To edit animations sometimes is very slow to use archives of big resolution and many times to greater greater resolution noise. Or it was it is necessary to clean more the drawings and paint them goes back but complicated.
My solution is to scan it to 1bit to 150 DPI, paint it in this resolution edit the animation and afterwards escalarlos using quinema-escalar. This application uses potrace to increase each layer of colour without losing quality.
quinema-escalar -c -s 2 draw.png draw2.png