System for generating rolled fingerprint images

A method for operating a programmable processor to generate data characteristic of a rolled fingerprint image, including:

• providing an optical device having a finger receiving surface;
• rolling a finger across the finger receiving surface of the optical device and propagating fingerprint images of finger portions in contact with the surface from the device;
• imaging the finger receiving surface of the optical device and generating digital data representative of fingerprint images propagated therefrom;
• storing arrays of digital data characteristic of the images propagated from the optical device;
• identifying active portions of the arrays which are representative of fingerprint features as a mathematical function of the stored digital data;
• and
• generating a composite array of data characteristic of the rolled fingerprint image as a mathematical function of the data representative of the identified active portions of the stored arrays.

A method for generating data characteristic of a rolled fingerprint image in real time, including:

• (a) providing an optical device having a finger receiving surface;
• (b) continuously rolling a finger across the finger receiving surface of the optical device and propagating fingerprint images of finger portions in contact with the surface from the device;
• (c) imaging the finger receiving surface of the optical device and generating digital data representative of fingerprint images propagated therefrom;
• (d) storing a first array of data characteristic of a fingerprint image of a first finger portion;
• (e) identifying leading and trailing active area boundaries of the first array which define areas substantially including only data characteristic of a fingerprint image;
• (f) merging the first array of data into a composite array;
• (g) storing a second array of data characteristic of a second finger portion, after the first array is merged into the composite array;
• (h) identifying leading and trailing active area boundaries of the second array which define areas substantially including only data characteristic of a fingerprint image;
• (i) determining the amount of fingerprint image overlap characterized by the second and composite arrays as a mathematical function of the active area boundaries;
• (j) determining the direction of motion of the finger as a mathematical function of the active area boundaries;
• (k) activating an alarm if the fingerprint image overlap is less than a predetermined amount or the direction of motion changes;
• (l) merging the second array into the composite array, including storing data in the composite array as a mathematical function of the data in the composite array and second array which are characteristic of overlapping image portions of the fingerprint images, if the direction of motion has not changed and the amount of overlap is not less than the predetermined overlap;
• and
• (m) repeating steps (g)-(l) for third and subsequent arrays until the composite array characterizes the rolled fingerprint image.