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January 2001
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2001.01.12 21:48 "What is the proper number of bytes in a TIFF 6.0 "word"", by Dave Abercrombie
The TIFF 6.0 spec uses the word "word" a little losely. In the description of an Image File Header, bytes 4-7 are an offset in bytes of the first IFD, and then goes on to say that the IFD "must begin on a word boundary". But there is no mention there of the size of a "word". Shortly thereafter, in the description of an IFD, bytes 8-11 contain the Value Offset. "The Value is expected to begin on a word boundary; the corresponding Value Offset will thus be an even number." I suppose this answers the question, but if a "word" were four bytes long, it would still be even. If I'm not mistaken, a "word" was a dominant term in the days of the 16-bit architecture; and C had to make the distinction between a "short" and a "long" (word). Since TIFF 6.0 was finalized in 1992, I suppose one could presume that words were predominantly two bytes at the time. What is the consensus among the TIFF experts? Regards, Dave Abercrombie