The Hidden Truths of Monitor Calibration

What you perceive may not be what your viewers perceive. You might think that purchasing a calibration probe is the solution. There are various products available, ranging from $100 to $1000, which come with software. However, what you end up with is not only a counterfeit product, but also potentially worse results than the default factory settings, especially if you have a high-end professional monitor. It's a risky move to transition from reference quality to class 3 or even worse.

So, why does this occur and why do many users remain oblivious to it?

Let's delve into the reasons behind the failure of colorimeters. Believe me, all the shades of gray and colors you see here are visually identical because they have been calibrated to match high-end calibration tools.

Most inexpensive probes are colorimeters, similar to camera sensors that use RGB color filters. You may have noticed that camera sensors often perceive colors differently on various monitors, even if they appear identical to you. The reason behind this is that different monitors have different spectral properties. To put it simply, you end up measuring incorrect values.

Additionally, cheap probes are not temperature stable. When you attempt to measure thousands of colors, the probes heat up due to the display's energy. Consequently, if you measure the same color after, let's say, 30 or 120 minutes, you will obtain different values. Moreover, and most importantly for generating 3D LUTs, cheap colorimeters are unable to accurately measure deep blacks. They are particularly useless for OLED displays! Another major issue is that most basic calibration software does not allow you to set the target gamut. As a result, you may not realize that you are measuring a P3 gamut when you actually want to work with REC709.

Even after the so-called "calibration," you are still within the display's gamut or the preset gamut used by the display. For instance, Apple laptop displays are not sRGB/REC709, but if your target audience is YouTube, you need REC709 and not P3.

The problem with inexpensive probes is that they lack the sensitivity required to calibrate HDR properly, especially in darker areas that make up around 10% of the video level. These areas contain a lot of important details, and if you watch YouTube video reviews, you'll often hear complaints about LG OLEDs not being able to display these areas accurately. This is in contrast to high-end reference monitors, which excel in this aspect.

The Problem with cheap probes

Cheaper probes like i1 display pro or Spyder, are unable to measure below 0.1 cd/m2. These cheaper measuring programs only measure 0% and then 10% in increments of 10 up to 100%, whereas we measure in 8 steps below 10% as shown here! When it comes to higher values, it's similar to cameras.

The sensors produce a lot of noise and the signal isn't stable with cheap probes, usually up to around 20-25% signal level or about 5 nits depending on SDR or HDR.

If you purchase monitors with specifications like 100% REC709, does that mean it's a flawless display?

Well, not necessarily. While many displays may meet the color gamut limits of REC709 and achieve 100% coverage, it doesn't guarantee that all the colors within the gamut are accurately represented. Most inexpensive calibration software only calibrates the white point and works in a two-dimensional manner, leaving many other color locations incorrect.

Even if the white point is corrected, the overall color gamut limits may still be inaccurate, as seen with laptop displays. Don't waste your money and time on this. I can share my own experience with you, as I've bought numerous cheap probes and tried different generations of them, only to realize their limitations and why they don't work effectively.

Give it a try yourself, but be prepared to waste your money. If you want to achieve accurate results and match different displays, such as reference monitors and client monitors, you'll need a high-end spectroradiometer like the JETI 1511. These spectroradiometers have excellent spectral resolutions and can correct the colorimeter's poor recognition of different spectral properties from various display technologies like OLED, PLASMA, LCD, etc.

However, keep in mind that you'll need to perform this correction process for each display individually. Even if you opt for cheap probes with better software and calibration presets for different display types, you'll still fall short if you aim for reference quality.

Cheap spectroradiometers like the i1Pro lack sufficient resolution to provide exact color accuracy for reference quality. You'll be at least Delta E2000 of 0.5 to over 1.0 away from the correct color. A good reference display typically has an average Delta E2000 of only 0.5 to 0.75.

Bottom line:

Having a cheap probe is better than not calibrating at all (goes without saying).

But if you income depends on reliable colors, hire a pro for calibration.