[Hard core Rikki]

- The DEVIL image library or ImageMagick could be used as a start base.
It also supports many of the such functionalties people expect from an image viewer. Its LesserGPL, so possible to include with closed-source apps.
ImageMagick is more Imageviewer material, also since it supports more formats and features out of the box (its BSD too), and can allow for basic image-editing capabilities.

- A thumbnail collecting database wouldnt be bad, along with maintainance operations, like purging dead entries, reoptimizing, and advance thumbnail generating (like generating a folder's thumbnails in advance).

- Some hardware-accelerated display (but color-accurate operations like zooming).

- 3 thumbs up for cache-ahead and cached/viewed pics kept in memory for faster sequential display. Some image viewers suck specifically for absence/medicrity of this one.

- skipping the integrated functions DEVIL and ImageMagick can already handle out of the box, like HDR support, format conversion, multithread/core parallelization, integrated and manually colorspace support and manually set ones for display in app, RAW (the windows7 one does not support RAWs, so this one's likely to be one of imageviewers most interesting points of differentiation from the win7 app)...

- some quickupload strings for imageshack, flickr, photobucket, email and the likes maybe.

- thumbnail preview generating if rightclicking on pic in Explorer (as desktop integration, desirably opt-in just to be safe).


I was thinking of suggesting the same in the past, funnily enough (along with other small apps, possibly for an aruantec 'collection'. One single apps cant be fit with everything, and separation makes for an interesting portfolio).

 

[Hard core Rikki]

Picture and Fax viewer has a Zoom filter that prevents images from jagging up as you zoom in, while photoviewer does not.
Which behavior is preffered. Also if possible does anyone know of any low performance costing HQ filters that can improve the display of the zoomed image?

Just bicubic would do well in pretty much all cases, and lanczos3 or lanczos4 sharpening (non-instant cache-ahead turns more important here, as these filters along with sequential picture browsing when set for autofitting the a display window can bring a cpu spike for cached-ahead big pics/RAWs.
For sprites, pixel art and GIFs though, I presume leaving the possibility for no smoothing would look better, as long as the image isnt fully rerendered at another resolution everytime you zoom it up/down (classic facepalm material from the lousy Irfan).

Maybe we can use the same zoom filter as firefox's? it seems to be relatively good quality.

Firefox' sucks big time if you ask me. Quick bilinear doesnt get any worse. Many smoothing/sharpening filters are available with DEVIL and Imagemagick already.
I'd be very interested to see an implementation for HQ4x for multilayer images (the most appropriate material to apply that one to IMO, edges looks kinda ugly due to unoptimal edge separation in singlelayer pics)

 

[Hard core Rikki]

I was certainly not making mention to that of the old versions. If it still sucks in 3.5, you bet it did in the earlier 3.x branch as well.