Compression of Binary Facsimile Images by Preprocessing and Color Shrinking
The compression of binary facsimile images has now become widespread and has led to the adoption of standard codes implemented in VLSI chips. In this paper, we reexamine the heuristic and formal basis for the techniques used in compressing such data. This leads us to suggest a decomposition into the successive operations of preprocessing, image segmentation or color shrinking, and modeling and coding of color blocks. Such a decomposition allows a reevaluation of the comparative performance of standard codes and leads us to propose a new simple code, the PCSE code, which, using preprocessing and color shrinking prior to encoding, outperforms the READ code by from 7 to 42% for the standard CCITT test images with a very small change in image quality.