Visuals on your screen – on TVs, monitors, projectors, phones, and so on – are made up of various forces interacting together. Brightness, gamma, and contrast are three things you might already know of just from having looked at the Settings on an app or device at some point!
However, of these, the most important for how rich the colors and how clearly defined the edges are that determine the clarity of what you see is the contrast ratio.
The contrast ratio can be defined as the range, or the ratio, between the darkest and brightest colors being produced on a screen (or that it’s capable of giving in a situation) in terms of luminance.
What is a good contrast ratio? Speaking ceteris paribus (keeping everything else equal), higher contrast ratios are desirable since the image doesn’t feel dimmed out whereas lower contrast ratio makes everything feel less lifelike and realistic.
Note that we brought up that obscure and pretentious Latin term to highlight an important point: the differences in devices and mediums is key. Cinemas would have a different contrast ratio as compared to 4K TVs, and even the best gaming projectors might be limited in some ways as compared to their counterparts amongst gaming monitors.
Ultimately, is contrast ratio the primary ingredient for how good your screen is? We’ll delve deeper into this as we proceed.
What is Contrast Ratio?
In other words, how would someone measure the contrast ratio? While you can define it simply in terms of more details or more subtlety in the colors seen, it can also be measured numerically in a white-to-black ratio, such as 10000:1.
The monitor contrast ratio would have to be different from the projector contrast ratio. If the number given in the previous paragraph stands as an example, the white is ten thousand times brighter than the black. For a projector, the contrast ratio would need to be stronger, since the room will absorb a lot of the colors, and the wall will “reflect” or bounce back a lot of the luminance.
Static vs. Dynamic Contrast Ratios
This brings up the question of static and dynamic contrast ratios.
The static contrast ratio can very simply be defined as what device itself holds, or the native or “true” contrast capability, as opposed to the Setting. (Think of turning up the contrast all the way high on VLC Player and making the whole screen completely white).
Dynamic ratio, on the other hand, looks more at situational ability, using a processor to adjust the backlight level as the visuals change. A lot of newer models of display devices have a separate setting for dynamic contrast ratio.
Dynamic contrast ratio can be thought of as a single dimming zone in a single frame, localized and edge-lit. It replicates what HDR does by adjusting to what’s on the screen instead of manual adjustments being made to what’s been seen. It can be best understood as a system to adjust the brightness and gamma in conjunction to help the contrast between colors appear more striking.
In a lot of cases, it works simply by making the darkest shade align with what the device itself is capable of, and the same for the whitest shade. The display will turn down the brightness in a scene with a lot of dark colors (viewers of the final season of Game of Thrones will understand), which then helps shadows look less washed out. This means that both the brightest and darkest are prioritized separately based on the visuals.
Measuring Contrast Ratio
Contrast ratio can be measured through the Full On/Off and ANSI Contrast methods.
The Full On/Off contrast method, as hinted by the name, compared two states: a solid white and a solid black. The 100 IRE test pattern, and the 0 IRE test pattern. Full on, full off. Taking the same number as before, a reading of 10000:1 would mean the white is ten thousand times brighter than the black.
This method is a favorite among marketers, since the number it produces is more easily manipulated for consumers and always a higher, quantitatively, than the contrast ratio reading measured on the meter from the ANSI Contrast Method (especially since the method used is not required to be specified!).
The ANSI Contrast Method, then, uses 16 checkboard-pattern alternating (eight) black and (eight) white rectangles. The average “brightness” measured output of the white is divided by the black, resulting in the ANSI contrast ratio, resulting in a more accurate number than the one determined by the Full On/Off method, owing to the image being more realistic in terms of variety.
How to Control For Ambient Light With Contrast Ratios
Many projector contrast ratios fight an uphill battle against ‘perceived contrast’. The layout of the room, the natural light, and the placement of the projector all add up to something of a headache.
Light-controlled rooms are the solution to this. Anyone setting up a home theater or a projection room should know how to “black out” their home cinema’s theater room to control for perceived contrast.
Here it’s not just the device itself, but the medium that comes into play. Knowing how to build or install a frame and blackout curtains can enhance the viewing experience and allow for a deeper, richer contrast ratio.
It also helps to have a higher quality projector, to begin with. Utilizing the HDR of a 4K projector makes for maximum benefits in the contrast ratio department, as well as running the gamut of the DCI/P3 color range.
There are as many articles out there trying to claim that their word is the final and most definitive on contrast ratios being meaningless as there are well-meaning guidelines to equip consumers with enough information to make informed decisions (such as the one you just read). Ultimately, the contrast ratio is something the average viewer should be aware of, and the difference it makes on the viewing, watching, and gaming experience.