Backlight bleed is light from an LCD’s backlight leaking around the edges of the panel, so a black screen shows brighter patches along a side or in a corner. For an LCD, the check runs black first, then the dark gray fields where clouding shows, then the viewing angle pattern that tells glow from leaks.
Press Start full-screen test. The bar under the pattern hides itself after a few seconds so nothing covers the bottom edge; tap the pattern to bring it back, or press H to keep it hidden.
1. Set up the way Dell recommends
Dell’s guide to telling IPS glow from light leakage on its monitors asks for three things before you judge: the room slightly lit rather than dark, brightness at 30 to 50%, and the monitor warmed up for 30 minutes. Bleed you only see in a pitch-black room at full brightness rarely shows in normal use.
2. Bleed or IPS glow?
With the black screen up, look at each edge and corner from your normal seat, then move: sit back, lean left and right, stand up.
- Stays the same wherever you look from: backlight bleed (light leakage). It is usually a fixed patch or streak along an edge.
- Changes as you move, often fading when you look straight on from further away: IPS glow, a property of IPS panels rather than a fault.
3. Gray fields and viewing angle
Clouding, patchy brighter areas away from the edges, shows on the darker grays. Mark Problem when you can see it from your seat on the 5% or 10% field. The viewing angle pattern then shows how much the picture washes out as you move, which helps you judge whether a corner glow is the panel type at work.
What to do with the result
If the bleed is plain in normal use, take photos with the room lit as above and contact the seller inside the return window; the shared screen check records which tests you marked. For dead or stuck pixels use the dead pixel test, and for a plain black screen the black screen.