Criteria for an imageviewer

Kevin Puetz puetzk at
Sun Jun 5 18:45:57 BST 2005

Maksim Orlovich wrote:

>> Load images blazingly fast -- no matter how large they are. If they are
>> very
>> large the imageviewer shouldn't load the whole image but only the amount
>> of
>> data which is necessary to display the actual view of the image if
>> possible.
>> If you want a rather extreme testcase use this as a reference:
> That's pretty much infeasible, effort-wise to do that well with all
> formats, IMHO (particularly since unlike tiff, the important ones are
> actually decently compressed, and I don't think libPNG or libJPEG can do
> this sort of manipulation), though libJPEG can subsample [khtml in recent
> KDE3 takes advantage of that as a form of DoS protection]. Or are you
> suggesting doing seeking over http !?

well, libpng can do progressive reading, and enormous pngs can be written
interlaced to allow low-resolution preview without decoding the whole
thing. But not all of them are, and AFAIK libpng can't do an interlaced
read of a file that was written normally.

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