Backlight Bleed Test
Turn off your room lights, open pure black fullscreen, and look at the corners and edges. A little glow on IPS panels is normal; large bright patches are not.
Click Start for pure black, then dim your room lights. Glow around edges = backlight bleed.
How to use this test
Click Start — the test opens fullscreen over this page (nothing is installed, nothing leaves your browser). A control bar at the bottom of the screen lets you switch colors and exit with one tap — touch screens included; the Esc key and your browser's back button work too. Judge the screen in the lighting the test asks for; judging bleed or uniformity in a bright room defeats the test.
Frequently asked questions
Is some backlight bleed normal?
Yes — almost every IPS and laptop panel has a trace of it. Only judge it in a dark room against a truly black screen.
Does backlight bleed get worse?
Slowly, with panel aging and heat. Sudden worsening after a drop means physical damage.