In very early cartoons made before the use of the cel, such as Gertie the Dionosaur (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 Barre the background and the animated objects were drawn on separate papers. 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. The cel animation process was invented by Earl Herd and John Bray in 1915.