[lowfighter]

Well, it does change hue, take lowland_1.tga, just rename and load in game. Then take also lowland_1.bumph rename accordingly and then load again. Difference in hue is quite big.
But there might be another thing too, maybe you already figured but: when we take an unopenable tga then use the trick with the splash screen screenshot, does this kind of conversion let the original hue unchanged etc? It's not clear to me because there are also the tgb's besides the bumph files.