Color Image Coding Methods for Pre-press Images [II]

Unreversible Coding Methods

Abstract

This paper presents many unreversible data compression methods for color pre-press images. At first, two kinds of basic unreversible coding method, i.e., general digital data compression algorithms and orthogonal transformation methods like Descrete Cosine Transformation, are introduced. Next, main tasks about international standard for color image at ISO/JTC1/SC2 and CCITT SG VIII are described. The evaluating items for international standard and Adaptive Descrete Cosine Transformation (ADCT) algorithm, which has the highest posibility as the standard, are introduced. These unreversible methods are very useful for data compression of color pre-press image because extremely high compression ratio can be got using them.