Editing the .dds image files

Hello all,

I decided to make the move from Galciv III to IV. I'm currently in the process of making a small mod that would make Venus a colonizable "corrosive world" in the Sol System. I managed to edit the xml files properly, but I noticed that it seems to be quite difficult to edit or even view the .dds files. I wish to replace the clouds on Venus so that we would see its very thick atmosphere.

Are there any modders on this forum that can help me find the appropriate tools to edit the .dds images for this game? The usual pluggins don't seem to work.