Hi RV... I have another post coming up about bump/displacement (unless bb gets there first, if he's still around) but in the meantime...

"Convert to linear (colour) space" == "Do the gamma math"
(It's one and the same thing).

The assumption is that the colour map is done in sRGB colour space. To convert this to linear colour space, you need to anti-gamma correct it, i.e. raise the colour values to the power of your variable 'gamma', or 2.2 in this case.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)