Method for removing background regions from moving images

This paper proposes a background region removal method that extracts facial video images for their later superimposition onto retrieved images held in a video filing system. The method is robust against light intensity fluctuation. The background is eliminated from the camera signal by a combination of differential signal thresholding, filtering, and masking. Current thresholding methods are somewhat unstable because they fail to handle fluctuations in light intensity. The proposed method is very stable because it uses two assymetric thresholds in relation to the origin. The method is quite simple and fast. It consists of four steps: storing the background image in the background memory; subtracting the background image from the camera output; selecting two appropriate thresholds; and thresholding to generate a key signal as in the chroma-key technique. The key part of the method is threshold selection. Thresholds are selected by using a Gaussian and constant function approximations of the differential signal's histogram so as to eliminate histogram deterioration caused by light intensity fluctuations.