Black Screen and Backlight Test
Display a full-screen black reference to inspect bright pixels, backlight bleed, clouding, glow, and unwanted light in dark scenes.
A dark reference makes persistent bright points and broad light leakage or glow easier to compare across the panel. Darken the room moderately, use a normal viewing position, avoid excessive brightness, and allow your eyes a moment to adapt.
What does this test measure?
A dark reference makes persistent bright points and broad light leakage or glow easier to compare across the panel.
Why is this test important?
Display a full-screen black reference to inspect bright pixels, backlight bleed, clouding, glow, and unwanted light in dark scenes.
How do you run the test?
Darken the room moderately, use a normal viewing position, avoid excessive brightness, and allow your eyes a moment to adapt.
How should results be interpreted?
A fixed bright dot may be a bright or stuck pixel; broad corner glow or pale patches may vary with panel type, pressure, brightness, and angle.
Normal and problematic results
A fixed bright dot may be a bright or stuck pixel; broad corner glow or pale patches may vary with panel type, pressure, brightness, and angle.
Technical limitations
Photos often exaggerate black-level problems, and IPS glow can be normal; this test cannot set a universal warranty threshold.
Why can the score decrease?
Unstable measurements, denied permissions, unsupported browser APIs, background load, power saving, or an incomplete test can affect the result. When a score changes, the result screen explains the reason.
What should you do if a problem is found?
Lower brightness, view straight on, reset display settings, and compare another signal source before contacting the manufacturer.
Example Result Explanation
Frequently Asked Questions
What is backlight bleed and how is it different from a dead pixel?
Backlight bleed is light escaping around the edges of the panel, visible as glow or patches on a dark screen. It affects an area, while a dead pixel is a single unchanging point. Bleed is a characteristic of most LCDs and only matters when it is severe.
How dark does the room need to be?
As dark as you can reasonably make it, and give your eyes a minute to adjust. Judging black level in a lit room makes almost any panel look acceptable and hides exactly what this test is for.
A bright dot appears on the black screen. Is that repairable?
A pixel stuck bright on black is the most visible kind of defect. It sometimes clears by itself or after a colour-cycling pattern, but if it persists it is a hardware fault and worth checking against the pixel policy for your model.