Skin pattern feature extracting apparatus

A skin pattern feature extracting apparatus for displaying skin pattern images and assisting an operator to input their features, comprising:

• focal point instruction input means for inputting operators focal point instructions thereto, wherein the focal point instructions comprise a selected focal point within a 2-dimensional coordinate system used for displaying the skin pattern image;
• perspective transformation parameter determining means for determining the specification of perspective transformation from the characteristics of an input image in the proximity of the instructed focal point;
• and perspective transformation of the determined specification, wherein the perspective transformation parameter determining means determines an angle θ of geometrical rotation in the perspective transformation, and/or an extent of geometrical image compression in the perspective transformation with reference to an instructed local image as input;
• perspective transforming means for executing affine transformation operations on the input image according to the rotation angle θ and compression extent r determined by the perspective transformation parameter determining means,
• wherein the perspective transformation uses affine transformations for permitting clearer observation of the structures of a skin pattern, a first affine transformation rotating the given image by the angle θ, resulting in an image where a direction of ridges appearing in the given image are transformed from a horizontal direction to a vertical direction, a second affine transformation compressing the resulting image in the a vertical, Y, direction by r=cos θ, 0<r≦1.

A skin pattern feature extracting apparatus comprising:

• image storage means for storing digitized input image of a skin pattern;
• image display means for displaying the input image stored in the image storage means on a display screen;
• perspective transformation instruction input means for inputting an instruction of a desired perspective transformation of the displayed image, wherein the perspective transformation instructions comprise parameter data corresponding to an inclination angle, φ, and a rotation angle, θ, of a given image;
• perspective transforming means for generating perspective transformed image by executing an affine transformation according to the data fed from the perspective transformation instruction input means;
• perspective transformed image display for displaying the perspective transformed obtained in the perspective transforming means;
• manual input means, through manual plotting or manual tracing with reference to the perspective transformed image displayed on the perspective transformed image display, for inputting specified position feature data determined based on the manual plotting or manual tracing result;
• and
• feature data transforming means for transforming the specified position feature data to feature data for identification of a person in a skin pattern matching.

A skin pattern feature extracting apparatus comprising:

• image storage means for storing digitized input image of a skin pattern;
• image display means for displaying the input image stored in the image storage means on a display screen;
• focal point instruction input means for inputting position data of a local focal point, wherein the local focal point is within a 2-dimensional coordinate system used for displaying the skin pattern image;
• perspective transformation parameter determining means, receiving the position data from the focal point instruction means, for determining perspective transformation parameter data for effectively clarifying the features of the local image area,
• wherein the perspective transformation parameter data comprise parameter data corresponding to a rotation angle, θ, and compression extent r of a given image;
• perspective transforming means for generating perspective transformed image by executing an affine transformation according to the data fed from the perspective transformation parameter determining means;
• perspective transformed image display for displaying the perspective transformed obtained in the perspective transforming means;
• manual input means, through manual plotting or manual tracing with reference to the perspective transformed image displayed on the perspective transformed image display, for inputting specified position feature data determined based on the manual plotting or manual tracing result;
• feature data transforming means for transforming the specified position feature data to feature data for identification of a person in a skin pattern matching;
• and
• feature data superimposing unit for superimposing symbols on the input image, each symbol representing a skin pattern feature selected from the group of ridges, end points and bifurcations.

A method for extracting skin pattern features from an image, said method comprising the steps of:

• retrieving a stored digitized input image of a skin pattern;
• inputting an instruction of a desired two-dimensional perspective transformation of the displayed image, wherein the perspective transformation instruction comprises parameter data corresponding to a rotation angle, θ;
• generating a perspective transformed image by executing an affine transformation according to data input in the inputting step, wherein the perspective transformation uses affine transformations for permitting clearer observation of the structures of a skin pattern, a first affine transformation rotating the given image by the angle θ, resulting in an image where a direction of ridges appearing in the given image are transformed from a horizontal direction to a vertical direction, a second affine transformation compressing the resulting image in the a vertical, Y, direction by r=cosθ, 0<r≦1, where r is a compression ratio;
• and
• displaying the perspective transformed image obtained in the generating step on a display screen.