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TIFF and LibTiff Mail List Archive

Thread

2001.01.12 21:48 "What is the proper number of bytes in a TIFF 6.0 "word"", by Dave Abercrombie
2001.01.12 22:21 "Re: What is the proper number of bytes in a TIFF 6.0 "word"", by Helge Blischke
2001.01.12 22:52 "Re: What is the proper number of bytes in a TIFF 6.0 "word"", by Dave Abercrombie
2001.01.13 01:04 "Re: What is the proper number of bytes in a TIFF 6.0 "word"", by Tom Lane
2001.01.14 18:54 "Re: What is the proper number of bytes in a TIFF 6.0 "word"", by Andreas R. Kleinert

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