CN113158837B - Fingerprint image edge repairing method based on direction field - Google Patents
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- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
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Abstract
The invention provides a fingerprint image edge repairing method based on a direction field, which comprises the following steps: obtaining gradients of all pixels in the fingerprint image according to a preset algorithm; obtaining the fingerprint direction of the fingerprint image according to the gradients of all pixels; obtaining a direction included angle according to the fingerprint direction of the fingerprint image, wherein the direction included angle is formed by the fingerprint direction of the fingerprint image and the edge of the fingerprint image where the pixel to be repaired is positioned; obtaining a repair area according to the direction included angle, wherein the repair area comprises a plurality of pixels; and according to the pixel values of all the pixels in the repair area, pixel values of the pixels to be repaired are obtained. The invention also provides a fingerprint image edge repair module, fingerprint identification equipment, a computer-readable storage medium and electronic equipment. The fingerprint image edge repairing method based on the direction field remarkably improves the fingerprint image quality, facilitates the subsequent processing of steps such as feature extraction and recognition, and improves the fingerprint recognition rate, recognition speed and stability of the system.
Description
Technical Field
The present invention relates to the field of fingerprint image processing, and in particular, to a direction field-based fingerprint image edge inpainting method, a fingerprint image edge inpainting module, a fingerprint identification device, a computer readable storage medium, and an electronic device.
Background
At present, many intelligent mobile terminals are provided with fingerprint identification systems, and with the popularization of equipment, the experience requirements of users are higher and higher. The working flow of the fingerprint identification system carried on the intelligent mobile terminal is generally divided into six steps, namely finger detection, image acquisition, image preprocessing, feature extraction, feature comparison and identification and execution results. For example, success-unlock, failure-not-unlock, user experience is measured primarily by three indicators of unlock rate, unlock speed, and stability. The collected fingerprint image can be subjected to operations such as feature extraction, comparison and identification, and the like only after pretreatment, and the image pretreatment is the first step of fingerprint image processing, and has great influence on three indexes of user experience.
Specifically, the fingerprint image signal originates from a fingerprint sensor, which captures a fingerprint image when a finger touches the fingerprint sensor, and then transmits the image signal to the image preprocessing module. The fingerprint sensor has a certain size, and because of various condition limitations such as application scenes, the area of the fingerprint sensor of many intelligent mobile terminals is smaller than the size of a single finger, and only partial fingerprint images of the single finger can be acquired at a time, and finally the displayed image is not a complete fingerprint image but a part of the fingerprint of the single finger. In general, when the sensor collects, the outermost line and column of the fingerprint image, that is, the first line, the first column, the last line and the last column of the image, may be the outermost two lines and the last two columns, or may be only the top line, and the like, and the image of this part has obvious non-uniformity compared with other areas, such as a central area, due to the electric field characteristics of the sensor, and the non-uniformity of the image brightness of this area has adverse effects on subsequent steps of feature extraction, identification and the like. The existing technology comprises a method of disregarding the influence of the non-uniformity and not carrying out any treatment or using a direct replacement of pixels in a row and a column next to each other, wherein the method has the advantages of simple realization and very low information reduction degree and cannot truly reflect the actual trend and change of the finger lines of the areas.
Therefore, how to accurately repair the edge pixels of the fingerprint image is a problem to be solved.
Disclosure of Invention
The invention provides a fingerprint image edge repairing method based on a direction field, a fingerprint image edge repairing module, fingerprint identification equipment, a computer readable storage medium and electronic equipment, which can accurately repair pixel values of fingerprint image edge pixels.
In a first aspect, an embodiment of the present invention provides a method for repairing an edge of a fingerprint image based on a direction field, including:
obtaining gradients of all pixels in the fingerprint image according to a preset algorithm;
obtaining the fingerprint direction of the fingerprint image according to the gradients of all pixels;
obtaining a direction included angle according to the fingerprint direction of the fingerprint image, wherein the direction included angle is formed by the fingerprint direction of the fingerprint image and the edge of the fingerprint image where the pixel to be repaired is positioned;
obtaining a repair area according to the direction included angle, wherein the repair area comprises a plurality of pixels;
and according to the pixel values of all the pixels in the repair area, pixel values of the pixels to be repaired are obtained.
In a second aspect, an embodiment of the present invention provides a fingerprint image edge repair module, including:
a memory for storing program instructions of a direction field based fingerprint image edge inpainting method;
and the processor is used for executing program instructions to enable the fingerprint image edge patching module to realize the fingerprint image edge patching method based on the direction field.
In a third aspect, an embodiment of the present invention provides a fingerprint identification device, where the fingerprint identification device includes the fingerprint image edge repair module.
In a fourth aspect, an embodiment of the present invention provides a computer readable storage medium, where program instructions of the above-mentioned direction field based fingerprint image edge patch method are stored and can be loaded and executed by a processor.
In a fifth aspect, an embodiment of the present invention provides an electronic device, including:
a memory for storing program instructions of a direction field based fingerprint image edge inpainting method;
and the processor is used for executing program instructions to enable the electronic equipment to realize the fingerprint image edge repairing method based on the direction field.
According to the fingerprint image edge repairing method based on the direction field, the pixel to be repaired is repaired by finding the pixel area associated with the pixel to be repaired, so that different ridge lines are prevented from being connected together in the repairing process; or even gray values are filled in when repairing the pixels to be repaired, so that ridge lines and valley lines cannot be distinguished; or fail to purposefully connect the wrong repair of the ridge line, etc. The fingerprint image edge repairing method based on the direction field can recover the real image information of the area with uneven brightness around the fingerprint image, remarkably improve the fingerprint image quality, facilitate the processing of the following steps of feature extraction, recognition and the like, and improve the fingerprint recognition rate, recognition speed and stability of the system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It is apparent that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained from the structures shown in these drawings without inventive labor for those skilled in the art.
Fig. 1 is a flowchart of a method for repairing edges of a fingerprint image based on a direction field according to an embodiment of the present invention.
Fig. 2 is a first sub-flowchart of a method for repairing edges of a fingerprint image based on a direction field according to an embodiment of the present invention.
Fig. 3 is a second sub-flowchart of a method for repairing edges of a fingerprint image based on a direction field according to an embodiment of the present invention.
Fig. 4 is a third sub-flowchart of a method for repairing edges of a fingerprint image based on a direction field according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of a preprocessed fingerprint image according to an embodiment of the present invention.
Fig. 6 is a schematic diagram of the gradient of each pixel according to the embodiment of the present invention.
Fig. 7 is a schematic diagram of a pixel to be repaired and a repair area according to an embodiment of the present invention.
Fig. 8 is a schematic diagram of a pixel to be repaired, a repair area and an included angle between directions according to an embodiment of the present invention.
Fig. 9 is a schematic diagram of an internal structure of an electronic device according to an embodiment of the present invention.
Fig. 10 is a schematic diagram of a sub-image of a fingerprint image according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terms "first," "second," "third," "fourth" and the like in the description and in the claims of this application and in the above-described figures, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments described herein may be implemented in other sequences than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be noted that the description of "first", "second", etc. in this disclosure is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implying an indication of the number of technical features being indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present invention.
The texture of the fingerprint image is mainly divided into ridges, which are protruding textures in the fingerprint of the finger and can contact the surface of the fingerprint sensor, and valleys, which are recessed textures in the fingerprint and cannot contact the surface of the fingerprint sensor. In this embodiment, for convenience of explanation, a fingerprint image after preprocessing is selected, and as shown in fig. 5, white textures in the image are ridges and black textures are valleys. In some possible embodiments, some fingerprint images are inverted, with ridges in black and valleys in white. Fig. 6 is a schematic diagram of the ridge line trend of fig. 5, where the ridge line has a significant directionality in the fingerprint image, and if the fingerprint image does not exhibit a break point, bifurcation, etc., the fingerprint direction is substantially continuous, i.e., the pixel values are substantially uniform in the fingerprint image direction field.
In the embodiment, the direction field is used for introducing the geometric information of the ridge lines in the fingerprint image, and the trend of the ridge lines and the difference between the ridge lines and the valley lines can be accurately described after the direction field is introduced, so that different ridge lines are prevented from being connected together in the repairing process; or even gray values are filled in when repairing the pixels to be repaired, so that ridge lines and valley lines cannot be distinguished; or fail to purposefully connect the wrong repair of the ridge line, etc. Based on the characteristics of pixels on a direction field of the fingerprint image, pixels in an edge area of a brightness non-uniform area in the fingerprint image are patched by the direction field, so that the patching diffusion is only carried out along the ridge line direction, and the value of the patched fingerprint image between adjacent pixels in the fingerprint direction is more approximate, so that the patched fingerprint image is more approximate to a real fingerprint image, an ideal patching effect is achieved, the subsequent steps of feature extraction, identification and the like are facilitated, and the fingerprint identification rate, identification speed and stability of the system are improved. How the patch fingerprint image is implemented will be described in detail below.
Referring to fig. 1 in combination, a flowchart of a method for edge inpainting a fingerprint image based on a direction field according to an embodiment of the present invention is shown. The method for repairing the edges of the fingerprint image based on the direction field provided by the embodiment specifically comprises the following steps.
Step S101, obtaining gradients of all pixels in the fingerprint image according to a preset algorithm. For example, the sobel operator is used to calculate the gradient of all pixels in the fingerprint image. The preset algorithm also comprises the steps of calculating gradients of all pixels in the fingerprint image by using Roberts operator, prewitt operator, lapatian operator and the like. The actual use is determined according to the actual situation, and the examples herein are merely examples and are not limiting.
Step S102, the fingerprint direction of the fingerprint image is obtained according to the gradients of all pixels. Specifically, a coordinate system is established by taking a certain pixel in a fingerprint image as an origin, gradients dx and dy of each pixel in the fingerprint image in the x direction and the y direction are calculated respectively, the fingerprint image is divided into a plurality of non-overlapping sub-blocks with NxN size, N is a positive integer, dx and dy in each sub-block are counted, and then the directions of the fingerprints are calculated by using SVD, PCA and other methods. Among them, the singular value decomposition algorithm (Singular Value Decomposition, SVD) is an algorithm widely used in the field of machine learning, and is used for calculation of the fingerprint direction in the present embodiment. The dimension reduction algorithm (Principal Component Analysis, PCA) is a common data analysis method, and is commonly used for dimension reduction of high-dimension data, and in this embodiment, for calculation of fingerprint direction. Please refer to step S1021-step S1023.
Step S103, obtaining a direction included angle according to the fingerprint direction of the fingerprint image, wherein the direction included angle is formed by the fingerprint direction of the fingerprint image and the edge of the fingerprint image where the pixel to be repaired is located. Further, the direction included angle ranges from 0 ° to 180 °. The direction angle is set to θ in this embodiment, that is, 0 θ+.ltoreq.180°.
In some possible embodiments, the direction field based fingerprint image edge patch method calculates in the same way at two sets of angles, 0 ° to 45 ° and 135 ° to 180 °, for example (cos 30 °) 2 =（cos150°） 2 In some embodiments, the angles are converted to simplify the operation according to the actual situation.
In some possible embodiments, the direction field based fingerprint image edge patching method calculates in the same manner at two sets of angles, 45 ° to 90 ° and 90 ° to 135 °, for example (cos 60 °) 2 =（cos120°） 2 In some specific embodiments, the angle is turned according to the actual situationThe operation is simplified instead.
Step S104, a repair area is obtained according to the direction included angle, wherein the repair area comprises a plurality of pixels. Further, the repair area is a rectangular area, and the repair area at least comprises two pixels. The repair area corresponds to an angular range of 0 ° to 180 °. The total area available for repair is divided into four areas. When θ is 0 ° or less and <45 °, the first region is corresponding, when θ is 45 ° or less and <90 °, the second region is corresponding, when θ is 90 ° or less and <135 °, the third region is corresponding, when θ is 135 ° or less and 180 °, the fourth region is corresponding.
In this embodiment, all the direction angles are calculated as described above. Referring to fig. 7 in combination, dark gray represents the ridge, black represents the valley, and the light gray in the bottom row represents the last row of uneven brightness, where the pixel values need to be calculated using the pixels associated with the penultimate and third last rows. Referring to fig. 8 in combination, the gray arrows represent the trend of the fingerprint texture of the region, and the angle between the gray arrows and the edge of the fingerprint image is θ, and when θ=30°, the direction angle of the fingerprint region is in the range of 0 ° to 45 °.
In the fingerprint image actually acquired by the fingerprint sensor, the ridges and valleys are not a distinct boundary, but gradually change, as shown in fig. 5, even in the fingerprint image after preprocessing, the ridges and valleys have transition zones with several pixel widths, and the absence of the transition zones of the ridges and valleys does not affect the specific description of the present embodiment.
Step S105, pixel values of pixels to be patched are obtained according to pixel values of all pixels in the patched area. Please refer to step S1051-step S1053.
According to the direction field-based fingerprint image edge repairing method, the pixel to be repaired is repaired by finding the pixel area associated with the pixel to be repaired, so that the real image information of the area with uneven brightness around the fingerprint image is recovered, the fingerprint image quality is remarkably improved, the subsequent steps of feature extraction, recognition and the like are facilitated, and the fingerprint recognition rate, recognition speed and stability of the system are improved.
Please refer to fig. 2 in combination, which is a flowchart illustrating the substeps of step S102 according to an embodiment of the present invention. Step S102 obtains the fingerprint direction of the fingerprint image according to the gradients of all pixels, and specifically comprises the following steps.
S1021, cutting the fingerprint image into a plurality of sub-images. Specifically, the image is cut into a plurality of sub-images according to a preset scale, please refer to fig. 10 in combination, and the fingerprint image is divided into a plurality of sub-images 101.
S1022, counting gradients of all pixels in each sub-image to obtain gradient distribution data of a plurality of sub-images.
S1023, obtaining the fingerprint direction of the fingerprint image according to a preset fingerprint direction algorithm and gradient distribution data of the plurality of sub-images. Further, the preset fingerprint direction algorithm comprises SVD and PCA.
Please refer to the sub-step flowchart of step S105 provided in the embodiment of the present invention. Step S105 specifically includes the following steps according to pixel values of pixels to be repaired according to pixel values of all pixels in the repair area.
In step S1051, all pixels in the repair area are divided into a plurality of groups according to a preset grouping condition. Further, the preset grouping condition is that each group of pixels includes two adjacent pixels. Referring to fig. 7 in combination, 1, 2, 3, and 4 are repair pixels of the repair area, and in this embodiment, 1, 3 are set to be C groups, and 2, and 4 are set to be B groups. r is the pixel to be repaired.
Please refer to fig. 7 again, which illustrates how to recalculate the pixel value Vr of the pixel r to be repaired. In fig. 7 r the corresponding positions are selected, and 1, 2, 3, 4 are also selected accordingly. Since the light gray areas are all pixels to be repaired, the pixels of the light gray areas do not participate in the calculation when calculating the pixel value of r.
Step S1052, calculating the first pixel value of each group of pixels according to the direction included angle to obtain a plurality of first pixel values. Please refer to step S10521-step S10522.
In step S1053, the pixel value of the pixel to be repaired is obtained according to the plurality of first pixel values and the plurality of first coefficients, wherein the plurality of first pixel values and the plurality of first coefficients are in one-to-one correspondence, and each first coefficient is obtained according to the distance between the pixel to be repaired and each group of pixels. Specifically, when θ is equal to 0 degree, cos θ is equal to 1, sin θ is equal to 0, where the pixel value of r is determined by b4 and b3, b4 is the pixel value of patch pixel 4, b3 is the pixel value of patch pixel 3, and b4 and b3 are positive integers. When θ is equal to other values, cos θ and sin θ are not equal to 1 or 0, the pixel value of r is determined by the pixel values of the four patch pixels in the upper left corner.
In this embodiment, the calculation formula of Vr is vr=pb×vb+pc×vc, where Vr is the pixel value of r, vb is the first pixel value of the B group, vc is the first pixel value of the C group, pb is the weight of Vb, which may be also called a coefficient, pc is the weight of Vc, which may be also called a coefficient, and Pb and Pc are positive numbers, and the sum of Pb and Pc is 1. Specifically, pb and Pc may be set according to the distance between group B, group C and r, where group B is the position immediately adjacent to r, group C is the farthest from r, the distance is approximately twice the distance between group B and r, pb may be set to be equal to 2/3, and Pc may be set to be equal to 1/3. Vr=2/3×vb+1/3×vc, pb and Pc can be adjusted according to actual conditions, and different values can be set as required. If calculation is only to be performed with the patch pixels immediately adjacent to r, pc is set to 0 and pb is set to 1.
Please refer to fig. 4 in combination, which is a flowchart of sub-steps of step S1052 according to an embodiment of the present invention. Step S1052 calculates the first pixel value of each group of pixels according to the direction included angle to obtain a plurality of first pixel values, which specifically includes the following steps.
S10521, obtaining the corresponding coefficient of each pixel value in each group of pixels according to the direction included angle. The corresponding coefficient corresponds to the sine value or the cosine value of the direction included angle. Further, the corresponding coefficient is the square of the sine value of the direction angle or the cosine value of the direction angle, e.g., (cos 30 degree) 2 Or (sin 30 degree) 2 Etc. In this embodiment, the fingerprint image edge is taken as the x-axis, and the direction opposite to the fingerprint image is taken as the y-axis. Referring to fig. 8 in combination, the direction of the fingerprint ridge is shown to be closer to the x-axis, and when the angle θ is in the range of 0 ° to 45 °, the direction of the fingerprint ridge is shown to be closer to the edge of the fingerprint image, so that the weight in the x-direction is increased, and r is selectedTwo left and right adjacent pixels at the upper left of the pixel position are repair areas for calculating the pixel value of the pixel to be repaired.
Referring to fig. 7 in combination, four pixels of the patch area are numbered, and the relative positions of the pixels to be patched r are shown below, where r is the pixel to be patched, 1, 2, 3, 4 represents four patch pixels for patching, x represents an unrelated pixel,
1 2 x
3 4 x
x x r
the positional relationship between the pixel to be repaired and the repair area is shown in fig. 7, 8 and the above examples.
S10522, obtaining a first pixel value according to the pixel value of each pixel and the corresponding coefficient. Specifically, for a column immediately adjacent to the pixel r to be patched, it is assumed that the pixel values of two patched pixels are b2 and b4 in order from top to bottom, b4 is the pixel value of patched pixel 4, b2 is the pixel value of patched pixel 2, and b4 and b2 are positive integers. Then the pixel value Vb of group B, vb=b4 (cos θ) is calculated using the following formula 2 + b2 * （sinθ） 2 Vb is a first pixel value of r. For the other column, the pixel values of the two patch pixels are b1 and b3 in order from top to bottom, b1 is the pixel value of patch pixel 1, b3 is the pixel value of patch pixel 3, and b1 and b3 are positive integers. Then the pixel value of group C, vc=b3 (cos θ), is calculated using the following formula 2 + b1 * （sinθ） 2 Vc is a first pixel value of r.
The application also provides a fingerprint image edge repair module, fingerprint image edge repair module includes: and the memory is used for storing program instructions of the fingerprint image edge repairing method based on the direction field. And the processor is used for executing program instructions to enable the fingerprint image edge patching module to realize the fingerprint image edge patching method based on the direction field. For example, the fingerprint image edge patch module may be part of a hardware circuit including custom Very Large Scale Integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components.
The application also provides fingerprint identification equipment, and fingerprint identification equipment is equipped with foretell fingerprint image edge and repairs the module.
The invention also provides a computer readable storage medium. The computer readable storage medium has stored thereon program instructions for the above-described direction field based fingerprint image edge patch method that can be loaded and executed by a processor. For example, the program instructions may be transferred from one website, computer, server, or data center to another website, computer, server, or data center by a wired (e.g., coaxial cable, fiber optic, digital Subscriber Line (DSL)), or wireless (e.g., infrared, wireless, microwave, etc.). The computer readable storage medium may be any available medium that can be stored by a computer or a data storage device such as a server, data center, etc. that contains an integration of one or more available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid State Disk (SSD)), etc. Since the computer readable storage medium adopts all the technical solutions of all the above embodiments, at least all the beneficial effects brought by the technical solutions of the above embodiments are provided, and will not be described herein.
The invention also provides an electronic device 900, the electronic device 900 comprising at least a memory 901 and a processor 902. The memory 901 is used for storing program instructions of a direction field based fingerprint image edge patch method. A processor 902 for executing program instructions to cause a computer device to implement the above-described direction field based fingerprint image edge inpainting method. Referring to fig. 9 in combination, an internal structure of an electronic device 900 according to an embodiment of the invention is shown.
The memory 901 includes at least one type of readable computer readable storage medium including flash memory, a hard disk, a multimedia card, a card memory (e.g., SD or DX memory, etc.), a magnetic memory, a magnetic disk, an optical disk, etc. Memory 901 may be an internal storage unit of electronic device 900 in some embodiments, such as a hard disk of electronic device 900. The memory 901 may also be an external storage device of the electronic device 900 in other embodiments, for example, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital Card (SD), a Flash memory Card (Flash Card) or the like, which are provided on the electronic device 900. Further, the memory 901 may also include both internal storage units and external storage devices of the electronic device 900. The memory 901 may be used to store not only application software installed in the electronic device 900 and various types of data, such as program instructions of a direction field-based fingerprint image edge repair method, but also data that has been output or is to be output, such as data generated by performing the direction field-based fingerprint image edge repair method, and the like, temporarily.
The processor 902 may be a central processing unit (Central Processing Unit, CPU), controller, microcontroller, microprocessor or other data processing chip in some embodiments for executing program instructions or processing data stored in the memory 901. Specifically, the processor 902 executes program instructions of the direction field based fingerprint image edge patch method to control the electronic device 900 to implement the direction field based fingerprint image edge patch method.
Further, the electronic device 900 may further include a bus 903 may be a peripheral component interconnect standard bus (peripheral component interconnect, abbreviated to PCI) or an extended industry standard architecture bus (extended industry standard architecture, abbreviated to EISA), etc. The bus may be classified as an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in fig. 9, but not only one bus or one type of bus.
Further, the electronic device 900 may also include a display component 904. The display component 904 may be an LED (Light Emitting Diode) display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch device, or the like. The display component 904 may also be referred to as a display device or display unit, as appropriate, for displaying information processed in the electronic device 900 and for displaying a visual user interface.
Further, the electronic device 900 may also include a communication component 905, where the communication component 905 may optionally include a wired communication component and/or a wireless communication component (e.g., WI-FI communication component, bluetooth communication component, etc.), typically used to establish a communication connection between the electronic device 900 and other computer devices.
Fig. 9 shows only an electronic device 900 having components 901-905 and program instructions for implementing a direction field based fingerprint image edge repair method, it will be understood by those skilled in the art that the structure shown in fig. 9 does not constitute a limitation of the electronic device 900 and may include fewer or more components than shown, or may combine certain components, or a different arrangement of components. Since the electronic device 900 adopts all the technical solutions of all the embodiments, at least the beneficial effects of the technical solutions of the embodiments are provided, and will not be described herein.
In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product.
In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods may be implemented in other ways. For example, the above described embodiments of the direction field based fingerprint image edge patching method are merely illustrative, e.g. the division of the units is only a logical functional division, and there may be additional divisions in actual implementation, e.g. multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in part or all of the technical solution that contributes to the prior art, or in the form of a software product, which is stored in a computer readable storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the methods of the embodiments of the present application. And the aforementioned computer-readable storage medium includes: a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program instructions.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, if and when such modifications and variations of the present invention fall within the scope of the claims and the equivalents thereof, the present invention is intended to encompass such modifications and variations.
The above list of preferred embodiments of the present invention is, of course, not intended to limit the scope of the invention, and equivalent variations according to the claims of the present invention are therefore included in the scope of the present invention.
Claims (13)
1. The fingerprint image edge repairing method based on the direction field is characterized by comprising the following steps of:
obtaining gradients of all pixels in the fingerprint image according to a preset algorithm;
obtaining the fingerprint direction of the fingerprint image according to the gradients of all the pixels;
obtaining a direction included angle according to the fingerprint direction of the fingerprint image, wherein the direction included angle is formed by the fingerprint direction of the fingerprint image and the edge of the fingerprint image where the pixel to be repaired is positioned;
obtaining a repair area according to the direction included angle, wherein the repair area comprises a plurality of pixels, and the number of the pixels is at least two; and
and obtaining the pixel values of the pixels to be repaired according to the pixel values of all the pixels in the repair area.
2. The method for edge inpainting of a directional field based fingerprint image as recited in claim 1, wherein said inpainting region is a rectangular region, said inpainting region comprising at least two pixels.
3. The method for edge repair of a fingerprint image based on a direction field according to claim 1, wherein obtaining the fingerprint direction of the fingerprint image according to the gradient of all pixels comprises:
cutting the fingerprint image into a plurality of sub-images;
counting gradients of all pixels in each sub-image to obtain gradient distribution data of a plurality of sub-images;
and obtaining the fingerprint direction of the fingerprint image according to a preset fingerprint direction algorithm and the gradient distribution data of the plurality of sub-images.
4. A method for edge patching a fingerprint image based on a direction field as claimed in claim 3, wherein the preset fingerprint direction algorithm comprises a singular value decomposition algorithm and a dimension reduction algorithm.
5. The method for edge restoration of a fingerprint image based on a direction field according to claim 1, wherein the direction included angle ranges from 0 ° to 180 °.
6. The method for edge repair of a fingerprint image based on a direction field according to claim 1, wherein obtaining the pixel values of the pixel to be repaired according to the pixel values of all pixels in the repair area specifically comprises:
dividing all pixels in the repair area into a plurality of groups according to preset grouping conditions;
calculating a first pixel value of each group of pixels according to the direction included angle to obtain a plurality of first pixel values; and
and obtaining the pixel value of the pixel to be repaired according to the plurality of first pixel values and the plurality of first coefficients, wherein the plurality of first pixel values and the plurality of first coefficients are in one-to-one correspondence, and each first coefficient is obtained according to the distance between the pixel to be repaired and each group of pixels.
7. The method of claim 6, wherein the predetermined grouping condition is that each group of pixels includes two adjacent pixels.
8. The method for edge repair of a fingerprint image based on a direction field according to claim 7, wherein calculating the first pixel value of each group of pixels according to the direction included angle to obtain a plurality of first pixel values comprises:
obtaining a corresponding coefficient of each pixel in each group of pixels according to the direction included angle;
and obtaining the first pixel value according to the pixel value of each pixel and the corresponding coefficient.
9. The direction field-based fingerprint image edge inpainting method of claim 1, wherein said direction field-based fingerprint image edge inpainting method is identical in two sets of angles of 0 ° to 45 ° and 135 ° to 180 °; and
the fingerprint image edge repairing method based on the direction field has the same calculation mode in two groups of angles of 45 degrees to 90 degrees and 90 degrees to 135 degrees.
10. The utility model provides a fingerprint image edge repair module, its characterized in that, fingerprint image edge repair module includes:
a memory for storing program instructions of a direction field based fingerprint image edge inpainting method; and
a processor for executing the program instructions to cause the fingerprint image edge patch module to implement the direction field based fingerprint image edge patch method according to any one of claims 1 to 9.
11. A fingerprint identification device comprising the fingerprint image edge patch module of claim 10.
12. A computer readable storage medium having stored thereon program instructions for a direction field based fingerprint image edge patch method according to any of claims 1 to 9, which can be loaded and executed by a processor.
13. An electronic device, the electronic device comprising:
a memory for storing program instructions of a direction field based fingerprint image edge inpainting method; and
a processor for executing the program instructions to cause the electronic device to implement the direction field based fingerprint image edge patch method according to any one of claims 1 to 9.
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