2017.02.07 20:01 "Re: [Tiff] Qs about support for more than 2^16 IFDs and writing performance", by Olivier Paquet

2017-02-07 12:36 GMT-05:00 Dinesh Iyer <dsi.maillist@gmail.com>:

I am providing a link to an plot which shows how the time increases for each successive call to TIFFwriteDirectory. I have written 20000, 64x64 images to this TIFF file. The total time taken to write these 20000 images will be the sum of all these times.

It is very clearly O(N*N) and we even know why. This is a bug as far as I'm concerned.

As for the 64k limit, I think it's reasonably easy to fix it for sequential access but perhaps not so easy for functions like TIFFSetDirectory() because of the ABI. Whether we should fix the former only and how we could fix the latter are both interesting questions. I'm ok with fixing the internals as a first step so that at least sequential reading and writing works beyond 64k.

Olivier