ABSTRACT
A great development in visual effects was the latent image matte process. This technique involves the use of mattes to selectively obscure a portion of the frame, enabling this unexposed section to contain a new element shot at a later time. The ability to spread out the task of compositing elements over time was a vast improvement over the foreground miniature and glass shots, in which everything had to work all at once. The idea behind this technique is that photographic fi lm does not “expose black,” unlike video, which actually records a zero component, or black. If a black silhouette is photographed using motion picture fi lm, the emulsion regards that area just as it would a darkroom. The fi lm in that area remains unexposed and can still react to light at a later time unless processed. This black silhouette is known as a matte. If two exposures are recorded atop each other on fi lm, a double exposure or superimposition results in which light areas overtake darker areas, two lighter images combine to form an even brighter area, and two black images leave the fi lm dark where they overlap. This superimposition effect is good for ghost effects or atmospheric haze. If, however, a piece of art (a matte) is created that obscures a portion of the image in front of the camera lens (the sky, for example), the ground plane can be shot then the fi lm wound back, and by using a countermatte the unexposed sky area could be exposed (to a painting of a sky) while protecting the previously exposed ground plane. If the join between the matte and countermatte is done skillfully, a convincing composite results in which both photographic “elements” combine seamlessly. These mattes are known by many names: male and female, hold-out and burnin, cover matte, etc. The terms hold-out and burn-in relating to specifi c elements are the best way of describing the breakdown of the shot. For example, “lessen the density
of the fi re’s hold-out matte” refers to a black shadow image of the fi re “holding out” the background image and how opaque the fi re matte was to light. Mattes can obscure either 100% of the light they are holding back or merely a percentage. No matte at all would lead to the superimposition effect, whereas a 50% density would let half the amount of light through leading to a slightly transparent element, which is good for effects such as fi re and smoke that by nature are slightly transparent. Even though digital cameras can’t re-expose on a second pass like fi lm cameras, they still make use of mattes in postprocessing operations.
