Patent ID: 7301548

Claim:
A computer-implemented process for converting the contents of a planar object into a high-resolution image, comprising the process actions of: acquiring a sequence of images of portions of a planar object which have been captured in a prescribed pattern and wherein each subsequent image overlaps a previous image in said pattern; extracting points of interest in each image; matching said points of said interest between each pair of successive images thereby creating a set of point matches; computing a projective mapping between each pair of successive images using a least median squares technique which detects both false point matches and simultaneously estimates a homography matrix in order to determine corresponding pixel locations in the images, wherein said computing a projective mapping comprises, (a) inputting a first image and a second image; (b) drawing m random subsamples of a specified number of at least four different point matches of said set of point matches; (c) for each subsample J, computing a homograph matrix H j ; (d) for each H j , determining the median of the squared residuals, denoted by M j , with respect to the whole set of point matches, where the squared residual for match i is given by ∥m 21 −{circumflex over (m)} 1i ∥ 2 where {circumflex over (m)} 1i is point m 1i transferred to the second image by H j ; (e) retaining the estimate H j for which M j is minimal among all m M j 's; (f) computing a robust standard deviation estimate {circumflex over (σ)}; (g) declaring a point match as a false match if its residual is larger than k {circumflex over (σ)}, where k is set to a prescribed value; (h) discarding the false matches and re-estimating H by minimizing the sum of squared errors ∑ i ⁢  m 2 ⁢ i - m ^ 1 ⁢ i  2 where the summation is over all good matches; and (i) repeating process actions (a) through (h) until all images of the sequence of images have been processed; and generating a composite image from said sequence of images using said projective mapping.