...however, I'm supporting some old GPU's that don't provide this hardware. The standard solution here is to pretend that sRGB is the same as gamma

^{2.2}colour space, and use pow(y, 1/2.2) and pow(x,2.2) to perform linear->gamma

^{2.2}and gamma

^{2.2}->linear conversions.

..however, these old GPU's are also pretty slow at implementing pow, so I'm looking for other sRGB approximations. The best I've come up with is the quadratic below, but I'd appreciate any other links/hints on the subject!

From gamma-space to linear-space:

Correct for 0.0 and 1.0

Maximum error of 0.0149833 (

*~4/255*) at x=0.706.

Cost: 2x mul, 1x madd

Reverse transform (linear-space to gamma-space):

Cost: 2x madd, 1x sqrt