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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

*New User* Colour space and Gamma curves??

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BEN H

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Might anyone be able to give a simple explanation of these? What do they add in post production if you're shooting Raw?

From what I understand a log file allows for better retention of shadows and highlights but what's the point of this if you can switch between gamma curve settings in Post P?

Would that be useful in case the footage was *not* shot in Raw as a lower storage alternative?

Also, what do colour spaces do exactly? I've been fiddling around with them and only changes I see are in saturation and tones. Is there a benefit of using those VS colour grading the file?

Thanks
 
Ben, in the nicest possible way you appear to be starting at the very beginning of understanding the camera in your hands.

I recommend checking out the Red 101 articles, specifically this one which address your questions - http://www.red.com/learn/red-101/cinema-color-management
 
There's some good explanations on color space and color management in this free 50-page SIGGRAPH paper...

http://cinematiccolor.com

Let's just say it's a very, very complicated subject. To me, it all kind of hinges on "where is the ultimate delivery for this project going to be?" Once you can answer that question, then you can work backwards and figure out how to get the footage prepped for that final delivery in terms of color space, gamma range, and brightness.
 
Thanks everyone - I did some further reading and think I understand it a little bit better now. Is it fair to say that colour space should always be set to Rec.709 if the intended viewing platform is a computer monitor / hdtv? In terms of the gamma curve, from what I understand if you shoot RAW you get all the benefits of a LOG file, plus some more. In which case what changes are made to the file (in post) by changing the curve while working with RAW? Do you preserve more detail in the tones if you go for RedLog vs Rec.709 for example or is this only helpful if you weren't shooting RAW?
 
We're in the middle of a transition from "legacy" image processing to the new IPP2 system.

Under legacy, RED specific colour spaces DragonColor, DragonColor2, REDColor etc. target REC709 monitors. Pick which you like the look of. For Gamma use REDGamma 2, 3, 4, which all target a typical HDTV standard dynamic range display. Again, pick what you want the basic grade to look like.

For IPP2, for a typical HDTV use REC709/BT1886 for your output transform. For HDR use REC2020/SMPTE2084.

Graeme
 
BEN H said:
Thanks everyone - I did some further reading and think I understand it a little bit better now. Is it fair to say that colour space should always be set to Rec.709 if the intended viewing platform is a computer monitor / hdtv? In terms of the gamma curve, from what I understand if you shoot RAW you get all the benefits of a LOG file, plus some more. In which case what changes are made to the file (in post) by changing the curve while working with RAW? Do you preserve more detail in the tones if you go for RedLog vs Rec.709 for example or is this only helpful if you weren't shooting RAW?
Click to expand...
I think a lot of these boil down to mastering questions. I think there are quite a few ways to approach mastering and none of them are necessarily wrong, as long as you can still get there. A lot will depend on how you monitor the signal during the mastering process. If you're looking at an affordable (say, under $2K) Rec709 display, then I think finishing in 2.4 gamma and Rec709 color can work OK, and there are straightforward workflows that will get you out to theatrical P3 delivery.

I tend to prefer working in RedLogFilm as a starting point in Resolve, but I haven't encountered a project with IPP yet. Starting one literally tomorrow that was shot a year ago, so it's still DragonColor / RedLogFilm. Looks absolutely fine in Rec709, which will be 90% of its intended market.
 
All colorspace/gamma questions ultimately come down to what your display is capable of. You're taking hopefully a high dynamic range image with a huge gamut of colors and then trying to squeeze them down to an 8 stops of dynamic range TV with a very narrow color gamut.

Whenever you need to take a lot of rich data and squeeze it down to a less capable delivery medium you have to throw out information. The gamma curves RED provides are different subjective approaches to most gracefully discard information. You want all of the dynamic range without clipping so you have to roll off the bright highlights. You want deep rich shadows without crunching, so you ease into the shadows. You want those bright green tree frogs, but you don't want the saturation to clip, so you ease the rolloff of peak saturation to fit within rec709's colorspace.

Then there are the technical gammas like Cineon/RedLogFilm or Log3G10. These are just mathematical gammas whose only purpose is to efficiently store data in a big bucket. Honestly nobody should ever look at cineon or Log3G10 data natively, just like you never look at raw zip file data or header files on a tiff file. So yeah, you can translate quickly and easily between linear and Redlogfilm or Log3G10 and in a post pipeline you often do depending on the limits of the file format. Since a format like EXR can store values between -1,000 and 1,000.0 there is no reason to use log gamma spaces and you can just store natively in linear. A format like ProRes can only store values between 0.0 and 1.0 so to fit data that might extend up to 20.0+ you squish it down with a log curve to fit within -0.1 -> 20.0. Their only real purpose is to be a data interchange format.
 
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