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Can someone ELI5 ACES, Rec2020 and HDR

Tom Dowler

Tom Dowler

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I'd love someone to break down, in practical terms what ACES, rec2020 and HDR are, and mean.

Particularly interested in what those terms mean for those of us who acquire, edit and deliver content for a variety of platforms - web, DCP, etc.

For those who don't reddit, ELI5 is Explain Like I'm 5 years old, but it really means explain in layman's terms.
 
Tom Dowler said:
Yeah, I looked there and it was all pretty high level, and there was a lot of material to trawl through. Really hoping someone can break it down in a simple to understand way.
Click to expand...
Unfortunately, the simple stuff you probably already know. It's the details that you'll need to wrap your head around.

Another suggestion would be to pay for a month of FXPHD as they are offering some courses covering this stuff with the legend himself, Charles Poynton.
fxphd.com
 
Awesome, thanks Steve! Great resources.
 
To have an "universal master" that is ACES complient does the file have to be in open EXR format?
Just wondering if it's possible to have a master ACES compatible wich uses another codec than EXR. Is DPX even possible? What minimum bit depth requierments? Say if I want to finish a film in HDR for a future release.
 
Tom Dowler said:
I'd love someone to break down, in practical terms what ACES, rec2020 and HDR are, and mean.

Particularly interested in what those terms mean for those of us who acquire, edit and deliver content for a variety of platforms - web, DCP, etc.

For those who don't reddit, ELI5 is Explain Like I'm 5 years old, but it really means explain in layman's terms.
Click to expand...



ACES is a system. It has a number of goals - camera footage interchange (to easily cut between multiple camera source footage with the basic matching done by the common ACES space), preservation of dynamic range and colour gamut through grading and output independence (ability to grade in their space and output to any monitor or display, and have it look good). At the core of ACES is the use of linear light images in a wide colour space (AP0), and storing them in an EXR file format (REDCine-X supports export in this format). Other elements of the ACES system are the ACESproxy output from cameras (you can get this on your Red camera as a live output), ACEScc grading log and the AP1 colour space (used by ACESproxy and ACEScc). As noted the ACECcentral.com link is a great place to go and ask questions and learn about ACES.

REC2020 is a colour space. It's a wide gamut colour space (encompasses some very saturated colours, way beyond what a normal HD TV set can reproduce). REC2020 is the colour space for HDR (just as REC709 was the colour space for HD). REC2020 is a colour space that is supported in REDCine-X and in Red cameras.

HDR just means "High dynamic range". All Red cameras are high dynamic range cameras. With respect to displays (and the common usage of HDR), it means a display that can display a greater range of brightnesses than a normal display. Normal displays (what we call SDR for standard dynamic range), have a standard max brightness output of 100 nits (or cd/m^2). HDR displays are ones which can display brightnesses in excess of that 100nit figure. A Dolby reference display can go up to 4000nits and the current HDR standards can support up to 10,000nits. Of course, you can just display super-brightnesses and let black levels ride up along with them. To be HDR, the black levels also need to stay dark. The benefits of HDR are not just a brighter image with better contrast, but the reduced constraints on peak brightnes also allow for a wide colour gamut. REDCine-X supports HDR output to the SMPTE2084 format (also known as PQ), as do Red cameras.

Graeme
 
Graeme Nattress said:
ACES is a system. It has a number of goals - camera footage interchange (to easily cut between multiple camera source footage with the basic matching done by the common ACES space), preservation of dynamic range and colour gamut through grading and output independence (ability to grade in their space and output to any monitor or display, and have it look good). At the core of ACES is the use of linear light images in a wide colour space (AP0), and storing them in an EXR file format (REDCine-X supports export in this format). Other elements of the ACES system are the ACESproxy output from cameras (you can get this on your Red camera as a live output), ACEScc grading log and the AP1 colour space (used by ACESproxy and ACEScc). As noted the ACECcentral.com link is a great place to go and ask questions and learn about ACES.

REC2020 is a colour space. It's a wide gamut colour space (encompasses some very saturated colours, way beyond what a normal HD TV set can reproduce). REC2020 is the colour space for HDR (just as REC709 was the colour space for HD). REC2020 is a colour space that is supported in REDCine-X and in Red cameras.

HDR just means "High dynamic range". All Red cameras are high dynamic range cameras. With respect to displays (and the common usage of HDR), it means a display that can display a greater range of brightnesses than a normal display. Normal displays (what we call SDR for standard dynamic range), have a standard max brightness output of 100 nits (or cd/m^2). HDR displays are ones which can display brightnesses in excess of that 100nit figure. A Dolby reference display can go up to 4000nits and the current HDR standards can support up to 10,000nits. Of course, you can just display super-brightnesses and let black levels ride up along with them. To be HDR, the black levels also need to stay dark. The benefits of HDR are not just a brighter image with better contrast, but the reduced constraints on peak brightnes also allow for a wide colour gamut. REDCine-X supports HDR output to the SMPTE2084 format (also known as PQ), as do Red cameras.

Graeme
Click to expand...


exactly what I was looking for!! Thanks Graeme!
 
aces stands for "academy color encoding system", it's meant to be a common standard for filmmakers to maintain consistency and quality in color.

hdr stands for "high dynamic range", these are images (or motion pictures/moving images) that display light and color beyond the normal range.
^^be careful as this can refer to a great deal of things in different contexts

rec2020 defines a standard up to and including ultra-high-definition, ultra-high frame-rates, and ultra-high dynamic-range/color-fidelity.
^^mainly referred to as a color-space
 
Patrick Inhofer on MixingLight.com also has three or four insights on ACES and HDR, and how they're handled in post. (Note this is a pay site.)

Steve Shaw of LightIllusion has a thoughtful warning about ACES on his color management/calibration website:

The desire to use ACES for any project needs to be fully reviewed and assessed before its adoption, as its use can often prove to be more complex and costly, with no direct discernable benefit, when compared to alternative workflows. ACES is best suited to large productions, that will involve a large number of facilities, with a large quantity of VFX shots.

To me, that makes a lot of sense.

http://www.lightillusion.com/aces_overview.html
 
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