.

4. The method according to claim 3, wherein When a target stroboscopic signal state is detected, the controller controls the fill light to perform periodic fill light based on a control strategy corresponding to the target stroboscopic signal state through a timer group, including: When the signal falling edge is detected, the controller activates the lighting timer in the timer group and controls the fill light to turn off; When the lighting timer reaches a first timer duration, the controller activates the light-off timer in the timer group and controls the fill light to turn on; When the light-off timer reaches a second timer duration, the controller activates the lighting timer in the timer group and controls the fill light to turn off.

5. The method according to claim 3, wherein When a target stroboscopic signal state is detected, the controller controls the fill light to perform periodic fill light based on a control strategy corresponding to the target stroboscopic signal state through a timer group, including: When the signal rising edge is detected, the controller activates the light-off timer in the timer group and controls the fill light to turn on; When the light-off timer reaches a second timer duration, the controller activates the lighting timer in the timer group and controls the fill light to turn off; When the lighting timer reaches the first timer duration, the controller activates the extinguishing timer in the timer group and controls the supplementary light to turn on.

6. The method according to claim 4 or 5, characterized in that The second timer duration is greater than or equal to the single exposure duration of the camera, and the frame duration is an integer multiple of the sum of the first timer duration and the second timer duration.

7. The method according to claim 3, wherein Before the controller controls the supplementary light to perform periodic supplementary lighting through the timer group based on the control strategy corresponding to the target stroboscopic signal state when the target stroboscopic signal state is detected, the method further includes: When the target stroboscopic signal state is detected, reset the lighting timer and the extinguishing timer.

8. The method according to claim 2, wherein The controller receives the stroboscopic signal sent by the camera, including: The controller receives the first stroboscopic signal sent by the main camera, or receives the second stroboscopic signal sent by the slave camera; When the target stroboscopic signal state is detected, the controller controls the supplementary light to perform periodic supplementary lighting, including: When the target stroboscopic signal state of the first stroboscopic signal is detected, the controller controls the main supplementary light corresponding to the main camera to perform periodic supplementary lighting; When the target stroboscopic signal state of the second stroboscopic signal is detected, the controller controls the slave supplementary light corresponding to the slave camera to perform periodic supplementary lighting, and the slave supplementary light is different from the main supplementary light.

9. The method according to any one of claims 1 to 8, characterized in that The frame synchronization interface of the main camera is connected to the frame synchronization interface of the slave camera, and the frame synchronization interface of the main camera is configured to output a state, and the frame synchronization interface of the slave camera is configured to input a state; When a single exposure is completed, the main camera sends a frame synchronization signal to the slave camera, including: When a single exposure is completed, the main camera sends the frame synchronization signal to the slave camera through the frame synchronization interface.

10. The method according to claim 9, characterized in that, When a single exposure is completed, the main camera sends the frame synchronization signal to the slave camera through the frame synchronization interface, including: When the signal falling edge of the stroboscopic signal is detected, the main camera sends the frame synchronization signal to the slave camera through the frame synchronization interface, and the stroboscopic signal is used to indicate supplementary lighting, and the signal falling edge corresponds to the end moment of exposure.

11. The method according to any one of claims 1 to 8, characterized in that, When the first exposure control signal is received, the main camera performs periodic exposure, including: When the first exposure control signal is received, the main camera performs periodic exposure based on the exposure frequency and the single exposure duration, and the exposure frequency is configured by the controller.

12. The method according to any one of claims 1 to 8, characterized in that The controller sends the first exposure control signal to the main camera, including: When it is recognized that there is an object to be photographed within the photographing range, the controller sends the first exposure control signal to the main camera; The method further includes: When it is recognized that the object to be photographed leaves the photographing range, the controller sends a second exposure control signal to the main camera; When the second exposure control signal is received, the main camera stops periodic exposure.

13. An image acquisition device, characterized in that, The device includes: a control module configured to send a first exposure control signal to the main imaging module; the main imaging module configured to perform periodic exposure when the first exposure control signal is received; the main imaging module is further configured to send a frame synchronization signal to the slave imaging module when a single exposure is completed; the slave imaging module configured to perform exposure when the frame synchronization signal is received; the control module is further configured to control the fill light module to perform periodic fill light based on the exposure time of the imaging module, and the fill light period of the fill light module covers the exposure period of the imaging module; the main imaging module is further configured to transmit the acquired image data to the control module; the slave imaging module is further configured to transmit the acquired image data to the control module.

14. An image acquisition device, characterized in that, The image acquisition device includes a fill light, a main camera, a slave camera, a controller, and a memory. At least one program is stored in the memory, and the at least one program is loaded and executed by the controller to implement the image acquisition method according to any one of claims 1 to 12.

15. A computer-readable storage medium, characterized in that, At least one program is stored in the readable storage medium, and the at least one program is loaded and executed by the controller to implement the image acquisition method according to any one of claims 1 to 12.

16. A computer program product, characterized in that, The computer program product includes computer instructions. The computer instructions are stored in a computer-readable storage medium. The controller of the image acquisition device reads the computer instructions from the computer-readable storage medium, and the controller executes the computer instructions to implement the image acquisition method according to any one of claims 1 to 12.

Images