When looking at two screens side-by-side, it’s sometimes easy to see a screen with brighter colors, darker blacks, or a more vibrant color palette. However, it will be difficult for you to picture in your head when reading the specifications, as the colors on the screen are evaluated in many different ways.
Important parameters that users are interested in include: contrast, brightness, darkness, color range… To get an overview of the color of the screen, let’s learn some Basic concepts in the article below.
Contrast, one of the basic measurements of a monitor’s performance, measures the ratio between the darkest and brightest areas that the screen can display. A basic contrast like 1000:1 means that the white parts of the image are 1000 times brighter than the black parts.
When it comes to contrast, the higher the number, the better. High contrast, such as 4000:1, means that there are highlights, dark blacks and dark areas where details can still be perceived. In contrast, a contrast ratio of 200:1 means that blacks look like grays and colors look fuzzy and unclear.
Brightness is usually measured in “luminance”, a measurement that accurately represents how much light is emitted from a screen. The unit of measure is the candela per square meter (cd/m2), also known as “nit”. For HDR displays, the Video Electronics Standards Association (VESA) has standardized a luminance test using specialized test stickers. When comparing luminance parameters, check to make sure they use a unified test platform, rather than using separate measurements.
In all LCD screens, light from the back is required to pass through the liquid crystal. That’s the basis of contrast: for example, if a screen leaks 0.1% of the light from the backlight onto an area that should be black, that creates a 1000:1 contrast. LCD screens with zero light leakage will have infinite contrast. However, that is not possible with current LCD technology. LCD screens cannot reach zero darkness unless completely turned off.
The screen needs to display different colors. If there is no smooth transition between slightly different colors, we will see on the screen “banding” of colors. It’s an abrupt change between two different colors, creating visible bands of lighter and darker colors that should have been a seamless gradation. That phenomenon is also sometimes referred to as color “crushing”.
A monitor’s ability to display slightly different colors, and to avoid color banding and chromatic aberration, is measured by color depth. Color depth determines the amount of data (measured in bits) that the monitor can use to render the color of a pixel.
Each pixel on the screen has three color channels – red, green and blue – that are illuminated at different intensities to produce (usually) millions of colors. 8-bit color means that each color channel uses eight bits. The total number of colors that can be represented on a screen with an 8-bit color depth is 28 x 28 x 28 = 16,777,216.
Common color depths:
– 6-bit color = 262,144 colors
– 8-bit color or “True color” = 16.7 million colors
– 10-bit color or “Deep color” = 1.07 billion colors
True 10-bit monitors are rare – many use some form of internal color processing such as FRC (frame rate control) to get closer to greater color depth. A “10-bit” display can be an 8-bit display with FRC stage added, usually written as “8+2FRC”.
You often hear the “space” or “strip” of a monitor’s color, a term that is different from color depth. The color space defines the spectrum of colors that can appear, rather than just calculating the number of colors.
Your eyes can see a much wider spectrum of colors than current monitors can reproduce. To visualize all visible colors, a standard called CIE 1976 arranges colors onto a grid, creating a horseshoe graph. The color ranges available on monitors are subsets of this graph.