Hello Ras,
Thank you for your answer. I also have Irfanview (it was the first reader of DDS that I found), Plugins for Photoshop and another converter dxtbmp. In short, I am ready.
Yves
NB : I already tried to modify flags (to train no to replace yours that are magnificent). I succeeded but the quality is lower hers yours. But as one says at home, one doesn't become blacksmith in one day!