Blue Pixel Test
Show a full-screen blue reference to identify dark pixels, incorrect colors, flicker, and uneven blue-channel behavior across the display.
The blue field helps isolate pixel and subpixel behavior that may be less visible on white, black, red, or green backgrounds. Run the test at native resolution, inspect the complete panel, and compare any point with the same location on red, green, white, and black screens.
What does this test measure?
The blue field helps isolate pixel and subpixel behavior that may be less visible on white, black, red, or green backgrounds.
Why is this test important?
Show a full-screen blue reference to identify dark pixels, incorrect colors, flicker, and uneven blue-channel behavior across the display.
How do you run the test?
Run the test at native resolution, inspect the complete panel, and compare any point with the same location on red, green, white, and black screens.
How should results be interpreted?
A point that consistently differs from the surrounding blue field may be stuck, inactive, contaminated, or affected by scaling or signal processing.
Normal and problematic results
A point that consistently differs from the surrounding blue field may be stuck, inactive, contaminated, or affected by scaling or signal processing.
Technical limitations
The test cannot diagnose internal monitor electronics or confirm a warranty claim without additional manufacturer procedures.
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?
Check another cable, port, device, browser, and display preset; document a persistent mark with a camera if support requests evidence.
Example Result Explanation
Frequently Asked Questions
What does a blue screen reveal that red and green do not?
Blue is the dimmest of the three to human eyes, so faults in the blue subpixel often go unnoticed until the screen is filled with blue. It also exposes compression artefacts and banding more clearly than the other primaries.
Blue looks blotchy or purple in places. Is that a defect?
Slight tint variation across a blue field is common and rarely a fault in itself. Distinct blotches that stay in the same place when you move your head are worth noting, especially if they also appear on the grey uniformity test.
Why do my eyes struggle to focus on a blue screen?
Blue light focuses slightly in front of the retina compared with red, so a pure blue field genuinely is harder to focus on. This is normal and not a sign of a problem with the display.