AWARE SYSTEMS
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

2001.01.13 01:04 "Re: What is the proper number of bytes in a TIFF 6.0 "word"", by Tom Lane

If you look at figure 1 (page 14 of the spec), I think it is clear that a "word" is meant

to be a 2 byte quantity, though the spec doesn't define this term.

Clearer evidence is had from the text defining an IFD entry (at the top of page 15, in my copy of 6.0):

"The Value is expected to begin on a word boundary; the corresponding Value Offset will thus be an even number."

If it meant 4-byte alignment, it would say "will thus be divisible by four".

I agree that the terminology is now a bit dated, but I don't see how you can possibly read this part of the spec any other way. "Even number" is a well-defined term in my part of the world.

Years ago I made a list of a bunch of wording improvements I was intending to propose for TIFF 7.0, and I think this "word" business was one of them. Too bad we (the TAC) never got a chance to have any input on a 7.0...

regards, tom lane