“Running this code through NVShaderPerf gives (from memory) 5 cycles for 9 instructions. When inserted at the end of a longer shader where there is plenty of room for instruction pairing, the total overhead for the LogLuv conversion will be less than this, perhaps around 3 cycles. I haven’t checked with Marco to see how this compares to what he’s doing, but it matches the cycle numbers he mentioned in various posts so it’ll be pretty close.”