Color picker RGB values

Hi all.

I'm trying to write a script that manipulates colors when using gamma 2.2.

Basically I want to have a color picker ("old") so the user can choose a colour and one next to it ("new") that is the result of the following equation.

new=255*((old/255)^2.2)

This will make the RGB values correct when using gamma.

Any help on this would be much appreciated.

Cheers.