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Cross Correlation of Two Images Using an All-Points-Addressable Display

IP.com Disclosure Number: IPCOM000043430D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Stephenson, RA: AUTHOR

Abstract

Introduction This disclosure concerns a method of performing the cross correlation of a stored image with a realtime image using an all-points-addressable electrochromic display. The image to be verified can be a signature or a graphic image, such as a 'photofit' picture, etc. Method An image is written on the all-points-addressable display. The display is then illuminated by the realtime image focussed on the active area of the array. The formula giving the total back-scattered light from the illuminated surface will contain some dependence on the cross-correlation of the two images A and I (Fig. 1). Cross-correlation of A and I when then are displayed by x, y. = S I(i,j). A(i+x, j+y) I(i,j) is the grey level of the pel (picture element) at (i,j) in the image.

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Cross Correlation of Two Images Using an All-Points-Addressable Display

Introduction This disclosure concerns a method of performing the cross correlation of a stored image with a realtime image using an all-points-addressable electrochromic display. The image to be verified can be a signature or a graphic image, such as a 'photofit' picture, etc. Method An image is written on the all-points-addressable display. The display is then illuminated by the realtime image focussed on the active area of the array. The formula giving the total back-scattered light from the illuminated surface will contain some dependence on the cross-correlation of the two images A and I (Fig. 1). Cross-correlation of A and I when then are displayed by x, y. = S I(i,j). A(i+x, j+y) I(i,j) is the grey level of the pel (picture element) at (i,j) in the image. The observed grey level of the pel is linked to the available contrast ratio. Experimental results show that Contrast Ratio is approximately equal to (charge deposited x constant) over at least a decade of charge. A simplified equation for the intensity of light back-scattered from the display (L) is ***** SEE ORIGINAL ***** To determine the back-scattered light from the display, some simple measurements on the profile of the back-scattered radiation from the display surface are made. The following is observed, as illustrated in Fig. 2. Working in the approximate linear region, that is, back-scattered intensity at an angle measured wit...