2004.04.22 18:41 "Re: [Tiff] Large TIFF files", by Chris Cox

If we take a more revolutionary approach, I think we should liberally borrow ideas from the PNG spec, like their ASCII-transfer-detecting header and the bit that indicates whether unknown tags should be copied.

Actually, that's something that needs to be improved upon. I have yet to find a PNG with the preserve information set correctly (and in one case a major application says to preserve it's tags, then crashes when you preserve them and it tries to read the file back in). And there is no way to indicate "this tag must be modified if the image is modified".

But it does need to be solved - especially thanks to digital cameras writing proprietary EXIF tags that will cause problems if they are preserved (and complaints if they aren't preserved).

Also in that case, I would slightly prefer ASCII-like tags, it gives my eyes something to hang on to when viewing a TIFF in a hex editor (which will remain useful for corrupted files and derived-but-not-quite-TIFF formats like Microsoft's Office Document Imaging format).

I agree - but I don't want to bloat the file with tags (otherwise we end up with the file blowup of XML).

I'm sure Chris will bring in the lessons they've learned at Adobe when creating their PSB/Large Document Format.

PSB was only a minimal change to the PSD file format to use 64 bit offsets. But changing the file extension and version number did let me clean up some things that were held back by compatibility issues (when you have to be compatible with everyone, it's not easy to change the file format).

Chris