Patent ID: 7885480

Claim:
A correlation function peak finding method for use in an image correlation displacement sensing system for determining object displacements, the method comprising: capturing a reference image; capturing a displaced image; searching for and identifying an initial peak correlation function value point (CFVP) with pixel-level resolution, based on determining a plurality of respective CFVPs that are determined based on at least a portion of the reference image and the displaced image, at a plurality of respective offset positions and identifying the peak CFVP in that plurality of respective CFVPs; determining a complete set of CFVPs, the complete set of CFVPs including CFVPs that are determined at each of M×N offset positions included in an analysis region in the vicinity of the initial peak CFVP, where M and N are integers; estimating a preliminary correlation function peak location with sub-pixel resolution (x p ,y p ), based on CFVPs included in the analysis region in the vicinity of the initial peak CFVP; and performing curve-fitting operations to estimate a final correlation function peak location with sub-pixel accuracy, wherein the curve-fitting operations include the application of at least one of a windowing function and a set of weighting factors (W(x,y)) that is/are determined with reference to the preliminary sub-pixel correlation function peak location that is estimated with sub-pixel resolution.