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1997.02.12 16:37 "Photometric interp and CCIT Compression", by Ken Land
1997.02.12 19:02 "Re: Photometric interp and CCIT Compression", by Helge Blischke

1997.02.12 19:02 "Re: Photometric interp and CCIT Compression", by Helge Blischke

See page 50 of the TIFF 6.0 spec (Section 11, paragraph on PhotometricInterpretation). It clearly states that CCITT encoding is "self photometric"; and that the TIFF reader must reverse the meaning of white and black if the PhotometricInterpretation is set to BlackIsZero.

BTW, encoded zero runs are considerably shorter then encoded one runs, so it does make some sense to do the encoding according to the numeric pixel values instead on what is considered white or black.

H. Blischke