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Is Raw the same as 4:4:4


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#1 Ioannis Koutroubis

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Posted 04 July 2016 - 09:04 PM

Hello everyone I have a question well 2. First is raw the same as 4:4:4? Second question if 2 cameras filmed a subject one in RAW and one in 4:4:4 which one should the colors be more saturated?

Thank you very much.


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#2 Landon D. Parks

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Posted 04 July 2016 - 09:24 PM

Raw recording is not the same as 4:4:4. 

 

4:4:4 is a color and luminance sub-sampling system. 4:4:4 means that there is no color sub-sampling happening. Raw can either mean a particular format (CinemaDNG RAW, RED, etc.) or it can be used as a general term to describe images that are not processed in the camera.

 

So no, they are not the same... One (4:4:4) is more related to compression than is Raw, which is related to the actual processing of the image off the camera (white balance, color space, etc.). The two often go hand-in-hand though. For example, most raw systems record 4:4:4 color.


Edited by Landon D. Parks, 04 July 2016 - 09:27 PM.

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#3 David Mullen ASC

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Posted 04 July 2016 - 11:11 PM

To add to what Landon said, raw is an image off of the sensor pre-conversion to RGB, un-bayered, whereas 4:4:4, 4:2:2, etc. are all forms of color subsampling, which implies working with an RGB signal in the first place in order to then subsample it.

 

The other thing is that 4:4:4 doesn't tell you the gamma, whether it is Rec.709 or some sort of log gamma.

 

So it doesn't make sense to ask whether raw or 4:4:4 would be more saturated since raw isn't a color image (yet) and once converted, one option might be, for example, to convert it 4:4:4 in log gamma (which would look rather pastel on a Rec.709 monitor).


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#4 aapo lettinen

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Posted 05 July 2016 - 02:36 AM

one additional thing to note is that RAW image is not usually UNCOMPRESSED. almost always RAW is compressed slightly or very heavily depending on situation and system used. 

after debayering the RAW compression artifacts usually look very different from rgb/yuv format artifacts so they are maybe not considered compression artifacts or are not as apparent to the general viewer which may give a impression that the image is uncompressed which is not the case at all. for example heavily compressed redcode loses lots of fine details but does not create visible macro blocks (which are those which people usually seek when they look for compression artifacts) 


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#5 Ioannis Koutroubis

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Posted 06 July 2016 - 07:56 AM

Ok thank you very much for the info. I have a further question if you had the choice to either record your project in RAW or in 4:4:4 what would you choose to capture the highest colour quality?

Thank you all.


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#6 David Mullen ASC

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Posted 06 July 2016 - 10:17 AM

Color-wise, raw or 4:4:4 out of the camera should be almost the same, but there are other issues that will affect grading, like compression level, bit depth, gamma, etc. so if you plan on pushing that color around in post, you have to factor those things in. If quality is your biggest concern, it would be safer to shoot raw.


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#7 David Edward Keen

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Posted 06 July 2016 - 10:33 AM

I've been told that gamma is a synonym for the midtones. Is this a different gamma than the one above? Couldn't find it specifically in searches.
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#8 Landon D. Parks

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Posted 06 July 2016 - 10:57 AM

Gamma, at least to my eye, seems to adjust overall huh shifts in the image. It is possible that it affects mid-tones more than shadows and highlights, but in my experience in playing with gamma settings, it adjusts the entire image. In general, I avoid messing with gamma unless I'm going for a 70's 'special' look. Even slight adjustments turn things magenta or green, at least in my messing around with it. Then again, I'm no scientist and don't understand the ins and outs of gamma itself - just how its adjustment affects the image I'm working with.


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#9 David Mullen ASC

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Posted 06 July 2016 - 11:12 AM

Gamma loosely means the shape and degree of the slope when you chart exposure in one direction on a graph against the increase in density (with film) or signal (with digital) on the other axis.  So in crude, rough terms, it describes contrast.

 

You can see a log gamma curve on a chart here:

http://blog.abelcine...11/what-is-log/

 

In theory, you could have 4:4:4 (no color subsampling, equal bandwidth for each color channel) but in the more limited Rec.709 broadcast linear gamma (though technically Rec.709 is a color space, the display gamma is usually 2.4 or 2.2 depending on who you talk to).  But most people recording 4:4:4 are often recording it in some form of log gamma for extended dynamic range.

 

Take a look here:

http://www.provideoc...g_gamma_curves/


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#10 Bruce Greene

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Posted 06 July 2016 - 11:50 AM

Hello everyone I have a question well 2. First is raw the same as 4:4:4? Second question if 2 cameras filmed a subject one in RAW and one in 4:4:4 which one should the colors be more saturated?

Thank you very much.

I think, for this question, we should limit the choice between RAW and 444 Log capture.  RAW will record all the data that the sensor is seeing. But it's just data, not yet an image.  Log 444 is RAW processed into an image, recording the levels of Red, Green, and Blue.  Log is used to compress a large amount of data into a smaller container.  By converting the image into a Log curve, the recording has more discrete levels of R,G, and B in the parts of the image where it's most visible, and fewer gradations of highlights where it's hard to see subtle changes in exposure.  The effect, in the end, is to record almost all the useful image by throwing away the data we cannot see.  When all is said and done, it should be difficult to tell the difference between a RAW recording of a scene and a Log recording of the same scene.  There should be no difference in color saturation of your final image.

 

When color grading a scene recorded in RAW mode, the RAW image must be processed first into RGB, and is often converted to a Log rendition before color grading begins.  So, basically, you come to the same place:  Color grading a Log RGB image.  The difference is that the in-camera Log recording must adjust the processing settings in the camera (mostly white balance).  If you recorded RAW, you'll make that setting at the beginning of color grading.

 

Where the difference between the two approaches comes up is when the the white balance/color temperature setting in camera doesn't come close to matching the color of the lighting of the scene.  If that's the case, some data will be lost forever in the conversion from RAW in the camera.  If you've recorded RAW, then you could change this setting before processing the RAW for color correction.  In practice, if you're at all close in your camera color temperature settings, then the Log 444 image should be just as gradable as one recorded in RAW.

 

The one drawback of recording Log 444 in camera is that it is almost always to a compressed format like Apple ProRes.  This is a very good Codec for recording, but it is possible to see some compression artifacts, especially if there is a severe color adjustment applied in post.  Recording RAW allows the color grade to be done on an uncompressed image rathe than a compressed ProRes image.  This difference is usually impossible to see in the finished product.

 

I hopes this helps make the choice a little bit clearer :)


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#11 Landon D. Parks

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Posted 06 July 2016 - 12:21 PM

Perhaps I should have been clearer in my earlier explanation... I meant to say that 4:4:4 is similar to how RAW records, so in essence recording RAW is much like recording 4:4:4. RAW is, by its definition, without processing. Since 4:4:4 is still processing, you can't really have 4:4:4 RAW footage, but it amounts to the same thing.

 

LOG is a whole other ballgame from RAW. Yes, Log settings are simply a way to capture more dynamic range and color information. LOG images can then be processed or be stored raw. For example, VLOG on the GH4 is a log format, but it will be processed in camera to Rec 709 and stored in either MP4 or whatever compressed format is recorded externally. A camera like the Blackmagic Pocket also records a LOG image, but it can do that either to a raw format - CinemaDNG, or to a processed format, ProRes.

 

LOG also has no bearing on color sub-sampling either. So you can have a 4:2:2 log image recorded to ProRes in 10-bit, or you can have a log image recorded RAW, and then stored compressed or uncompressed.

 

An area I am unsure of is if you can record RAW is something like 10-bit or 8-bit format? Not that such a thing would be useful or suggested... But I am curious if bit depth can be used in Raw recording. 


Edited by Landon D. Parks, 06 July 2016 - 12:26 PM.

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#12 Tyler Purcell

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Posted 06 July 2016 - 01:05 PM

444 is only ONE small element of what RAW delivers.

RAW takes the imager data and records it, unaltered (though in most cases compressed) Bit depth and pixel count are based on the imager's electronics.

444 in most cases is still a REC709 format. It could be highly compressed 8 bit .h265 or it could be practically uncompressed Pro Res. Even though it delivers full 444 color space, the color information is still squeezed into a REC709 format. Even when using a LOG gamma curve, it's still a heavily compressed image.

So the difference between RAW and REC709 compressed LOG is pretty huge.

Pro Res XQ is NOT Rec709. To my knowledge, it's the ONLY quicktime compression codec that gives you higher bandwidth then REC709. It's a 12 bit 444 codec, but it doesn't conform to the REC709 standards.
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#13 David Mullen ASC

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Posted 06 July 2016 - 01:35 PM

If you are talking about Rec.709 as a color space, it is not compressed, it's just a certain sized triangle within the larger color space that we see -- P3 is slightly larger and Rec.2020 is very large.  If you are talking about Rec.709 as a gamma, then Log is not Rec.709, Log is Log.

 

Anyway, I don't think it is accurate to say that 444 is usually a Rec.709 format - most people who shoot 12-bit 4444 ProRes on an Alexa record Log-C gamma using a wide gamut color space that can be converted to P3 or Rec.709 in post.  So in terms of color information, there isn't a big difference between 12-bit Arriraw versus 12-bit ProRes 4444 Log-C.

 

But on other cameras, raw might have a larger bit depth than the ProRes recording.

 

Like I said, the issue might not be color information so much as the ability to grade that color information -- too much compression, too low a bit depth, etc. and you can't push that color around without picking up artifacts.


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#14 Tyler Purcell

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Posted 07 July 2016 - 04:01 PM

4444 pro res isn't the same as Pro Res XQ. Most people I work with shoot XQ on the Alexa. It is not a rec709 format. It actually records a larger color space then 709. Its nearly identical to RAW with the Alexa.
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#15 Bruce Greene

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Posted 07 July 2016 - 05:33 PM

4444 pro res isn't the same as Pro Res XQ. Most people I work with shoot XQ on the Alexa. It is not a rec709 format. It actually records a larger color space then 709. Its nearly identical to RAW with the Alexa.

A codec like ProRes 4444 defines the amount of data recorded, but not the range of the data.  Color space, such as REC709 is not relevant to the codec chosen.  Color space defines how the data will be represented upon viewing.  So you are basically correct, but maybe, for the wrong reason..


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#16 Tyler Purcell

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Posted 07 July 2016 - 05:36 PM

Actually the color space of pro res XQ is entirely different. I work with it all the time and it has a much higher range then the limited rec709.
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#17 David Mullen ASC

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Posted 07 July 2016 - 05:42 PM

I just can't stand to let msinformation get passed along... Apple ProRes 4444 XQ is, as the full name suggests, a variant of Apple ProRes 4444 but at 500 Mps instead of 330 Mps for 1080P/29.97.

And you can record wide color gamut (not just Rec.709) on the Alexa in ProRes 422, 4444, etc. -- not just 4444 XQ.

Bruce is correct, ProRes 4444 XQ does not define a color gamut, it's a compression scheme.

Here's a pretty good description of XQ:

https://larryjordan....prores-4444-xq/
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#18 Tyler Purcell

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Posted 07 July 2016 - 06:17 PM

I was on the beta team for pro res 4444. I know more about the codecs then most people do because I was trained by the guys who actually wrote the code, via Skype of course.

So Larry Jordan's ancillary comments aren't very valid. He does mention in his final amendment that XQ is the only pro res codec with REC2020 color space. But what he doesn't say is that each color is compressed separately and displayed separately, unlike the standard 4444 pro res.

So it works entirely different then the other codecs. As a professional post production specialist who works with XQ every day, I can tell you how entirely different the workflow is. Unlike 4444 which easily drops into all the modern editors, XQ needs to be converted and/or modified to be used. It works more like a single file raw workflow.
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#19 Robin R Probyn

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Posted 07 July 2016 - 07:10 PM

Its goes to 11..?


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#20 David Hessel

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Posted 07 July 2016 - 07:50 PM

Sorry you are incorrect, ProRes 4444 XQ is just a data compression scheme it doesn't care what color space it just compresses the data. I shot ProRes 4444 XQ all the time with my Codex and F35, all slog/sgamut.
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