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March 2005

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2005.03.05 22:02 "TIFFDefaultStripSize funky", by Bob Friesenhahn

Compression ratios when using deflate compression are supposed to 
improve up to 32K of data (according to Adobe spec).  Since 
TIFFDefaultStripSize uses a target of 8K of data per strip, I decided 
to estimate the number of rows for a 32K strip.  This value was then 
passed to TIFFDefaultStripSize() as the suggested value.  Rather than 
returning something close to my suggested value (36), 
TIFFDefaultStripSize() returned the same value (9) as it did when the 
strip_size argument is set to 0.  This behavior seems wrong to me.

I am at a loss as to why this happens since the code in libtiff seems 
to be designed to return the user-provided value unless the compressor 
choses to use a different estimator than _TIFFDefaultStripSize.

Bob
======================================
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/