Skin-pattern recognition method and device
First Claim
1. A method of authenticating a person by comparing information from a currently taken skin pattern with stored information from previously taken skin pattern, the currently taken skin-pattern being produced on a contact surface, an image of the print of the skin pattern on the contact surface being projected into a photo-detector device, the intensity variations of the image of the skin pattern in at least one region thereof impinging on the photo-detector device being assessed in digital form in a series of binary "1" units and "0" units to create a first digital signal train by setting a threshold intensity and judging image areas of intensity above the threshold as meriting one type of binary unit and other image areas of intensity below the threshold as meriting the other type of binary unit, a second digital signal train being derived from the stored skin pattern information and the first and second signal trains being compared to determine the degree of coincidence therebetween, an assessment of the determined degree being used to decide whether the currently taken and stored skin patterns are sufficiently similar to authenticate the person, the degree of coincidence between the first and second signal trains being assessed by looking for correlation between digital signal trains representative of respective first sub-regions of each of the currently taken and stored skin patterns and between respective second sub-regions of each of the currently taken and stored skin patterns while allowing relative translational and rotational movements between the first and second sub-regions of one of the skin patterns, the threshold used for the first digital signal train being adapted according to an average value of intensity within a sampling region of the skin pattern image used to create the first digital signal train, and the second signal train being derived by considering only determinate samples of the previously taken skin pattern image which can clearly be categorized as a binary "1" or a binary "0" so that in the correlation between the first and second signal trains, all "indeterminate" samples in the second signal train are discounted.
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Abstract
A method of authenticating a person by comparing information from a currently taken skin-pattern with stored information from a previously taken skin-pattern is characterized in that the currently taken skin-pattern is produced on a contact surface, an image of the print of the skin pattern on the contact surface is projected onto a photo-detector device (20), the intensity variations of the print image in at least one region thereof impinging on the photo-detector device is assessed in digital form in a multiplicity of different sub-regions of the or each said region to create (in unit 21) a first digital signal train, a second digital train is derived from the stored skin pattern information (in store 23) and the first and second signal trains are compared (in 24) to determine the degree of coincidence therebetween, an assessment of the determined degree being used to decide (on indicator 27) whether the currently-taken and stored skin patterns are sufficiently similar to authenticate the person.
96 Citations
8 Claims
- 1. A method of authenticating a person by comparing information from a currently taken skin pattern with stored information from previously taken skin pattern, the currently taken skin-pattern being produced on a contact surface, an image of the print of the skin pattern on the contact surface being projected into a photo-detector device, the intensity variations of the image of the skin pattern in at least one region thereof impinging on the photo-detector device being assessed in digital form in a series of binary "1" units and "0" units to create a first digital signal train by setting a threshold intensity and judging image areas of intensity above the threshold as meriting one type of binary unit and other image areas of intensity below the threshold as meriting the other type of binary unit, a second digital signal train being derived from the stored skin pattern information and the first and second signal trains being compared to determine the degree of coincidence therebetween, an assessment of the determined degree being used to decide whether the currently taken and stored skin patterns are sufficiently similar to authenticate the person, the degree of coincidence between the first and second signal trains being assessed by looking for correlation between digital signal trains representative of respective first sub-regions of each of the currently taken and stored skin patterns and between respective second sub-regions of each of the currently taken and stored skin patterns while allowing relative translational and rotational movements between the first and second sub-regions of one of the skin patterns, the threshold used for the first digital signal train being adapted according to an average value of intensity within a sampling region of the skin pattern image used to create the first digital signal train, and the second signal train being derived by considering only determinate samples of the previously taken skin pattern image which can clearly be categorized as a binary "1" or a binary "0" so that in the correlation between the first and second signal trains, all "indeterminate" samples in the second signal train are discounted.
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3. A method as claimed in claim 14, characterized in that third and subsequent sub-regions of each skin pattern are used if a predetermined correlation score is exceeded with the first and second sub-regions and authentication is determined only if a predetermined correlation score is exceeded with all sub-regions used.
Specification