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November 2003
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2003.11.27 17:40 "Strip and tile optimal sizes estimation.", by Andrey Kiselev
Hi, Igor, On Thu, Nov 27, 2003 at 03:23:31PM +0300, Igor V. Venevtsev wrote: > The problem appears on images with very large width, when > TIFFDefaultStripSize() returns 1 and some 2-d compression schemes (f.e > CCITT Group4) can't produce optimal result. Increasing strip size for > this images to reasonable value (f.e, to 2048 for tiff with > 42463x51928 pixel size) results in more than 6 times output file size > reducing! Group4 compression works better with larger strip sizes. I'm usually set the strip size equal to the image height to get the best results. But it may be unpractical for so large images as in your example, so I'm suggest just use as large strip as possible. In case of LZW or Deflate compression ratio depends on image nature. Sometimes tiles give higher ratio, sometimes not. Smaller tile size usually results in better compression. Andrey -- Andrey V. Kiselev Home phone: +7 812 5274898 ICQ# 26871517