The Research of Contrast Ehancement Algorithm in Laser Projection Display System

摘要

High contrast is one of the main advantages in laser projection display, and dynamic light control is the main way to increase it. Generally, image pre-processing is necessary for eliminating noise and decreasing partial over highlight. In this paper, we proposed and actualized a method by following 3 steps: Firstly the images were analyzed statistically to get the scope of gray-scale distribution and average gray-scale; images were divided into a number of sub-images. The over highlight pixels of sub-images, which are higher than a certain threshold in both number and range, are applied image segmentation by certain growth rules. The segmented sub-images are marked 1, and the rests are marked 0. The second step was region united. A sub-image has 3 relations between 8 sub-images around it: 1 and 1, 1 and 0, 0 and 0. Determine the conjunction between sub-images in accordance with the order of 11, 10, 00.Without affecting the actual vision, all over highlight pixels was reduced in a certain proportion. Lastly with the application of dynamic light control, the whole image signal was enlarged and brightness of light source was reduced, so as to achieve the desired effect in contrast enhancement.