grayscale desaturate under a color profile

[GreenKoopa]

I have a color image I would like to convert to grayscale. Of course I can use "-colorspace Gray" or "-modulate 100,0", or specify my own channel weightings using numerous methods. But doesn't the color management profile have something to say about this? Does anyone know a gray scale or desaturate method that makes use of the current -profile setting? For example, under Photoshop 7.0 (2002) desaturate gives the same results regardless of color profile, but grayscale does utilize the color profile.

[GreenKoopa]

BTW, the images I begin with are in the ProPhoto colorspace and it will hopefully end as a b&w process print. Of course it is also a bit of intellectual curiosity.

I've culled luminance, luminosity, relative luminance, luma, intensity, lightness (HSL), brightness (HSB), Y (various colorspaces), and L (LAB) from the documentation and forums. I'm not sure that these are always used consistently or correctly. I'm starting to wonder if I really know what I mean by grayscale. I guess I probably mean one of the Lums or the lightness L in Lab.

And Murkey always made it look so easy.

[GreenKoopa]

I think I have concluded the -colorspace operator is not affected by the current -profile. But then how is RGB converted to Gray, Lab, etc. without being well defined (primaries, white point, and such)? If not -colorspace, does -profile impact any operator other than subsequent -profile by triggering a conversion? Are there any settings/options that impact -profile conversions?

[GreenKoopa]

I achieved the grayscaling results I wanted by setting a -profile and then using a second -profile to cause a conversion. My hangup was that I somehow didn't realize that grayscale profiles existed. None were on my computer, I had to generate one using Photoshop. My question concerning what operations look at the current -profile still stands. I still can't figure out how to convert to Lab colorspace since I don't believe one can create a icc/icm profile for that. Yes -colorspace has a Lab option, but -colorspace seems to ignore the current -profile and so converts inaccurately.