How to Check a Screen for Dead Pixels, Backlight Bleed and Color Shift
A screen can look fine on a busy desktop while hiding stuck pixels, dim corners or uneven color. Use a short sequence of solid colors, grayscale ramps and edge checks in a quiet, well-lit room.
Start with solid colors
Open the Screen Test and enter fullscreen mode. Move through white, black, red, green and blue screens. A dead pixel usually stays black on bright colors, while a stuck pixel may remain red, green, blue or white when the rest of the panel changes.
Do not judge from one color only. Some defects appear only when a sub-pixel is asked to show a specific color.