Filling is probably the easiest step in the process. A separate ‘Fill’ layer is created below the ‘Ink’ layer and a Paint Bucket tool is used to spill ink into the the solid areas. The tool can be set to use any ‘ink line’ layers as containers while ignoring the sketch and text layers layers. You can even set the Paint Bucket tool to fill to the centerline of the vector paths, which simplifies color registration. Unlike Vector layers, the Paint Bucket tool only works in a bitmap (pixel-based) layer but resolution independence isn’t important with fill layers because any aliasing that occurs will be overlapped and hidden by the vector-based brush strokes.