POSITIONING METHOD AND APPARATUS FOR LINE SCANNED IMAGES

摘要

A method and computer implementation are disclosed for correcting skew and shiftwhich may occur as the image on a document or other field is scanned with line scanning apparatus. By selecting scans, lines are logically overlaid upon a memory map of the scanned image and a best-fit line is calculated through left-most image points near the left ends of the lines. The best-fit line substantially defines the left margin. The angle which complements the angle between the overlay lines and the best-fit line is calculated and the image map is rotated in storage, aligning the image with scanner's x-axis and y-axis. The method may be started while scanning is still in progress and the last portion of the image may be rotated according to the invention as it is being stored. The left margin is more accurately found by expanding the search for left-most pixels using search areas around the fit originally found left-most points. The best-fit line is further refined by calculating a standard deviation of each left-most point from the best-fit line and taking a new best-fit line through those points that deviate by less than for example two sigma from the original best-fit line.