It’s been a while since I’ve written one of these technical columns, but decided to do a new one after seeing this post.
People found my original Colour Correction Primer to be helpful, so a primer on Secondary Colour Correction seemed to be in order. Like the first primer, this is not intended to be a full study of SCC; it’s just an introduction so you can get started.
The rest took place in post-production, where we wanted to give the actor’s skin a greenish shade. Doing this with practical makeup would have taken much longer, plus would have caused issues with makeup rubbing off the actor’s hands onto everything he touched.
This is where Secondary Colour Correction comes in. The first step is to single out the colour you want to process. In our case, we wanted to target the skin tone of the one actor, so we outlined out the other actor entirely because she has a similar skin tone:
Then we used the “eyedropper” tool to pick an arbitrary point on the actor’s skin that would represent his average skin tone (so a place that’s not too overlit or shadowed). Then we adjusted the parameters around that starting point colour so that the mask generated by the plugin covered the areas we wanted to process. As you can see, we did a fairly good job of covering his face and hands. There are some extra spots on the wall and desk, but I wasn’t too concerned about those because they were relatively small. If we needed to, we could have simply tightened the outline mask we drew around the actor to eliminate those issues.
The use of a generated mask here is very similar to what’s done with Chroma Key. With Chroma Key, the goal is to take a specific colour (the greenscreen shade) and turn it transparent. With Secondary Colour Correction, the goal is to take a specific colour and transform it into another colour.
Once you have your processing mask where you need it, the next step is just specifying how to transform it. In our case, we wanted to change a pinkish skin tone to greenish, so we just modified the Hue value of the HSL (Hue/Saturation/Luminance) colour space. (In simple terms, Hue is the “rainbow colour” of the pixel.)
In the scrunchie problem described here, the best bet would be to loosely outline mask the scrunchie, apply SCC and then fiddle with Saturation and Luminance to turn the light blue into a deeper blue.
More elaborate things you can do with SCC include things like this shot from Sin City, where a single colour is processed to stand out:
I’m not familiar with the SCC plugins on every editor, but they all should function somewhat similarly. Good luck and let me know if you have any questions!