Labels:text OCR: 1. The rough pencil stage. 2. The ink stage. Note the lines defining the placement of shadow and highlight masks. The mask lines are red and blue. 3. The red, blue, and black lines are separated, the cel is painted, then the masks are applied, creating the final, painted cel. If additional masks are required, a separate tracing can be made, allowing up to three additional levels of mask per tracing.