Criteria for an imageviewer

[Kevin Puetz]

Maksim Orlovich wrote:

>> SPEED:
>> 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:
>> http://photojournal.jpl.nasa.gov/tiff/PIA03377.tif
> 
> 
> 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.