Pentium-MMX-based implementation of a digital copier

We develop real-time image processing programs for a digital copier using a general-purpose microprocessor. To exploit the inherent data parallelism in many image processing algorithms, we use Intel´s Pentium processor with multimedia extension (MMX). Each step of the digital copier process including the X-Zoom and the error diffusion halftoning is aggressively optimized for the Pentium MMX processor. The X-Zoom process that is based on the linear interpolation method is optimized using the software pipelining technique. For the error diffusion halftoning which requires nonlinear feedback, we exploit both the control-level and data-level parallelism. For the latter approach, a speculative quantization method is developed to break the dependency relation due to feedback and quantization operations. Our implementation acquires the maximum throughput of 30 ppm for A4-size paper using one 166 MHz Pentium MMX CPU, which is approximately five times faster than the code without MMX optimization