You're confusing texture co-ords with UV co-ords.
UV co-ords will go from 0 - 1 whereas your texture co-ords will go from 0 - x (where x is the size of the texture).
So if your texture is 128x128 for example. The UV of the bottom right pixel would be 1,1 the top left would be 0,0. 64 pixels across the texture would be 0.5 on the U co-ord.
I hope that makes some sense.
UV co-ords will go from 0 - 1 whereas your texture co-ords will go from 0 - x (where x is the size of the texture).
So if your texture is 128x128 for example. The UV of the bottom right pixel would be 1,1 the top left would be 0,0. 64 pixels across the texture would be 0.5 on the U co-ord.
I hope that makes some sense.