Bah. Gimp sucks. Can't edit the individual channels.
Not true, you can edit channels in gimp...
You can make it using "mask" and when work is done, apply the change created on the mask to a channel...
Of course, a lot of people decompose the channel to layer and work on the individual layer...
I tried a solution in another post that didn't work, it was decomposing the channels to RGBA, it shows some more of the ships forms, but there are no textures at all. =S
- colors > components > decompose ... rgba and decompose to layers
- select new picture
- colors > components > compose ... rgb... new picture will be the cl without alpha...
Myself, i make all my texture ( color, team color, specular, normal map, light, bloom, etc ) in tga format ( lossless )... only at the end, i compose then all in the various .dds ( loss of quality )...
In short, Gimp don't sucks ( for example, http://media.moddb.com/images/mods/1/12/11043/Military2.jpg , one of my numerous texturing made in Gimp ) ... only guy who don't know how to use Gimps say that it sucks...
Note : for any guy being serious about texturing for game, GIMP is great but you work quality will greatly improve with GPS...