The animation in AutoManga is produced using a logical analog to traditional cel animation. In the traditional approach, animation key frames are sketched on animation paper, and hand ``flip-booked'' back and forth to check the animation process. Then, these are cleaned up by erasing stray lines and re-drawing lines to thicken them as needed. This is then passed to an ``inker'' who places a cel (i.e. a sheet of celluloid or acetate) over the page, and careful traces the picture onto the cel. This cel is allowed to dry a bit, then passed on to a ``colorist'' who flips the cel over and paints on the ``wrong'' side of the cel. This produces the classic ``clean'' color look of cel animation. The reverse-side painting covers up brush strokes and the inked lines hide the boundaries so that small painting errors are not evident in the finished product.
The resulting cels are cataloged and used in producing animation layups, which are photographed. Each layup consists of a background (usually not a cel, and usually of somewhat higher quality -- they are often painted), with successive layers of cels. Usually each character in a scene is on a separate cel, and non-moving parts are separated from the parts that move (such as head or mouth). This reduces the effort required to animate the scene, by allowing the same cels to be re-used.
This process produces beautiful animation, but is of course, very labor intensive. There are usually several animators and dozens of inkers and colorists involved in even a modest-sized film project. Animation is cheaper than live-action film, but still very expensive. Needless to say, we don't have that kind of budget!
Numerous computerized approaches have been used to reduce the labor cost of producing these kinds of films, starting with the elimination (or simpification) of the inking and coloring steps, which are now routinely done by scanning penciled art into the computer and coloring it automatically. Less routine, is the practice of converting scanned art into vector graphics (or directly creating vector graphic art on the computer). There is also 3D animation, but that is something I regard as a different art form, so it is not really addressed in AutoManga, which is based on 2D animation throughout.
For ``The Light Princess'' we decided to go with vector cel animation in which the vector graphics were captured from original art scans using AutoTrace (another free software package). The resulting vector graphics are being manipulated in Sketch, and will be stored in SVG (``Scaleable Vector Graphics'' a W3C Consortium standard) format. These will be pre-rendered into PNG format files where feasible, JPG files may be used for backgrounds and other ``smooth art''. This gives us a minimum support base to target with AutoManga: SVG, PNG, and JPG. The animation files will be described in a native XML-compliant AutoManga format, which will also be allowed to embed XML code for use by other game components (such as the character and world engines).