A common method for real-time segmentation of moving regions in image sequences involves “background subtraction”. Background subtraction as proposed by Stauffer-Grimson models pixel intensity as a mixture of Gaussians. The Gaussians’ mean and variance adapts continuously in accordance with observed intensity at a given pixel of the image sequence. Since this method has a limited tolerance towards sudden intensity variations at a particular foreground/background pixel, it fails to model intensity variations induced by effects such as Camara’s Automatic Gain Control (AGC). We propose an enhancement to the Stauffer-Grimson method where we model such intensity variations robustly. Camera AGC is estimated with the aid of comparagram between consecutive frames of a video sequence