TIFF and LibTiff Mail List Archive


2007.07.10 14:51 "[Tiff] FILLORDER = 25920 ??", by Oliver Geisen
2007.07.10 15:24 "Re: [Tiff] FILLORDER = 25920 ??", by Joris Van Damme

2007.07.10 15:24 "Re: [Tiff] FILLORDER = 25920 ??", by Joris Van Damme


what if a regular bilevel TIFF (G4-Compressed) tells me to have an FILLORDER of 25920?!

I thought this could only be 1 or 2.

Any and all corruption and bad values occur, given sufficient time, in the files 'out there'. I don't know of any standard or de facto usage of FILLORDER other then 1 or 2, so in the absence of more information, the best we can do is classify this as corruption or bad value.

The standard behaviour when dealing with total undefined values for basic tags required in the decoding process, is to revert to their default value. It may not make sense, but it's the best chance you have of possibly rendering a seemingly correctly decoded image. You should also have a 'warnings' system, and emit a warning for this situation, so that in the event your user sees a decoding and rendering clearly different from the intention, the user is able to trace the likely origin of the problem.

A more careful approach is to fail with proper error message. This is more careful, in that there's no chance of emitting an image different from writer's intention. But there's also no chance of robustly recovering and making some sense, so it cuts both ways.

Best regards,

Joris Van Damme
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