[Endoperez]

Some hints: Change the Filter (Video Options) OFF. Play the game in windowed more (Alt+Enter in Windows, also an option on the Video Options, or possibly some other options screen; -w parameter on command line). And take the screenshot from the Unit Description window. If you are not using black map as background, set GUI Opacity (again from Video Options) so as the unit graphics doesn't change. 100 IIRC the meaning of the word correctly, 0 if I don't.

When you do this, you will get the units' true pixels (windowed more has preset height/width, in which the units' size is as they should be in custom TGAs), with very minor changes in its coloring. Hopefully, I'll post a guide soon.