White Screen Test (Free Online Full-Screen Panel)
Check your display for pressure spots, stuck sub-pixels, and panel dirt using our interactive full-screen light box tool.
Interactive White Screen Tones
Choose your preferred color temperature below before starting fullscreen mode:
Select a white color tone and click 'Start Fullscreen'. Scan your panel for darker patches or colored spots.
What Can You Find with a White Screen Test?
A full-screen white canvas acts as an uniform backdrop, exposing discrepancies in how light passes through the screen glass and polarizers. Inspect your panel for these three common hardware anomalies:
1. LCD Pressure Marks
These appear as bright, hazy white spots where light is focused unevenly. They are caused by localized physical pressure compressing the liquid crystals or bruising the internal plastic diffuser sheets.
2. Backlight Bleed & IPS Glow
Typically visible along bezel borders. A white panel helps identify display frame pinching, where parts of the screen edges look darker or dimmer due to structural pressure.
3. Dirt & Dust Spots
Tiny dark specs that do not shift when you clean the front glass. This indicates dust or particulate entry during factory assembly, trapping debris between LCD layers.
Diagnosing Display Defects
- Isolating Stuck Pixels: If you spot a tiny dot that stays red, green, or blue against the white canvas, it is a stuck sub-pixel. You can run our Dead Pixel Test to flash colors and unfreeze the transistor.
- Assessing Backlight Uniformity: Move your eyes across the screen. If the corners look significantly dimmer or warmer than the center, it points to poor backlight distribution, common in cheap edge-lit monitors.