Screen uniformity and dirty screen effect test.

How this test works

Inspect neutral full-screen fields to see whether brightness and color stay consistent across the panel.

1. Prepare the display using the checklist below.
2. Select Start test and allow fullscreen mode if your browser asks.
3. Use the arrow keys, on-screen controls, or click the pattern to move through the test.
4. Exit the runner and save a local observation if useful.

Before you begin

• Warm up the display for 20 minutes
• Use your normal viewing position
• Turn off dynamic contrast

What to look for

• Dark or bright patches
• Color tint near edges
• Vertical bands on gray fields

Compare broad fields at normal viewing distance

Uniformity is about how even the panel looks across an area, not whether one isolated pixel is stuck. The runner offers white, 75%, 50%, and 25% gray, plus near black. Let the display warm up and begin with a middle gray at your normal brightness. Look for stable broad patches, vertical bands, or color tint that remain tied to the same location. Move your attention across the whole panel, including the edges, but avoid treating every small variation as a defect. Most displays are not perfectly uniform under all artificial patterns.

A pale area on white may behave differently from a dark band on gray or a corner glow on near black. Note which specific field exposes the issue. If a mark is only one dot, use the dead pixel test; if it is concentrated around the bezel on an LCD during a dark field, compare the backlight bleed page. The purpose here is a repeatable visual comparison of larger regions. It is not a numerical map of brightness, Delta E, or uniformity percentage.

Control lighting and picture processing

Room reflections, viewing angle, and dynamic contrast can create or hide apparent variation. Inspect from the position you use for work or play, then move your head slightly to see whether a glow follows your viewpoint. Keep the monitor’s brightness near your normal setting. If local dimming or an automatic contrast mode changes the appearance, compare once with that feature off and then restore your preferred setting. Changing one variable at a time makes the observation more useful than comparing unrelated screenshots taken under different conditions.

Camera exposure, lens shading, white balance, and compression can greatly exaggerate patches and tint. Judge with your eyes first. A photo can show where a band appears, but it should not be treated as a calibrated uniformity map. If you compare two monitors, use similar content, room light, viewing distance, and brightness where practical. A wider or curved screen also changes viewing angle toward its edges, so moving closer can make normal off-axis behavior look more dramatic than it does in everyday use.

Connect the pattern to real content

Some people notice dirty-screen effect during camera pans over skies, sports fields, or other broad flat scenes. If a patch appears in the test, check whether it also interrupts the material you normally watch or edit. Record the color field, position, brightness, picture mode, and whether the display had warmed up. Avoid deciding from a single near-black field in a completely dark room if you normally use the display in moderate light. The practical impact matters alongside the controlled visual observation.

If the issue is new or severe, consult the maker’s policy and compare with a known input or mode before concluding the panel is at fault. The browser cannot measure luminance uniformity or identify whether a band comes from electronics, backlight, coating, compensation, or the content path. This page helps you describe the scale and circumstances of variation. For OLED image-shaped retention, use the OLED-specific page and keep static fields brief; for individual bright or dark points, use the dedicated pixel pattern.

Frequently asked questions