This visual check can help photographers, video editors, and everyday users who notice pale details blending together. Before starting, clean the display and reduce direct reflections; view it from your usual seating position so you can judge the patches under familiar conditions.
How to use White Level Test
- Select Start Test to begin.
- Choose a Pattern mode: Nine patches or Nine bars. Both show patch values against a white background.
- Look for visible separation between the near-white patches and the background. Read the white patches from left to right, then top to bottom: 224, 232, 240, 244, 248, 250, 252, 254, and 255. The test also includes black patches with values 0, 2, 4, 6, 8, 12, 16, 24, and 32.
- Use Previous and Next, or the Left and Right arrow keys, to move between patterns. Press Space for automatic mode; reduced motion keeps progression manual.
- Select Fullscreen or press F to expand the pattern. Press Escape to exit, or use Exit fullscreen. In fullscreen on a phone, tap the left or right half to move between patterns. Legends stay outside fullscreen.
- Select Reset or press R to return to the starting point.
When to use it
- Before a return window closes: Inspect a new monitor and note any near-white patches that seem to merge.
- While buying a used screen: Run the pattern during an in-person check to see whether adjacent highlights remain distinct.
- After changing display settings: Compare the same pattern before and after the change to see whether visible separation shifts.
- When switching HDR/SDR processing: Check how the patch sequence looks in the mode you use for your usual content.
- When pale details look washed out: See whether the lighter steps remain distinguishable against the white background.
- For a quick check before photo or video work: Inspect the screen's near-white range, then review actual content as well.
- When comparing two displays: Use the same pattern and keep the viewing conditions and settings as consistent as practical.
Tips for a useful comparison
Focus on whether neighboring patches look different, rather than judging the screen by how bright it feels overall. The White Level Test is a visual comparison, not a target that every monitor should display in an identical way.
If you are checking a settings change, note the setting and pattern mode you used, then compare under similar room lighting and from the same position. This makes it easier to tell whether a difference is associated with the display setup rather than a change in viewing conditions.
Stop if the bright patterns cause discomfort. If you are checking more than one screen, remember that each result reflects that display in its current setup.
Limits of the test
The patch numbers are digital values; they do not measure physical brightness or contrast. HDR/SDR processing and display settings can change highlight separation, so a patch that is hard to see is not, by itself, proof of a defect. Treat the result as an observation of the screen under the current conditions, not a calibrated reading.
A browser-based visual pattern cannot diagnose or repair a monitor, and it does not identify why patches appear merged. For an accurate luminance reading, use suitable calibrated measuring equipment. If a problem persists during ordinary use, check the display's settings and contact the seller or manufacturer for advice.