Image correlation processing by addition of reaggregation

A computer-implemented method of image correlation, the method comprising:

• obtaining a first image frame with a set of distinct features;
• obtaining a second image frame at least partially overlapping the first image frame such that at least some of the features of the first image frame are visible in the second image frame, the first and second image frames being obtained by an image sensor comprising an array of pixels;
• carrying out a cross-correlation operation of the first and second image frames to obtain a cross-correlation result indicating correlation values for different offset positions of the second image frame with respect to the first image frame, the highest correlation value with its associated offset position in the cross-correlation result indicating the most likely offset position of the second image frame with respect to the first image frame;
• carrying out a reaggregation operation of the cross-correlation result to generate a distinct global maximum correlation value from a plurality of non-distinct correlation values in a reaggregated cross-correlation result, wherein the reaggregation operation involves carrying out a convolution of the cross-correlation result with a 1×2, 2×1, or 2×2 array of 1′s, said convolution being carried out over every 2×2 or 1×2 or 2×1 grouping in the cross-correlation to produce a new array of values;
• and
• correcting a mouse pointer position of an optical mouse based on the distinct global maximum correlation value generated by carrying out the reaggregation operation of the cross-correlation results.