What is Contrast Ratio? Monitor’s Contrast Ratio Explained

How many times did you get confused after reading the contrast ratio numbers on a monitor’s specifications? Not only the computer monitor, but all display products such as TV and projector also have a contrast ratio figure. In this article, we will discover what is contrast ratio and how it works.

You might assume that the higher numbers are better, technically the answer is yes. A high contrast display delivers better picture quality compared to a low contrast ratio display. Without knowing what is the contrast ratio, it is possible to get confused by different contrast ratio numbers.

What is Contrast Ratio?

To simplify the answer, the contrast ratio is the luminance difference between the brightest white and the darkest black that a monitor can produce. Luminance is used to measure the amount of light/candela per square meter or cd/m² on a surface.

Forget about the technical details, did you notice a brightness figure in nits on your monitor’s specification? That’s the luminance, nits are just another metric to measure luminance.

For example, a 1000:1 contrast ratio means the brightest scene is 1000 times brighter than the darkest part of a picture. Pictures look washed out due to the poor contrast ratio mostly in a dark sense. The overall picture quality depends on the contrast ratio, a higher contrast ratio delivers better image quality.

Native VS Dynamic Contrast Ratio.

The native contrast ratio is the default contrast ratio that the panel alone can do without any backlight undervolting. We refer to the native contrast ratio when purchasing a new monitor. Based on the panel, the contrast ratio also varies by a large margin.

Dynamic contrast ratio is also known as Advance Contrast Ratio (ACR) and sometimes Smart Contrast Ratio. This ACR ratio usually comes in a sky-high figure such as 50000:1 and monitor’s manufacturers often love to highlight this contrast value for attention.

Dynamic contrast ratio is nothing but a backlight trickery, underpowers some portion of the backlight to enhance the dark scene of the pictures. This technique makes the black deeper and shines the light area, makes images look great but also a bit overexposed at the same time.

Contrast Ratio and Backlight

Each monitor or display unit must have a back-light source to display pictures. So how do these back-lights work?

Let’s assume that we turn on all available backlights for a completely white scene and simply turn off for a pure black scene. Well, some websites measure the monitor’s contrast ratio by this method, which is not the best way as real-life pictures are a mixture of dark and bright areas.

For a mixture image, some backlight turned full-on for the brightest part, few are dimmed, and the rests are completely turn off to produce black. That’s why we didn’t get pure black from the monitor rather than OLED.

Technically, no monitor can produce pure black, pure black is only possible in the lab environment. Even some of the backlights are dimmed or turned off, few backlights remain on for the brightest part of the image.

HDR AND Local Dimming
Monitors with HDR (High Dynamic Range) have a better contrast ratio, shadow highlights, and deep black level. Most of these high-end HDR monitors have full-array local dimming backlight instead of the regular edge-lit backlight.

As a full-array local dimming backlight is distributed in several zones, it has much better light control to enhance the contrast ratio. Of course, not all HDR monitor has local dimming backlight. All entry-level VESA DisplayHDR 400 monitors are edge-lit but with higher brightness and HDR 10 support theoretically.

Contrast Ratio by Panel Type

Let’s start from the worst, the TN panels are known for the worst contrast ratio along with their bad viewing angles. The legacy TN tech is outdated now, and the numbers of TN monitors are decreasing rapidly every year. Only some eSports monitors use the TN panel as it has a really fast response time and low input lag. The average TN panel has an 800:1 contrast ratio while some best TN panels can rock the 1000:1 contrast range.

IPS panels are the most popular display type for their superior color reproduction and excellent viewing angles, but it also suffers from poor contrast ratio. Even some top-selling IPS gaming monitors have serious contrast issues, though they have 1000:1 contrast figures in the specification, the real-world performance is 850-900:1 and sometimes even lower.

Some fine-tuned IPS monitor has excellent contrast ratio, up to 1400-1500 marks, but they can’t match even lower end VA Panel which is 2000:1 contrast ratio as a minimum. There are some superb VA monitors with a 6000-7000 contrast ratio.

OLED holds the crown for the best contrast ratio among all display panels. OLED backlighting technique is unique, individual lighting for every single pixel that results in pure black and very sharp details.

The OLED contrast ratio is infinite, there are only a few OLED monitors available in the market, and most of them are out of reach for sky-high pricing. Some industry-leading display manufacturers including LG, DELL, SONY, ASUS already launched some top-tier OLED displays and the numbers will increase rapidly in near future.

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