Fine tuning for green screen matting

This paper addresses the problem of fine tuning thresholds of a color difference method for green screen matting. The conventional color difference method uses two thresholds to control a result matte. However, the thresholds are applied to all pixels in an image which sometimes present structures in the image. In order to provide a flexibility to control each group of pixels that have the same property in an image locally in the property space, this paper proposes a method that allows a user to adjust the thresholds associated to each group. In this paper, we use the luminance of a pixel to group the pixels in an image. Pixels with similar luminance are clustered into the same bin of a histogram. Local maxima extracted from the histogram will be used to initialize the thresholds associated to the groups corresponding to the local maxima. The experimental results will present that our proposed method take a little more effort adjusting thresholds to obtain a higher quality matte result.