split-and-merge

代码说明：

  segments image F by using a split-and-merge approach based on quadtree decomposition. MINDIM (a positive integer power of 2) specifies the minimum dimension of the quadtree regions (subimages) allowed. If necessary, the program pads the input image with zeros to the nearest square size that is an integer power of 2. This guarantees that the algorithm used in the quadtree decomposition will be able to split the image down to blocks of size 1-by-1. The result is cropped back to the original size of the input image.