2006.04.04 16:50 "[Tiff] BigTIFF Suggestion", by Larry Michaels

2006.04.04 21:56 "Re: [Tiff] BigTIFF Suggestion", by Joris Van Damme


How often do applications append something to a TIFF file instead of writing the whole file at once?

I don't think this is a common enough occurrence to change the file format.

I would agree...

Plus, I think TIFF is about simplicity, avoiding redundancy. Other file formats are best at performing all kinds of tricks to optimize all kinds of operations, and letting redundancy and complication and scruff creep in. There are clearly benefits to that, performance-wise and feature-wise. But TIFF is about the simplest possible form of things. The single linked list at the very top of file format organisation is the perfect example. There are clearly benefits to this, too.

There are little benefits to muddying the water and end up with neither fish, nor flesh. I think it best to stick with simplicity in TIFF and avoid as much as possible all redundancy.

Add to this that BigTIFF is designed as minimum possible change to TIFF. One very practical reason for that, is smooth transition of existing libraries. Larry's proposal would be a step away from that minumum-change strategy that we've applied very consistently sofar.

And what about the fact that the BigTIFF proposal has been on-line in a very visible place for two years now? I know of at least one complete implementation (my own), but I think it likely some people have at least taken some steps now, even if it's been only a proposal all this time.

I must admit Larry's proposal does have some appeal. But at the end of the day, I'd vote against it, because of all above reasons.

If applications continuously re-open a BigTIFF file, to append some pages... Possibly, depending on the nature of the application, they can do some independent caching of last page offset together with file properties like filename, file size, and file dates and such. If all other properties are unchanged, they could assume last page offset is unchanged, too. Perhaps that solves Larry's need without spoiling BigTIFF, in some situations at least.

Best regards,

Joris Van Damme
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