Abstract

An apparatus and method for storing a reference scene and a scene under search in separate addressable memories. The reference scene is addressed along a scan line at a selected angle giving the impression that the reference memory has been rotated. The search area information is convolved with a stored reference information to obtain a count representing the number of matches for each search position at a plurality of selected angles. The convolved count is accumulated and the search stopped when the accumulated count exceeds a given threshold value. The X Y coordinates of the best search is determined by evaluating the highest accumulation count. The angle orientation of the search area is determined by addressing each scan line readout of the stored reference area at small angles, convolving the readout against the memory readout, accumulating the count for a selected number of scan angles and determining the angle position having the highest count as a measure of the alignment angle of the search area.