Display Testing Explained: How We Test PC Monitors

In all Tom’s Hardware monitor reviews, we briefly describe our testing methods. Our goal is to perform a series of benchmark tests that look at each aspect of video performance to help you decide which display is best for your needs.

You might be looking for the best gaming monitor or insist on the est 4K gaming monitor specifically. Perhaps you're looking for a general-use or professional monitor or crave the best HDR monitor you can afford. No matter what your intended use may be, we look to break down the various aspects of the screen that affect what you'll see in daily use.

We separate the tests into seven major categories: panel response, screen uniformity, contrast, grayscale, gamma, color, and HDR performance. In doing this, you can prioritize image parameters and decide which is most important before making your purchase.

In this detailed rundown, we’ll describe our testing methods, what equipment we use, and what the data means in terms of image quality and display usability.

Equipment

To measure and calibrate monitors, we use an X-Rite i1 Pro spectrophotometer, i1 Display Pro colorimeter, and the latest version of Portrait Displays Calman software. We get our test patterns from an AccuPel DVG-5000 signal generator via HDMI. An HD Fury Integral provides HDR signals. This approach removes graphics cards and drivers from the signal chain, allowing the display to receive true reference patterns.

Meters

The i1 Pro is very accurate and best-suited for measuring color on all types of displays, regardless of the backlight technology used. Since the i1 Display Pro is more consistent when measuring luminance, we use it for our contrast and gamma tests.

Accupel

The AccuPel DVG-5000 can generate all types of video signals at any resolution and refresh rate up to 1920 x 1080 (1080p or FHD) at 60 Hz. It can also display motion patterns to evaluate a monitor's video processing capabilities.

On rare occasions that a monitor isn’t compatible with the AccuPel, we connect it directly to a PC and use Portrait Displays CalPC Client to generate patterns. All lookup tables are disabled here so that we can evaluate the product’s raw performance. Calibration is still performed with on-screen display (OSD) controls only. We don't use Direct Display Control unless there is no other way to correct errors.

Spears

We can also generate 4K patterns in HDR10, HDR10+, and Dolby Vision formats by using a Panasonic DP-UB9000 Ultra HD Blu-ray Player connected via HDMI. It is a reference unit that supports all the latest HDR formats. The test disc is Spears & Munsil’s Ultra HD Benchmark, which has a plethora of static and moving patterns to test every aspect of display performance.

Methodology

The i1 Pro or i1 Display is placed at the center of the screen (unless we’re measuring uniformity) and sealed against it to block out any ambient light. Calman controls the AccuPel pattern generator (bottom-right) through USB. In the photo below, Calman is running on the HP laptop on the left.

Our version of Calman Ultimate allows us to design all the screens and workflows to best suit the purpose at hand. To that end, we’ve created a display review workflow from scratch. This way, we can collect all the data we need with a concise and efficient set of measurements.

The charts show us the RGB levels, gamma response, and Delta E error for every brightness point from 0-100%. The table shows the raw data for each measurement. In the upper left are luminance, average gamma, Delta E, and contrast ratio values. This screen can also be used for individual luminance measurements. We simply select a signal level at the bottom (0-100%) and take a reading. Calman calculates things like contrast ratio and gamma for us.

Every primary and secondary color is measured at 20, 40, 60, 80, and 100% saturation. The color saturation level is simply the distance from the white point on the CIE chart. You can see the targets moving out from white in a straight line. The farther a point is from center, the greater the saturation until you hit 100% at the edge of the gamut triangle. This shows us the display’s response at a cross-section of color points. Many monitors score well when only the 100% saturations are measured, but hitting the targets at lower saturations is more difficult and factors into our average Delta E value. This explains why our Delta E values are sometimes higher than those reported by other publications.

In the following pages, we’ll explain each group of tests in greater detail. Let’s take a look.