Use nodes to compute the difference between two images, usually a matte or background shot and then the same shot with actors in the set. This technique was used in the film "Death Becomes Her" starring Meryl Streep, Goldie Hawn, and Bruce Willis. Use this technique to create ghosts, glass people, or to uncover watermarks and prove video ownership. Whether you're new to the Blender Foundation's popular 3D modeling program or a seasoned graphic artist just interested in better acquainting yourself with the application, you're sure to be well served by this free video tutorial. For more information, including detailed instructions, take a look!