Hierarchical block matching method for fast rotation of binary images.

In this paper, we develop a block matching method for fast rotation of binary images. We define coarse and fine blocks to extract bit patterns of an original image and calculate their predrawn mapping patterns (PMPs) using the given rotation angle. The traditional calculation for rotation of images can be thus replaced with simple matching of bit patterns of blocks and drawing of their two dimensional (2-D) PMPs at the output plane. A scheme of overlapping blocks is also used to solve problems of hole generation and topology variation usually occurring in rotation. Experimental results demonstrate that our proposed method performs best in terms of rotation speed compared to other algorithms.