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setting CMYK values

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DougJ:
Hi folks,

When correcting skin colour I tend to follow Lee Varis' approach of adjusting the RGB values in a CS5 curve adjustment layer to nudge the CMY values in to their correct relationships. 

However, on some occasions, I change my colour mode (for the image) from RGB to CMYK so that I can enter specific output values for each of the C, M, and Y colours.  Then I revert to RGB and continue.

Tonight a neuron fired :) and I thought, gosh I should just invoke Curvemeister, work in CMYK while entering my specific output values, save and continue working in CS5 in RGB. 

My problem is that I don't see where (or how) to enter specific %age values for the C, M, and Y colours.

If someone can show me the way I'd be grateful.

Ciao,

Doug

curvemeister:
Click on the cmyk curve, and type the desired value into the edit box that appears on each of the CMY curves.  Or use one of the built-in skin tone pins, or a hue pin that is set to your desired CMY values, and drag that onto the desired area of the image .

Let me know how it goes!

Mike

DougJ:
I now see that--sorry I couldn't see that last night. :(

Two related questions:

1.  I start in RAW and then export to and work in RGB ProPhoto.  In CS5 I changed mode to CMYK, used the CS5 CMYK curves to enter my desired output values, then changed back to RGB--which I'm now sensing is not a good thing to do.  Anyway, that change back to RGB put me into sRGB and that's not where I want to be.  Am I missing something or is this because the CMYK gamut is so much smaller than the ProPhoto?

2.  I am thinking that when I use CM to adjust CMYK values directly, that I never leave my ProPhoto colour space.  However, the resulting colour (and I'm working with a colour managed workflow) is not close to what I get when using the mode change in CS5.  What version of CMYK should I be using?

May be this looking to adjust the CMYK values directly is the wrong way to work and I should work harder at getting to my Y>=M>C (roughly) for skin by adjusting the individual RGB curves.

Again, TIA for any suggestions you care to make--I do value what you have to say.

Ciao,

Doug

PS: did you see my other post on latest "approved" version of CM?

curvemeister:
Hi Doug,

No problem - I always enjoy answering questions.

1. It sounds like you have your default RGB space set to sRGB.  Type ctrl-shift-K to check, and adjust this.  You are correct that CMYK is a much smaller gamut that ProPhoto.  Curvemeister, however, uses wgCMYK, which is a wide gamut version of CMYK.

2. Curvmeister uses wgCMYK, not CMYK.  The color "weights" of the CMY channels are more equal than in CMYK, where, for example the Cyan ink is weaker (requires proportionally more) than the other channels.

You can use wgCMYK, which is essentially a repackaged RGB, to adjust your ProPhoto images with no gamut penalty.  That was actually the original inspiration for Curvemeister: to encourage use of CMYK for people who did not want to go through the conversion "loss".

I do have Lee Varis's "Skin" book, if that is what you are referencing.  The ratios of CMY that he (as well as Dan Margulis) recommend are really specifying a hue and saturation value.  Here's another way to go about it and get a similar result: you'll get a good skin tone if you use the hue clock - point just to the right of the R at the top of the clock, set saturation so that the hand is just over half the distance to the outside edge of the clock, and you'll get a good average skin tone.

Mike

curvemeister:
The current version of Curvemeister is 3.3.6, available on the downloads area of the forum. - Mike

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