1. Within an image acquisition device, a method of detecting rotation from matching corner regions of acquired images, comprising: acquiring a sequence of image frames; and determining a measure of frame-to-frame rotation, including: performing a global XY alignment of a first frame and a second, following frame of said sequence of image frames; determining local XY alignments in at least two matching corner regions of the first and second frames after the global XY alignment; and based on the differences between said local XY alignments, determining a global rotation of the second frame relative to the first frame; performing a further action based on the determined global rotation; determining horizontal and vertical integral projection vector gradients for each of the first frame and the second, following, image frame in said sequence; normalizing said integral projection vector gradients; and determining locations of primary maximum and minimum peaks of said integral projection vector gradients; and wherein the global rotation determining is further based on normalized distances between the primary maximum and minimum peaks.