A comparative study of lossless coding techniques for screened continuous-tone images

The huge sizes of screened colour-separated photographic images makes lossless compression very bene cial for both storage and transmission. Because of the special structure induced by the half-tone dots, the compression results obtained on the CCITT test images might not apply to high-resolution screened images and the default parameters of existing compression algorithms may not be optimal. In this paper we compare the performance of di erent classes of lossless coders: general-purpose one-dimensional coders, non-adaptive two-dimensional black-and-white coders and adaptive two-dimensional coders. Firstly, experiments on a set of test images screened under di erent conditions showed that MGBILEVEL and JBIG perform best with respect to compression e ciency; the di erence with the other coders is signi cant. Secondly, we investigated the in uence of the screening method (stochastic or classical screening) and screening resolution on the compression ratio for these techniques.