On a side note, I was reading at
http://www.brucelindbloom.com/index.htm ... yHelp.html
that the visible Lab gamut exceeds
a and
b of -128 to +127. At
https://en.wikipedia.org/wiki/CIELAB_color_space
it says:
The a* and b* axes are unbounded, and depending on the reference white they can easily exceed ±150 to cover the human gamut. Nevertheless, software implementations often clamp these values for practical reasons. For instance, if integer math is being used it is common to clamp a* and b* in the range of −128 to 127.
Calculating the ranges using the XYZ color matching functions, the visible range goes out to about
a: -165 to +145,
b: -145 to +146. Using actual conversions to ProPhoto, the ranges are
a: -185 to +144,
b: -170 to +170, but some of these are probably not real colors.
(Of note, the minimum
a value in Adobe RGB is -128, possibly accounting for the odd range, -128 to +127, that the other program uses.)
Just think, if the
a and
b ranges in PhotoLine were extended, it could be the only photo editor that uses the whole Lab gamut!