Reducing noise

[Oliver De morassé]

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)

[Andrew Somers]

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).

[Pierre Jasmin]

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

[Oliver De morassé]

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!

[Andrew Somers]

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.

[Oliver De morassé]

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?

[Oliver De morassé]

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?

[Andrew Somers]

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.

[Oliver De morassé]

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.

[Oliver De morassé]

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.