That is a good approach, actaully my firmware is full of all kinds of array processing to flip values and so on. I thought I was cheating.
I guess I imagined there would be a formula that would let me plot a line against a curve to find the right ratio. For instance I can do it for the lower LEDs by multiplying the value times 1.2 of itself, but then it's off again close top the middle and goes too high towards the top. So it's like I need to multiply by a variable that starts out with the value 1.0, then 1.1, then 1.2, then 1.3, then 1.2 then 1.1 then 1.0 - or something like that.
I suppose I can stick those in an array, too... It just FEELS like there should be a more elegant way. Where's that calculus book...?