initial gamma correction implementation

[sajattack]

Using a lookup table, I think the on-the-fly method would be too slow.
Here's a shitty gif showing orange (looks yellow) versus gamma-corrected orange (looks a bit too red in this gif but better irl):

Do you want me to add this demo to smart-leds-samples?

[david-sawatzke]

Adding an example is a good idea. Not too happy about the lookup table, but you're probably right about it being too slow. A note about this fixing the colors & that gamma correction should come after the brightness adjustment would be great.

[sajattack]

I did the gamma correction and then the brightness, that's wrong?

[david-sawatzke]

Sorry that wasn't very clear. I just want to add a note about that in the doc comments