Once you've processed your line art, you can go back into the file and add color or shades of gray. Simply convert the image from a bitmap mode to either grayscale or CMYK. You'll use grayscale mode for black-and-white reproduction. CMYK mode is for color work.

Preparing the Layers

After you've prepared the line art in Photoshop according to the directions in the preceding section, open the Layers palette. Double click on the Background layer. A dialogue box will appear. Rename this layer “Line art” and OK the dialogue box.

Select your Line art layer by clicking once on it in the Layer palette box and then click and hold the arrow on the right-hand side of the Layer palette box. You'll see several options. Choose Duplicate layer. When the dialogue box appears, name this layer “Color.” You now have two layers: Color and Line art.

Click on the Color layer in the Layers palette and drag it so it's under the Line art layer. Click on Line art and then select Darken from the layer options (it's a roll-down menu that should currently read “Normal”). Now, select the Color layer by clicking it once. You will do all your color work on this layer. You will do nothing more to the Line art layer.

The Layers palette, correctly set up for colorizing. Remember, once you set up the line art layer correctly, you will do all the colorizing on the color layer.

Using the Fill Tool

It's easiest to use the Fill tool to apply large areas of color. If you have drawn closed-off shapes, you can fill that area. You can close off open shapes with your brush tool.

You don't have to close it off in black, though. Use the color you're planning to use to fill in the shape. The image in the Line art layer will contain the actual black lines that will be seen in the final image.

Use the fill color to close off shapes in the Color layer.

Advanced Techniques

Once you've established flat colors with the Fill tool, you can use Photoshop's other tools to add highlights and shading as well as more advanced visual effects. For quickest results, you can select the areas you want to refine with the Magic Wand tool. Once these areas are selected, consider using the Burn tool for highlights and the Dodge tool for shadows.

Final Processing

Save the file as a Photoshop document. This preserves the layers so you can go back and make changes later. For your final output, you can choose Save As from the File menu and save the file as a TIFF. The TIFF will be smaller, because the layers will be condensed onto one single layer.

Now that you've added shading, this may be a rather large file. You may need to sacrifice some line sharpness to gain a more acceptable file size. Go to Image and pull down to Image Size. In the resulting dialogue box, make sure the Resample Image box is clicked. Change the resolution to 300 dpi. If the image size of the Photoshop document slows down your computer, you could do this step earlier in the process without harm.