Value as colour representation

Question

Converting a value to a colour is well known, I do understand the following two approaches (very well described in changing rgb color values to represent a value)

Answer 1

What you need is a transfer function.
given a float number, a transfer function can generate a color.

see this:

http://http.developer.nvidia.com/GPUGems/gpugems_ch39.html

and this:

http://graphicsrunner.blogspot.com/2009/01/volume-rendering-102-transfer-functions.html

the second article says that the isovalue is between [0,255]. But it doesn't have to be in that range.

Normally, we scale any float number to the [0,1] range, and apply transfer function to get the color value.