I wanted to see how easy it would be to build a chroma keyer from scatch inside of Motion 5, so this effect is the result of that experiment.
This effect allows you to select a color from your source image (using the Mac Color picker) and then make the rest of the image black and white. You can also use the Invert.Key switch to quickly have the reverse effect. There is also a control for boosting the selected colour for extra impact, as well as affecting the black/white/gamma of the black & white portion of the final image and adding an optional tint.
See the video for details on how it all works. The default is for the Desaturation switch to be Off so that you can properly select your key colour. Once you have done so, turn on the View.Key switch to see a grayscale image of the key.
To get the required result you will need to tweak the Strengthen.Kept.Color and the Strengthen.Excluded controls (while looking at the View.Key) for firming up the key depending on your source image.
Once you are happy with the key, then turn on the Desaturate.On/Off switch to see the result.
As I say, this is an experiment and the chroma keyer might not work immediately in all cases. If you find that the key looks completely black, then you will need to boost the luminance of the key color - you can do this with the individual sliders but it's best to use the luminance slider in the Mac Color Picker. Conversely if the key looks too thin (not enough detail in the area you want to keep), adjust the luminance the other way to get a stronger key. Sometimes (though not often) it might help to tweak the individual colour sliders for the best effect. (This is mainly because it's not possible to create conditional expressions in Motion - which is something we can only hope Apple will address at some point. Hence the keyer is not as good as I would like it to be, but it's good enough for this effect.)
Of course, you can do all this in the Color Board, but a) I thought it would be an interesting challenge to make the keyer from scratch, and b) with this effect you can actually see the key while you're working on it (which is quite a big plus), and also you can blur the key (which is a feature that isn't available on the Color Board).
Many thanks to Andy Neil for pointing me in the direction of the Motion 5 Channel Mixer filter which is the "key" to building this keyer.
Thanks, Ben. Unfortunately the limitations of Motion 5 mean that it's a lot less efficient as a keyer than I'd really like, but it's good enough for this purpose. What would be nice would be if Apple could finally give us expressions in Motion and then we'd really be talking! I can't imagine it would be that hard to implement ...
Crossed wires here, I think. I'd agree that the keyer is Motion 5 is excellent - and better than the slightly slimmed-down version of the same thing that you get in FCPX.
The issue is that you can't publish the Motion 5 keyer in any meaningful way - at least that I've been able to find, and I notice nobody else appears to have managed it yet. For this reason, I set about building a keyer from scratch inside Motion 5, which uses the Channel Mixer as a starting point, but which has nothing to do with the built-in keyer itself.
It works, more or less, and certainly just about enough for this particualr effect though it wouldn't stand up as a stand-alone keyer.
The limitations arise from the lack of expressions inside Motion as well as the fact that you can't swap colour space and so on.
But overall I am a big fan of Motion and always have been and Motion 5 is a genuine step forward in so many ways. It would just be that much more powerful if they could add in a few more of the under-the-hood features that you need for more advanced compositing, and which obviously you get in AE, not to mention all the major compositing packages.
I can not speak for Simon, but meanwhile (this topic is from 2012!!), to single out a color and mask evrything else can easily be accomplished with FCPX' built-in color-mask feature in the Color Correction tab....