Getting Around in GIMP - More Color Curves (Skin)

In my previous post on Color Curves for Toning/Grading, I looked at the basics of what the Curves dialog lets you do in GIMP. I had been meaning to revisit the subject with a little more restraint (the color curve in that post was a little rough and gross, but it was for illustration so I hope it served its purpose).

The rest of my GIMP tutorials can be found here:
Getting Around in GIMP

I'm also trying something new for me for a change, and that is a video. I don't normally like video tutorials personally, but in this case I thought it might help to illustrate the text below. You'll find the video embedded at the end of the tutorial (or head over there right now to watch it).

This time I want to look at the use of curves a little more carefully. You'd be amazed at the subtlety that gentle curves can produce in toning your images. Even small changes in your curves can have quite the impact on your final result. For instance, have a look at the four film emulation curves created by Petteri Sulonen (if you haven't read his page yet on creating these curves, it's well worth your time):

Original

Portraesque (Kodak Portra NC400 Film)

Proviaesque (Fujichrome Provia)

Velviaesque (Fujichrome Velvia)

Crossprocess (E6 slide film in C-41 neg. processing)

I can't thank Petteri enough for releasing these curves for everyone to use (for us GIMP users, there is a .zip file at the bottom of his post that contains these curves packaged up for us to use). Personally I am a huge fan of the Portraesque curve that he has created. If there is a person in my images, it's usually my go-to curve as a starting point. It really does generate some wonderful skin tones overall.

The problem in generating these curves is that one has to be very, very familiar with the characteristics of the film stocks you are trying to emulate. I never shot Velvia personally, so it is hard for me to have a reference point to start from when attempting to emulate this type of film.

What we can do, however, is to use our personal vision or sense of aesthetic to begin toning our images to something that we like. GIMP has some great tools for helping us to become more aware of color and the effects of each channel on our final image. That is what we are going to explore...