07-01-2021 дата публикации
Номер: US20210004560A1
Принадлежит:
The present invention relates to a method to segment slap images and to generate accurately labelled individual fingerprints, said method comprising the following steps: 1. A method to segment slap images and to generate accurately labelled individual fingerprints , said method comprising the following steps:reception of inputs images from a contactless fingerprint reader under controlled lighting conditions;computation of a variance in the received images to estimate a slap area as a foreground slap mask in the input images;identification of individual fingers by finding boundary of each finger;verification of a number of fingers and of geometric constraints;calculation of pose and orientation based on shape and geometry information;identification of effective fingertip area on each detected finger according the pose, orientation, as well as geometric information;output of individual fingerprints.2. The method to segment slap images according to claim 1 , wherein the images acquired under controlled lighting conditions are images acquired with and without flash light.3. The method to segment slap images according to claim 1 , wherein the individual finger identification step comprises an adaptive binarization sub step applied to an original lighted image with the foreground slap mask by calculating the dynamic range of both global and local dynamics according to the equation Thres(x claim 1 ,y)=α(x claim 1 ,y)+pα(x claim 1 ,y)β(x claim 1 ,y)−q) claim 1 , where α(x claim 1 ,y) is a local dynamic factor claim 1 , β(x claim 1 ,y) is a global dynamic factor and p claim 1 ,q are pre-defined parameters claim 1 , this adaptive binarization sub step outputting individual finger's masks.4. The method to segment slap images according to claim 1 , wherein the step of calculation of pose and orientation based on shape and geometry information comprises a convexity check to detect fingertip points of the fingers.5. The method to segment slap images according to claim 1 , ...
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