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Oliver de Morassé
Reducing noise
on Mar 8, 2012 at 10:11:07 am

I have some green screen footage with a full body shot of a person. They are wearing a dark suit and I am having a problem with noise below the waist. I have used the plugin "Reduce Noise" from Neat Video - seems to do a nice job but the image becomes a little too smooth and the skin tones start to get a plastic look.

Any other tips of reducing the noise / crackling on the trousers and black shoes would be appreciated. Many thanks.


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Tudor "Ted" Jelescu
Re: Reducing noise
on Mar 8, 2012 at 1:37:23 pm

Keylight should enable you to tweak the key and get rid of some of that noise, however, in some instances, black or dark clothing will still have a lot of noise. Using Neat Video or Remove Grain can help. You can either use roto garbage masks to apply them over the problem areas without affecting the skin, or try to pull a second color range key o separate these areas. Of course you need to do that by duplicating the layer and applying the effects on the top one.

Tudor "Ted" Jelescu
Senior VFX Artist


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Frank Brown
Re: Reducing noise
on Mar 8, 2012 at 1:50:49 pm

DenoiserII from Red Giant Software is very cool and smart plugin for removing noise.
http://www.redgiantsoftware.com/blog/2012/02/28/magic-bullet-denoiser-ii-is...

It is removing only noise, not making smooth and blurry image such as Neat Video plugin.


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Oliver de Morassé
Re: Reducing noise
on Mar 8, 2012 at 10:29:43 pm

@ Frank - thanks for Denoiser II tip from Red Giant... currently testing. Is it best to use the plugin before or after Keylight?


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Dave LaRonde
Re: Reducing noise
on Mar 8, 2012 at 8:15:09 pm

I've had noisy keys from keylight under the same circumstances as yours. I've used the noisy key as an alpha matte for the original footage with success.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Oliver de Morassé
Re: Reducing noise
on Mar 8, 2012 at 10:31:01 pm

Sorry Dave, not really sure what you mean by using the noisy key as an alfa matte - but sounds good ;O)


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Benjamin Ausmith
Re: Reducing noise
on Mar 9, 2012 at 7:32:28 pm

I believe Dave means using Keylight to generate basically a cookie-cutter layer-- not for the color correction. Sometimes keylight can produce noisy artifacts. So if you use keylight to generate just the alpha layer-- that is, the layer that says whether video is transparent or opaque-- then combine that layer with your original footage by using Track Matte > Alpha Matte. Keylight will cut out the shape that you want, but you'll be able to preserve your original color because we'll actually be seeing your original footage without Keylight's noisy processing.


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jim bachalo
Re: Reducing noise
on Mar 9, 2012 at 3:42:30 am

I've heard from others that Neat video is THE best noise reduction solution for video. have you tried tweaking the settings?

Local is the new global


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Frank Brown
Re: Reducing noise
on Mar 9, 2012 at 9:12:17 am

jim
I`ve tried both in different situations. IMHO Denoiser is the best solution, because of its smart filter.


Oliver
I didn`t compare KeyLight and Denoiser on green screen footages, but if the problem only noise, Denoiser should fit you.


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Andrew Somers
Re: Reducing noise
on Mar 12, 2012 at 4:34:17 am

I'm assuming we are talking about the same shot of the blonde in a tux.?

To address the noise in the first place, as I indicated in the earlier threads, your "greenscreen" is not a good narrow band of green - it contains a lot of blue, at least as you are shooting it.

As a result, you are making the keyer (Keylight, what have you) work harder, and when you make it work harder, you may then be causing noise to become more obvious.


Since you also have the "white line" in the red channel issue, this could be an artifact of the debayering or the compression algorithm due to the excessive blue in the green screen you are using.


NOTE: how are you white balancing your camera? It is VERY important when shooting green/blue screen that you NEVER EVER use AUTO WHITE BALANCE.

White balance to a neutral grey card that is lit with the same color temperature lighting used on the green screen (and use that same color temperature lighting for the subject).

This is critically important especially when shooting to an 8 bit compressed format like in a dSLR.


If you ARE properly white balanced, try this:

http://www.rosco.com/us/scenic/ultimatte.cfm


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Oliver de Morassé
Re: Reducing noise
on Mar 12, 2012 at 10:20:54 am

I use both a DSLR camera & camcorder dependent on the shooting. My lights use a Color Temperature of approx. 5400K. I have experiemented with the white balance settings... I think I shot around 4900k.

Should I be using a 18% grey card for setting my white balance manually?


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Andrew Somers
Re: Reducing noise
on Mar 13, 2012 at 3:31:11 am

Oliver said: "My lights use a Color Temperature of approx. 5400K. I have experiemented with the white balance settings... I think I shot around 4900k."



Don't do that.

With lighting at 5400K, setting WB to 4900K will fill the green screen with BLUE. If you were shooting RAW, you could fix it later, but because you are shooing to an 8 bit format, with 4:2:0 color and highly compressed H264 - you must white balance your camera such that the green screen is ending up in the green channel, and not the red or blue.


Oliver said: "Should I be using a 18% grey card for setting my white balance manually?
"


Yes.

You want to WB your camera to your lighting, ESPECIALLY the lighting on the green screen. You want your camera to give you a file that has that green screen in the G channel, and NOT in the R or B.

This is ESPECIALLY critical in 8-bit, 4:2:0, DCT compressed files.



If you bring your footage into After effects, in LINEAR 32-bit space (which you should always be using for compositing), and you eyedropper the GREEN screen, your numbers should look like one of these examples:





Your screen does not look like that, here are values for the file you gave me last month:




This is not good. Your blue channel has barely a stop difference from the green channel.

Again, if you were shooting RAW, it could be corrected - but shooting in 8Bit, your camera is having to debayer this wacked white balanced footage,, then cram it into a 4:2:0 H264 container. And then you're stuck.


RAW does not have a whitebalance - your white balance is what guides the camera in how to debayer, gamma encode, and YUV encode the file. If your white balance is wrong, so will be your shot.


LET'S GET BACK TO BASICS:


1) Use a green that is *very narrow band* (nearly florescent, or Ultimatte, etc.).

2) Light it evenly, and keep it at meter and no more than 2 stops UNDER meter. Overexposing will hurt you, so err on the side of exposing it darker. I normally aim for one stop under meter for green screen exposure.

3) Whitebalance the camera to the light source, and make sure that the Green Screen is mainly in the G channel, and not in the R or B. There should be about 3 stops (or more) difference between the G and the next brightest channel.

4) Never use sharpening in camera.

5) Never use filters on the camera, except ND or polarizers.

6) Be careful what "picture style" you use in a Canon dSLR. I can't say if Cinestyle is the right choice, but it might work great. I don't use Canon, so I can't experiment here.

7) A camera that shoots RAW like the Red Epic or Scarlett is IDEAL for green screen.

PECKING ORDER OF MOST PREFERRED, TO MOST AVOIDED, CAMERA/FILE TYPES
For Green/blue screen.

BEST: RAW.

SECOND BEST: After "RAW", the next preferred solution is RGB or 4:4:4 YUV in 10 bit or 12 bit.

THIRD BEST: 4:2:2 in 10 bit or 12 bit with moderate compression or uncompressed.

FOURTH BEST/AVOID if possible: 4:2:2 and 4:2:0 in 8 bit. 422 8-bit is better than 420, but 420 is not that much worse that 422 8 bit.

420 is not the end of the world - it is useable if shot and handled correctly. Some formats like HDV do much worse - but HDV is not bad just because of the 420 - it's bad because it also uses non-square pixels that have to be stretched, and it uses severe compression. Some say that HDV is bad for greenscreen because it uses 420 - but in reality HDV is bad for greenscreen because HDV is overall a very low fidelity format.

So don't use HDV. Having said that, I've pulled plenty of good keys using 420 dSLR video.

DO NOT USE: 4:1:1 or 3:1:1 for green/blue screen work. Just don't. (unless you are a masochist.) Unlike 420 that has equal color res both vertical and horizontal )1/2 res vertical and 1/2 res horizontal), 411 has 1/4 the horizontal res, making it nearly useless. Similar issue for 311.

And having said that, I've pulled "useable" keys from 411 and 311. But I wasn't very happy about being in that situation.

8) Keep your subject as far away from the green screen as possible - among other things this allows keeping the green screen as out of focus as possible.


I'll add some more tips later, dinner time... :)


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Oliver de Morassé
Re: Reducing noise
on Mar 13, 2012 at 10:03:03 am

Wow Andrew - thanks for your tremendous feedback!

You mention "you must white balance your camera such that the green screen is ending up in the green channel, and not the red or blue" - how do I do this? Separate shots of the greenscreen with different white balance values and then analyse in AE?

I have set my Project to a Color Depth of 32-bits - but my working space is set to none. The options I have are:

What should I be using?

You metion that "your blue channel has barely a stop difference from the green channel". What exactly do you mean here - when analysing the green using the eyedropper, what represents 1 stop? What do I need to be looking at in order to make sure that the difference between the G and B is 3 stops (or more)?

You keep mentioning "at meter". Is this the value I get when evaluating my WB using the 18% grey card? You then mention that I need to go 1 to 2 stops under my meter value - what should I be doing here... changing my aperture values from what I used when evalating the WB (from let's say f2.8 to f3.0)?

DSLR aside, I have also been testing various camcorders and capturing the video uncompressed using a Black Magic DeckLink Card. The video stream produced is a 4:2:2 10-Bit YUV - should be OK right? When capturing to their internal cards, I get differencing results.

Panasonic AG-HPX250EJ:


Sony PMW-EX1R:


Here screenshots of the results:

Panasonic uncompressed
Panasonic Card
Sony uncompressed
Sony card

With the Sony I shot with an aperture of f2.7 and WB 4800k, with the Panasonic f3.4 and WB 4900k. I find that the Sony produces much cleaner results - perhaps because of the large CMOS chips?

Thanks again for all your help in this matter - I'm learning lots ;O)


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Andrew Somers
Re: Reducing noise
on Mar 13, 2012 at 8:35:36 pm

You are still white balanced incorrectly for both cameras.

The Sony is better because (aside from the fact that Sony makes better camera's than Panasonic), the SONY is a 1/2" THREE chip camera, and the Panasonic is a 1/3" SINGLE chip camera.

A single chip camera requires debayering, that substantially reduces the true/effective resolution (relative to the seonsor native resolution) (which is why you actually want a chip that is much higher resolution than what you are "ending up with" for single chip cameras).



As for AE workingspace: Set AE to:

32 bit
sRGB
Linear
Compensate for Scene Referred



WORKING SPACE:





If you are shooting with a dSLR like the Canon, set it to sRGB, and make sure that sRGB is the colorspace that the footage is INTERPRETED as in AE.




If your footage is from an HD camcorder, then it will most likely be Rec709, and should be interpreted as Rec709 - but your AE working space should still be sRGB linear.

REASON: Rec709 and sRGB both use the same primaries, however, the gamma curve of Rec709 does not linearize well as a working space in After Effects (appears to a be a bug).


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Oliver de Morassé
Re: Reducing noise
on Mar 14, 2012 at 9:30:51 am

Thanks for your feedback Andrew.

I believe the Panasonic has 3 Chips - it has a 1/3-type 2.2-megapixel 3MOS image sensor. However, due to the larger 1/2" chips from Sony... that's probably where the quality difference is - right?

I have changed the AE working space settings as you suggested - now I get strange results with my denoiser from Neat Video:
Set to none - Neat Video
Set to sRGB - Neat Video
Set to none - Result
Set to sRGB - Result
A much darker image to analyse resulting in a slight purple tinge around the person.

Here the AE interpretations of the workspace:

Panasonic uncompressed

Panasonic card

Sony uncompressed

Sony card


You mention that I keep white balancing incorrectly. Please can you give me some tips... what am I doing wrong? If you can also further expand on the "-1 & -2 stop" and "at meter" issues.

Thanks again, you're a tremendous help!


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Andrew Somers
Re: Reducing noise
on Mar 14, 2012 at 10:53:34 am

I stand corrected on the Panasonic - One brochure I read led me to believe it was a single chip camera. regardless I have never liked Panasonic cameras in practice, for what it's worth.


Regarding your WORKING SPACE.

When working in Linear, you ALSO must enable "Display Color Management": for each sequence/comp (this is a COMP setting and NOT a project setting, so it could be on or off for every comp in your project).



ALSO, make sure your monitor is calibrated and profiled correctly. AND, it is important to note that when working in LINEAR space that you *CAN NOT just go out via video preview - you first must pass through a LIN to VID profile conversion to use After Effect's Video Preview (unless you have an HD card that uses LUTs that you can setup for the lin to vid conversion).

The sRGB example you posted above is the first thing I've seen you post that is close to correct in terms of the green screen - I was able to pull a PERFECT key in under 20 seconds in Keylight.

I can't say the same for the version set to "None" and it was also very noisy.

I don't use "Neat Video Denoiser" so I can't advise there, but you may find that with the correct settings elsewhere that you don't need it at all.


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Oliver de Morassé
Re: Reducing noise
on Mar 14, 2012 at 12:38:24 pm

Thanks Andrew,

I assume the image where you were able to pull a perfect key was this one - right? This is the image that Neat Video shows me when I denoise - unfortunately, this is not the one I can use for Keylight. Is the whole image not too dark - is this what I should be aiming at? The original footage is here - any good? Shot with the Sony at 4800k & F3.4.

I have played with monitor calibration through Windows 7 and "Simulate Output" settings in AE - I was able to see little change in my video preview or rendered image. My settings are:


I have tried both "HDTV (Rec. 709)" and "sRGB IEC61966-2.1" within Project Settings, Working Space and althought I can't really see a difference between the two I should stick with using "sRGB IEC61966-2.1" - right?


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Oliver de Morassé
Re: Reducing noise
on Mar 15, 2012 at 3:35:30 pm

Just received a 18% grey card. Quick question to white balancing my camera. Should I do all the picture profile settings first (like no sharpness, neutral etc.) and then do the white balance - or does it not matter when I white balance?


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Andrew Somers
Re: Reducing noise
on Mar 16, 2012 at 2:15:46 am

You don't need a custom output simulation - just select "Display Color Management" and use the HDTV simulation.


You won't notice a big difference between sRGB and rec709 working spaces - they are virtually identical in linear mode - but there is (or was) a bug in AE that did not linearize rec709 correctly. Other than that, Rec709 and sRGB use the same primaries.


But again, the first issue is that your camera is not white balance correctly for your lighting.


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Oliver de Morassé
Re: Reducing noise
on Mar 16, 2012 at 7:53:09 am

Thanks for all your feedback Andrew - you're a tremendous help.

Reading through the post again, I have come across a couple of questions where I am still a little confused. Would be great if you could comment on my questions regarding white balance, stops and metering on "Mar 13, 2012 at 11:03:03 am":

You mention "you must white balance your camera such that the green screen is ending up in the green channel, and not the red or blue" - how do I do this? Separate shots of the greenscreen with different white balance values and then analyse in AE?

You metion that "your blue channel has barely a stop difference from the green channel". What exactly do you mean here - when analysing the green using the eyedropper, what represents 1 stop? What do I need to be looking at in order to make sure that the difference between the G and B is 3 stops (or more)?

You keep mentioning "at meter". Is this the value I get when evaluating my WB using the 18% grey card? You then mention that I need to go 1 to 2 stops under my meter value - what should I be doing here... changing my aperture values from what I used when evalating the WB (from let's say f2.8 to f3.0)?


Thanks again.


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Oliver de Morassé
Re: Reducing noise
on Mar 16, 2012 at 4:59:00 pm

I've done a whole load more testing with all 8 picture styles the Canon DSLR has. All movies shot at ISO 320 with an aperture of 3.5. I changed to each picture style, did a manual white balance and filmed. Here are the original movies as a 70MB zip download. FYI, RGB & white balance values for each picture style:

R: 0.0595 G: 0.4233 B: 0.2789 | 4300k | Cinestyle
R: 0.0000 G: 0.4735 B: 0.1981 | 4300k | Faithful
R: 0.0000 G: 0.6584 B: 0.2423 | 4500k | Landscape
R: 0.0168 G: 0.4397 B: 0.2502 | 4300k | Marvels Adv
R: 0.0021 G: 0.3864 B: 0.2122 | 4300k | Marvels Cine
R: 0.0137 G: 0.5395 B: 0.2918 | 4200k | Neutral
R: 0.0003 G: 0.5395 B: 0.0630 | 4300k | Portrait
R: 0.0038 G: 0.6472 B: 0.3486 | 4200k | Standard

I would very much appreciate your comments as to which picture style you believe best suits the greenscreen and if the white balancing is now better?

Thanks again.


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Andrew Somers
Re: Reducing noise
on Mar 18, 2012 at 9:53:56 pm

A) In theory when you are correctly white balanced, a green element that is sufficiently narrow should (in theory) occupy the green channel with little cross talk in the red and blue.

B) When you are working in AE in LINEAR color space, then a stop is just like in the real work - one half or double - i.e. 0.5 is one stop less than 1.0, and 0.25 is one stop less than 0.5, or two stops less than 1.0.

C) As for AT METER, when measuring REFLECTANCE using a SPOT METER on the surface, "at meter" implies that you are setting exposure for that value. If we are saying that you are setting exposure using the reflectance of an 18% card (putting that card in "Zone 5", then your green screen can be as much as two stops darker than *that* level.

Of course, there are issues relating to the angle of reflectance, etc etc et that I am not going go into deeply here (for instance, in reality the meter inside dSLRs is calibrated to be "at meter" based on a 12% card, and this is a subject I am not going to get into at the moment, but here are two links with opposing viewpoints on the subject:

http://www.bythom.com/graycards.htm

http://dpanswers.com/content/tech_kfactor.php


But in terms of YOUR situation: If using a spot meter on an 18% grey card at your SUBJECT's location you get a specific reading, and then point that spot meter at the green screen at roughly the same angle, the green screen should be NO BRIGHTER than the grey card, and can in fact be as much as 2 stops darker than the grey card. I normally aim for 1 stop darker than the grey card.

This assumes that you are shooting your subject "at meter" that is, at the settings as indicated by a light meter.

As the brightness of the green screen increases past "meter", you will get into a region where it becomes clipped and/or washed out - washed out means that you are adding red and blue to the image which is exactly what you DON'T want.


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Oliver de Morassé
Re: Reducing noise
on Mar 19, 2012 at 9:52:01 am

Thanks for the tutorial Andrew - very informative ;O)

I would be interested in what you think of the sample videos I posted:

1. Is the white balance now better?
2. Which picture style do you think is best for keying?

Thanks again.


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Oliver de Morassé
Re: Reducing noise
on Mar 19, 2012 at 3:30:51 pm

Have I understood correctly, based on the results I posted, the picture styles have the following approximate stop differences between the green & blue channels:

Cinestyle: 0.5
Faithful: 1.5
Landscape: 1.5
Marvels Adv: <1
Marvels Cine: <1
Neutral: <1
Portrait: >3
Standard: <1

Based on these findings, then either Faithful, Landscape or Portrait would give the best keying results?


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Oliver de Morassé
Re: Reducing noise
on Mar 22, 2012 at 11:51:23 am

Hi Andrew,

Have you managed to have the time to check out my demo files? If you have the time, I would really appreciate your comments on which picture styles you find best and if the white balance is OK.

Many thanks ;O)


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Oliver de Morassé
Re: Reducing noise
on Mar 28, 2012 at 3:55:21 pm

Hi Andrew, any chance of your comments to my final question. Many thanks in advanced.


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Oliver de Morassé
Re: Reducing noise
on Apr 10, 2012 at 6:41:19 pm

Hi Andrew,

I've got a recording coming up tomorrow - I would really appreciate your thoughts on which picture style best suits keying.

thanks again for your tremendous input.


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Pierre Jasmin
Re: Reducing noise
on Mar 14, 2012 at 1:58:51 am

We also have DE:Noise you can check out :)
revisionfx.com/products/denoise/
Just made some adjustments so it works better when it's more grainy then video low-light sensor type noise, that should show up in next month.

Pierre



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