Monitor Test: Full-Screen Screen Test Patterns

How to use the monitor test

1. Set up. Let the screen warm up and set it to its native resolution. In Chrome, Edge and Firefox the line patterns are drawn in its own pixels at any browser zoom; in Safari, keep the page at 100%. Dim the room for the dark tests.
2. Start. Press Start full-screen test (or F). Space or → moves to the next pattern and ← goes back; on a phone or tablet, tap the pattern to show or hide the buttons.
3. Mark each test. Read the line under the pattern, look, then press Looks fine (P) or Problem (X). Marking jumps to the next test. You can also mark tests in the checklist under the tool, and tap a test’s name to jump to it.
4. Share the screen check. When you have marked what you checked, Share result gives you a link to a card with your marks, handy for a seller, a forum thread or your own notes before a return.

The nine tests and what they find

• Uniformity (5%, 10%, 20%, 50% gray and white): dark corners, clouding, vertical bands and blotches. RTINGS tests gray uniformity with a full-screen 50% gray and calls the blotchy spots the “dirty screen effect”; it shows most in large flat areas such as sports and panning shots.
• Burn-in and image retention: flat gray and solid colors for marks left by static content, then slowly moving color bars for retention to fade. For where burn-in shows first on phones, TVs and monitors, and what the makers’ refresh cycles do, see the OLED test.
• Backlight bleed and IPS glow: black in a dim room. Light that stays put when you move your head is bleed; glow that changes with angle and distance is IPS glow.
• Gradient banding: gray and red, green, blue ramps with all 256 levels, and a stretched dark ramp for shadow banding.
• Black level, white level and gamma: numbered squares near black and near white, and a gamma chart.
• Sharpness and text: text from 9 to 20 pixels, single-pixel lines, a pixel checkerboard and a ring pattern that shows moiré when the picture is scaled.
• Viewing angle: grays, skin tones and color bars to watch as you move.
• Color: primaries, a neutral gray scale, skin tones, and sRGB beside Display P3 for wide-gamut screens.
• Edges and scaling: a white border on the outermost pixels, with 2.5% and 5% guides, to catch a picture that is cropped or not filling the panel.

How to read the results

Some unevenness is normal. No LCD is perfectly even at 5% gray, and IPS glow in the corners of a dark screen is part of how those panels work. Mark a problem when you would notice it in normal use: a patch you see in dark films, a band in a gray web page, a glow from your usual seat.

Black level: on an ideal monitor every square from 1 to 24 is visible, as in Lagom’s classic black level test. If the first few disappear, raise brightness or check a black-level or “HDMI range” setting. White level: squares that melt into white mean highlights are clipped, so lower contrast.

Gamma: step back and squint. Lagom’s gamma test explains that monitors are meant to follow the sRGB standard, which is very close to gamma 2.2, so the 2.2 column should be the one where the solid patch blends into its striped surround.

Text: colored fringes on small text come from sub-pixel smoothing. On Windows, the ClearType Text Tuner (type cttune in the Start search) lets you pick the version that looks sharpest to you.

Banding: the page is drawn with 8 bits per channel, so it can’t show whether a panel is 10-bit. Smooth 256-step ramps with no wide stripes or tints are the result to hope for.

Tips and troubleshooting

• Scaling: in Chrome, Edge and Firefox the line patterns stay one physical pixel wide at any browser zoom (in Safari at 100%), so shimmering lines or a wavy ring pattern mean the screen itself is scaling the picture. Set the screen’s native resolution (and on a TV, the picture size setting that shows every pixel).
• Turn off picture “enhancements” such as dynamic contrast, sharpness boosts or eco modes before judging banding and uniformity: they change the image as you look at it.
• Dust or a defect? Wipe the screen and look again. A sharp dot that stays on every color is a pixel; find and map those with the dead pixel test.
• Motion: blur, ghosting and dropped frames are covered by the refresh rate test, which also reads your screen’s Hz.
• Just need a solid color? The black screen fills the display with black, white or any color for cleaning or a quick look.
• iPhone: Safari doesn’t let web pages go full screen, so the patterns fill the browser window. Turn the phone to landscape.