>> Each time I tried 16-bit TIFF lossless compression (from scanned film), >> I got files bigger than their uncompressed version! So I hardly believed >> in the 50% 16bit thing... > > It't difficult to compare film scans, the noise is often very high and > compression algorithms don't compress noise very well.
Indeed. The raw (CRW) compression on my old Canon S45, and presumably other cameras, took an interesting approach. The highest 8 bits were compressed as bytes (only RLE I think), then the remaining bits were in a separate set of planes (I can't remember if its raw was 10 or 12 bit now). Anyway, the 8 bit data didn't have too much of the noise in, so compressed reasonably well, where the rest was left uncompressed. I'm not sure if this was a clever design to maximise compression; or the fact they had 8 bit raw files first, then tacked the extra data on the end as an afterthought in later cameras. In any case, it seemed to work okay. Maybe we could revert back to planar image formats; save everything as compressed IFF ILBM or something :) Love, Light and Peace, - Peter Loveday -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
