Cel animation — drawings inked onto transparent cellulose acetate sheets and photographed against painted backgrounds — was the dominant production technique in Japanese television and theatrical anime from the 1950s until the late 1990s. Its conventions still shape how digital anime is composed today, since the digital production pipeline largely simulates cel-on-background composition rather than replacing it.
Cel technique in outline
A traditional cel-animation shot is constructed from at least two distinct visual layers: a painted background, executed in opaque gouache or acrylic on board, and one or more transparent acetate sheets on which animated figures are drawn and painted. The cels are photographed against the background one frame at a time. Multiple cel layers per frame allow foreground, midground, and animated elements to move independently.
Limited animation as economic choice
TV anime from 1963 onward used substantially fewer drawings per second than American theatrical animation — typically eight cels per second, dropping to three or fewer for held shots. This 'limited animation' was a direct response to the per-episode budgets imposed by sponsors. Mushi Production's Astro Boy defined the practice. Several techniques — stock backgrounds, mouth-only animation, the 'cycle' (a short loop of repeating drawings), the slide (sliding a single cel across a background) — became standard.
The transition to digital
Through the 1990s, scanned cels increasingly entered digital compositing pipelines. By the late 1990s, several studios — Toei first among them — had moved to fully digital ink-and-paint, with line drawings scanned and coloured on computer rather than inked onto physical acetate. Sazae-san (Eiken) was the last major weekly anime to use traditional cels, switching to digital in 2013.