Disclosed is an electronic device and a method to generate alpha masks of video frames in a video comprising a plurality of video frames including a first video frame and a second video frame following the first video frame, where the method comprising; obtaining a first alpha mask of the first video frame; providing a first downscaled video frame, wherein the first downscaled video frame is a lower resolution version of the first video frame; providing a first downscaled alpha mask of the first alpha mask; estimating a first primary coefficient and a first secondary coefficient based on the first downscaled video frame and the first downscaled alpha mask; and generating a second alpha mask for the second video frame based on the first primary coefficient and the first secondary coefficient.