PBS: IBL in UE4

Hello there, while reading the slide on Siggraph 2013 - Real Shading in UE4,
I had a question about coordinate system of 2D LUT(part. IBL- Environment BRDF).
According to what I understand, that image was not texture coordinate.
So in order to use that texture I must convert it to texture coordinate.
Hence, is it the right way to translate the 2D LUT image into vertical and apply
tex2D(LUT, float2(Roughness, NdotV).r code?