Curvemeister Forum

This is an attempt at skin tone correction using LAB.  I found the upper right points better. 

Is there a rational method to choose between upper right, lower left, or dragging the center?

I re did it.  Step in RGB to remove cast (?)

step 2  wg cmyk to increase contrast. (with my little work around)

Step 3 a little lab color boost. (no screen shot).  I could not color boost too much because of the red nose.

He looks pretty good but the skin tones are a bit too much in some areas...I moved the sample around and found a few places where he's too red...not a big problem just dial it back a bit.  Everything else looks good.  The greens are nice and the rest of the image has good contrast.

Nice work...
Greg

Steve,
OK I was going to answer your first question...and I will.  In LAB moving the corners is pretty safe so long as you do not introduce too much of a color cast.  It generally accomplishes the same thing. Remember that the center of the grid is 0,0 and if you move off of that you are adding a color cast.

Moving the corners will increase the "color contrast" and increase the saturation of one side of the channel more than the other.  It is related to the slope of the line in the grid.  If you watch the saturation slider when you move it in LAB the color channels twist about the neutral, the selected point, or the area pinned in the grid.

Greg