White Screen for Laptop
Fullscreen white on a laptop's built-in display, with notes below.
Simulated dimming — browsers can't raise a panel's backlight.
Laptop-specific notes
Backlight bleed near the hinge is common and often not a defect. Laptop panels are held under slightly different pressure near the hinge than a standalone monitor, which can produce mild bleed along the bottom edge specifically. Run the backlight bleed test and compare the hinge edge against the other three edges — bleed that’s only along the hinge and mild is common; bleed that’s just as bad on other edges, or severe anywhere, is worth raising with the manufacturer.
Lid angle changes colour and contrast more than you’d expect. Laptop screens are viewed from a narrower range of angles than a desktop monitor, and cheaper panels shift colour and contrast noticeably as you tilt the lid. Test at the angle you’d actually use the laptop at, not perfectly perpendicular — a panel that looks fine dead-on but washes out at a normal working angle is a real usability issue.
Battery saver mode dims and colour-shifts the display. Most laptops automatically reduce brightness and sometimes apply a warmer colour profile on battery saver. Plug in and disable battery saver before doing any colour or brightness comparison — see the brightness test once that’s confirmed off.
External monitor comparison. If you have a second monitor, open this tool on both at once (drag the browser window across) to directly compare the laptop panel’s colour and brightness against a known-good external display side by side.