초록

A fingerprint image capture system reduces tip smear by ceasing to update a data array characteristic of the rolled fingerprint image behind an advancing freeze column at least about half way from the trailing edge to the leading edge of a finger contact strip.

대표청구항 ▼

[ What is claimed is:] [1.] A method of reducing smear in a rolled fingerprint image represented by a rolled image array, comprising the steps of:sequentially generating frames of an optical image signal which includes data values characteristic of light intensities of corresponding locations of an

[ What is claimed is:] [1.] A method of reducing smear in a rolled fingerprint image represented by a rolled image array, comprising the steps of:sequentially generating frames of an optical image signal which includes data values characteristic of light intensities of corresponding locations of an optical image, wherein the optical image includes a fingerprint image of a finger rolling on a surface;determining, for each frame of the optical image signal, a freeze column representing a line positioned between leading and trailing edges of the fingerprint image and oriented transverse to a direction of roll of the rolling finger;sequentially updating an interim array that is an accumulation of the frames of the optical image signal and characteristic of an interim image of a rolled fingerprint, a current update of the interim array being formed by reducing pixel values of the interim array by a portion of the difference between corresponding data values from a current frame of the optical image signal and the pixel values of the interim array if the corresponding data values of the current frame of the optical image signal are less than the pixel values of the interim array; andgenerating the rolled image array by transferring portions of the interim array to the rolled image array, wherein the transferred portion of the current update of the interim array extends forward in the direction of finger roll from the freeze column determined from a preceding frame of the optical image signal that preceded the current frame of the optical image signal.