Methods and apparatus for generating a projection of an image

The disclosure of this patent document contains material that is subject to copyright protection. The owner thereof has no objection to facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. Novel methods for generating a projection of an image according to the invention concurrently rotate, scale, translate, skew, shear, or otherwise transform the image via a sequence of two one-dimensional transformations. A first intermediate image is generated via affine transformation of the source along a first axis. The intermediate image is then subjected to affine transformation along a second axis, e.g., perpendicular to the first. A projection of the resultant image is generated along a selected one of the first or second axes by summing pixel intensities in corresponding rows (or columns) or by summing counts of pixels whose intensities are above or below a threshold.