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FYI, Monitoring in RAW isn't really RAW!!!

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Russell Lasson
FYI, Monitoring in RAW isn't really RAW!!!
on Jan 10, 2009 at 6:19:06 am

I just thought that I'd clear up a common misconception about the RAW setting on the RED ONE.

Most RED users think that monitoring in RAW off of the camera shows what the sensor is seeing. After all, the camera shoots in RAW, so naturally, monitoring in RAW would show exactly what the sensor is seeing.

THIS IS NOT THE CASE!!!!

It's not a conspiracy or anything malicious by RED, but monitoring in RAW isn't what most people think it is. It is the RAW data, but a REC709 gamma curve has been added to it, making it brighter, mostly in the shadows and mid-tones. This is why there isn't a major luminance difference between monitoring in RAW and monitoring in REC709.

If you want to see what the camera sensor is really seeing, pull up an R3D file in REDAlert and change the Output LUT/Gamma Space to Linear Light. Or in REDCine, hit the Color button at the top of the screen. This is the RAW data interpreted with a linear gamma, which is how the sensor records it.

What does this mean? In most situations, this isn't a big deal. But I've noticed that in low light situations, people are often underexposing more than they thought they were.

Let's say that you're monitoring in RAW on the camera and a waveform says that the brightest thing in the shot is about 45 IRE (remember, this is a low light situation). Some people are going to say, "45 IRE isn't horrible. I can brighten it up in post. Let's shoot this." So they shoot it thinking that the sensor is seeing the highlights at 45 IRE. But the sensor isn't seeing it at 45 IRE. It's actually seeing it closer to 25 IRE! This is because the of the REC709 curve that's applied to the image brightens the image and can be misleading.

This is even a bigger deal if you're monitoring in REDSPACE because REDSPACE brightens the image even more that REC709. So instead of a 20 IRE difference, it's closer to a 40 IRE difference!!! This is a really big deal. If you thought your highlights were are 45 IRE, but they're really closer to 5 or 10 IRE, your footage is going to have a lot more noise in it that you thought it would. For this reason, I don't suggest monitoring in REDSPACE because of how different it is from what the sensor is seeing.

The great thing about RED is that I've still never seen footage that couldn't be used. I've seen footage where the actual RAW data was between 0 and 10 IRE and it's still been useable. It's great to have so much flexibility.

So how do you work with this?

Currently there isn't anyway to monitor in RAW with a linear gamma (linear light) from the camera. But just knowing that monitoring in RAW is actually brighter than what the sensor is actually seeing will help, especially in low light situations.

As GI Joe would say, "Knowing is half the battle!"

-Russ



Russell Lasson
Ridgeline Digital Cinema Mastering
Universal Post
Salt Lake City, UT


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Uli Plank
Re: FYI, Monitoring in RAW isn't really RAW!!!
on Jan 10, 2009 at 7:46:26 am

I agree with you on that observation.
But I think that folks exposing like this misunderstand the whole concept of RAW. The rule is simple: expose to the right (ETTR), like on any DSLR. Don't care for any IRE in the frame, just make sure that your highlights are protected (apart from light sources or local reflections). So, it's not about bringing the levels up in post (which would bring up your noise floor), but about bringing them down if needed.

BTW, the histogram in RAW mode on the camera is correct – if it touches the right side, your sensor is saturating. I agree on the impressive flexibility of the Red's footage as well, but I have seen properly exposed footage with extreme scene contrast where we could not bring up detail in some dark background. It became blotchy there (after all, Red is compressed!) and we needed to crush the blacks.

Best regards,

Uli




Director of the Institute of Media Research (IMF) at Braunschweig University of Arts


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David Battistella
Re: FYI, Monitoring in RAW isn't really RAW!!!
on Jan 10, 2009 at 11:24:31 pm

[Russell Lasson] "It's not a conspiracy or anything malicious by RED, but monitoring in RAW isn't what most people think it is. It is the RAW data, but a REC709 gamma curve has been added to it, making it brighter, mostly in the shadows and mid-tones. This is why there isn't a major luminance difference between monitoring in RAW and monitoring in REC709. "

Russell,

I have noticed a huge difference between REDSPACE, REC 709 and RAW mode. I have the RAW VIEW mapped to the LCD user key and I use it often to check RAW vs. REDCODE.

Why would RED call it RAW and then apply a curve?

Are you certain about this?

David




Peace and Love :)
Read my Blog
http://blogs.creativecow.net/DavidBattistella


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Russell Lasson
Re: FYI, Monitoring in RAW isn't really RAW!!!
on Jan 11, 2009 at 6:19:40 am

[David Battistella] "Why would RED call it RAW and then apply a curve?
Are you certain about this? "


Yup. It's in the RED documentation, though it's not written out very clear. I've also heard it from Graeme Nattress from RED on another RED related forum. Here's his quote:

"RAW view is no matrix or colour or exposure adjustment and a pure REC709 gamma curve."

Someone mentioned wanting to call it RAW 709 or something like that which I think would help clear up some of the confusion.

I'd really like to see more documentation about this and also what the other data from the exposure tools is based on. Just having clear information on how things are being processed can help maximize what you can get out of the camera.

-Russ

Russell Lasson
Ridgeline Digital Cinema Mastering
Universal Post
Salt Lake City, UT


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gary adcock
Re: FYI, Monitoring in RAW isn't really RAW!!!
on Jan 11, 2009 at 4:31:49 pm

[David Battistella] "Why would RED call it RAW and then apply a curve? "

You guys are not thinking about this.
Red is send a RAW signal, it is the devices that read it making the Mods. This is no different that color printers or cameras - they maybe close- but they all modify the signal to fit the output.

RAW output is delivered as a file, however when one outputs this on a device it is you that is making it display using RED 709.

All output devices offer / apply some color profile. Signals over HDSDI are read by devices that look at REC 601 and REC 709 outputs- These displays map to these color spaces based on the incoming signal, so any HD signal over HDSDI would be mapped to a REC 709 output on virtually ALL Panasonic, JVC, and Sony displays, ESPECIALLY prosumer products no matter what the video signal originated on.

CineTal and Astro monitors allow you to view an incoming video signal without mapping to REC 709 on there systems,but the vast majority of displays are 8bit at REC 709 output.







gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Inside look at the IoHD
http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Alex Elkins
Re: FYI, Monitoring in RAW isn't really RAW!!!
on Jan 14, 2009 at 10:26:14 am

Russell,

Does all of this mean that when we expose the camera, the pitcure in the monitor should actually look over-exposed if we want it exposed correctly (unless we use a monitor that truly displays RAW, as Gary mentions in the thread)?
How does this information affect our workflow, both in production and in post?

Thanks,
Alex


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David Battistella
Re: FYI, Monitoring in RAW isn't really RAW!!!
on Jan 14, 2009 at 2:34:12 pm



What it means is that there are options.

It means that before using this tool you should take the time to understand it. This is not a video camera that records to tape and is burned in, but you can operate it that way if you like.

It depends mainly on the job.

If you know that you are doing a film finish then you need to know if you are preserving the highlights because you loose picture information at the top end.

If you are doing a fast turnaround job that is a QT finish, then chances are it will end up much like what you see in your monitor. (although you still have the chance to tweak.

Just remember, the basics. It's a very flexible system and you should take the time to truly understand what is going on under the hood.

RAW view and the RAW exposure meter (in build 17) are two excellent ways to see if you are clipping the channels, but your LOOK file will determine how your QT's are processed and screened (unless of course they are altered or tweaked)

David


Peace and Love :)
Read my Blog
http://blogs.creativecow.net/DavidBattistella


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Russell Lasson
Re: FYI, Monitoring in RAW isn't really RAW!!!
on Jan 14, 2009 at 5:01:48 pm

Really this is more for people's information. In some cases, knowing this information will change some decisions on set, mostly in low light situations and dark scenes.

-Russ



Russell Lasson
Ridgeline Digital Cinema Mastering
Universal Post
Salt Lake City, UT


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gary adcock
Re: FYI, Monitoring in RAW isn't really RAW!!!
on Jan 14, 2009 at 5:10:36 pm

[Alex Elkins] "Does all of this mean that when we expose the camera, the pitcure in the monitor should actually look over-exposed if we want it exposed correctly"

Actually the viewing of raw content over HDSDI does not effect exposure as much as it conforms both color and contrast into Rec 709 with a fixed color space and a 2.2 gamma.

I can correctly monitor Raw content from ANY camera (RED, SII, Phantom) using Iridas Speed Grade and a Cinetal Cinemage monitor connected via DVI and then calibrated using the Iridas software, while not inexpensive, it does offer the highest quality of monitoring available currently no matter what your output.

Contrary to Davids comment, I have to add that in the more than 100+ RED projects I have worked on I have only seen 4 of them output to film. Only 4 went for filmouts and 2 of those were projects to play in Europe.



gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Inside look at the IoHD
http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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