Detect dead pixels, backlight bleed and color uniformity issues.
A dead pixel appears black on all colors. A stuck pixel shows only one color (red/green/blue). If you find a stuck pixel, try running the Pixel Healer for 20–40 minutes.
Use the Black test in a dark room. If screen edges glow grey or yellow instead of pure black, your panel has backlight bleed. This is common on IPS and VA displays.