Returns an NSColorSpace object representing an extended gray color space with a gamma value of 2.2.
The NSColorSpace object.
This color space has the same colorimetry as Generic Gray 2.2, but component values below 0.0 and above 1.0 may be encoded in this color space. Negative values are encoded as the signed reflection of the original encoding function. y(x) = sign(x)*f(abs(x))