System and method for counting ridges in a captured print image
A system and method for counting ridges in a captured print image frame is described. A pixel path through the captured print image frame is traversed. A hysteresis band for the pixel path is determined. A number of crossings of the determined hysteresis band is counted while traversing the pixel path. A number of print ridges based on the counted number of hysteresis band crossings is determined.
1 - 34 . (canceled)
35 . A method for counting print ridges in a captured print image frame, comprising the steps of:
(1) traversing a pixel path through the captured print image frame;
(2) counting a number of crossings of a first pixel intensity threshold and a second pixel intensity threshold while traversing the pixel path; and
(3) determining a number of print ridges in the captured print image frame based on the counted number of crossing of the first pixel intensity threshold and the second pixel intensity threshold.
36 . The method of claim 35 , wherein step (3) comprises determining the number of print ridges by dividing the counted number of first pixel intensity threshold and second pixel intensity threshold crossings by two.
37 . The method of claim 35 , further comprising the step of:
(4) determining the first pixel intensity threshold and the second pixel intensity threshold.
38 . The method of claim 37 , wherein step (4) comprises determining a third pixel intensity threshold based on a first maximum pixel intensity value and a first minimum pixel intensity value in the captured print image frame.
39 . The method of claim 38 , wherein step (4) further comprises determining a delta value based on the first maximum pixel intensity value and the first minimum pixel intensity value in the captured print image frame.
40 . The method of claim 39 , wherein step (4) further comprises determining the first pixel intensity threshold as a sum of the third pixel intensity threshold and the delta value.
41 . The method of claim 39 , wherein step (4) further comprises determining the second pixel intensity threshold as a difference of the third pixel intensity threshold and the delta value.
42 . The method of claim 35 , further comprising the steps of:
(4) traversing a second pixel path across the captured print image frame; and
(5) repeating steps (2) and (3) using the second pixel path.
43 . The method of claim 35 , further comprising the steps of:
(4) storing the number of print ridges; and
(5) evaluating the stored number of print ridges to determine a quality of the captured fingerprint image.
44 . A print scanner system, comprising:
an optical system enabled to direct light to an imaging surface of a platen of the optical system;
a camera enabled to capture a print image frame from light reflected by the print surface and directed to the camera by the optical system;
a memory coupled to the camera and enabled to store the captured print image frame; and
a ridge counter coupled to the memory and enabled to traverse a pixel path through the captured print image frame, count a number of crossings of a first pixel intensity threshold and a second pixel intensity threshold while traversing the pixel path, and determine a number of print ridges in the captured print image frame based on the counted number of crossings.
45 . The print scanner system of claim 44 , wherein the ridge counter is enabled to determine the number of print ridges by dividing the number of crossings by two.
46 . The print scanner system of claim 44 , wherein the ridge counter is enabled to determine a region of interest in the captured print image frame.
47 . The print scanner system of claim 44 , wherein the ridge counter is enabled to determine a first pixel intensity threshold and a second pixel intensity threshold.
48 . The print scanner system of claim 47 , wherein the ridge counter is enabled to determine a third pixel intensity threshold based on a first maximum pixel intensity value and a first minimum pixel intensity value in the captured print image frame.
49 . The print scanner system of claim 48 , wherein the ridge counter is enabled to determine a delta value based on the first maximum pixel intensity value and first minimum pixel intensity value in the captured print image frame.
50 . The print scanner system of claim 49 , wherein the ridge counter is enabled to determine the first pixel intensity threshold as a sum of the third pixel intensity threshold and the delta value.
51 . The print scanner system of claim 49 , wherein the ridge counter is enabled to determine the second pixel intensity threshold as a difference of the third pixel intensity threshold and the delta value.
52 . A ridge counter embodied in software and including control logic for counting print ridges in a captured print image frame, comprising:
first control logic means for enabling a processor to traverse a pixel path through the captured print image frame;
second control logic means for enabling a processor to count a number of crossings of a first pixel intensity threshold and a second pixel intensity threshold while traversing the pixel path; and
third control logic means for enabling a processor to determine a number of print ridges in the captured print image frame based on the counted number of first pixel intensity threshold crossings and second pixel intensity threshold crossings.
53 . The ridge counter of claim 52 , further comprising fourth control logic means for enabling a processor to determine the number of print ridges by dividing the counted number of crossings of the first pixel intensity threshold and the second pixel intensity threshold by two.
54 . The ridge counter of claim 52 , further comprising fourth control logic means for enabling a processor to determine the first pixel intensity threshold and the second pixel intensity threshold.