This page got its information from these sources: The Illusion of Life: Disney Animation, by Frank Thomas and Ollie Johnston; The Animator's Workbook, by Tony White; and the Animation Art Definitions site. For further research, these three sources are well worth checking out.
Inking by hand. A professional inker can painstakingly copy the animator's drawing by hand, with any medium that the cel can hold. This freedom of media comes with a price: time. A single complex drawing can take hours to ink by hand. The results, however, are often fit to be hung in art galleries. You can see examples of hand-drawn inks in classic Disney films, such as the original Fantasia (which threw everything but the kitchen sink onto celluloid).
Animation Art Gallery's Classic Disney Cels
I also recommend borrowing a copy of The Illusion of Life from the library, for further reference. To quote the slipcover of my copy, this 575-page book offers "489 plates in full color" and "thousands of black-and-white illustrations." (Plus, the book's account of what Disney's ink-and-paint team went through for the original Fantasia should leave your jaw hanging somewhere about your ankles).
An artistic drawback to inking by hand, though, is that the results, no matter how good (and classic Disney cels look great), will never perfectly match the original pencils. One reason is the media -- pens and brushes do not behave like pencils, and a cel's surface is as smooth (and as difficult to draw on) as glass.
A second reason is human imperfection. Here's a parallel from the comic book world:
Left: a 2H pencil sketch. Right: inked with a brush, the original pencil lines erased.
I both penciled and inked this piece, yet the ink lines do not perfectly follow the pencil lines. While some of the changes were intentional (such as the extra lock of hair and the extra details in the T-Shirt), there were several subtle, unintentional changes (such as the lines that define the shoulders, face, and ears). I never get an exact copy of my own drawings. I always end up redrawing the art in ink, using the original pencils as a guide, while trying to keep the "feel" of the original drawing as intact as possible.
Take it from someone who's struggled to master inking for the past five years: an inker does not merely "trace" lines!!! -- Jen Hachigian
Xerography. Here, the pencil drawing is xeroxed directly onto the cel. Xerography is faster than inking by hand, cheaper than hiring an inker, and produces an exact copy of the animator's pencils. Also, if you want to enlarge or reduce the size of the drawings over time (to make a character appear to get smaller as he runs away from the camera and into the distance, for example), you can do that kind of "special effect" easily with the xerox process.
However, a xerox copy of a pencil drawing can look harsh, especially when compared to hand-drawn inks. Disney used xerography for the "inks" on several feature films, starting with 101 Dalmations. While nothing now stood between the animators' pencils and the audience, most of the audience (and Walt Disney himself) missed the delicate look of hand-drawn inking. Xerography improved by the time of The Rescuers, which used a medium-grey toner for a softer-looking "line" (the cel artists added some color inks, too, but xerography handled most of the inking).
I'm not sure, but I think several animated TV series (both here and in Japan) use this type of low-cost, high-speed inking. I don't often see it in modern animated features, though.
An Online Anime Cel Gallery -- at these resolutions, I can't tell if these cels were inked by hand or xeroxed onto the cel. Which is probably a good example as any of why xerography wouldn't hurt the look of an animated TV series. Ink lines that look rough at print/film resolutions can look just fine at TV resolutions:
A third option is digital inking. Here the cel artist uses a computer program to do what would normally take hours to do by hand. These programs handle more than just inks, though. Toonz was used to ink, paint, and add computer FX to such films as Balto, Anastasia, and Mononoke Hime. At Sony's SIGGRAPH '98 booth I saw a live demonstration of another computer system (I wish I knew its name), which artists used to ink, paint, and add computer FX to the incredible Shamanic Princess.
Digital inking, at its best, combines the precision of xerography with the clean look of inking by hand.
A Gallery of Shamanic Princess Screen Captures
A Great Screen Capture from Shamanic Princess
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