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January 2009
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2009.01.13 22:11 "Re: Libtiff compression ratios", by Frank Warmerdam
Nick wrote: > Setting TIFFTAG_PREDICTOR to PREDICTOR_HORIZONTAL worked beautifully. > With the predictor running, libtiff's compression ratios reach parity > with Photoshop. > > Increasing the deflate compression ratio to its maximum via > TIFFTAG_ZIPQUALITY had only marginal effects on compression (a 2% > improvement) while tripling the computation time required. > > I appreciate the advice! Perhaps PREDICTOR_HORIZONTAL might make a good > default value for the libtiff predictor tag? Nick, A case could be made for it being the default, though there are types of images that it would perform poorly or at least with no improvement, for. I am however not inclined to change stuff like this without careful consideration and the impacts are not too clear to me. Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Programmer for Rent