2007.07.04 21:40 "Re: [Tiff] 16-Bit-Per-Channel Lossless Compression", by Stephen Carlsen

Andy,

Ok, see the 10 megapixel 57.7 MB 16-bit image B1, at http://tiff2.com/.

The best space/performance/simplicity balance point I've found so far is to compress it losslessly by separating the high and low order bytes, using LZW (with predictor) on the high order bytes, and no compression on the low order bytes. This yields a 39 MB file.

Have fun :-),

Stephen

Hi Stephen.

If you could, that would be interesting. If I have some spare time, I might try a few things/ideas.

Yup, I've actually done quite a bit of testing, and running LZW with predictor tends to compress 16-bit digital camera photographs very little, or even not at all. The problem, of course, is that the low order bits tend to look a lot like noise.

I can post some sample files if you like. On one of my images from my Canon XTi, exported from DNG to uncompressed TIFF (using Lightroom), the uncompressed size is 57.7 MB, but is 68.8 MB with LZW (plus predictor) compression.

Flate tended to generally do worse than LZW, and be a lot slower, in my testing.