Method to rotate a bit map image 90 degrees

Abstract From the Canadian patent

An algorithm for rotating an image 90 degrees starts with an array or r rows and c columns of pixels. Each column of the pixel array is partitioned intowords of w pixels each and the rows, the columns, the words in each column andthe pixels in each word of the pixel array are all numbered starting at zero. Let v = rr/w1, where rr/w1 is the smallest integer greater than or equal to r/w. Similarly let h = rc/wl. The algorithm stores words of the original pixel array into a linear word organized memory as follows: it circular right-shifts each word i of column j by(j)mod w pixel positions and then writes in parallel this modified word into word address vj + i of the memory. The algorithm …