UBC Theses and Dissertations

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UBC Theses and Dissertations

Advanced methods for controlling dual modulation display systems Atkins, Robin


This thesis presents a novel method for controlling a dual-modulation display, also commonly known as a local dimming display. Dual modulation is a technology that improves the contrast and power efficiency of liquid crystal displays (LCDs) by dimming the backlight in image regions that need less light. This is an important improvement as although LCD technology accounts for nearly 90% of today’s displays, it has relatively poor performance in contrast and efficiency. A critical component of a dual modulation display is the control algorithm. Present control algorithms cause an image artifact termed LCD clipping that affects the high spatial frequencies and is highly objectionable to many viewers. In this thesis we introduce an image metric designed to measure this artifact, as we found that existing metrics were not sufficient. The main contribution of the thesis is a new control algorithm for dual-modulation displays that eliminates the LCD clipping artifact, with minimal other tradeoffs in image quality and power efficiency. The new control algorithm requires less computational resources than previous algorithms and no change to display hardware, making it a relatively straightforward upgrade for today’s dual modulation displays.

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Attribution 3.0 Unported