Required: The GIMP (see www.gimp.org)
A plug-in I wrote to easy exporting images at two resolutions for iOS development (retina displays). The idea is that you design the graphics at the retina resolution and then export them to two different size PNGs.
It works pretty straight-forward so an extensive tutorial seems very unnecessary.
As with other GIMP Scheme plug-ins, you need to put the file in
/usr/share/gimp/2.0/scripts/ and either restart
The GIMP or choose Filters / Script-Fu / Reload Scripts.
To use the plug-in, select it from the menu. It will ask for the image base-name
and an output directory. The final images will end up being called
base-name@2x.png and base-name.png.
You probably need to right-click and choose "Save Link As...")
If you have any problems and/or comments, let me know, thanks!