DOWN downsamples an image by a given factor Usage: y=down(x,r) image y is obtained from image x by summing and down sampling image y will have the size (floor(m/r),floor(n/r)) where (m,n) is the size of image x Author: Ali Mohammad-Djafari Date: Nov. 4, 2002 Test: x=rand(9); y=down(x,2); y=down(x,3);