How We Test Monitors
We test desktop monitors of all stripes here at PCMag, from barebones budget screens to moderately priced mainstream displays to high-end, big-screen Ultra High Definition (UHD) models that cost thousands of dollars. Every monitor we review is subjected to a series of image-quality and performance tests that we use to draw a comparison to other monitors in the same class, which in turn helps us to assign a rating to each monitor. Read on to see how we test monitors.
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Basic Settings
All monitors are first tested in an out-of-the-box state. We do not calibrate the monitor or tweak color settings unless indicated and special circumstances call for it.
To ensure accurate, repeatable testing results, however, we use the monitor’s Standard picture mode while testing and turn off all digital processing settings (such as dynamic contrast ratio, adaptive contrast, and color and black-level enhancers). The monitor is always tested at its native resolution over a DisplayPort 1.4b cable (assuming that this video input is supported). If it is not, we default to HDMI 2.0.
If the monitor has specialized color configurations built in (Adobe RGB, DCI-P3, and the like), we will also test those presets using the matching settings in our CalMAN testing software.
Our Testing Suite
To test monitors, we use the CalMAN monitor calibration software(Opens in a new window), a Murideo Six-G(Opens in a new window) signal generator, and a Klein K10-A colorimeter to take the measurements.
CalMAN is a professional-level program that is most often used for calibrating monitors and televisions to be as color-correct as possible. To that end, it comes with a host of tools that can accurately read the color variance, luminance output, and overall color quality of any monitor we’re testing. CalMAN is installed identically on two testbed machines that circulate around PC Labs: an Asus Republic of Gamers Strix Hero II laptop, and a custom-built desktop equipped with an Nvidia GeForce RTX 2080 Founders Edition graphics card.
Hooked into CalMAN is the Klein K10-A(Opens in a new window), a $7,000 colorimeter that is used to take the measurements off the screen. Finally, there’s the Murideo Six-G(Opens in a new window), a $2,500 signal generator that we use to guarantee all colors scanned by the Klein K10-A are accurate to the color space standard we are testing (Rec. 709, DCI-P3, and so on).
We also use our graphics-card testbed desktop to test either FreeSync or G-Sync performance where required. The appropriate AMD Radeon or Nvidia GeForce GPU is swapped in depending on the monitor’s adaptive-sync support.
Testing Procedure
To test color accuracy, we let the monitor warm up for at least 30 minutes, and we use the CalMAN 5 software in concert with the Klein colorimeter to measure the monitor’s color accuracy, compared with the sRGB, Adobe RGB, and DCI-P3 standards, and the manufacturer’s claims about each.
To gather these results, we point our Klein directly at the middle of the panel using an 18 percent window. (This is in reference to the size of the testing window relative to the full size of the screen.) We set a 3-second delay for each run (indicating the amount of time a color will appear onscreen and when the Klein K10-A takes a reading).
The results, in each case, are captured and plotted on a chromaticity chart, with our measurements represented by the colored dots and the CIE coordinates represented by the boxes, along with a percentage representation of the complete color-gamut coverage. A sample chart appears below…
After that, using the luminance sweep feature, we test the peak SDR and HDR luminance ratings for the monitor, expressed as a peak lux figure in candelas per square meter (cd/m2). This process also gives us our gamma readings (a measurement of the luminance level at which pixels on the monitor will display colors), and contrast ratio. The contrast ratio is calculated by taking the peak lux and dividing that number by the lowest recorded black level of the monitor.
Finally, to test input lag, we use an HDFury 4K Diva(Opens in a new window), a video upscaling tool that also happens to have an input lag tester inside…
Most monitor-testing sites use a similar tool, known as the Leo Bodnar Video Signal Lag Tester, and PCMag employed this method until mid-2019. We’ve discovered, however, that the Leo Bodnar hits a floor of around 10 milliseconds (ms) and can’t measure lesser input lag than that. That’s why we’ve switched over to the HDFury 4K Diva, which has lowered the floor of our testing all the way down to 0.5ms.
Non-Quantitative Testing
Our non-quantitative testing includes looking at everything involved in the design of the monitor and its cabinet, all the while gauging it against competing models. This includes factors such as the size of the bezels, the overall aesthetic, the placement and selection of video inputs and other ports, the stand’s adjustability and styling, and any VESA-mounting compatibility.
In monitors that include HDR functionality, we use this linked Costa Rica 4K video(Opens in a new window) to gauge how good content looks while viewed on the monitor. We also use a standard folder of high-resolution images to see how well a monitor might perform in Photoshop and other creative applications.
Viewing-angle performance (how the display looks when viewed from top, bottom, and side angles) is tested by looking for changes in luminance and color fidelity at various off-center angles. We use standard images to look for faded blacks in text, color shifting (where whites appear tan, and red colors may take on a brownish tone), and posterization, in which subtle grades of color disappear into broad patches. We also check for dimming and washed-out images, both of which are common characteristics in low-cost twisted nematic (TN) panels. If a panel shows any of the above signs, we report how far off dead-center (in degrees) we have to move before noticing a change.
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