When searching for a new display, you may get confused a bit when confronted with the various ways manufacturers describe their abilities to show more colors. You'll hear terms such as True Color, Wide Color Gamut, Cinematic Color, 4K Color, etc. Let's break down what matters and spend a little time explaining it. When it comes to calibrating a display, Color Gamut is the industry term used for the range of colors available on a display. Simply put, Color Gamut is the number of colors available on your display. And color gamut can be measured using several different standards. The standards that we're concerned most with are Rec.709 (HDTV), DCI-P3 and Rec.2020.
The chart above is what we use to calibrate displays. Pay no attention to the inner triangle at this time, just look at the full color triangle that has a hump for a point out towards green. That humped triangle represents the colors that our eyes are able to see in a two dimensional format. Luminance is something that can be measured and displayed in a different fashion which I'll get to later. So going back to the inner highlighted triangle, this triangle represents Rec.709 which is the standard that came out for HDTV. You can see from the chart that displays were only capable of showing less than half of the visible spectrum. It should be noted that before Rec.709 the standard was Rec.601 or SMPTE-C. But I don't intend to make this a history lesson and manufacturers should not be listing this old standard as a spec for any current display. You can see that gamuts on HDTV displays were clearly lacking in the green and red areas of the visible spectrum.
This brings us to today. A lot of manufacturers use the term Wide Color Gamut (WCG) to describe their color gamut. But what does Wide Color Gamut mean exactly? That's a good question and one in which I'm sure we will see several different responses but I view the term as meaning a color gamut larger than Rec.709. It does mean that and it also means a higher bit depth too. Bit depth is the gradation of color from one to another. This means that higher bit depth displays will display more gradations or shades of color from one to the other. So not only are you increasing the number of colors by making the triangle larger, you're also increasing the amount of shades or gradations of each color within the triangle. Make sense? I'll get more into bit depth later in a different post as well.
The above image represents the standard where most displays are at today - DCI-P3. It is roughly 26% larger than the Rec.709 standard pushing out more towards the green hump of the visible spectrum and down a bit more towards red. DCI stands for Digital Cinema Initiative and it is the standard used for content delivered to your local digital cinemas. What makes this important is the biology of the human eye. Our eyes see red and green better than we see blue therefore it is relatively easy to see the benefit of an expansion of the gamut into the green and red areas of visible colors.
This image represents Rec.2020 or the standard of the future. Outside of some production displays used in mastering content, no displays are capable of displaying Rec.2020 yet. But you can see that the standard does push even further out towards green and red covering most of the visible spectrum. While evaluating a display by eye the difference may not jump out at you unless compared to a Rec.709 display side by side. And the major improvements will be in the green and red portions as those are the areas where the improvements have benefit most. Color gamut has expanded primarily in the green and red areas of our visible spectrum.
Which brings us to evaluating color gamut on displays and how to quantify it. The way to evaluate a display and to relay that in layman's terms is currently being done via a Color Volume measure. Color Volume measures the colors within the triangles above while also adding the third dimension measure (luminance) to the equation. A display is then evaluated as to what percentage of each particular standard it is capable of reproducing. If you have read my LG C7 OLED review here, you have seen these particular measures. Here's a graphic depiction of 3D Color Volume:
The animated gif (courtesy of Bruce Lindbloom's color site) starts out showing the two dimensional Rec.709 triangle and then rotates into showing the three dimensional aspect of adding luminance to the equation.
So when you're looking for a new display and it declares that it is capable of Wide Color Gamut, ask the salesman "How wide?"
The chart above is what we use to calibrate displays. Pay no attention to the inner triangle at this time, just look at the full color triangle that has a hump for a point out towards green. That humped triangle represents the colors that our eyes are able to see in a two dimensional format. Luminance is something that can be measured and displayed in a different fashion which I'll get to later. So going back to the inner highlighted triangle, this triangle represents Rec.709 which is the standard that came out for HDTV. You can see from the chart that displays were only capable of showing less than half of the visible spectrum. It should be noted that before Rec.709 the standard was Rec.601 or SMPTE-C. But I don't intend to make this a history lesson and manufacturers should not be listing this old standard as a spec for any current display. You can see that gamuts on HDTV displays were clearly lacking in the green and red areas of the visible spectrum.
This brings us to today. A lot of manufacturers use the term Wide Color Gamut (WCG) to describe their color gamut. But what does Wide Color Gamut mean exactly? That's a good question and one in which I'm sure we will see several different responses but I view the term as meaning a color gamut larger than Rec.709. It does mean that and it also means a higher bit depth too. Bit depth is the gradation of color from one to another. This means that higher bit depth displays will display more gradations or shades of color from one to the other. So not only are you increasing the number of colors by making the triangle larger, you're also increasing the amount of shades or gradations of each color within the triangle. Make sense? I'll get more into bit depth later in a different post as well.
The above image represents the standard where most displays are at today - DCI-P3. It is roughly 26% larger than the Rec.709 standard pushing out more towards the green hump of the visible spectrum and down a bit more towards red. DCI stands for Digital Cinema Initiative and it is the standard used for content delivered to your local digital cinemas. What makes this important is the biology of the human eye. Our eyes see red and green better than we see blue therefore it is relatively easy to see the benefit of an expansion of the gamut into the green and red areas of visible colors.
This image represents Rec.2020 or the standard of the future. Outside of some production displays used in mastering content, no displays are capable of displaying Rec.2020 yet. But you can see that the standard does push even further out towards green and red covering most of the visible spectrum. While evaluating a display by eye the difference may not jump out at you unless compared to a Rec.709 display side by side. And the major improvements will be in the green and red portions as those are the areas where the improvements have benefit most. Color gamut has expanded primarily in the green and red areas of our visible spectrum.
Which brings us to evaluating color gamut on displays and how to quantify it. The way to evaluate a display and to relay that in layman's terms is currently being done via a Color Volume measure. Color Volume measures the colors within the triangles above while also adding the third dimension measure (luminance) to the equation. A display is then evaluated as to what percentage of each particular standard it is capable of reproducing. If you have read my LG C7 OLED review here, you have seen these particular measures. Here's a graphic depiction of 3D Color Volume:
The animated gif (courtesy of Bruce Lindbloom's color site) starts out showing the two dimensional Rec.709 triangle and then rotates into showing the three dimensional aspect of adding luminance to the equation.
So when you're looking for a new display and it declares that it is capable of Wide Color Gamut, ask the salesman "How wide?"
Last edited: