How do you choose the right video color space for your project? I want to take you through a few basic color spaces and their applications.
While HDR is sexy and more UHD HDR ready TV’s are going into living rooms around the world, I doubt anyone reading this post has a calibrated HDR reference monitor for color grading just yet. Unless you’ve got a spare $30k lying around, true reference class HDR monitoring is still out of reach for most of us.
While the information I’m going to share is applicable to any video source in post production and delivery, I am skewing this website towards smartphone filmmakers, and so far there are no smartphones that allow you to record HDR video. However, I have a feeling that this will change very soon.
So for now, I’m going to introduce you to the common video color spaces you’ll want to use for the web, mobile screens, tablets and standard televisions.
For the most part a single color space is all you need to be concerned with, and that’s the standard HDTV Rec. 709, or BT.709.
If you’re not sure what a color space is, you can check out my post, What Is A Color Space?
sRGB is a color space created for CRT computer monitors, graphics and print. It is based on the same primaries and has basically the same gamut as Rec. 709. sRGB has a non-linear gamma in order to approximate the response of CRT display technology.
sRGB is still the standard for computer imaging, most consumer to mid level cameras and home printers. For professional printing and pre-press purposes Adobe RGB is often used which has an extended gamut that can be reproduced with professional CMYK printing.
Rec. 709 is the recognized standard video color space for HDTV with a gamut almost identical to sRGB.
For broadcast it is defined in 8-bit color depth where black is level 16, and white is level 235.
In the case of 10-bit color depth, common for post production, full range levels are between 0 and 1023, but the final output is mapped to broadcast standard 8-bit 16-235 when creating deliverables.
Rec. 709 is by far the most common working and delivery color space for most projects. Its gamut is supported by all common display technologies across many devices.
DCI-P3 is a wide gamut video color space introduced by SMPTE for digital cinema projection. It is designed to closely match the full gamut of color motion picture film.
It is generally not a consumer standard and is mostly used for content destined for digital theatrical projection. However, notably Apple have adopted P3 color across many device displays, and the ability to capture photo and video in the P3 color space since iOS10.
Most professional reference monitors are able to display the full DCI gamut.
Rec. 2020 defines the specifications for UHDTV. As far as color gamut, it covers a large percentage of the full XYZ color space. The standard defines 10-bit or 12-bit color depth. A few display technologies are Rec. 2020 compliant but as yet, it is not a common video color space to be working in for post unless you are mastering for HDR delivery.
This is becoming more common for commercial high-end delivery, but not something the home colorist or enthusiast will be equipped to undertake for some time to come. The average consumer HDR television is not going to cut it as a reference display for post production.
Choosing The Right Video Color Space
The source camera files we typically deal with from todays digital cinema cameras provide at least 10-bit color depth and cover a native color gamut that exceeds the requirements for DCI-specification, and in many cases even Rec. 2020. Needless to say, your iPhone does not.
Ideally you should be working in a wide gamut color space that encompasses all the expected output standards and have your monitoring calibrated to match.
If cinema is one of the requirements, typically you would want to work in DCI-P3, most likely using a calibrated DCI-spec projector, or a monitor that covers the DCI-P3 gamut. Granted, this is equipment not many of us have access to.
If HD broadcast delivery is the widest gamut color space expected, or computer desktop / mobile / web, you will want to work in Rec. 709.
Whatever the color space you are working in, implementing professional color management is important for the best results. This means setting up your working environment according to the standards and calibrating all displays.
That said, many of us have to make do as best we can with a consumer monitor or laptop screen, and for the typical smartphone filmmaker this is usually fine.
I hope this has provided a basic understanding about color spaces, what they are, some common standards, and how you should be using them.
For a more in depth look at professional color management the following paper from www.cinematiccolor.com is well worth reading: Cinematic Color, From Your Monitor to the Big Screen