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US 2018/0322332 A1Published application
Method and apparatus for identifying pupil in image
AssigneeChina Unionpay Co., Ltd.
InventorsLiang Feng, Zihao Cai, Yawei Yin
Life of this patent
Estimating the term…
Abstract
A method and device for identifying a pupil in an image is provided. The method comprises four steps including: A. image preprocessing, B. edge detecting, C. building connected graphs, and D. screening connected graph pairs.
Claims10
A method of identifying a pupil in an image, comprising:
- A. image preprocessing;
- B. edge detecting;
- C. building connected graphs, comprising:
- marking off connected regions based on edge lines of edge graphs,
- dividing connected regions into two categories having a grey-scale value between 100 and 200 and a grey-scale value over 200, respectively,
- for connected graphs of these two categories, selecting connected graph pairs, in which edge lines of a connected graph b having a grey-scale value over 200 are included in edge lines of a connected graph a having a grey-scale value between 100 and 200;
- D. screening connected graph pairs, comprising:
- for each of connected graph pairs, calculating a centroid pixel location b_Location of the connected graph b, a pixel length b_Major of a major axis and a pixel length b_Minor of a minor axis of an ellipse that has the same standardized second-order central moment as its connected region,
- connecting the connected graphs a and b to obtain a new image c, calculating a centroid pixel location c_Location of the image c, a pixel length c_Major of a major axis and a pixel length c_Minor of a minor axis of an ellipse that has the same standardized second-order central moment as its connected region,
- for each of connected graph pairs, calculating a pixel distance L between the centroid pixel location b_Location and c_Location, a ratio R of b_Major to c_Major, and a ratio P of b_Minor to c_Minor,
- for each of connected graph pairs, calculating W=L−m*R−n*P, wherein m and n are weight factors,
- selecting the connected graph b in the connected graph pair that has the maximum value of W as the identified pupil.
9 more elements
A device for identifying a pupil in an image, comprising:
- A. an image preprocessing unit;
- B. an edge detecting unit;
- C. a connected graph building unit configured to perform steps of:
- marking off connected regions based on edge lines of edge graphs,
- dividing connected regions into two categories having a grey-scale value between 100 and 200 and a grey-scale value over 200, respectively,
- for connected graphs of these two categories, selecting connected graph pairs, in which edge lines of a connected graph b having a grey-scale value over 200 are included in edge lines of a connected graph a having a grey-scale value between 100 and 200;
- D. a connected graph pair screening unit configured to perform steps of:
- for each of connected graph pairs, calculating a centroid pixel location b_Location of the connected graph b, a pixel length b_Major of a major axis and a pixel length b_Minor of a minor axis of an ellipse that has the same standardized second-order central moment as its connected region,
- connecting the connected graphs a and b to obtain a new image c, calculating a centroid pixel location c_Location of the image c, a pixel length c_Major of a major axis and a pixel length c_Minor of a minor axis of an ellipse that has the same standardized second-order central moment as its connected region,
- for each of connected graph pairs, calculating a pixel distance L between the centroid pixel location b_Location and c_Location, the ratio R of b_Major to c_Major, and the ratio P of b_Minor to c_Minor,
- for each of connected graph pairs, calculating W=L-m*R-n*P, wherein m and n are weight factors,
- selecting the connected graph b in the connected graph pair that has the maximum value of W as the identified pupil.
9 more elements
Dependencies are inferred from the claim text.