Method and system for enhancing ridges of fingerprint images
AssigneeNational Kaohsiung University of Applied Sciences
InventorJing-Wein Wang
Life of this patent
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Abstract
A fingerprint processing system includes an input unit, a calculation unit and an output unit. The input unit is applied to input an original fingerprint image. The calculation unit is applied to decompose the original fingerprint image to a decomposed image by singular value decomposition (SVD) and the decomposed image is transformed into a plurality of sub-band images by discrete wavelet transformation (DWT) with a template. A plurality of compensation weight coefficients of DWT are calculated to compensate the sub-band images to generate a plurality of compensated sub-band images which are rebuilt by an inverse DWT. After rebuilding the compensated sub-band images, the output unit is applied to output an enhanced fingerprint image.
Claims18
A fingerprint processing method comprising:
- decomposing a fingerprint image to obtain a decomposed matrix of the fingerprint image by a singular value decomposition method, with the decomposed matrix having a M×N SVD matrix of the fingerprint image with (M≦N) which is calculated as A=UΣVT, wherein U=[u1, u2, . . . , um] and V=[v1, v2, . . . , vn] are orthogonal matrixes, with a diagonal of Σ=[D,O] including a plurality of singular values, where D is diag (λ1, λ2, . . . , λk), O is a zero matrix and Σ is intensity information of the fingerprint image;
- transforming the M×N SVD matrix of the decomposed matrix of the fingerprint image to a plurality of sub-band images by a discrete wavelet transformation method with a predetermined template to obtain a plurality of decomposed sub-band images, with calculating the M×N SVD matrix with A=[am, n], wherein Aε{LL, HL, LH, HH} are four decomposed sub-bands, aε{ll, hl, lh, hh} are wavelet coefficients of the four decomposed sub-bands, and m=0, 1, . . . , M/2−1;
- n=0, 1, 2, . . . , N/2−1 are values of the wavelet coefficients;
- calculating a plurality of wavelet-transformed compensation coefficients according to the plurality of decomposed sub-band images;
- compensating the plurality of decomposed sub-band images with the plurality of wavelet-transformed compensation coefficients to obtain a plurality of decomposed and compensated sub-band images;
- and
- rebuilding the plurality of decomposed and compensated sub-band images by an inverse discrete wavelet transformation method to obtain an enhanced fingerprint image.
A fingerprint processing system comprising:
- an input unit connecting with a fingerprint image source to input a fingerprint image therefrom;
- a calculation unit connecting with the input unit and decomposing the fingerprint image to obtain a decomposed matrix of the fingerprint image by a singular value decomposition method, with the decomposed matrix of the fingerprint having a M×N SVD matrix with (M≧N) which is calculated as A=UΣVT, wherein U=[u1, u2, . . . , um] and V=[v1, v2, . . . , vn] are orthogonal matrixes, with a diagonal of Σ=[D, O] including a plurality of singular values, where D is diag (λ1, λ2, . . . , λk), O is a zero matrix and Σ is intensity information of the fingerprint image, with the M×N SVD matrix of the decomposed matrix of the fingerprint image transformed into a plurality of sub-band images by a discrete wavelet transformation method with a predetermined template to obtain a plurality of decomposed sub-band images, with the M×N SVD matrix calculated with A=[am,n] wherein Aε{LL, HL, LH, HH} are four decomposed sub-bands, aε{ll, hl, lh, hh} are wavelet coefficients of the four decomposed sub-bands, and m=0, 1,. . . , M/2−1;
- n=0, 1, 2, . . . , N/2−1 are values of the wavelet coefficients, with a plurality of wavelet-transformed compensation coefficients calculated according to the plurality of decomposed sub-band images, with the decomposed sub-band images compensated with the plurality of wavelet-transformed compensation coefficients to obtain a plurality of decomposed and compensated sub-band images, with the plurality of decomposed and compensated sub-band images rebuilt by an inverse discrete wavelet transformation method to obtain an enhanced fingerprint image;
- and
- an output unit connecting with the calculation unit for outputting the enhanced fingerprint image.
Dependencies are inferred from the claim text.