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July 2007
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2007.07.04 20:37 "Re: 16-Bit-Per-Channel Lossless Compression", by Andy Cave
Hi Stephen. If you could, that would be interesting. If I have some spare time, I might try a few things/ideas. Thanks. Andy. ----- Original Message ----- From: "Stephen Carlsen" <sc42business@mac.com> To: <tiff@lists.maptools.org> Sent: Wednesday, July 04, 2007 6:49 PM Subject: Re: [Tiff] 16-Bit-Per-Channel Lossless Compression > Hi Andy, > > 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. > > Stephen >