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Key Green Screen image with depth of field
I watched a before and after video of keyed footage of people driving in cars. It looked beautiful with the background out of focus. Any tips on how to key blurry footage. I tried it once and it didn’t go well.
Stephen Smith
Check out my Vimeo page
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18 Replies
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Shoot with the best possible camera you can lay your hands on.
Budget cameras have crazy amounts of boiling sensor noise which means they are a nightmare for keying soft focus areas (and reflections and fine hair detail, etc.).
If you are stuck using a budget camera, use a decent denoiser to calm down the temporal noise. Neat Video does a good job but there are other workable solutions.
Denoise only the matte not the foreground for best results.
Simon Ubsdell
tokyo productions
hawaiki -
That has nothing to do with what he is asking…
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Absolutely and great question! Check out this awesome video from Andrew Kramer covering this exact issue: https://www.videocopilot.net/tutorials/advanced_soft_keying/
And lastly it is worth mentioning… I know this is an AE forum but I haven’t actually used After Effects to key anything since the day I picked up Nuke. I couldn’t suggest it more. And if you do go that route, Mr. Lyons is the master of keying: https://compositingmentor.com/. That’s some pretty damn complex stuff, but if you really wrap your head around it you’ll be doing ILM-level keys!
– Spencer
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[Spencer Tweed] “Check out this awesome video from Andrew Kramer covering this exact issue: https://www.videocopilot.net/tutorials/advanced_soft_keying/“
That tutorial, although excellent, has nothing to do with the question posed.
It’s about keying reflections, which is a very different issue.
Simon Ubsdell
tokyo productions
hawaiki -
Dave LaRonde
“Well, there’s nothing that says you can’t blur an in-focus, keyed image AFTER you pull a nice key….”
If I’m filming 2 people driving a car and I want behind them to be out of focus that would add a lot of work to blur the back ground after the fact. Plus the layers (distance) of depth looks really different when you do it in camera instead of after the fact with a camrea lens blur effect.
Stephen Smith
Check out my Vimeo page
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Correct, the Videocopilot tutorial isn’t what I’m talking about. Take a look at this video:
Note at 15 seconds the dads face out of focus. Or at 45 seconds the guy in the back with glasses is out of focus.
Obviously, I won’t be able to do everything in 1 key and will have to mask out parts of the scene. But what are some tricks for the blurry part? The last time I did it it ended up keying most of the blurry edges away and then I had to re-blur them.
Stephen Smith
Check out my Vimeo page
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[Stephen Smith] “The last time I did it it ended up keying most of the blurry edges away and then I had to re-blur them.”
Why did you key out the blurry parts? Was it because the key was too noisy? Or was there some other reason?
The general idea, if your source footage is of good enough quality, is to pull a nice soft key that includes things like motion blur and out of focus areas. You should not have to compromise on those.
That said, every really good key tends to be composed of a series of “patches” that treat each area of the frame in the best possible way.
The notion that it’s possible to have one key that fits everything is one to be avoided at all costs – unless you’re in a tearing hurry and you don’t have time to worry about the quality of the result.
Simon Ubsdell
tokyo productions
hawaiki -
Hey Stephen,
Believe it or not, you can use the techniques in that tutorial to get your blurry key ???? It’s actually the same problem – you’re just trying to get a “soft key”. Don’t take the tutorial too literally, just see how you can apply the techniques to your footage.
That said I will give you one other piece of advice. A lot of times it isn’t the matte generation that is the issue, it is actually how you treat the edges. PARTICULARLY with blurry edges, you’ll actually need to mix in the footage into your foreground BEFORE you matte it on top of the background. It’s takes a lot of precomps, which is why I use Nuke… Anyway check out CineGobs “Spill Suppression” which is a fantastic plugin I could not key without. First you’re going to want to use that plug-in to despill the foreground. Then separately you can actually create a SUPER soft matte with that plugin (I wouldn’t even call this a key because it is quite soft and dirty), which you use to overlay your background plate on TOP of your foreground greenscreen footage. Precomp the whole thing and THEN matte it out by your original matte, and put this precomp over the background plate. Lastly play around with how much you blur the background plate before you overlay it on the greenscreen footage.
Whew, hopefully that makes sense… Let me know if you need a step-by-step.
– Spencer
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[Simon Ubsdell]
Why did you key out the blurry parts? Was it because the key was too noisy? Or was there some other reason?
To answer this question with the previous question. I film with an 8K RED Epic-W. It creates a great image and looks really sharp and nice when it is seen in HD. Nothing in the image felt noisy but I honestly haven’t looked for noise in the blurry sections.
[Simon Ubsdell]
That said, every really good key tends to be composed of a series of “patches” that treat each area of the frame in the best possible way.I agree. It is very rear that I can do a key with just 1 key. I always have to mask out sections like a person’s hair to get it and the persons body the way I like them. I hope no one interprets my comment as a way to key the whole thing in 1 key but as do you have any tricks to keep as much blurriness as possible.
Stephen Smith
Check out my Vimeo page
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Could you post an example of a shot you are trying to key?
Perhaps that will make it easier to recommend a method.
Blurriness is really just another form of transparency, in terms of how you want to approach the key. That means that you need to be as gentle with it as you possibly can.
Perhaps your keyer is not giving you enough control? Which one are you using?
Simon Ubsdell
tokyo productions
hawaiki
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