High-contrast is one of the main advantages in laser projection display, and the method of DCC (Dynamic Contrast Control) is the main way to increase the contrast. Generally, image pre-processing is necessary for eliminating noise and decreasing the over-highlight. In this paper, we proposed and actualized a method by following 3 steps: Firstly, the original image was analyzed statistically to get the scope of gray-scale distribution and average gray-scale; and then the image was divided into a number of sub-images. The sub-images whose pixels are higher than a certain threshold in both number and range, are applied image segmentation by certain growth rules. The sub-images satisfied with the growth rules are marked 1, and the rests are marked 0. Secondly, the sub-images are uniting. A sub-image has 3 relations between 8 sub-images around it: 1 and 1, 1 and 0, 0 and 0. The sub-images marked 1 are uniting together, and the sub-images marked 0 are uniting together. Without affecting the visual vision, all over-highlight pixels were reduced in a certain proportion. Lastly, based on the application of DCC, the whole image signals were enlarged and the brightness of light sources were reduced, so as to achieve the desired effect in contrast enhancement.
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