Those .png icons are a serious pain to retouch--they're not even true pixel art, and I think someone downscaled most of them from larger or vector
originals.
Which we don't have, of course. :(
The best solution I have found (which is far from ideal of course!) is to use hqx to upscale the largest image available as much as possible. This them becomes the master image, and all the other images are regenerated from it as needed.
We've been doing something like that, using the highest quality image found and then downscaling as needed for the others. :) kiconedit works great for that.
Darrell
My process was slightly different; I upscaled the image first using a program (hqx) which attempts to get rid of the "jaggies" normally associated with upscaling pixel art. This provides a smoother source image from which to downscale.
Just my $0.02. :-)
Tim