I just finished this illustration for my diary of Hera’s stuff, and thought I’d share the simple technique I use for colouring pen illustrations in Photoshop. Clicking on the images below will bring up a close-up image.
Step 1 | Open the scan of your drawing in Photoshop, and create two new layers below it. One will be your background colour (I’ve used white here), and the other will be for painting in the colours of your drawing.
Step 2 | Adjust the brightness and contrast until the paper is as white as possible.
Step 3 | Select the background of the sketch with the magic wand tool, and delete it. Make sure all little bits of paper speckle are removed so the colour comes out nice and clean.
Step 4 | Set the drawing layer to Multiply. This will allow the colours below to show through your drawing, and make the pen work come out nice and dark as it multiplies over the colours below.
Step 5 | Use the magic wand tool to select the background of the sketch. Then invert the selection so that you have only the drawing selected. Feather the edges of the selection (Menu Bar > Select > Feather.) Click on the blank layer below the sketch (multiply) layer and fill the entire sketch with a predominant colour.
Step 6 | From here in, apply colour to this colouring layer whichever way you feel comfortable. Applying colour on its own layer(s) makes it easy to adjust the colours later while keeping your drawing in its original condition.I use a combination of the paintbrush and the magic wand / lassoo tools to select areas from the sketch and fill with colour. You can experiment and go as elaborate as you want with colour, shade and textures.