Method, apparatus and device for fingerprint identification

Abstract

The present disclosure provides a method, device and equipment for fingerprint identification. First, a first image containing a fingerprint is subjected to Fourier transform to obtain a first frequency spectrum image. Then, the first frequency spectrum image is processed to obtain a second frequency spectrum image containing the fingerprint. Next, whether the maximum value exists in the ratio of the median of the amplitude corresponding to the specified frequency point in the second frequency spectrum image is determined to determine the target processing mode. Finally, the first image is processed based on the target processing mode to obtain a target image for fingerprint identification. Thus, the adaptive identification and filtering of moire can not only improve the accuracy of moire identification and filtering, but also improve the speed and accuracy of fingerprint identification.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of display, and in particular, to a fingerprint identification method, device and equipment. BACKGROUND

[0002] The application of optical fingerprint identification brings users a safe and convenient user experience. How to further improve the speed and accuracy of fingerprint identification has become a problem to be solved in the field of fingerprint identification. SUMMARY

[0003] The present disclosure provides a fingerprint identification method, device and equipment. The specific scheme is as follows:

[0004] An embodiment of the present disclosure provides a fingerprint identification method, comprising:

[0005] performing Fourier transform on the obtained first image containing a fingerprint to obtain a first frequency spectrum image;

[0006] performing band-pass filtering processing on the first frequency spectrum image to obtain a second frequency spectrum image not containing a fingerprint;

[0007] determining a median ratio of amplitude corresponding to each frequency point in the second frequency spectrum image;

[0008] determining the target processing mode according to whether the median ratio of amplitude corresponding to a specified frequency point is the maximum value among the median ratios of amplitude corresponding to all frequency points, wherein the specified frequency point is a moire frequency point corresponding to a fingerprint acquisition module for acquiring the first image;

[0009] performing processing on the first image based on the target processing mode to obtain a target image for fingerprint identification.

[0010] Another embodiment of the present disclosure provides a fingerprint identification device, comprising:

[0011] a first obtaining module configured to perform Fourier transform on an obtained first image containing a fingerprint to obtain a first frequency spectrum image;

[0012] a second obtaining module configured to perform band-pass filtering processing on the first frequency spectrum image to obtain a second frequency spectrum image containing a fingerprint;

[0013] a first determining module configured to determine a median ratio of amplitude corresponding to each frequency point in the second frequency spectrum image;

[0014] a second determining module configured to determine the target processing mode according to whether the median ratio of amplitude corresponding to a specified frequency point is the maximum value among the median ratios of amplitude corresponding to all frequency points, wherein the specified frequency point is a moire frequency point corresponding to a fingerprint acquisition module for acquiring the first image.

[0015] a processing module, configured to process the first image based on the target processing mode to obtain a target image for fingerprint identification.

[0016] Another aspect of the present disclosure provides a device, a fingerprint collection module and a fingerprint identification apparatus as described above.

[0017] The fingerprint identification apparatus is configured to perform the method as described above to identify the fingerprint image collected by the fingerprint collection module.

[0018] Another aspect of the present disclosure provides a device, comprising a fingerprint collection module, a first switching device, a Gaussian filter circuit, a second switching device, a fingerprint identification circuit and a controller.

[0019] An output end of the fingerprint collection module is connected to an input end of the controller and a first connection end of the first switching device.

[0020] A second connection end of the first switching device is connected to an input end of the Gaussian filter circuit, and an output end of the Gaussian filter circuit is connected to a first connection end of the second switching device.

[0021] A second connection end of the second switching device is connected to an input end of the fingerprint identification circuit.

[0022] A third connection end of the first switching device is connected to an input end of the fingerprint identification circuit.

[0023] A first output end of the controller is connected to a control end of the first switching device, and a second output end of the controller is connected to a control end of the second switching device.

[0024] The controller is configured to perform the method as described above to determine whether the image collected by the fingerprint collection module contains moire, and control the connection state of the first switching device and the second switching device according to whether the image contains moire.

[0025] The method, device and equipment for fingerprint identification provided by the embodiments of the present disclosure first perform Fourier transform on the first image to obtain a first frequency spectrum image, then perform band-pass filtering on the first frequency spectrum image to obtain a second frequency spectrum image containing the fingerprint, then determine the median ratio of the amplitude of each frequency point in the second frequency spectrum image, and then determine the target processing mode according to whether the median ratio of the amplitude of the specified frequency point is the maximum value, and finally perform processing on the first image based on the target processing mode, so as to obtain the target image for fingerprint identification. In this way, the moire pattern is adaptively identified and filtered out, which not only improves the accuracy of moire pattern identification and filtering, but also improves the speed and accuracy of fingerprint identification.

[0026] Additional aspects and advantages of the present disclosure will be described in the following description and become apparent from the following detailed description, or can be learned from the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0027] The above and / or additional aspects and advantages of the present disclosure will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0028] Figure 1 A flowchart of a method for fingerprint identification provided by an embodiment of the present disclosure;

[0029] Figure 2 A flowchart of another method for fingerprint identification provided by an embodiment of the present disclosure;

[0030] Figure 3 A flowchart of still another method for fingerprint identification provided by an embodiment of the present disclosure;

[0031] Figure 4 A structural schematic diagram of a device for fingerprint identification provided by an embodiment of the present disclosure;

[0032] Figure 5 A structural schematic diagram of a device for fingerprint identification provided by an embodiment of the present disclosure;

[0033] Figure 6 A structural schematic diagram of another device for fingerprint identification provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0034] The embodiments disclosed by the present disclosure are described in detail below, and examples of the embodiments are shown in the drawings, in which the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present disclosure, and cannot be understood as a limitation of the present disclosure.

[0035] For the convenience of understanding, the professional terms involved in the present disclosure are first explained below.

[0036] Moiré, a kind of high-frequency interference stripe that appears in the photosensitive element of the device such as scanner. When the spatial frequency of the photosensitive element pixel and the spatial frequency of the stripe in the image are solved, moiré will be produced. The existence of moiré will affect the accuracy of optical fingerprint identification, therefore, in the process of optical fingerprint identification application, how to quickly and accurately filter out moiré becomes an important factor affecting the accuracy and speed of fingerprint identification.

[0037] The method, device and equipment for fingerprint identification provided by the present disclosure will be described in detail below in combination with the drawings.

[0038] Figure 1 The flowchart of the method for fingerprint identification provided by the present disclosure. The method for fingerprint identification provided by the present disclosure can be executed by the device for fingerprint identification provided by the present disclosure, which can be configured in any device with optical fingerprint identification module. As shown in the figure, the method includes but is not limited to the following steps: Figure 1

[0039] Step 101, Fourier transform the obtained first image containing fingerprint to obtain the first frequency spectrum image.

[0040] Since moiré is a kind of high-frequency interference stripe, in the present disclosure, after obtaining the first image containing fingerprint, the first image can be first Fourier transformed to determine the first frequency spectrum image corresponding to the first image.

[0041] Step 102, band-pass filter processing the first frequency spectrum image to obtain the second frequency spectrum image containing fingerprint.

[0042] Specifically, since the distribution of fingerprint usually has a fixed period, such as the distribution period of 200-400 microns (um). In the present disclosure, in order to reduce the data processing amount as much as possible, it is only necessary to determine whether the moiré is contained in the fingerprint distribution period. Therefore, the frequency spectrum data corresponding to the fingerprint image can be first extracted from the first frequency spectrum image according to the distribution period of the fingerprint. For example, a band-pass filter can be used to filter the first frequency spectrum image to obtain the second frequency spectrum image containing fingerprint.

[0043] Step 103, determine the median ratio of the amplitude value corresponding to each frequency point in the second frequency spectrum image.

[0044] Wherein, the median ratio of the amplitude value is used to describe the ratio between the amplitude value corresponding to the frequency point and the median of the amplitude value corresponding to the region where the frequency point is located.

[0045] ​In the present disclosure, in order to more accurately determine the frequency point corresponding to the moire, the amplitude value corresponding to each frequency point can be normalized as much as possible, and then based on the normalized amplitude value, the frequency point corresponding to the moire is determined. In the present disclosure, in order to improve the processing speed as much as possible, the amplitude value corresponding to each frequency point can be normalized based on the amplitude values corresponding to other frequency points in the region where each frequency point is located.

[0046] For example, it can be determined that the N*N region where each frequency point is located is the reference region corresponding to each frequency point, and then the amplitude value corresponding to the frequency point is normalized based on the reference region. Wherein, N is a positive integer, preferably, N can take the base, that is, a region of a certain size centered on each frequency point is the reference region corresponding thereto. Optionally, the amplitude median ratio M(i,j) of the frequency point X(i,j) can be determined with reference to the following formula (1):

[0047] M(i,j) = x(i,j) / median(i,j)

[0048] Wherein, i,j are the first direction coordinate and the second direction coordinate of the frequency point in the second frequency spectrum image respectively, X represents the amplitude value of the frequency point with coordinate (i,j) in the second frequency spectrum image, and median(i,j) represents the amplitude median of the reference region corresponding to the frequency point X(i,j).

[0049] That is, in the present disclosure, the amplitude value corresponding to each frequency point in the second frequency spectrum image and the amplitude median of the reference region corresponding to each frequency point can be determined first; the ratio of the amplitude value corresponding to each frequency point to the amplitude median of the corresponding reference region is determined as the amplitude median ratio corresponding to each frequency point.

[0050] Step 104, according to whether the first amplitude median ratio corresponding to the specified frequency point is the maximum value in the amplitude median ratios corresponding to all frequency points, the target processing mode is determined, wherein the specified frequency point is the moire frequency point corresponding to the fingerprint acquisition module for acquiring the first image.

[0051] Step 105, based on the target processing mode, the second frequency spectrum image is processed to obtain a target image for fingerprint identification.

[0052] Generally, since the moire frequency points corresponding to different fingerprint collection modules can be different, in the present disclosure, the moire frequency point corresponding to the fingerprint collection module can be determined by testing after the assembly of the fingerprint collection module is completed, that is, the specified frequency point. Then, when performing fingerprint recognition, it is directly determined whether the ratio of the median of the first amplitude corresponding to the specified frequency point in the second frequency spectrum image is the maximum value among the ratios of the medians of the amplitudes corresponding to all frequency points, to determine whether the second frequency spectrum image currently collected contains moire. Then, the target processing mode corresponding to the second frequency spectrum image is determined according to whether the second frequency spectrum image contains moire, and the second frequency spectrum image is processed based on the target processing mode, to obtain the target image for fingerprint recognition.

[0053] It can be understood that if the second frequency spectrum image contains moire, the ratio of the amplitude median corresponding to the moire frequency point will be obviously greater than the ratios of the amplitude medians corresponding to other frequency points, which are affected by the moire. Therefore, in the present disclosure, whether the second frequency spectrum image contains the moire frequency point can be directly determined according to the ratio of the amplitude median corresponding to the specified frequency point.

[0054] The method for fingerprint recognition provided by the present disclosure first performs Fourier transform on the first image containing the fingerprint to obtain a first frequency spectrum image, then performs band-pass filtering processing on the first frequency spectrum image to obtain a second frequency spectrum image containing the fingerprint, then determines the ratio of the amplitude median corresponding to each frequency point in the second frequency spectrum image, then determines the target processing mode according to whether the ratio of the first amplitude median corresponding to the specified frequency point is the maximum value among the ratios of the amplitude medians corresponding to all frequency points, and finally processes the second frequency spectrum image based on the target processing mode, to obtain the target image for fingerprint recognition. Thus, whether the image contains moire can be quickly and accurately determined by whether the ratio of the amplitude median corresponding to the specified frequency point in the image collected by the fingerprint collection module is the maximum value, and then the image is processed by using the appropriate target processing mode, thereby improving the speed and accuracy of fingerprint recognition.

[0055] From the above analysis, it can be seen that in the present disclosure, the moire frequency point corresponding to the fingerprint collection module can be determined by testing after the assembly of the fingerprint collection module is completed, and the process of determining the moire frequency point will be described in detail below. Figure 2 .

[0056] Figure 2 The flowchart of another method for fingerprint recognition provided by the present disclosure is shown in FIG. 6. As shown in FIG. 6, the method includes but is not limited to the following steps: Figure 2 .

[0057] Step 201: Obtain a flesh color calibration image collected by a fingerprint collection module.

[0058] The flesh color calibration image is an image of a flesh color calibration head collected by the fingerprint collection module when performing under-screen fingerprint calibration. The image only contains a flesh color region or also contains moire.

[0059] Step 202: Fourier transform the flesh color calibration image to obtain a third frequency spectrum image.

[0060] Step 203: Perform band-pass filtering on the third frequency spectrum image to obtain a fourth frequency spectrum image containing a fingerprint.

[0061] Step 204: Determine a median ratio of an amplitude corresponding to each frequency point in the fourth frequency spectrum image.

[0062] The specific implementation process of steps 201 to 204 can refer to the detailed description of any embodiment of the present disclosure, which will not be repeated here.

[0063] Step 205: Determine at least one frequency point corresponding to a median ratio of an amplitude greater than a second threshold value and being the largest in the fourth frequency spectrum image as a specified frequency point.

[0064] The second threshold value can be a preset value or a value determined according to the median ratio of the amplitude corresponding to each frequency point in the fourth frequency spectrum image. For example, the average of the median ratio of the amplitude corresponding to each frequency point in the fourth frequency spectrum image is determined as the second threshold value, or the median of the median ratio of the amplitude corresponding to each frequency point in the fourth frequency spectrum image is determined as the second threshold value, and the present disclosure does not limit this. In addition, the fourth frequency spectrum image after Fourier transform can be divided into four quadrants, and the frequency points in the first and second quadrants can reflect the changes of the image in different directions, respectively. Therefore, in the present disclosure, at least one frequency point corresponding to a median ratio of an amplitude being the largest and greater than the second threshold value can be screened from the frequency points contained in the first and second quadrants of the fourth frequency spectrum image, respectively.

[0065] Optionally, if the moire contained in the flesh color calibration image is only strong in one direction, then in the first and second quadrants, there can be only one frequency point corresponding to a median ratio of an amplitude being the largest and greater than the second threshold value. If the moire contained in the flesh color calibration image is strong in two directions, then in the first and second quadrants, there can be one median ratio of an amplitude being the largest and greater than the second threshold value, respectively.

[0066] It should be noted that the first and second quadrants each contain one moire frequency point, which means that the moire is strong in two directions, but the amplitudes corresponding to the two frequency points are the same because the two frequency points are obtained by Fourier transform of the same moire in the time domain. That is, the median ratio of the amplitudes corresponding to the two moire frequency points is the same.

[0067] Step 206: Perform a Fourier transform on the acquired first image containing the fingerprint to obtain the first spectral image.

[0068] Step 207: Perform bandpass filtering on the first spectral image to obtain a second spectral image containing the fingerprint.

[0069] Step 208: Determine the ratio of the median amplitude for each frequency point in the second spectrum image.

[0070] The specific implementation of steps 206 to 208 can be found in the detailed description of any embodiment of this disclosure, and will not be repeated here.

[0071] Step 209: If the first amplitude median ratio is the maximum value among the amplitude median ratios corresponding to all frequency points, determine the target processing mode as performing Gaussian filtering.

[0072] In this disclosure, since the moiré frequency points corresponding to the fingerprint acquisition module are known, after determining the second spectrum image corresponding to the acquired fingerprint image, it is possible to directly determine whether the median amplitude ratio corresponding to the moiré frequency points in the image is the maximum among all the median amplitude ratios. If so, it indicates that the amplitude at that frequency point is different from other regions, meaning that the larger amplitude at that frequency point is due to the superposition of the amplitudes of the moiré patterns in the image. Therefore, Gaussian filtering is required for this frequency point.

[0073] Optionally, the Gaussian filter parameters can be determined by the difference between the first amplitude median ratio and the amplitude median ratios corresponding to the other frequency points. For example, if the difference between the first amplitude median ratio and the amplitude median ratios corresponding to the other frequency points is large, the standard deviation of the Gaussian filter can be appropriately reduced so that after the second spectrum image is Gaussian filtered, the first amplitude median ratio is as close as possible to the amplitude median ratios corresponding to the other frequency points.

[0074] Step 210: If the first amplitude median ratio is not the maximum amplitude median ratio among all frequency points, determine the target processing mode as not performing Gaussian filtering.

[0075] If the first amplitude median ratio is not the maximum value among the amplitude median ratios corresponding to all frequency points, that is, there is no additional superposition of moiré amplitude values ​​other than fingerprints at the specified frequency point, then there is no need to perform filtering on the first image. In other words, the target processing mode is to not perform Gaussian filtering.

[0076] Optionally, if the target processing mode is determined to be Gaussian filtering, the second spectrum image can be input into the Gaussian filtering circuit to obtain the target image output by the Gaussian filtering circuit. Alternatively, if the target processing mode is determined to be without Gaussian filtering, the second spectrum image can be input into the fingerprint recognition circuit for fingerprint recognition.

[0077] In other words, in this disclosure, different circuits can be selected to process the second spectrum image based on whether it contains moiré patterns. If the second spectrum image contains moiré patterns, a high-speed filtering circuit is used to filter it before fingerprint recognition. Otherwise, fingerprint recognition is performed directly on the second spectrum image. Step 211: Based on the target processing mode, the second spectrum image is processed to obtain a target image for fingerprint recognition.

[0078] The specific implementation of step 211 above can be found in the detailed description of any embodiment of this disclosure, and will not be repeated here.

[0079] In this disclosure, after the fingerprint recognition module is assembled, the corresponding moiré frequency points can be determined through testing. Then, during fingerprint acquisition, it can be determined whether the ratio of the median amplitude of the moiré frequency points in the acquired fingerprint image is the maximum value. If so, it indicates that the image contains moiré patterns, and the second spectrum image can be Gaussian filtered; otherwise, Gaussian filtering is unnecessary. Therefore, through adaptive moiré pattern recognition and filtering, not only is the accuracy of moiré pattern recognition and filtering improved, but also the speed and accuracy of fingerprint recognition are increased.

[0080] As the above analysis shows, in this disclosure, when performing fingerprint recognition, the presence of moiré patterns in the second spectrum image can be determined by whether the ratio of the median amplitude at a specified frequency point in the first image is at its maximum value, thus determining whether moiré pattern filtering should be performed. In some possible implementations, due to significant differences in fingerprints among different users, if the periodic distribution of some of a user's fingerprints is close to the frequency of the moiré pattern frequency point of the fingerprint acquisition module, the ratio of the median amplitude at the specified frequency point may not be at its maximum value even if moiré patterns are present in the second spectrum image. In this case, if Gaussian filtering is not performed, the accuracy of fingerprint recognition may be affected. The following section discusses this further. Figure 3 The above situation will be explained in detail.

[0081] Figure 3 This is a schematic flowchart illustrating another fingerprint recognition method provided in an embodiment of this disclosure. Figure 3 As shown, the fingerprint recognition method provided in this disclosure includes, but is not limited to, the following steps:

[0082] Step 301: Perform a Fourier transform on the acquired first image containing the fingerprint to obtain a first spectral image.

[0083] Step 302: Perform bandpass filtering on the first spectral image to obtain a second spectral image containing the fingerprint.

[0084] Step 303: Determine the ratio of the median amplitude corresponding to each frequency point in the second spectrum image.

[0085] Step 304: If the first amplitude median ratio is the maximum value among the amplitude median ratios corresponding to all frequency points, determine the target processing mode as performing Gaussian filtering.

[0086] The specific implementation of steps 301 to 304 can be found in the detailed description of any embodiment of this disclosure, and will not be repeated here.

[0087] Step 305: If the first amplitude median ratio is not the maximum value among the amplitude median ratios corresponding to all frequency points, determine the absolute value of the difference between the second amplitude median ratio and the first auxiliary median ratio corresponding to each frequency point within the preset range of the specified frequency point.

[0088] The size of the preset range can be set as needed. For example, the preset range can be a circular area with a radius of 10 frequencies centered on the specified frequency; or it can be set to a 9*9 square area centered on the specified frequency, etc. This disclosure does not limit this.

[0089] Step 306: If the ratio of each absolute value to the median of the first amplitude is greater than or equal to the first threshold, the target processing mode is determined to be no Gaussian filtering.

[0090] Step 307, otherwise, determine the target processing mode as performing Gaussian filtering.

[0091] The first threshold can be a preset value, which is used to measure whether there is a sudden change in the ratio of the median amplitude of frequencies around a specified frequency point compared with the first median amplitude ratio. The size of the first threshold can be set as needed, for example, it can be 0.7, 0.8, 0.9, etc.

[0092] In other words, when the ratio of each absolute value to the first amplitude median is greater than or equal to the first threshold, it indicates that there is no abrupt change in the amplitude median ratio compared to the specified frequency point. At this point, it can be determined that there are no moiré patterns in the second spectrum image, and therefore Gaussian filtering is unnecessary.

[0093] If at least one or more frequencies surrounding a specified frequency point exhibit a sudden change in the ratio of their median amplitudes compared to the specified frequency point, it indicates that moiré patterns exist in the direction of the specified frequency point and the directions of these frequencies. In this case, a small-scale smoothing process can be applied to the specified frequency point; that is, the standard deviation of the Gaussian filter can be appropriately increased. Optionally, the Gaussian filter parameters can be determined based on the magnitude of the absolute values. For example, a smaller absolute value indicates a smaller degree of change, while a larger absolute value indicates a larger degree of change. Therefore, the standard deviation of the Gaussian filter corresponding to a smaller absolute value can be slightly larger than the standard deviation of the Gaussian filter corresponding to a larger absolute value.

[0094] Step 308: Based on the target processing mode, process the second spectrum image to obtain a target image for fingerprint recognition.

[0095] The specific implementation of step 308 can be found in the detailed description of any embodiment of this disclosure, and will not be repeated here.

[0096] In this embodiment, after acquiring a first image containing a fingerprint, it is first determined whether the median amplitude ratio of a specified moiré frequency point in the second spectral image corresponding to the fingerprint image is at its maximum value. If so, the target processing mode is determined to be Gaussian filtering. Otherwise, it is determined whether there is a sudden change in the median amplitude ratio of the frequency points surrounding the specified frequency point compared to the specified frequency point. If not, it is determined not to perform Gaussian filtering; otherwise, it is determined to perform Gaussian filtering. This effectively ensures that moiré patterns can be reliably filtered out under any circumstances, guaranteeing the accuracy and reliability of fingerprint recognition.

[0097] Figure 4 This is a schematic diagram of the structure of a fingerprint recognition device provided in an embodiment of this disclosure. Figure 4 As shown, the device 400 includes: a first acquisition module 41, a second acquisition module 42, a first determination module 43, a second determination module 44, and a processing module 45.

[0098] The first acquisition module 41 is used to perform a Fourier transform on the acquired first image containing the fingerprint to obtain a first spectral image;

[0099] The second acquisition module 42 is used to perform bandpass filtering on the first spectrum image to acquire a second spectrum image containing the fingerprint.

[0100] The first determining module 43 is used to determine the ratio of the median amplitude corresponding to each frequency point in the second spectrum image;

[0101] The second determining module 44 is used to determine the target processing mode based on whether the amplitude median ratio corresponding to the specified frequency point is the maximum value among the amplitude median ratios corresponding to all frequency points, wherein the specified frequency point is the moiré pattern frequency point corresponding to the fingerprint acquisition module that acquires the first image;

[0102] The processing module 45 is used to process the second spectrum image based on the target processing mode to obtain a target image for fingerprint recognition.

[0103] Optionally, the second determining module 44 described above is further configured to:

[0104] If the first amplitude median ratio is the maximum value among the amplitude median ratios corresponding to all frequency points, the target processing mode is determined to be Gaussian filtering.

[0105] If the first amplitude median ratio is not the maximum amplitude median ratio among all frequency points, the target processing mode is determined to be not to perform Gaussian filtering.

[0106] Optionally, the aforementioned processing module 45 is also used for:

[0107] If the target processing mode is determined to be Gaussian filtering, the second spectral image is input into the Gaussian filtering circuit to obtain the target image output by the Gaussian filtering circuit; or...

[0108] If the target processing mode is determined to be not to perform Gaussian filtering, the second spectrum image is input into the fingerprint recognition circuit for fingerprint recognition.

[0109] Optionally, the second determining module 42 described above is further configured to:

[0110] If the first amplitude median ratio is not the maximum value among the amplitude median ratios corresponding to all frequency points, determine the absolute value of the difference between the second amplitude median ratio and the first auxiliary median ratio for each frequency point within the preset range of the specified frequency point;

[0111] If the ratio of each absolute value to the median of the first amplitude is greater than or equal to the first threshold, the target processing mode is determined to be not to perform Gaussian filtering.

[0112] Otherwise, the target processing mode is determined to be Gaussian filtering.

[0113] Optionally, the processing module 45 described above is also used to determine the Gaussian filter parameters based on the magnitude of the absolute value.

[0114] Optionally, the first acquisition module 41 described above is further configured to: acquire the flesh-colored calibration image acquired by the fingerprint acquisition module; and perform Fourier transform on the flesh-colored calibration image to acquire a third spectral image;

[0115] The second acquisition module 42 is further configured to perform bandpass filtering on the fourth spectrum image to acquire a fourth spectrum image containing fingerprint data;

[0116] The first determining module 43 is further configured to determine the amplitude median ratio corresponding to each frequency point in the fourth spectrum image; and to determine at least one frequency point in the fourth spectrum image that has an amplitude median ratio greater than the second threshold and is the largest as the designated frequency point.

[0117] Optionally, the first determining module 43 is further configured to determine the value of the second threshold based on the ratio of the median amplitude corresponding to each frequency point in the fourth spectrum image.

[0118] Optionally, the first determining module 43 is further configured to: determine the amplitude corresponding to each frequency point in the second spectrum image, and the median amplitude of the reference region corresponding to each frequency point; and determine the ratio of the amplitude corresponding to each frequency point to the median amplitude of the corresponding reference region as the median amplitude ratio for each frequency point.

[0119] The fingerprint recognition apparatus of this disclosure, after acquiring a first image containing a fingerprint, first performs a Fourier transform on the first image to obtain a first spectral image, then performs bandpass filtering on the first spectral image to obtain a second spectral image containing the fingerprint, then determines the ratio of the median amplitude corresponding to each frequency point in the second spectral image, and then determines a target processing mode based on whether the ratio of the first median amplitude corresponding to a specified frequency point is the maximum value, and finally processes the first image based on the target processing mode to obtain a target image for fingerprint recognition. Therefore, through adaptive recognition and filtering of moiré patterns, not only is the accuracy of moiré pattern recognition and filtering improved, but also the speed and accuracy of fingerprint recognition are increased.

[0120] Based on the fingerprint recognition method and apparatus provided in the above embodiments, this disclosure can also provide a device. This device can be a portable user device, such as a mobile phone or PDA, or other devices with fingerprint input functionality; this disclosure does not limit its scope.

[0121] Figure 5 This is a schematic diagram of the structure of a device provided in an embodiment of this disclosure. Figure 5 The device 50 includes a fingerprint acquisition module 51 and a fingerprint recognition device 52.

[0122] The fingerprint acquisition module 51 is an optical fingerprint module used to acquire fingerprint images through optical elements. The fingerprint recognition device 52 is used to recognize the fingerprint images acquired by the fingerprint acquisition module 51.

[0123] The device of this embodiment, after acquiring a first image containing a fingerprint, first performs a Fourier transform on the first image to obtain a first spectral image, then performs bandpass filtering on the first spectral image to obtain a second spectral image containing the fingerprint, then determines the median amplitude ratio corresponding to each frequency point in the second spectral image, and then determines a target processing mode based on whether the median amplitude ratio corresponding to a specified frequency point is the maximum value, and finally processes the first image based on the target processing mode to obtain a target image for fingerprint recognition. Therefore, through adaptive recognition and filtering of moiré patterns, not only is the accuracy of moiré pattern recognition and filtering improved, but also the speed and accuracy of fingerprint recognition are increased.

[0124] Figure 6 This is a schematic diagram of another device provided as an embodiment of this disclosure. (See attached diagram.) Figure 6 The device 60 includes a fingerprint acquisition module 61, a first switching device 62, a Gaussian filter circuit 63, a second switching device 64, a fingerprint recognition circuit 65, and a controller 66.

[0125] The output terminal of the fingerprint acquisition module 61 is connected to the input terminal of the controller 66 and the first connection terminal of the first switching device 62, respectively.

[0126] The second connection terminal of the first switching device 62 is connected to the input terminal of the Gaussian filter circuit 63, and the output terminal of the Gaussian filter circuit 63 is connected to the first connection terminal of the second switching device 64.

[0127] The second connection terminal of the second switching device 64 is connected to the input terminal of the fingerprint recognition circuit 65;

[0128] The third connection terminal of the first switching device 62 is connected to the input terminal of the fingerprint recognition circuit 65;

[0129] The first output terminal of the controller 66 is connected to the control terminal of the first switching device 62, and the second output terminal of the controller 66 is connected to the control terminal of the second switching device 64;

[0130] The controller 66 is configured to execute the fingerprint recognition method as described in any of the above embodiments, to determine whether the image acquired by the fingerprint acquisition module 61 contains moiré patterns, and to control the connection state of the first switching device 62 and the second switching device 64 based on whether the image contains moiré patterns.

[0131] The first switching device 62 and the second switching device 64 can be any device with the functions of turning on and turning off.

[0132] Specifically, the controller 66 is used to control the first connection terminal of the first switching device 62 to connect to the second connection terminal and the first connection terminal of the second switching device 64 to connect to the second connection terminal when the image acquired by the fingerprint acquisition module 61 includes moiré patterns.

[0133] If the image acquired by the fingerprint acquisition module 61 does not include moiré patterns, the first connection terminal of the first switching device 62 is connected to the third connection terminal, and the first connection terminal of the second switching device 64 is disconnected from the second connection terminal.

[0134] In the device provided in this embodiment, a Gaussian filter circuit is used for Gaussian filtering. The controller determines whether the Gaussian filter circuit needs to be connected to the fingerprint recognition loop based on whether the image acquired by the fingerprint acquisition module contains moiré patterns. This not only ensures that moiré patterns in the image can be reliably filtered out, but also improves the filtering speed by using the circuit for Gaussian filtering, further increasing the speed of the fingerprint recognition process.

[0135] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.

[0136] Although embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A fingerprint recognition method, characterized in that, include: Perform a Fourier transform on the acquired first image containing the fingerprint to obtain a first spectral image; The first spectral image is subjected to bandpass filtering to obtain a second spectral image containing the fingerprint; Determine the ratio of the median amplitude for each frequency point in the second spectrum image; Determine whether the first amplitude median ratio corresponding to a specified frequency point is the maximum value among the amplitude median ratios corresponding to all frequency points, wherein the specified frequency point is the moiré pattern frequency point corresponding to the fingerprint acquisition module that acquires the first image; If the first amplitude median ratio is the maximum value among the amplitude median ratios corresponding to all frequency points, the target processing mode is determined to be Gaussian filtering; If the first amplitude median ratio is not the maximum value among the amplitude median ratios corresponding to all frequency points, the target processing mode is determined to be not to perform Gaussian filtering; If the first amplitude median ratio is not the maximum value among the amplitude median ratios corresponding to all frequency points, determine the absolute value of the difference between the second amplitude median ratio and the first auxiliary median ratio corresponding to each frequency point within the preset range of the specified frequency point; If the ratio of each absolute value to the median of the first amplitude is greater than or equal to the first threshold, the target processing mode is determined to be not to perform Gaussian filtering. Otherwise, the target processing mode is determined to be Gaussian filtering; Based on the target processing mode, the second spectral image is processed to obtain a target image for fingerprint recognition.

2. The method as described in claim 1, characterized in that, The step of processing the first image based on the target processing mode to obtain a target image for fingerprint recognition includes: If the target processing mode is determined to be Gaussian filtering, the second spectral image is input into the Gaussian filtering circuit to obtain the target image output by the Gaussian filtering circuit; or... If the target processing mode is determined to be not to perform Gaussian filtering, the second spectrum image is input into the fingerprint recognition circuit for fingerprint recognition.

3. The method as described in claim 1, characterized in that, After determining that the target processing mode is to perform Gaussian filtering, the method further includes: The Gaussian filter parameters are determined based on the magnitude of the absolute value.

4. The method as described in claim 1, characterized in that, Also includes: Obtain the flesh-colored calibration image acquired by the fingerprint acquisition module; The flesh-colored calibration image is subjected to Fourier transform to obtain the third spectral image; The third spectral image is subjected to bandpass filtering to obtain a fourth spectral image containing fingerprint data; Determine the ratio of the median amplitudes for each frequency point in the fourth spectral image; At least one frequency point in the fourth spectrum image that corresponds to the median ratio of the amplitude that is greater than the second threshold is determined as the designated frequency point.

5. The method as described in claim 4, characterized in that, After determining the ratio of the median amplitudes corresponding to each frequency point in the fourth spectral image, the method further includes: The value of the second threshold is determined based on the ratio of the median amplitude corresponding to each frequency point in the fourth spectrum image.

6. The method according to any one of claims 1-5, characterized in that, Determining the ratio of the median amplitude corresponding to each frequency point in the second spectrum image includes: Determine the amplitude corresponding to each frequency point in the second spectrum image, and the median amplitude of the reference region corresponding to each frequency point; The ratio of the amplitude corresponding to each frequency point to the median amplitude of the corresponding reference region is determined as the median amplitude ratio for each frequency point.

7. A fingerprint recognition device, characterized in that, include: The first acquisition module is used to perform a Fourier transform on the acquired first image containing the fingerprint to obtain a first spectral image; The second acquisition module is used to perform bandpass filtering on the first spectrum image to acquire a second spectrum image containing the fingerprint. The first determining module is used to determine the ratio of the median amplitude corresponding to each frequency point in the second spectrum image; The second determining module is used to determine whether the first amplitude median ratio corresponding to a specified frequency point is the maximum value among the amplitude median ratios corresponding to all frequency points, wherein the specified frequency point is the moiré pattern frequency point corresponding to the fingerprint acquisition module that acquires the first image; if the first amplitude median ratio is the maximum value among the amplitude median ratios corresponding to all frequency points, the target processing mode is determined to be performing Gaussian filtering; if the first amplitude median ratio is not the maximum value among the amplitude median ratios corresponding to all frequency points, the target processing mode is determined to be not performing Gaussian filtering; if the first amplitude median ratio is not the maximum value among the amplitude median ratios corresponding to all frequency points, the absolute value of the difference between the second amplitude median ratio and the first auxiliary median ratio corresponding to each frequency point within a preset range of the specified frequency point is determined; if the ratio of each absolute value to the first amplitude median ratio is greater than or equal to a first threshold, the target processing mode is determined to be not performing Gaussian filtering; otherwise, the target processing mode is determined to be performing Gaussian filtering. The processing module is used to process the second spectrum image based on the target processing mode to obtain a target image for fingerprint recognition.

8. A device, characterized in that, Includes a fingerprint acquisition module and a fingerprint recognition device as described in claim 7; The fingerprint recognition device is used to perform the method as described in any one of claims 1-6 to recognize the fingerprint image acquired by the fingerprint acquisition module.

9. A device, characterized in that, It includes a fingerprint acquisition module, a first switching device, a Gaussian filter circuit, a second switching device, a fingerprint recognition circuit, and a controller; The output terminal of the fingerprint acquisition module is connected to the input terminal of the controller and the first connection terminal of the first switching device, respectively. The second connection terminal of the first switching device is connected to the input terminal of the Gaussian filter circuit, and the output terminal of the Gaussian filter circuit is connected to the first connection terminal of the second switching device. The second connection terminal of the second switching device is connected to the input terminal of the fingerprint recognition circuit; The third connection terminal of the first switching device is connected to the input terminal of the fingerprint recognition circuit; The first output terminal of the controller is connected to the control terminal of the first switching device, and the second output terminal of the controller is connected to the control terminal of the second switching device. The controller is configured to perform the method as described in any one of claims 1-6 above, to determine whether the image acquired by the fingerprint acquisition module contains moiré patterns, and to control the connection state of the first switching device and the second switching device based on whether the image contains moiré patterns.

10. The device as claimed in claim 9, characterized in that, The controller is used to control the first connection terminal of the first switching device to connect to the second connection terminal and the first connection terminal of the second switching device to connect to the second connection terminal when the image acquired by the fingerprint acquisition module includes moiré patterns. If the image acquired by the fingerprint acquisition module does not include moiré patterns, the first connection terminal of the first switching device is connected to the third connection terminal, and the first connection terminal of the second switching device is disconnected from the second connection terminal.

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