Heat Map

Useful if you ever want to better visualize data images.

Basic idea is to put the data in the red channel, normalize it between zero and one, then make sure the green and blue channel are both set to one and convert the colourspace from HSV to Linear.

Blackpoint and Whitepoint are set to the minimum and maximum samples from the render. Gain is set to 0.666667 so that the range is mapped from Red to Blue, rather than Red through to Red.