#0 - April 14, 2007, 10:14 a.m.
/console screenshotFormat tga
/console screenshotQuality 10
You can also look for the 2 lines in config.wtf:
SET screenshotFormat <value>
SET screenshotQuality <value>
Change them to what you want and start the game.
Both commands are important, the screenshotQuality is set to 3, which makes it look like a JPG, but in TGA format.
So this concludes my guide on how to change to TGA when 2.1.0 hits, and if you want it back to normal you can use these commands:
/console screenshotFormat jpg
/console screenshotQuality 3
Optionally you could could create an addon utilizing this, using SetCVar ( http://www.wowwiki.com/API_SetCVar )
Edit: Some screenshots(I converted the TGA's to png because of imageshack)
<quality shots are down>
Edit: It should be noted that Mac can choose between .tga .jpg and .png so using screenshotformat png is valid on the Mac client.