DIRECT LINEAR SUB-PIXEL CORRELATION BY INCORPORATION OF NEIGHBOR PIXELS INFORMATION AND ROBUST ESTIMATION OF WINDOW TRANSFORMATION

Standard methods for sub-pixel matching are iterative and nonlinear; t hey are also sensitive to false initialization and window deformation. In this paper, we present a linear method that incorporates informati on from neighboring pixels. Two algorithms are presented: one 'fast' a nd one 'robust'. They both start from an initial rough estimate of the matching. The fast one is suitable for pairs of images requiring negl igible window deformation. The robust method is slower but more genera l and more precise. It eliminates false matches in the initialization by using robust estimation of the local affine deformation. The first algorithm attains an accuracy of 0.05 pixels for interest points and 0 .06 for random points in the translational case. For the general case, if the deformation is small, the second method gives an accuracy of 0 .05 pixels; while for large deformation, it gives an accuracy of about 0.06 pixels for points of interest and 0.10 pixels for random points. They are very few false matches in all cases, even if there are many in the initialization.