Hardware for image rotation by twice skew transformations

Image processing systems in real time are going to be used in various fields, in both factories and offices. However, these performances are not sufficient when a very short processing time is required. This paper presents quite a new method of high-speed image rotation. Here an image is rotated only by twice skew transformations, whereby each pixel is shifted in parallel with each coordinate axis. With this algorithm, an image can be rotated very quickly, since such a parallel shifting is performed by simple address controlling, i.e., brief additions of address values. The processing time to rotate a gray scaled image made up of 256 × 256 pixels is about 5 s, even by an 8 bit microcomputer. Furthermore, we propose a hardware for image rotation based on this algorithm. In the case of the hardware, the processing time to rotate an image made up of 516 × 516 pixels is estimated to be about 10 ms, when a high-speed 16 bit microcomputer is used for data setting.