Turn your entire screen black with one click. Black is the field for finding dust, lit stuck pixels, and backlight bleed on LCD panels, and for checking that an OLED really switches its pixels off.
F for fullscreen, Esc to exit
With the black field up, shine a desk lamp or phone torch across the glass at a shallow angle. Dust catches the light and shows as bright specks.
In a dark room, a black field shows light leaking in from the edges and corners of an LCD. The backlight bleed test explains what is normal and what is not.
A stuck pixel is locked on, so against black it glows as a coloured or white dot. Dead pixels are dark and hide here, so pair black with white.
An OLED switches black pixels off entirely. In a dark room the field should be indistinguishable from the bezel. A faint glow means the panel, or a setting, is not doing that.
An LCD blocks a backlight that stays on the whole time, so in a dark room a black field shows as dark grey, and often brighter along an edge or in a corner. That leak is what the backlight bleed test looks for.
An OLED has no backlight. Each pixel is its own light and black means off, so there is nothing to bleed.
A retained image is a small difference in brightness. On black the pixels are dark or off, so there is nothing for the difference to show against. Burn-in shows on a uniform mid-grey, which is where the burn-in test starts.
Written by Piero Nanni. If a panel of yours behaves differently, tell me and I will correct it. Updated .
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