Patent ID: 7970239

Claim:
An apparatus configured to process images, comprising: a region of interest locator for segmenting an image in a frame into a set of sectors which forms a circle; a projection generator configured to generate a plurality of projections in any sector from the set of sectors; a rotational integrator configured to generate a plurality of sums, wherein a sum is formed by adding the plurality of projections in the any sector; a memory for storing a first plurality of sums generated by the rotational integrator and a second plurality of sums generated by the rotational integrator; a projection correlator configured to compare the first plurality of sums with the second plurality of sums and configured to generate a set of projection correlation error (pce) values; a pce value index selector configured to select a minimum shift value determined by selecting a shift value that corresponds to the minimum pce value amongst the set of pce values; a look-up-table for mapping the minimum shift value to a rotation angle estimate between a first frame and a second frame; and a frame registrator configured to generate an updated base image-component comprising a first adder to add the rotation angle estimate to an image-component, wherein the frame registrator is further configured to generate an early exit signal comprising a detector for detecting a sign-bit output of a comparator for comparing the rotation angle estimate to a shift threshold.