CN112507974A - Palm print identification method based on texture features - Google Patents
Palm print identification method based on texture features Download PDFInfo
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- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
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- G06V10/40—Extraction of image or video features
- G06V10/44—Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components
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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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- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
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Abstract
The invention discloses a palm print identification method based on texture characteristics, which comprises the following steps: s1, collecting a palm print image of the palm print to be matched, and carrying out gray processing on the palm print image to form a gray image; s2, detecting a palm print main line in the gray level image, and acquiring a main line image of a palm print to be matched; s3, extracting texture detail features from the palm print dominant line image to be matched; s4, k palm print main line template images which are most matched with the palm print main line image to be matched are obtained in the matching library, the palm print main line template image which is matched with the texture detail features of the palm print to be matched is obtained from the k palm print main line template images, and the identification of the palm print to be matched is completed. The accuracy and the rapidity of palm print identification are improved, and the effect of identifying the identity information of people through the palm print characteristics is achieved.
Description
Technical Field
The invention belongs to the technical field of palm print recognition, and particularly relates to a palm print recognition method based on texture features.
Background
Biometric identification is widely applied in the fields of bank service, intelligent office buildings, intelligent security and the like, and an accurate biometric identification technology is a key technology for confirming the identity of a person. The biological characteristic identification method comprises a fingerprint identification method, a face identification method, a palm print identification method and the like, wherein the fingerprint identification method is used for matching and acquiring information of a person by detecting and identifying fingerprint characteristics, but the fingerprint texture characteristics are less, so that the problem of insufficient identification information is caused; the face recognition method determines the identity information of a person by recognizing the biological characteristics of the face, but the stability of the face is poor, and the face can change along with the age, so that the problem of reliability of recognition is caused; the palm print identification method based on the texture features is one of the current mature methods for identifying the biological features of human bodies, the skin surface texture of the palm print has stability and uniqueness, cannot be greatly changed along with the growth of age, has richer texture information compared with fingerprints, and is a more reliable biological feature identification technology.
The existing process for identifying the identity of a person based on a palm print outline and an edge texture feature comprises the following steps: collecting a palm print image, preprocessing the image, decomposing the palm print image into a main line contour and a main line edge texture by using mean filtering, respectively extracting features by using a gray histogram and a difference box, and finally matching by using a chi-square distance to finish identity recognition. This solution has the following problems: the mean filtering cannot well protect image details, and the detail part of the image is damaged while the image is denoised, so that the image becomes fuzzy, noise points cannot be well removed, and the segmentation processing of edge details is not facilitated.
Disclosure of Invention
The invention provides a palm print identification method based on texture features, aiming at improving the problems.
The invention is realized in such a way that a palm print identification method based on texture features specifically comprises the following steps:
s1, collecting a palm print image of the palm print to be matched, and carrying out gray processing on the palm print image to form a gray image;
s2, detecting a palm print main line in the gray level image, and acquiring a main line image of a palm print to be matched;
s3, extracting texture detail features from the palm print dominant line image to be matched;
s4, k palm print main line template images which are most matched with the palm print main line image to be matched are obtained in the matching library, the palm print main line template image which is matched with the texture detail features of the palm print to be matched is obtained from the k palm print main line template images, and the identification of the palm print to be matched is completed.
Further, the method for extracting the texture detail features specifically comprises the following steps:
s31, h image blocks are formed from the nxn matrix, and adjacent image blocks are overlapped;
s32, equally dividing the filtering angle into m intervals at 180 degrees, sampling the angle value in each angle interval as the filtering direction of the filtering function, forming a filtering image based on each filtering direction, accumulating the amplitude m (x, y) of each pixel point on all the filtering images, and forming an m-dimensional gradient amplitude accumulation histogram HC of each pixel point;
accumulating m-dimensional gradient amplitude accumulation histograms HC of all pixel points in an image block to form a histogram HB corresponding to the image block, and constructing a standardized histogram NHB of the image block;
the normalized histograms NHB of the h image blocks are integrated to form a line energy direction histogram feature HOLEGaborI.e. the texture detail feature of the palm print to be matched.
Further, the step S4 specifically includes the following steps:
s1, acquiring the overlapping area of the palm print main line template image and the palm print main line image to be matched, and calculating the matching characteristics S of the overlapping area relative to the palm print main line image to be matched and the palm print main line template image1、S2;
S2, calculating matching characteristics S1、S2And obtaining k palm print main line template images with the minimum distance Dist.
Further, matching the feature S1And S2The calculation formula of (a) is specifically as follows:
wherein L (x, y) andpixel values of the x row and y column pixel points in the palm print main line image to be matched and the palm print main line template image are respectively, and N is the width and the height of the palm print main line image to be matched and the palm print main line template image.
According to the method, a Canny operator is used for palm print contour detection to obtain palm print main line characteristics, and then palm print detail characteristics are extracted according to a gray level image to obtain line energy direction histogram characteristics (HOLE)GaborThe method comprises the steps of performing hierarchical matching, namely performing coarse screening on a test image and database template image main line characteristics according to a defined matching degree method, extracting key line energy direction histogram characteristics respectively according to template images screened in the coarse matching process, matching the key line energy direction histogram characteristics with the test image line energy direction histogram characteristics, finding a template image with the closest matching degree, namely a final matching result, completing recognition, and improving the accuracy of palm print recognition; in addition, matching is carried out based on the main line characteristics, most images are screened out, and matching time is saved.
Drawings
Fig. 1 is a flowchart of a palm print recognition method based on texture features according to an embodiment of the present invention.
Detailed Description
The following detailed description of the embodiments of the present invention will be given in order to provide those skilled in the art with a more complete, accurate and thorough understanding of the inventive concept and technical solutions of the present invention.
The method uses Canny operator to carry out palm print contour detection, obtains palm print main line characteristics, and then carries out palm print contour detection according to a gray level diagramExtracting the detail features of the palmprint to obtain the line energy direction histogram feature HOLEGaborAnd then, carrying out hierarchical matching, namely, carrying out coarse screening on the test image and the database template image mainline characteristics according to a defined matching degree method, respectively extracting key line energy direction histogram characteristics according to the template image screened in the coarse matching process, matching the key line energy direction histogram characteristics with the test image line energy direction histogram characteristics, finding the template image with the closest matching degree, namely, a final matching result, completing the identification, improving the accuracy and rapidity of the palm print identification, and achieving the effect of identifying the identity information of a person through the palm print characteristics.
Fig. 1 is a flowchart of a palm print recognition method based on texture features according to an embodiment of the present invention, where the method specifically includes the following steps:
the identification of the palm print comprises a palm print extraction process and a palm print matching process, wherein the palm print extraction process specifically comprises the following steps:
s1, image preprocessing: firstly, carrying out weighted average on a palm print image to be matched, which is acquired by a camera, and converting the palm print image into a gray image, wherein a calculation formula of the weighted average is as follows:
Y=0.3R+0.59G+0.11B
wherein, Y is the gray value of the pixel point in the gray image, and R, G, B represents the RGB values of the pixel point respectively. And removing the noise of the gray level image by using bilateral filtering on the acquired gray level image.
S2, detecting the main line edge of the palm print to be matched: the method comprises the following steps of performing dominant line contour detection on a palm print to be matched by using a Canny operator on a gray level image to obtain a palm print dominant line image of the palm print to be matched (the dominant line is also called flexor print and refers to the thickest lines on the palm. most people have three dominant lines which are generally called a life line, an emotional line and a smart line and are also called a first flexor print, a second flexor print and a third flexor print), and the calculation steps mainly comprise:
calculating an image gradient amplitude value Z and a gradient direction f of the gray level image, wherein the formula is as follows: wherein f isx、fyTemplate matrix representing sobel operator, fxFor convolution arrays acting in the x-direction, fyFor arrays of convolutions acting in the direction of the y-axis, e.g.And performing rough identification on a palm print main line based on the image gradient amplitude value Z and the gradient direction f, and then sequentially performing non-maximum suppression operation and high-low threshold connection edge on the palm print main line image to realize main line fine identification of the palm print to be matched, namely acquiring a main line image of the palm print to be matched, namely the main line image with the matched palm print, namely the image with the matched palm print main line image for short.
S4, extracting detail features of the palm print texture: extracting texture detail features of the palm print dominant line image to be matched, wherein the method for extracting the texture detail features comprises the following steps:
dividing the acquired gray level image into nxn matrix blocks, wherein each matrix block comprises axb pixels; h image blocks are formed from the nxn matrix, each image block is composed of cxd pixels, and adjacent image blocks are overlapped;
then, filtering the xth pixel point I (x, y) of the xth line of the image block by using a two-dimensional linear Gabor filter, wherein the Gabor filter has a definition formula as follows:
wherein θ is the direction of the filter function, μ is the frequency of the sine wave, δ is the standard deviation of the gaussian envelope, the fixed parameters μ and δ, and G (x, y, θ) is the pixel value of the pixel I (x, y) in the filter direction θ;
changing theta to obtain a group of filter banks in r directions, respectively convolving the image blocks to obtain r filtered images of the image blocks, wherein the value number of the directions of the k filtering function ranges from 1 to n, and the amplitude m (x, y) of the pixel points in each filtering image is known by a Gabor filter principle formula:
m(x,y)=min(I(x,y)G(x,y,θk)),k=1,2,...,n
then, equally dividing the filtering angle of 180 degrees into m intervals, sampling an angle value in each angle interval as a filtering direction of a filtering function, forming a filtering image based on each filtering direction, sampling the angle value based on a set angle step length, accumulating the amplitude m (x, y) of each pixel point on all the filtering images, and forming an m-dimensional gradient amplitude accumulation histogram HC of each pixel point;
accumulating m-dimensional gradient amplitude accumulation histograms HC of all pixel points in the image block to form a histogram HB corresponding to the image block, standardizing by using L2 norm to construct a standardized histogram NHB of the image block, and calculating a formula:
HBj={HC1,HC2,...,HCj,...,HCh};
wherein, HBjHistograms HB, NHB representing the jth image BlockjThe normalized histogram NHB, e ≈ 1.732 representing the j-th image block.
The normalized histograms NHB of the h image blocks are integrated to form a line energy direction histogram feature HOLEGaborThen, the formula is expressed as: HOLEGabor={NHB1,NHB2,...,NHBkAnd finishing the extraction of detail features of the palm print main line and the main line texture of the gray level image.
S5, palm print matching and identifying process: finding out k palm print main line template images which are most matched with the palm print to be matched in a matching library based on the palm print main line, wherein the matching library is used for storing the palm print main line template images and corresponding identity information;
calculating the feature matching degree of the palm print main line template image and the palm print main line image to be matched in the matching library, wherein the calculation formula is as follows:
wherein L (x, y) andrespectively the pixel values of the x row and y column pixel points in the palm print mainline image to be matched and the palm print mainline template image, N is the width and height of the image, S1Matching characteristics of the image divided by the overlapping area of the palm print main line template image and the palm print main line image to be matched relative to the palm print main line image to be matched S2Obtaining the matching characteristic S for the matching characteristic of the image of the overlapping area of the palm print main line template image and the palm print main line image to be matched relative to the palm print main line template image1And matching feature S2Then, the distance between features Dist is defined as:
the smaller the distance Dist is, the larger the matching degree is, namely the closer the master palm print template image is, the k master palm print template images with the maximum matching degree are obtained, and the preliminary coarse matching is completed;
and extracting the key line energy direction histogram characteristics of the palm print main line template image, matching the key line energy direction histogram characteristics with the line energy direction histogram characteristics of the matched image, and finding the palm print main line template image with the closest matching degree to finish the identification.
The invention has been described above with reference to the accompanying drawings, it is obvious that the invention is not limited to the specific implementation in the above-described manner, and it is within the scope of the invention to apply the inventive concept and solution to other applications without substantial modification.
Claims (4)
1. A palm print identification method based on texture features is characterized by specifically comprising the following steps:
s1, collecting a palm print image of the palm print to be matched, and carrying out gray processing on the palm print image to form a gray image;
s2, detecting a palm print main line in the gray level image, and acquiring a main line image of a palm print to be matched;
s3, extracting texture detail features from the palm print dominant line image to be matched;
s4, k palm print main line template images which are most matched with the palm print main line image to be matched are obtained in the matching library, the palm print main line template image which is matched with the texture detail features of the palm print to be matched is obtained from the k palm print main line template images, and the identification of the palm print to be matched is completed.
2. The palm print recognition method based on texture features as claimed in claim 1, wherein the extraction method of the texture detail features is as follows:
s31, h image blocks are formed in the main line image of the palm print to be matched, and adjacent image blocks are overlapped;
s32, equally dividing the filtering angle into m intervals at 180 degrees, sampling the angle value in each angle interval as the filtering direction of the filtering function, forming a filtering image based on each filtering direction, accumulating the amplitude m (x, y) of each pixel point on all the filtering images, and forming an m-dimensional gradient amplitude accumulation histogram HC of each pixel point;
accumulating m-dimensional gradient amplitude accumulation histograms HC of all pixel points in an image block to form a histogram HB corresponding to the image block, and constructing a standardized histogram NHB of the image block;
the normalized histograms NHB of the h image blocks are integrated to form a line energy direction histogram feature HOLEGaborI.e. the texture detail feature of the palm print to be matched.
3. The palm print recognition method based on texture features as claimed in claim 1, wherein the step S4 specifically comprises the steps of:
s1, acquiring the overlapping area of the palm print main line template image and the palm print main line image to be matchedCalculating the matching characteristic S of the overlapping area relative to the master line graph and master line template image of the palm print to be matched1、S2;
S2, calculating matching characteristics S1、S2And obtaining k palm print main line template images with the minimum distance Dist.
4. A palm print recognition method based on texture features as claimed in claim 3, characterized in that the matching features S1And S2The calculation formula of (a) is specifically as follows:
wherein L (x, y) andpixel values of the x row and y column pixel points in the palm print main line image to be matched and the palm print main line template image are respectively, and N is the width and the height of the palm print main line image to be matched and the palm print main line template image.
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