RGB values -- how to match (not percentile)

[Trollheart]

Hi all.
Maybe this question has been asked before, and if so apologies, but I've had a quick skim through and can't see where it has been, so here goes...
My problem concerns RGB values and matching them. Basically, I have a picture onto which I want to paste a new face, but the pasted face is a slightly different colour than the one I'm pasting on to. If I paste as is I end up with a very green or yellow-looking face on an otherwise ok body.
I can use the colour picker (I'm using both v 4.12 and XI --- I have an abiding love for 4.12!) and get the RGB value of the face of the picture I'm pasting onto. But if I then try to adjust the picture to be pasted on (ie the selection) via the Adjust Colour/Red-Green-Blue) it only goes up to 100 for red (being percentile), and the red I need is 128 (or something).
Any way I can freely adjust the RGB values of the colours from -255 t0 +255, or any other way I can equalise the colours so that my picture doesn't end up looking like some sort of medical experiment?
I've attached an example here, so you can see the problem I'm having...
DSCI8897 is the original picture, DSCI8897A is my attempt at pasting. You can see how it really didn't work!
Thanks for any help.
Trollheart

[coningham]

There are many methods for getting the result you want.

If you want to use the RGB value (which is only the value of one pixel or the average for a few pixels), you'll need to paint over the image using the Paint Brush with the blend mode set to "Color".

Another method is to select the portion that you want to modify (if you pasted it in a new layer the work will be even easier) and apply the available photo editing adjustments.
On the image I posted, for example, I used (using version X, btw) Red/Green/Blue, Hue/Saturation/Lightness and Curves. Not that all 3 were really necessary, but this gives you an idea of what you can use.

Another thing is to soften the edges from the pasted portion so that it blends even better with the rest. In this case, you could use the Eraser tool set at a low opacity on the neck.

This is really a fun process, but a lot of experimentation is involved, so don't be afraid to try new tools