Method and apparatus for fingerprint image reconstruction
View Patent ↗Enhanced accuracy finger position and motion sensors devices, algorithms, and methods are disclosed that can be used in a variety of different applications. The sensors can be used in conjunction with partial fingerprint imagers to produce improved fingerprint scanners. Such improved scanners can use image analysis techniques, such as interpolation between partial fingerprint images to correct for missing data, or discarding redundant partial fingerprint image data, to produce adequate fingerprint images even when the finger has not been applied to the sensor using an optimum technique.
1. A non-transitory machine readable medium storing instructions that, when executed by a computing device, cause the computing device to perform a method, the method comprising:
reconstructing a fingerprint image from a series of partial fingerprint images of a finger surface, by:
capturing a series of partial fingerprint image sections of a finger surface moving with respect to a partial fingerprint imager;
calculating a speed at which the partial fingerprint imager traverses the finger surface;
determining if the speed is above a preset fast swipe value;
if the speed is above the preset fast swipe value, filling in any gap intermediate partial fingerprint image segments by generating an additional synthetic partial fingerprint image segment by interpolating between partial fingerprint image segments on either side of the gap;
if the speed is below the preset fast swipe value, then determining if the speed is below a preset slow swipe value;
if the speed is below the preset slow swipe value, detecting any redundant portion of a partial fingerprint image segment; and
reconstructing the fingerprint image of the finger surface using the partial fingerprint image segments and inserting any additional synthetic image segment and removing any redundant portion of any partial fingerprint image segment.
2. The non-transitory machine readable medium of claim 1 , the method further comprising: the partial fingerprint imager is a deep finger penetrating radio frequency (RF) based sensing array.
3. The non-transitory machine readable medium of claim 1 , the method further comprising: interpolating between partial fingerprint image segments on either side of the gap is done using a non-adaptive algorithm selected from the group consisting of bicubic, bilinear, lanczos, nearest neighbor, sinc and spline algorithms.
4. The non-transitory machine readable medium of claim 1 , the method further comprising: interpolating between partial fingerprint image segments on either side of the gap is done using an adaptive algorithm.
5. The non-transitory machine readable medium of claim 1 , the method further comprising: interpolating between different fingerprint image segments on either side of the gap uses an anti-aliasing algorithms.
6. The non-transitory machine readable medium of claim 1 , the method further comprising: a redundant portion of a partial fingerprint image segment is detected and discarded by selecting a portion of each partial fingerprint image segment suspected of being redundant, computing a sum of the differences between pixels of the respective portions of the partial fingerprint image segments suspected of being redundant, and determining if this sum is less than a preset threshold.
7. The non-transitory machine readable medium of claim 1 , the method further comprising: the speed at which the partial fingerprint imager traverses the finger surface is determined by data collected by at least one finger position sensor array.
8. The non-transitory machine readable medium of claim 7 , the method further comprising: the finger position sensing array is a deep finger penetrating radio frequency (RF) based sensing array.
9. The non-transitory machine readable medium of claim 7 , the method further comprising: the finger position sensing array is an optical sensing array.