why am I getting noise the moment I begin chromakeying with Keylight 2.0???

N

Nicholas Natteau

Veteran
I had some green screen footage that I shot on an AF100 using an Atomos Samurai and recording via SDI out as Apple Pro Res HQ.

What I can't understand is that there is no noise in my original footage but the moment I proceed to key out my Reflecmedia Chromaflex green background, using Keylight 2.0, Keylight seems to add lots of noise everywhere around the subject.

Can anyone tell me why I'm seeing this noise all of sudden that wasn't in the original footage. As far as I know I was careful to light my scene evenly and well. I just don't understand why all this noise shows up only after I apply Keylight to key out the background.

No matter what settings I tweak in Keylight, the noise remains there. So what is it about Keylight that adds noise and how can this noise be avoided? SHould I be using another Afetr Effects plugin or other chromakey software instead?
 
I've had two problems in Keylight in AE with AF 100 files;

1 - Noise in the shadows - Similar to your complaint. I haven't worked on this problem, but a search on the web did provide discussion about this and solutions. Try some searches and I'm sure you will re-discover the discussion I found. The problem is not unique to you.

2. - We've discussed on this forum, another kind of problem that I wouldn't call noise, but an artifact that looks like the material is interlaced. The odd thing is that the problem is not consistent. Some material from the AF-100 cameras works fine while others have this problem. The discussion was regarding Keylight on AE CS5. Posts on other forums say that the issue is that AE cannot deal with AVCHD and the problem is fixed by re-wrapping the video into a full-frame coding scheme. I tried it and it works. I'll post the link for this discussion if I find it.

I have not pursued either of these issues because I don't need the green screen right now. I've only been experimenting.
 
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Hi Paul, thanks very much for the examples. So I read the entire thread started by someone who had similar problems after shooting on the AF100.

So is it a problem with Keylight or AE in general? I'm experiencing the same issue when I try to key with FCP X or with Keylight in FCP7. I just don't understand it because my original footage was shot in Apple Pro Res HQ, and the original footage has no artefacting, no mpeg sizzle, no noise. It's clean. All this trouble happens only after applying a chromakey.

I tried everything and nothing seems to work. Tried duplicating my track and then turning on "Track Matte Alpha" in AE, tried the same in FCP7. Tried switching from "Soft Color" to "Hard Color" to "Source" to "None". Nothing seems to work. I'm feeling so frustrated. It seems that no matter how well I light, no matter what I use (Samurai recording to Pro Res HQ), the moment I apply the chromakey, I get horrible noise all over the edges of my subject. Read through many forums and threads, followed tutorials on green screening, but still haven't been able to solve this problem. I'm really despairing at this point. I wish I knew what the source of the problem is.
 
Nicholas Natteau said:
I had some green screen footage that I shot on an AF100 using an Atomos Samurai and recording via SDI out as Apple Pro Res HQ.

What I can't understand is that there is no noise in my original footage but the moment I proceed to key out my Reflecmedia Chromaflex green background, using Keylight 2.0, Keylight seems to add lots of noise everywhere around the subject.

Can anyone tell me why I'm seeing this noise all of sudden that wasn't in the original footage. As far as I know I was careful to light my scene evenly and well. I just don't understand why all this noise shows up only after I apply Keylight to key out the background.

No matter what settings I tweak in Keylight, the noise remains there. So what is it about Keylight that adds noise and how can this noise be avoided? SHould I be using another Afetr Effects plugin or other chromakey software instead?
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"noise everywhere around the subject" - what does this mean? on peripheral edges or farther away ? stuff farther away is usually eliminated with a rough garbage matte

How is the matte ? is it solid ? - view it in status mode. If not, you have to adjust the settings

Describe the lighting setup - this is usually the culprit for most keying problems

Posting a sample will help
 
Hi PDR and thanks for replying. The noise is really around the edge of the subject and especially over the hair. In Status mode the matte is nearly solid with a little stray noise, not much. What I can't understand is that the noise only shows up once I begin chromakeying. It's not there in the original unkeyed footage. No matter what chromakey software I use, it seems to appear as soon as the key is applied. I'll post samples.

Perhaps the problem is that I'm using Reflecmedia chromaflex instead of a traditional green screen. Some people have said that you need to follow the opposite rules when using Reflecmedia: i.e. get the subject as close as possible to the screen instead of as far as possible. I wish Reflecmedia or anyone using Reflecmedia could post a tutorial, that would really help. Unfortunately, I don't have the room to set up a traditional green screen where you need a good distance from the subject/talent to the screen.

Will try to post new samples later today.
 
Most of my experience is keying already grainy HVX footage, and the Keylight spill suppressor just completely ruins it. What I do is duplicate the greenscreen footage, and use the top layer with keylight as an alpha matte over the original footage. Then I pull this comp over my background, and work on my color and spill separately from keylight.
 
Hi Renee,

Thank you very much for that tip. Can you elaborate a little more? Is duplicating the track and applying an alpha matte enough to kill the noise? Do you just use Keylight? Or do you also use other AE plug-ins like Red Giant's Pro Keyer. What I can't get my head around is that my original footage is evenly lit and devoid of noise (not underexposed), yet as soon as I apply the chromakey, I get noise on the hair and edges of my subject/talent.

I wish I knew why the chromakey is adding noise that wasn't there before. Not knowing what I'm doing wrong is so frustrating.
 
Probably a lighting and setup problem. Spill.

Did you try any suggestions in your AF100 thread or do anything differently yet?
http://www.dvxuser.com/V6/showthrea...-first-test...buzzing-artifacts-major-problem...

Paul's comment about the 2nd problem doesn't affect you because you are keying Prores; Renee's comment doesn't really apply to you , because she started with grainy footage and you are starting with clean footage - although it may help to pull multiple keys and work in sections. Even properly lit footage usually requires more than 1 pass for good results. If you feel keylight (and /or any keying program's) auto spill supressor is the culprit , another variation is to do the edge matte pass using "intermediate result" mode, and take care of the spill separately (e.g. selective channel range with hue/saturation filter and reduce the saturation, combined with roto'ed mattes)
 
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Hi PDR and anyone else interested in this problem, I posted a photo gallery of my Reflecmedia setup and I uploaded two clips in my Dropbox Public folder. Would love to know from anyone using AE Keylight if you find that the noise pops up as soon as you apply Keylight. My problem is that I don't see the noise in the original clip, it only appears after applying the key.

My setup here:

http://gallery.me.com/nicholasnatteau#100471

My two files here:

http://dl.dropbox.com/u/27223798/T5.mov

http://dl.dropbox.com/u/27223798/T6.mov
 
Ok... it's pretty clear to me what the problem is. i didn't know you were using reflecmedia stuff. This product is find for quick and dirty stuff, but looking at your quicktime files reveal serious colour issues. It's not the camera, it's that grey halo, and lack of colour information thats causing a problem.
 
Thanks very much Bgundu. But what I can't understand is that everyone except me seems to be getting great results with the Reflecmedia. I was told that the only way to get rid of the halo was to put the subject as close to the screen as possible. Nearly touching the screen. But when I try that I can't get my backlights to make the halo and seperate subject from background. Thanks again.
 
Hello everyone,

I just uploaded a short screencast about the noise issue I keep getting in AE Keylight. Can anyone please take a look at it and tell me what I must be doing wrong in Keylight that's giving me this noise in the keyed footage. Again, the noise isn't there in the original, only after I apply Keylight. Thanks very much in advance for your help.

http://vimeo.com/37021102
 
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Nice screencast Nicholas. I might suggest providing a link to the original footage, however, since it might further clarify a couple of things in terms of what issue could be. Even if you provided a still (ideally the first frame) it would allow us to try and come up with a solution on our own. Just a suggestion of course. Hope you get to the bottom of the problem either way.
-B
 
OK - I looked at the sample file The problems are:

1. The footage is noisy (your ISO / gain is too high open up the f-stop or add more lights)

2. There is a slight grey halo around your character. So instead of looking for the difference between green and hair... the computer is trying to figure out the difference between grey-green screen and grey-yellow hair. That's probably due to the Reflectmedia thing

3. The AF100 is a pretty low resolution camera, with a bit of softening AND aliasing thrown in. So hair details are being lost there.

4. The compression is making mincemeat of whatever thin hair detail there was remaining - oh hang on, you used a Samurai. Wow, AF100 must be crap then.

If I HAD to composite this shot, here's what I'd do:

1. Run noise reduction on the entire thing (Neat Video or if I didn't have that, Remove Grain with light detrain and Temporal Reduction on). We do this ALL THE TIME in the compositing world.

2. Get clever with multiple layers / multiple keys to get the hair to blend in transparently

3. Use Primatte instead of Keylight

4. Complain loudly (but all compositors do that anyway, even if only in their heads :)

Bruce Allen
www.boacinema.com
 
Nicholas Natteau said:
Hello everyone,

I just uploaded a short screencast about the noise issue I keep getting in AE Keylight. Can anyone please take a look at it and tell me what I must be doing wrong in Keylight that's giving me this noise in the keyed footage. Again, the noise isn't there in the original, only after I apply Keylight. Thanks very much in advance for your help.
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No no no - there is noise there. Try a de-noise pass beforehand and you'll see a huge improvement.

It's made a lot worse by the screen going kinda grey around the character. And the lack of resolution. And the aliasing. And the fact that you're keying hair.

But rule #1 is if you see noise in your key, try a de-noise. Don't just look at the footage and say there's no noise in it. Try de-noise and see what it does!

Bruce Allen
www.boacinema.com
 
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Bgodoy and bruceallen, thank you both very much for taking the time to help me with this. I really appreciate it.

Bgodoy, thanks. I tried hosting the original file in my public dropbox folder and even on my me.com public folder, but people were unable to access the file. I'd be happy to send you the original file if you like via "yousendit".

Bruceallen, thanks very much for all those tips and thanks especially for taking time out to work on it yourself. I didn't know the AF100 is considered low res (I shot in 1080p24). Do you think I would have had better results with say the Sony FS100? (Unfortunately, RED is way out of my budget). I'm sure my poor results are due to mistakes I made in the shooting and keying process. Because I've seen people get very good chromakeying results with the AF100, even with the AVCHD codec. Though I always intend to use Apple Pro Res now that I have the Samurai.

Thanks again very much for your help.
 
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Nicholas Natteau said:
Bruceallen, thanks very much for all those tips and thanks especially for taking time out to work on it yourself.
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Sure thing!

Nicholas Natteau said:
I didn't know the AF100 is considered low res (I shot in 1080p24).
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I know it says it does 1080p but I don't think it really resolves 1080p worth of detail. I think it resolves more like 800p or so. If you look at Barry Green's FS100 vs AF100 tests, you can't see much difference on the Vimeo link, but if you download the file, it is night and day at 1080p. I remember criticizing the hair details at 1080p on his shot - and everyone at DVXuser got really angry at me and said I was seeing things. It was weird because the combination of aliasing and softness was really obvious to me but folks on DVXuser don't really do stuff like good keying all of the time and just get emotional without looking at the image clearly.

Nicholas Natteau said:
Do you think I would have had better results with say the Sony FS100? (Unfortunately, RED is way out of my budget).
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Um, yes, I think you'd get better results with the FS100.

However, I also think you'd get better results by selling your AF100 and reflecmedia screen and buying
- a cheap but "actually resolves 1080p" small-sensor 3CCD camera (HMC150, even Z10000 in 2D mode)
- a normal greenscreen
- some proper lights

I think you'd even have cash left over!

Nicholas Natteau said:
I'm sure my poor results are due to mistakes I made in the shooting and keying process.
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Well yes - if you had more light / faster lens stop (so your image is less noisy) - it would help.

Also, to get rid of the resolution issues on the AF100: if you're shooting say a tall shot of a person against a greenscreen, turn the camera on its side. So then you're recording a 1080x1920 image :)

Then rotate back in post and scale down.

Nicholas Natteau said:
Because I've seen people get very good chromakeying results with the AF100, even with the AVCHD codec.
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You have? With good fine hair detail? Links please!

Although anything is possible with enough hard work. I could probably get more hair detail back if I manually made a bunch more layers - but that would require quite a lot of manual work...

Bruce Allen
www.boacinema.com
 
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