Purpose
Black makes light leaking from an LCD edge easier to see. It also shows bright specks. It cannot, by itself, tell bleed from IPS glow or from a reflection of the room.
Preparation
- Darken the room and keep lamps out of the glass.
- Sit straight on, then shift your head a little.
- Do not press the panel or the bezel.
- On an OLED, treat this as a black-level look, not an LCD bleed test. There is no backlight to leak.
What to look for
Corners or edges that stay bright when you sit still. A bloom that grows and shrinks as you move is often described as IPS glow. A lamp, a white shirt or a bright wall can fake both.
Common false positives
Reflections, raised camera exposure, and OLED near-black processing. A phone photo of a black screen often lifts the blacks and invents glow.
Limitations
The field is #000000. How black it looks depends on the panel and the brightness you already set. This test does not turn brightness up or down, and the pause warning after a few minutes is not a promise about burn-in.
Questions
Do I need a dark room?
Yes for this check. Ordinary light is better for white, colour and grey tests. Edge glow is hard to see with a lamp in the room.
Is glow the same as backlight bleed?
Not always. IPS glow often shifts when you change angle. Bleed is more fixed at an edge or corner. Reflections from the room can mimic both. The field does not name which one you have.
What about an OLED?
An OLED has no backlight, so LCD bleed does not apply. Use the black field for bright specks and uneven near-black. Do not leave a bright field running unattended.
Should I push the bezel?
No. Do not press the screen or the bezel to see if the glow changes.