What You Need to Know about Color Gamuts and Wide Gamut Monitors

Gamut means ‘the complete range’. A color gamut is the complete range of colors in something.

‘Something’ usually means either:

• The complete range of actual colors in a video
• The complete range of actual colors a device can use or show

Let’s understand it with an analogy.

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The Jujube Problem

Let’s say we have to fill up three boxes with jujubes of as many colors as possible. Each box is a different size.

As a hypothetical scenario, let’s assume the biggest box is a gift for your boss while the smallest one is for your best friend. You’re sure both will understand.

First step: We contact the Jujube Corporation – the renowned candy purveyors – to prepare their so?called delicious jujubes in every available color.

The Jujube Corporation produces jujubes in 31 hues – more colors than the average person can name. They assure us, rather proudly, that just three machines suffice, each dedicated solely to Red, Green, or Blue. By mixing these colors in varying proportions they are able to produce 31 different colors.

Our excitement is borderline absurd when the Jujube Corporation truck arrives and Mr. Jujube himself steps out to deliver one enormous bag stuffed with jujubes in all 31 colors.

They’ve mixed all the colors together!

We’re not going to let that spoil our day, so we graciously accept the package and dump all the jujubes on a table. We line up the boxes and fill each one till they’re all full.

A few jujubes stubbornly remain on the table. Small mercies.

Now let’s equate this to the color gamut.

Let’s say the “color gamut” of the jujube Corporation is 31 colors.

Each box can be a computer monitor, a camera, a smartphone, a piece of paper or anything. The box represents any device or thing that has anything to do with real colors. Some boxes are bigger, some smaller.

Also, there’s no guarantee all 31 colors will be present in each box. Some boxes might miss a few colors.

Or worse, you can fill up an entire box with jujubes of only one color.

The average human can distinguish millions of colors. A person who is colorblind (or visually challenged) can see a smaller gamut than the average person.

However, our boxes (i.e., devices) are under no obligation to replicate the capability of the human eye. Much like no two individuals share an identical color perception, each box is free to exhibit its own unique palette.

The difference between a color model, a color space and the color gamut

In our analogy, this is how things compare:

• The RGB machine is the color model, which as we have learned in Color, Color Bit Depth and Color Model, is based on the human eye. By mixing these three primaries, we produce the perception of color.
• The entire range of colors produced by the corporation is the gamut of the human eye. Fun fact: Our eye can see about 10 million actual colors.
• The Color Space is the theoretical number. The Gamut is the actual number.
• The size of each box is the color space – which is a theoretical limit (or space) imposed on a device or display.
• The actual range of jujubes in each box is the color gamut of that box. If one box has only 29 colors, then that’s its gamut. The second box could have all 31, and the third box could have 15, and so it goes.

Real-world devices have practical limits. I hope the analogy bridges the gap between the ideal of human color perception and the practical limitations of device displays.

Real-world Scenarios

• Two monitors can both claim to support Rec. 709, but they might look different (assuming every other factor is constant) if their actual gamuts are different.
• This happens because monitors are designed using physical materials, just like our eyes. This is the fundamental reason why LCD TVs are different from OLED or Plasma, and all of these are different from CRTs. Physical things react differently to color stimuli.
• When you see a display is 97% of a color space, or whatever percentage, it means its missing colors.
• Two grading projectors, each producing 100% of a color space, say DCI P3, is expected to show similar imagery with an image encoded in DCI P3. If they don’t, one or both of those monitors are not what they claim to be.
• Two different cameras, both shooting 100% Rec. 709, will show different colors because their sensors have different gamuts – assuming everything else is constant. This is the fundamental reason why CCDs have a different color look to CMOS sensors. It is also why film stock is so different from digital sensors – the colors of chemicals are different from the colors of semiconductors, among other important differences.
• All said and done, colors are just sensations produced in our brain. Our acceptance of black and white imagery, pencil art and other such imagery shows clearly that color is not everything.

Here’s an interesting video to ponder over:

How the Gamut works in the real world

We fire up our trusty Sony FX6 (Amazon, B&H) in S-Log3 log. This captures our film in an expansive, raw spectrum. This footage is only the first draft of our cinematic vision.

After editing, we usher the footage into DaVinci Resolve, where we grade it in the Davinci Wide Gamut space. Here, every conceivable nuance is teased out, ensuring that no color detail goes unnoticed.

Being a low budget film, we are monitoring on a professional Sony broadcast monitor to finish in Rec. 709.

The way the colors change is dictated by the color transform algorithms between S-Log3 to Davinci WG to Rec. 709. A different grading application or LUT will give you a different “color result”, even if all the color spaces are the same.

Now we decide our movie will be shown in theaters, or in a film festival that demands a DCP.

So we convert the film into DCI XYZ for the DCP. The colors will subtly shift their personalities in the process. It won’t be drastic, but the shift is definitely noticeable in a side-by-side comparison. Some scenes look fine, others might look “off”.

Our film makes its grand debut on the projector, displayed in DCI P3. Here, the limitations of the specific projector, lamp, and screen come into play, each imposing its own quirks on the final film.

Then, we use the Rec. 709 master to make a version for OTT platforms. The way they approach color might be different. Even so, our movie will look different on different TVs and monitors.

Even if you keep a strict “one color” pipeline, e.g., Rec. 709 all the way through, what you shoot will not be what the end user watches.

That’s why gamuts are important.

What is a wide gamut monitor?

Wide, wider or widest? It doesn’t matter.

A wide gamut color space is a color space that supposedly has more colors than the human eye.

True, there are certain colors produced by a monitor that the eye might not be able to see, simply because these are two different physical things.

But the question is: What use is it then? If the monitor displays it, but the eye can’t see it, the eye will make it appear different to us.

Monitors that claim to be 10-bit (1 billion) or higher should in theory have more color than the human eye. But we can’t know for sure.

There are many advantages of working in a larger color space, just like a bigger arena gives more room for maneuverability. But as far as I know, there is no point in having a device with a gamut larger than the eye can see. Who’s it for?

What you’re looking for is a professional broadcast or grading monitor that is designed for one or more color spaces. Don’t fall for the ‘wide gamut’ marketing speak.

Tomorrow they’ll start selling wide gamut jujubes. Don’t you believe it.