Composite curves

[derekfountain]

I was just thinking about something Mike said a while ago in one of the Photoshop newgroups. Using curves with RGB and WGCMYK colour modes gives a composite curve, as well as the individual ones. That is, as well as a red, green and blue curve, there's also a RGB curve - 4 in all.

Am I correct in thinking that if I make a change to, say, the blue, green and RGB curves, then the blue and green curve changes are applied to the image, then the RGB curve changes are applied on top of them?

[mikemeister_admin]

I was just thinking about something Mike said a while ago in one of the Photoshop newgroups. Using curves with RGB and WGCMYK colour modes gives a composite curve, as well as the individual ones. That is, as well as a red, green and blue curve, there's also a RGB curve - 4 in all.

Am I correct in thinking that if I make a change to, say, the blue, green and RGB curves, then the blue and green curve changes are applied to the image, then the RGB curve changes are applied on top of them?

When you set CM to see all the rgb curves at once  , you see changing the picture when you pull the curves green and blue. Also with green. You see instantly change the overal historgram of the RGB curve.
But when you pull only the Overal RGB curve you see changes of lightening, like L in LAB mode.
So, what do you really mean ?
You can do one thing at the time?
Frits

[-default]

The RGB composite curve takes the output of the red, green, and blue curves as input, and applies the same curve to each of them.  Colored objects will change hue and saturation when the RGB curve is used, so it is generally not recommended.