90o AND 270 .HALF UP o ROTATION OF A 2n BINARY IMAGE USING A 2n BIT PROCESSOR
Original Publication Date: 1988-May-01
Included in the Prior Art Database: 2005-Feb-15
An algorithm is described for performing 90o and 270o rotations of a 2n by 2n binary image. A binary image of any size may be rotated by 90o or 270o by dividing the image into smaller subimages, rotating each subimage and placing the rotated subimages at the correct final locations. When the image data is stored in a linearly addressed one dimensional RAM, final placement of the rotated subimages is a simple matter of address manipulation. The actual rotation of the subimages is the more compute intensive operation. The algorithm described below is an efficient method of rotating a 2n by 2n image in a 2n microprocessor based system.