I use textures to pass huge amount of datas to my vertex shader, and it works (the point is to convert each rgba pixel into a 32 bit float). the thing is that recently, I tried to use dds format instead of jpg (much faster to load). It works for all my colors / normals textures (just had to vertically invert images), but it causes all my data maps to bug. I tryed several things, like disabling alphas, which work on jpg but not on dds. I think this is caused by pixel interpolation which seems to be different between jpg/png/bmp and dds.
Is there a way to disable that interpolation?
If the problem isn't interpolation, do you know what could it be?
Like pleluron said, my dds textures uses DXT compression, wich leads to a quality loss. That coupled with RGBA to float decoding results in wrong datas. Interpolation isn't the problem here.