Panel & Backlight
Brightness Uniformity Test
A 50% gray field, a 9-zone grid and a panning gray to spot uneven backlighting.
▶ Start full-screen testGray field← / → or tap the sides to switch · Esc to exit
How to use
- 1Click Start and view the gray field full-screen.
- 2Use ← / → to switch to the 9-zone grid and the panning gray.
- 3Compare the brightness of the center against each corner.
- 4On Panning gray, follow the drifting bands with your eyes: smudges or stripes that stay put are the panel's dirty screen effect.
- 5Press Esc to exit.
FAQ
How much variation is acceptable?
Good monitors stay within roughly 10% brightness variation across the panel. Larger differences show as visibly darker corners or brighter hotspots.
What is the dirty screen effect?
Blotches and faint vertical bands on large panels, most visible when the camera pans across a uniform area such as a sports pitch. The Panning gray frame recreates that: the bands drift, and any patches that stay fixed belong to the panel.
Tips
- Compare the center against each corner one at a time rather than scanning the whole field.
- Take a photo and even out exposure — your eyes auto-adjust and hide real differences.
Related tests
Dead Pixel TestFull-screen solid colors to find dead, stuck, and bright pixels.Open test→Backlight BleedReveal LCD backlight leakage and IPS glow in a dark room.Open test→Blooming TestA bright object on black to judge local-dimming halos.Open test→Burn-in TestFull-screen fields and a checkerboard to reveal OLED burn-in.Open test→
Related guides
Learn more about what this test reveals and how to act on the results.
How to Test a New TV for Dead Pixels and UniformityUse your TV's browser or a phone to run solid-color and gray tests that reveal panel defects and dirty-screen effect.The Complete New-Device Screen Test ChecklistA 10-minute routine to inspect any new laptop, monitor, phone, or TV for dead pixels, bleed and tint before the return window closes.How to Test a Monitor Before (and Right After) BuyingWhat to check in the store and at home so you don't keep a monitor with dead pixels, bleed, or the wrong refresh rate.How to Set Up a Monitor for Photo EditingGamut, brightness, calibration, and room-lighting choices that keep your edits looking right on other people's screens and in print.