Oct 18 2014
Nuke is lucky to have a great number of keyers at its disposal, probably the one that is least intuitive to come to grips with, but can be dead handy sometimes for squeezing that extra edge detail out of a key, is the IBK. Below I will list a few tutorials that I think help explain things pretty well.
The IBK was developed at Digital Domain and the IBK colour node uses some Ultimatte keyer code (under license) to produce the clean plates (any uses of older versions of Ultimatte on other platforms will remember the clean plate generation step in that plug in, …the IBK colour node is a different take on that (same code, different approach)). This two step process of producing a clean plate then doing the actual key means that you can pull keys off some pretty non-uniform, bad greenscreens/bluescreens, …but it also means it can be confusing to get your head around when you first start keying this way. Personally I will usually use a combination of keylight, primatte and basic keyer (or use colour manipulation nodes to grade up a matte from particular colour channels) to get my base key, and then look at IBK to add detail in the edges. I also like to use the Neat Video degrainer to provide a degrain plate to key off, then copy the final alpha back onto the original (grainy) footage (you never ever want to degrain then regrain, always use the original plate for your comp (…there are of course exceptions to this rule, but the general rule is to use the source plate whenever you can, …for keying you only use a degrained plate for getting your alpha, that is it). I won’t waffle on any further, but instead point you in the direction of resources to help learn this keyer. Hope the links help, and always remember if you are having problems, there are lots of forums (such as the official Nuke mailing list) that can help you out with more specific queries.
First Up is the great 3 part intro series to IBK that Steve Wright did for the Foundry a few years back. Great for introducing you to IBK workflow.
Next is one of the best rundowns on the specifics of the IBK color node I have seen. It is by Jan Burda and while you’re there you should check out the other couple of tutorials he has posted there. The tip in the comments at the end about stacking multiple IBK color nodes is a good one too (can make things slower in the script, so good idea to render that step out separately if things get sluggish). Click on the image below to go there:
Creative Lyons tutorials also includes a more in depth look at IBK tricks (more on the color stacking trick mentioned above) and is well worth a look. The video is below: