System and method of image reconstruction with dual line scanner using line counts

Abstract

A fingerprint scanning and image reconstruction system and method including a fingerprint scanner providing a first scan line and a second scan line separated by a line separation distance in a scanning direction. The system includes an image reconstruction module accumulating scan lines including at least the first scan line and the second scan line over a time period t. The image reconstruction module a value for decimation (t) necessary to produce a selected y axis resolution in the scanning direction based at least in part on (line count(t)/line separation distance)*a selected y resolution, where line count(t) is the number of lines accumulated in time t, and decimation(t) indicates of whether the line count(t) is greater than or less than the number of lines accumulated as a function of the time period t that will result in a selected reconstructed image y resolution in the scanning direction.

What is claimed is: 
     
         1 . A method of scanning a biometric object moving in direction of swiping and reconstructing an image of the biometric object, the method comprising:
 scanning a first scan line utilizing a first linear array of biometric object scanning elements and a second scan line utilizing a second linear array of biometric object scanning elements, the first linear array of biometric object scanning elements and the second linear array of biometric scanning elements being separated by a scanning line separation distance in the direction of swiping the biometric object, and sampling, respectively, at a first scanning time and a second scanning time; and   reconstructing the biometric object image, based in part on at least one of the scanning line separation distance and the time period between the first scanning time and the second scanning time, without calculating a velocity of the biometric object moving in the scanning direction.   
     
     
         2 . The method of  claim 1  and further comprising accumulating scan lines including at least the first scan line and the second scan line during the period of time separating the first scanning time and a second scanning time. 
     
     
         3 . The method of  claim 1  and further comprising:
 reconstructing the biometric object image with a selected reconstructed image resolution in the scanning direction based at least in part on a determination of whether the number of lines accumulated during the period of time between the first scanning time and the second scanning time is greater than or less than the number of lines as a function of the time period between the first scanning time and the second scanning time that will result in the selected reconstructed image resolution in the scanning direction. 
 
     
     
         4 . The method of  claim 1  and further comprising:
 determining a value for decimation relating to the time period which is necessary to produce a selected y axis resolution in the scanning direction based at least in part on the number of lines accumulated during the time period divided by the product of a line separation distance between the first line scanner and the second line scanner and the selected y-axis resolution, wherein the decimation for the time period is a ratio indicative of whether the number of lines accumulated during the time period is greater than or less than the number of lines accumulated that will result in the selected y axis resolution in the scanning direction. 
 
     
     
         5 . The method of  claim 1  and further comprising:
 receiving the output of the biometric object scanner and comparing the first scanned line of biometric object image data to the second scanned line of biometric object image data and culling from the output of the biometric object scanner the second scanned line of biometric object image data, when the second scanned line of biometric object image data is effectively redundant as compared to the first scanned line of biometric object image data, and repeating this step with a first un-culled second scanned line as a new first scanned line, to produce a plurality of un-culled second scanned lines of biometric object image data having an effective line scanning rate; 
 receiving the un-culled second scanned lines of biometric object image data and accumulating the un-culled second scanned lines of biometric object image data over a time period; and 
 determining a value for decimation relating to the time period which is necessary to produce a selected y axis resolution in the scanning direction based at least in part on the number of un-culled second scanned lines accumulated during the time period divided by the product of a line separation distance between first line scanner and the second line scanner and the selected y-axis resolution, wherein the decimation for the time period is a ratio indicative of whether the number of un-culled second scanned lines of biometric object image data accumulated during the time period is greater than or less than a number un-culled second scanned lines that will result in the selected y axis resolution in the direction of movement of the biometric object. 
 
     
     
         6 . The method of  claim 1  wherein the biometric object is a fingerprint. 
     
     
         7 . The method of  claim 2  wherein the biometric object is a fingerprint. 
     
     
         8 . A biometric object imaging apparatus comprising:
 a biometric object imager configured to scan a biometric object moving in a direction of swiping and reconstruct an image of the biometric object comprising:   a first linear array of biometric object scanning elements and a second linear array of biometric object scanning elements, separated by a scanning line separation distance in the direction of swiping the biometric object, configured to sample scanned lines of biometric object image data at a first scanning time and a second scanning time;   a biometric object image reconstruction apparatus configured to reconstruct the biometric object image, based in part on at least one of the scanning line separation distance and the time period between the first scanning time and the second scanning time, without calculating a velocity of the biometric object moving in the scanning direction.   
     
     
         9 . The apparatus of  claim 8  further a scan line accumulator configured to accumulate scan lines including at least the first scan line and the second scan line during the period of time separating the first scanning time and a second scanning time. 
     
     
         10 . The apparatus of  claim 8  and further comprising:
 the biometric object image reconstruction apparatus configured to reconstruct the biometric object image with a selected reconstructed image resolution in the scanning direction based at least in part on a determination of whether the number of lines accumulated during the period of time between the first scanning time and the second scanning time is greater than or less than the number of lines as a function of the time period between the first scanning time and the second scanning time that will result in the selected reconstructed image resolution in the scanning direction. 
 
     
     
         11 . The apparatus of  claim 8  and further comprising:
 a decimation determination apparatus configured to determine a value for decimation during the time period which is necessary to produce a selected y axis resolution in the scanning direction based at least in part on the number of lines accumulated during the time period divided by the product of a line separation distance between the first line scanner and the second line scanner and the selected y-axis resolution, wherein the decimation for the time period is a ratio indicative of whether the number of lines accumulated during the time period is greater than or less than the number of lines accumulated that will result in the selected y axis resolution in the scanning direction. 
 
     
     
         12 . The apparatus of  claim 8  further comprising:
 a scanned line culling apparatus configured to
 receive the output of the biometric object scanner and compare the first scanned line of biometric object image data to the second scanned line of biometric object image data and culling from the output of the biometric object scanner the second scanned line of biometric object image data, when the second scanned line of biometric object image data is effectively redundant as compared to the first scanned line of biometric object image data, and repeating this culling with a first un-culled second scanned line as a new first scanned line, to produce a plurality of un-culled second scanned lines of biometric object image data having an effective line scanning rate; 
 accumulate the un-culled second scanned lines of biometric object image data over a time period; and 
 determine a value for decimation relating to the time period which is necessary to produce a selected y axis resolution in the scanning direction based at least in part on the number of un-culled second scanned lines accumulated during the time period divided by the product of a line separation distance between the first line scanner and the second line scanner and the selected y-axis resolution, wherein the decimation for the time period is a ratio indicative of whether the number of un-culled second scanned lines of biometric object image data accumulated during the time period is greater than or less than a number of un-culled second scanned lines that will result in the selected y axis resolution in the direction of movement of the biometric object. 
 
 
     
     
         13 . The system of  claim 8  wherein the biometric object is a fingerprint. 
     
     
         14 . The system of  claim 9  wherein the biometric object is a fingerprint. 
     
     
         15 . A non-transitory machine readable medium storing instructions which, when executed by a computing device, cause the computing device to perform a method, the method comprising:
 scanning a first scan line utilizing a first linear array of biometric object scanning elements and a second scan line utilizing a second linear array of biometric object scanning elements, the first linear array of biometric object scanning elements and the second linear array of biometric scanning elements being separated by a scanning line separation distance in the direction of swiping the biometric object and sampled, respectively, at a first scanning time and a second scanning time; and   reconstructing the biometric object image, based in part on at least one of the scanning line separation distance and the time period between the first scanning time and the second scanning time, without calculating a velocity of the biometric object moving in the scanning direction.   
     
     
         16 . The method of  claim 15  further comprising:
 accumulating scan lines including at least the first scan line and the second scan line during the period of time separating the first scanning time and a second scanning time. 
 
     
     
         17 . The method of  claim 15  and further comprising:
 reconstructing the biometric object image with a selected reconstructed image resolution in the scanning direction based at least in part on a determination of whether the number of lines accumulated during the period of time between the first scanning time and the second scanning time is greater than or less than the number of lines as a function of the time period between the first scanning time and the second scanning time that will result in the selected reconstructed image resolution in the scanning direction. 
 
     
     
         18 . The method of  claim 15  and further comprising:
 determining a value for decimation relating to the time period which is necessary to produce a selected y axis resolution in the scanning direction based at least in part on the number of lines accumulated during the time period divided by the product of a line separation distance between the first line scanner and the second line scanner and the selected y-axis resolution, wherein the decimation for the time period is a ratio indicative of whether the number of lines accumulated during the time period is greater than or less than the number of lines accumulated that will result in the selected y axis resolution in the scanning direction. 
 
     
     
         19 . The method of  claim 15  and further comprising:
 receiving the output of the biometric object scanner and comparing the first scanned line of biometric object image data to the second scanned line of biometric object image data and culling from the output of the biometric object scanner the second scanned line of biometric object image data, when the second scanned line of biometric object image data is effectively redundant as compared to the first scanned line of biometric object image data, and repeating this step with a first un-culled second scanned line as a new first scanned line, to produce a plurality of un-culled second scanned lines of biometric object image data having an effective line scanning rate; 
 receiving the un-culled second scanned lines of biometric object image data and accumulating the un-culled second scanned lines of biometric object image data over a time period; and 
 determining a value for decimation relating to the time period which is necessary to produce a selected y axis resolution in the scanning direction based at least in part on the number of un-culled second scanned lines accumulated during the time period divided by the product of a line separation distance between first line scanner and the second line scanner and the selected y-axis resolution, wherein the decimation for the time period is a ratio indicative of whether the number of un-culled second scanned lines of biometric object image data accumulated during the time period is greater than or less than a number of un-culled second scanned lines that will result in the selected y axis resolution in the direction of movement of the biometric object. 
 
     
     
         20 . The method of  claim 15  wherein the biometric object is a fingerprint.