Glossary A–ZLetter L
Local dimming
Local dimming is a technique in LCD screens in which the backlight is divided into many zones that are individually brightened or darkened depending on the image content.
Dark parts of the picture receive less light. As a result, black looks deeper and contrast increases.
The effect depends on the number of zones and their arrangement. If the diodes sit only at the edge of the screen, control is coarse; if they are spread across the area behind the panel, smaller regions can be controlled separately. With videos and images that contain dark areas, this clearly improves the impression, and power consumption can fall when large parts of the picture are dark.
In digital signage, local dimming also has weaknesses. Bright text on a dark background can be surrounded by a halo because a zone is larger than the letter. On video walls, each device may regulate differently, so that the surface looks uneven. With bright, flat content, the technique achieves little. Operators should test the function with their own content and switch it off if necessary.