Thanks to all who have contributed. It makes for some very interesting reading. The link from the digitaldog to the colspacepdf addresses my original questions and is an excellent read for anyone interested.
I think there is a misunderstanding regarding the "inversed" curve you talk about.
tho_mas, it would seem that I do indeed have a fundamental misunderstanding.
I referred to it as an ‘inverse curve’ as there seems to be a strange relationship between the RGB workspace gamma (TRC) and the Grey workspace gamma; reading from the numbers in the Photoshop info pallet, changing the gamma of one space affects editing in the other and visa versa, eg:
Case 1 Workspace Color Settings: RGB Gamma 2.2 , Grey Space Gamma 2.2
Applying 50% K brush results in 50% tint in a new RGB file and a 50% tint in a new Grayscale file.
Case 2 Workspace Color Settings: RGB Gamma 1.0, Grey Space Gamma 2.2
Applying 50% K brush results in 27% tint in a new RGB file AND
a 27% tint in a new Grayscale file despite the gamma setting of the Greyscale workspace being the same as in Case 1!
Case 3 Workspace Color settings: RGB Gamma 2.2, Greys Space Gamma 1.0 (or Dot Gain 0%)
Applying 50% K brush results in 78% tint in a new Grayscale file AND
a 78% tint in a new RGB file despite the gamma setting of the RGB workspace being the same as in Case 1!
I’m sure there is a very good reason why RGb and Grey work spaces are linked in this way (although it seems counter intuitive) but I do not know what it is and can’t figure it out. If it has already been answered in this thread then I missed it.
Can anyone provide the reason?