Monitor Test on Windows 11
Before running monitor tests on Windows 11, configure the display pipeline so OS settings do not distort the result. Windows 11 manages monitor settings through Display Settings and the HDR pipeline.1 Incorrect configuration such as a wrong refresh rate can make the monitor appear to perform worse than it actually does.2 Active Night Light or a mismatched ICC profile can also shift colour output and affect test results.3 Set these up correctly before running any test patterns.
HDR pipeline and why to test in SDR first
Windows HDR applies a tone-mapping pipeline that alters brightness, colour saturation, and contrast output before the signal reaches the monitor.1 DisplayHDR certification is based on measurable panel behaviours such as peak luminance, black level, active dimming, colour gamut, and rise time, so HDR mode can change the operating point you are testing rather than the native SDR panel behaviour.4 Running panel tests with HDR active gives you results that reflect the HDR pipeline rather than the native panel quality you want to evaluate.
Disable HDR before baseline panel tests
Run all test patterns in SDR mode first: disable HDR in Settings > System > Display > Use HDR. Check dead pixels, uniformity, and glow at SDR settings, which represent the conditions for most productivity and gaming tasks. If you also want to evaluate the HDR pipeline separately, re-enable HDR after the SDR tests and run the same patterns to compare how uniformity and glow behaviour differ between the two modes on your specific unit.
If the test result changes significantly when you toggle HDR off versus on, the difference tells you whether the panel behaviour you are observing is a native SDR characteristic or an HDR pipeline effect. A uniformity gradient that appears only in HDR mode may be a tone-mapping artefact rather than a physical panel defect, and documenting this distinction prevents a false warranty claim based on pipeline behaviour.
How to confirm Windows settings are not skewing the test
Before diving into the specific details of this section, it is worth establishing the broader context that frames what you are testing and why these particular characteristics matter for your daily experience, because understanding the underlying principles behind each test helps you make more informed decisions about panel quality and return thresholds. ### How to confirm Windows settings are not skewing the test
Before drawing any conclusions about panel quality on Windows 11, systematically verify that the operating system is not actively altering the display output in ways that could mimic or mask genuine hardware defects. Disable Night Light, ensure HDR is turned off for baseline testing, and confirm the correct maximum refresh rate is selected in Advanced Display settings, because any of these active software layers can make uniformity, colour accuracy, and motion clarity appear substantially worse than the panel itself would produce under neutral conditions.
If a suspicious result visibly changes or disappears entirely after you correct the Windows display settings, discard the earlier result and use the corrected-configuration result as your true baseline for all subsequent tests. If the same specific patch, corner glow area, or pixel defect remains clearly visible after all software variables have been normalised, you have successfully separated a correctable setup issue from a genuine panel hardware characteristic, and that distinction is especially valuable when you need to contact the retailer or manufacturer support for a replacement or return claim.
G-Sync and FreeSync configuration for the VRR test
The VRR flicker test requires a VRR-capable path rather than a fixed refresh presentation before you can observe low-FPS flicker.5 On Nvidia GPUs, open Nvidia Control Panel > Display > Set Up G-Sync and verify G-Sync or G-Sync Compatible is enabled for your monitor. On AMD GPUs, open Radeon Software > Display and confirm FreeSync is enabled.
Per-application VRR state
Some games disable VRR by default or override it with a fixed frame rate. Confirm VRR is active in your test scenario by opening the Windows Xbox Game Bar (Win+G) and checking whether the refresh rate readout varies with the game frame rate. A readout fixed at the monitor maximum refresh rate indicates VRR is not active in that application, and you will not observe flicker regardless of the frame rate you are testing at.5
Multiple monitor setups: testing the right display
On a system with two or more monitors, Windows lets you choose the target display in Advanced Display settings and the browser window follows the monitor it currently occupies.2 To test a specific monitor, drag the browser window onto that display before entering full-screen mode. If you press F11 while the browser is on your primary monitor, the test pattern fills the primary monitor regardless of which display you intended to evaluate.
Isolating the display under test in a multi-monitor setup
For multi-monitor setups where you suspect a specific panel has an issue, power off the second monitor before running the test. A second monitor's ambient glow or reflections can interfere with subjective assessments of uniformity and black levels, particularly when the monitors differ significantly in brightness or colour temperature. Removing that ambient variable gives you a cleaner, more reliable result on the display under test.
Notes
Before running any test: open Settings > System > Display > Advanced Display and confirm the refresh rate matches the monitor specification. Disable Night Light under Settings > System > Display > Night Light. If you use a colour management app (f.lux, Iris, Windows Night Light), disable it during testing, as these alter colour output and will affect uniformity, colour, and dead pixel test results. For HDR monitors, run Windows SDR tests before enabling HDR, then re-test if evaluating the HDR pipeline separately.
Examples
Enable maximum refresh rate on Windows 11
Settings > System > Display > Advanced Display > Choose a refresh rate
Select the highest available Hz that matches your monitor specification. If your target rate does not appear, check that you are using DisplayPort or HDMI 2.1, not a USB-C adapter that caps bandwidth.
Disable Night Light for testing
Settings > System > Display > Night Light > toggle off
Night Light shifts the display white point warm, which skews dead pixel and uniformity colour tests. Always disable it before testing.
Load the correct ICC profile
Settings > System > Display > Advanced Display > Colour profile
Select the ICC profile shipped with your monitor (typically on a USB stick in the box or downloadable from the manufacturer). A wrong profile shifts all colour output and makes uniformity results unreliable.
Try in the tool
Windows 11 pre-test checklist
- HDR Settings > System > Display > Use HDR — disable for baseline SDR tests
- Night Light Settings > System > Display > Night Light — disable, it shifts white point warm
- Refresh rate Settings > System > Display > Advanced Display — confirm it matches the monitor spec
- VRR active check Xbox Game Bar (Win+G) — refresh readout should vary with frame rate, not stay fixed
Verify with the Dead Pixel & Flicker Test Suite tool.
Try it in the tool ↑- 1.
Microsoft Support, "HDR settings in Windows," support.microsoft.com, accessed June 2026. https://support.microsoft.com/en-us/windows/hdr-settings-in-windows-2d767185-38ec-7fdc-6f97-bbc6c5ef24e6
- 2.
Microsoft Support, "Change the refresh rate on your monitor in Windows," support.microsoft.com, accessed June 2026. https://support.microsoft.com/en-us/windows/change-the-refresh-rate-on-your-monitor-in-windows-c8ea729e-0678-015c-c415-f806f04aae5a
- 3.
Microsoft Learn, "Adaptive Color," learn.microsoft.com, accessed June 2026. https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/sensors-adaptive-color
- 4.
VESA, "VESA Certified DisplayHDR Performance Criteria 1.2," displayhdr.org, May 2024. https://displayhdr.org/performance-criteria/
- 5.
Microsoft Learn, "Variable refresh rate displays," learn.microsoft.com, January 2021. https://learn.microsoft.com/en-us/windows/win32/direct3ddxgi/variable-refresh-rate-displays
This usually means the cable is not carrying enough bandwidth. HDMI 2.0 cannot deliver 1440p at 165 Hz or 4K at 120 Hz; use DisplayPort 1.4 or HDMI 2.1 for high refresh rate at high resolution. Check that the cable is rated for the bandwidth, not just physically compatible.
Yes. When Windows HDR is active, the OS applies an HDR tone-mapping pipeline that alters brightness and colour output. Run CapyToolkit's test patterns in SDR mode (HDR off in Display Settings) for accurate uniformity and colour results.
No. Run the uniformity test at factory defaults first to get a baseline. If uniformity looks acceptable, then calibrate for colour accuracy. Calibration does not fix physical uniformity variation; it only corrects the centre measurement point.
Windows applies the active ICC profile to all content including this tool. For panel-level testing (backlight uniformity, dead pixels), the ICC profile has minimal effect. For colour accuracy evaluation, use the profile shipped with your monitor or a generic sRGB profile.
Yes. The test patterns work on any display that can run a browser. Laptop panels often have better uniformity than desktop monitors in the same price tier. Run the same tests, dead pixel sweeps and the uniformity patterns, to verify your laptop panel quality.
Monitor Test on macOS
On macOS, colour management can shift test results before the panel is at fault, so disable True Tone and Night Shift first. macOS applies its own colour pipeline on top of monitor hardware output, including True Tone colour temperature adjustment and automatic Night Shift.1 These features alter the colour output of the display and must be disabled before running colour, uniformity, or dead pixel tests to get an accurate picture of the panel's native quality.
Display P3 and why the colour profile matters for testing
When macOS uses a P3-based display profile, colours can render in a wider gamut than sRGB.2 For tests that check physical panel properties such as backlight uniformity and dead pixels, the colour profile has minimal effect. For colour accuracy evaluation, tonal uniformity, or stuck pixel detection on colour-pattern tests, the expanded gamut shifts what you see.
Choose sRGB before colour-sensitive tests
Before running any colour-sensitive tests on macOS, set the display profile to sRGB IEC61966-2.1 in System Settings > Displays > Color Profile.3 This gives the test patterns a standard web colour baseline before you compare what the panel produces natively and record consistent results across multiple testing sessions. Return to your preferred profile after testing is complete, because the sRGB profile intentionally limits the gamut to match standard web and sDR content expectations.
If you leave the default Display P3 profile active, a stuck pixel on a colour pattern may appear shifted in hue or saturation, making it harder to confirm the exact sub-pixel type. Switching to sRGB removes this variable so the colour patterns match the standard web baseline that CapyToolkit patterns are designed around.
How to confirm macOS settings are not skewing the test
Before diving into the specific details of this section, it is worth establishing the broader context that frames what you are testing and why these particular characteristics matter for your daily experience, because understanding the underlying principles behind each test helps you make more informed decisions about panel quality and return thresholds. ### How to confirm macOS settings are not skewing the test
Before evaluating any panel test result on macOS, systematically disable the colour-management and display features that actively alter what the browser renders on screen, because these software layers can significantly distort your perception of the panel's true hardware characteristics. Disable True Tone and Night Shift, set the colour profile to sRGB for neutral baseline testing, and confirm the external monitor is running at its maximum rated refresh rate in System Settings > Displays, since a warm white-point shift from True Tone or a 60 Hz default refresh rate can make an otherwise excellent panel appear substantially worse than it actually is.
If a suspicious test result visibly changes or disappears after you correct those macOS settings, discard the earlier observation and adopt the corrected-configuration result as your true baseline for all subsequent testing. If the same specific glow pattern, backlight bleed, pixel defect, or uniformity patch remains clearly visible after all software variables have been normalised, you have successfully separated macOS colour management effects from genuine panel hardware characteristics, and that clean separation gives you a much more reliable basis for deciding whether to keep, return, or recalibrate the monitor.
Full-screen mode and browser choice on macOS
Running test patterns in a browser window rather than full-screen mode on macOS leaves the menu bar and Dock as overlays, reducing the usable test area and creating ambient brightness from those UI elements during dark tests.4 Enter full-screen mode before running any black, grey, or uniformity pattern. Use your browser's full-screen command, or the macOS full-screen shortcut if the browser supports it.
Full-screen mode on an external display
For external monitors connected to a Mac, open the browser on the external display before entering full-screen mode. Full-screen mode fills the display the browser window currently occupies. If the browser window is on the built-in Retina display when you enter full-screen mode, the test runs on the built-in panel. Drag the browser to the external display first, then enter full-screen mode to confirm the test patterns appear on the monitor you are evaluating.
External monitor ICC profiles on macOS
Without a manufacturer-specific ICC profile installed, macOS falls back to a generic profile that can shift colour temperature and saturation compared to the panel's native output. For panel-level tests, load the ICC profile supplied by your monitor manufacturer in System Settings > Displays > Color Profile before running colour-sensitive patterns.
Loading the manufacturer profile for accurate colour evaluation
Download the profile from the manufacturer's support page, then select it in System Settings > Displays > Color Profile.1 A mismatched profile does not affect the black uniformity test or the dead pixel test at the sub-pixel level, but it does affect the accuracy of the solid-colour patterns used for stuck pixel detection and tonal uniformity evaluation. Removing that variable gives you cleaner, more repeatable results that reflect the panel itself rather than a generic macOS colour assumption.
Notes
Before running any test: open System Settings > Displays and set the colour profile to sRGB (or the nearest generic profile for your monitor). Disable True Tone via the checkbox in Displays settings: True Tone shifts colour temperature based on ambient light and will interfere with colour and uniformity testing. Disable Night Shift under System Settings > Displays > Night Shift. For external monitors on a Mac, set the refresh rate to maximum via Displays > dropdown at top right of the display preview.
Examples
Disable True Tone on macOS
System Settings > Displays > uncheck True Tone
True Tone adjusts white balance dynamically to match ambient lighting. It must be off for consistent colour test results.
Set maximum refresh rate for an external monitor
System Settings > Displays > select monitor > Refresh rate dropdown > choose highest Hz
macOS sometimes defaults to 60 Hz on external monitors. Check this after connecting a new monitor. Some rates require a specific cable; see the monitor spec sheet for cable requirements.
Set colour profile to sRGB for testing
System Settings > Displays > Color Profile > sRGB IEC61966-2.1
macOS default Display P3 profile on Apple silicon expands colour gamut. For panel-level testing of non-P3 monitors, sRGB is the correct baseline profile.
Try in the tool
macOS pre-test checklist
- True Tone System Settings > Displays — uncheck, it shifts white balance to ambient light
- Night Shift System Settings > Displays > Night Shift — disable
- Color profile sRGB IEC61966-2.1 — the standard baseline for colour-sensitive tests
- External refresh rate macOS sometimes defaults to 60 Hz — confirm the max Hz in the Displays dropdown
Verify with the Dead Pixel & Flicker Test Suite tool.
Try it in the tool ↑- 1.
Apple Support, "Displays settings on Mac," support.apple.com, accessed June 2026. https://support.apple.com/guide/mac-help/displays-settings-on-mac-mh40768/mac
- 2.
Apple Developer, "Displays," developer.apple.com, October 2017. https://developer.apple.com/library/archive/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/Displays/Displays.html
- 3.
W3C, "CSS Color Module Level 3," w3.org, January 2022. https://www.w3.org/TR/css-color-3/
- 4.
Apple Support, "Use apps in full screen on Mac," support.apple.com, accessed June 2026. https://support.apple.com/guide/mac-help/use-apps-in-full-screen-mchl9c21d2be/12.0/mac/12.0
True Tone shifts the display white point, which changes how solid colour patterns appear. A white pattern with True Tone active will look warmer (more yellow) than the panel native white. CapyToolkit keeps this check local in your browser, so you can inspect the screen without uploading photos. Disable True Tone before testing to see the panel at its factory white point.
Yes, but only with the right cable and connection. An M-series Mac connected via Thunderbolt/USB-C at full bandwidth supports up to the monitor maximum. Some USB-C adapters limit bandwidth to 60 Hz. Use a Thunderbolt 3/4 or USB4 cable for high refresh rate at high resolution.
Open System Settings > Displays. The current resolution and refresh rate are shown below the monitor diagram. If the rate is lower than the monitor maximum, check your cable and connection type.
For physical uniformity (backlight brightness gradients, DSE patterns), the ICC profile has minimal effect; these are hardware characteristics of the panel. For colour uniformity evaluation, set the profile to sRGB to remove macOS colour science from the measurement.
Yes. The test patterns fill the browser window. For testing an external monitor connected to a Mac, open the browser on the external display before entering full-screen mode.