This is how I build a colour comic in Photoshop.
Scan the original drawing.
I start by scanning a black-and-white drawing.
The drawing should be drawn with colouring in mind. Large dark areas are generally added during the colouring, so they should not be done as part of the black-and-white drawing.
The colouring style I describe here relies on using the ‘bucket’ tool to fill large areas; they can also be filled using brushes.
Clean up the drawing in Photoshop.
I open the scanned drawing in Photoshop.
For ease in colouring, the scanned linework should be smooth, high-contrast, and without gaps surrounding each area that will be coloured. Even though I draw in india ink, I generally have to increase the contrast to make the drawing as black and as white as possible. Spending time cleaning things up here makes the next steps much easier.
Add colour ‘flats’.
I start colouring the drawing by selecting white areas to fill with solid single colours, ‘flats’.
These colours don’t have to be the final colours; they are just to make areas easy to select. These areas can be a single colour later in the final artwork, or they can later be gradients or patterns. The colours go on a new layer.
To make a flat, choose the layer with the linework. Select whitespace in an area that you want to be coloured all the same. If the selection ‘escapes’ from the area you want, check the linework to see whether there are any small gaps. Close the gaps in the linework and reselect.
The selection should go to the edge of the linework. However, the colour flats will eventually meet on another layer behind the linework, so the selection area needs to be made bigger. Expand the selection by a pixel or two.
Choose the layer that the flat will go on. The selection now applies to this layer.
Fill the selection with a solid colour.
Continue by selecting other areas on the linework layer, switching to the colour flats layer, and filling the selections there.
Eventually you will have a set of solid colour areas resembling the picture. If you make the linework visible, it should cover the seams between the flats.
Add final colours.
Once the flats are created, they can be easily selected to add more colours. For example, I wanted to add gradients to the sky, clouds, and ground.
These gradients will go on another layer that will be above the flats and below the linework. Create this layer.
Choose the flats layer. Select a flat.
Choose the new layer. Place the gradient in the selection.
The drawing now has layers, in order from top to bottom: linework, gradients, colour flats. With the linework visible, it looks like this:
Add text and smaller details
Additional details can be added as additional sets of linework, flats, and gradients. In this case, the text is all on one layer of additional linework, except for the letter ‘L’ near the bottom, which has another colour flat of white behind it on another layer.
And that’s my way of colouring on the computer.
If I wish to colour outside the computer, for instance with watercolours, that becomes a bit different, especially if I want to keep the linework separate. I’ve been doing a few tests of that.