Editing Traditional animation (section)

===Cels===
{{see also|#Ink and paint}}
[[Image:Animation cells.png|frame|This image shows how two transparent cels, each with a different character drawn on them, and an opaque background are photographed together to form the composite image.]]

The cel animation process was invented by [[Earl Hurd]] and [[J. R. Bray|John Bray]] in 1915. The [[cel]] is an important innovation to traditional animation, as it allows some parts of each frame to be repeated from frame to frame, thus saving labor. A simple example would be a scene with two characters on screen, one of which is talking and the other standing silently. Since the latter character is not moving, it can be displayed in this scene using only one drawing, on one cel, while multiple drawings on multiple cels are used to animate the speaking character.

For a more complex example, consider a sequence in which a person sets a plate upon a table. The table stays still for the entire sequence, so it can be drawn as part of the background. The plate can be drawn along with the character as the character places it on the table. However, after the plate is on the table, the plate no longer moves, although the person continues to move as they draw their arm away from the plate. In this example, after the person puts the plate down, the plate can then be drawn on a separate cel from them. Further frames feature new cels of the person, but the plate does not have to be redrawn as it is not moving; the same cel of the plate can be used in each remaining frame that it is still upon the table. The cel paints were actually manufactured in shaded versions of each color to compensate for the extra layer of cel added between the image and the camera; in this example, the still plate would be painted slightly brighter to compensate for being moved one layer down.

In TV and other low-budget productions, cels were often "cycled" (i.e., a sequence of cels was repeated several times), and even archived and reused in other episodes. After the film was completed, the cels were either thrown out or, especially in the early days of animation, washed clean and reused for the next film.  In some cases, some of the cels were put into the "archive" to be used again and again for future purposes in order to save money. Some studios saved a portion of the cels and either sold them in studio stores or presented them as gifts to visitors.

====Cel overlay====
A ''cel overlay'' is a cel with inanimate objects used to give the impression of a foreground when laid on top of a ready frame.{{sfn|Laybourne|1998|p=168}} This creates the illusion of depth, but not as much as a multiplane camera would. A special version of cel overlay is called ''line overlay'', made to complete the background instead of making the foreground, and was invented to deal with the sketchy appearance of xeroxed drawings. The background was first painted as shapes and figures in flat colors, containing rather few details. Next, a cel with detailed black lines was laid directly over it, each line is drawn to add more information to the underlying shape or figure and give the background the complexity it needed. In this way, the visual style of the background will match that of the xeroxed character cels. As the xerographic process evolved, line overlay was left behind.

====Pre-cel animation====
[[File:How Animated Cartoons Are Made (1919).webm|thumb|''How Animated Cartoons Are Made'' (1919), showing characters made from cut-out paper]]

In very early cartoons made before the use of the cel, such as ''[[Gertie the Dinosaur]]'' (1914), the entire frame, including the background and all characters and items, were drawn on a single sheet of paper, then photographed. Everything had to be redrawn for each frame containing movements. This led to a "jittery" appearance; imagine seeing a sequence of drawings of a mountain, each one slightly different from the one preceding it. The pre-cel animation was later improved by using techniques like the slash and tear system invented by [[Raoul Barré]]; the background and the animated objects were drawn on separate papers.{{sfn|Thomas|Johnston|1995|p=30}} A frame was made by removing all the blank parts of the papers where the objects were drawn before being placed on top of the backgrounds and finally photographed.