Patent Document ID: 4637057
Application ID: 06635869
Patent Status: 1

Claim One:
1. A method of rotating a digital image defined by a matrix of pixels A.times.B an angle .phi. where tangent .phi.=h/A wherein h is a number such that both A and B are divisable by h including the steps of: a. Dividing the image into blocks of size a.times.b where a=A/h and b=B/h; b. Denote by i and j the columns and rows of a particular block with 0.ltoreq.ij&lt;A/h; c. Displace the (i, j) block by i pixels in the vertical direction and by j pixels in the horizontal direction; wherein the improvement comprises the steps of: d. Scaling down the original image by a factor proportioned to cosine .phi.; and e. Making each block in the original image at least one pixel wider to overlap with a neighbor block.