Flash animation

Onion skinning is a 2D graphics term for a technique used in creating animated cartoons and editing movies to see multiple frames at once.The animator or editor can make decisions on how to create or change an image based on the previous image in the sequence.In traditional cartoon animation, the individual frames of a movie were initially drawn on thin onionskin paper over a light source. The animators  would put the previous and next drawings exactly beneath the working drawing, so that they could draw the 'in between' to give a smooth motion.