As more and more traditional publishers accept digital images, artists are turning to free and open source software (FOSS) tools to create cartoons and illustrations.
Both vector and bitmap drawing programs let you draw lines. Generally speaking, vector lines are more reusable and revisable, while bitmap lines are more artistic.
Before starting a drawing in any tool, plan how many layers your drawing will have. A simple bitmap drawing may have only three or four layers, such as a background, a character, and a car. A vector drawing may have more layers; even a single property in your drawing may have several layers. Using layers can make it easier for you to revise your drawing or reuse it in another drawing in the future.
When drawing lines with a bitmap program, you'll need a good pen tablet, such as one from Wacom. (Check out Nathan Willis's article on how to get started with Wacom tablets in Linux.) Open source applications such as the GIMP (for Windows, Linux, Unix, and Mac) and Paint.NET (for Windows only) offer line tools such as a pencil, a paintbrush, and an airbrush. You can adjust settings such as the brush width, fill style, antialiasing mode, and blending mode, and save your favorite brushes for future use.
One of the major benefits of vector lines is that you can revise them easily. FOSS tools for vector graphics include Inkscape (for Windows, Linux, and Mac), Xara Xtreme for Linux, and Skencil (for Linux or Unix).
If a vector drawing has too many layers, you can combine several finished layers into a group to make the scene simpler. In Inkscape, for example, you can group the layers by navigating to Object -> Group. If you want to edit the group again, simply double-click it or navigate to Object -> Ungroup.
You can also convert a bitmap image to a vector image by using Inkscape's trace bitmap tool (Shift-Alt-B). This technique is useful for artistic portraits. For example, you could create a caricature portrait by importing a photo and converting it to vector lines. You could then transform the vector lines by using the editing nodes tool (F2), then make the jaw bigger, the cheek bone higher, the lips thicker, and so on.
Color your drawings
Coloring vector and bitmap images is relatively simple. If you want to color a vector image in a bitmap program, first export the image as a bitmap. Paint.Net's Paint Bucket and GIMP's Bucket Fill tools offer dozens of patterns for bitmap coloring. You can also use the line tools to draw colored patterns.
In the GIMP, you can color images on the same or a different layer. Using a different layer may take more time, but it allows you to revise the colors or the lines separately in the future.
You can color bitmap images in vector programs (for example, drawing lines in Paint.Net but adding colors in Xara Xtreme for Linux) to create special effects, but the process is more complicated because you need to draw more vector shapes to contain the colors first.
Properties and background
Google SketchUp can help you draw properties and backgrounds quickly. With the line, rectangle, circle, and arc tools, you can draw objects and a background simply by dragging the cursor through three-dimensional coordinates. Google SketchUp offers more than 100 materials, including brick and cladding, wood, stone, tile, vegetation, carpets, and water. Sketchy Effects helps you create a hand-painted effect on your drawing. If you find that SketchUp's style is just what you need, you can export your work directly as a bitmap file and put it in a layer of your drawing program, or revise it in another drawing program.
Other FOSS tools can help you create properties as well. For example, you can use the emboss tool in Paint.Net to create an embossed artwork as a property in a scene. You can also simply create a rectangle and fill it with colors and patterns to make a background.
Improve, polish, and send out your drawing
Editors usually accept JPG files because of their relatively small size compared to other kinds of graphics files. Before exporting your drawing as a JPG file, see how your image looks in its compressed form. You may need to revise some of the layers. For example, if a background layer is too glaring, you can darken or blur it. You can also use Paint.Net or the GIMP to give your work an artistic effect. For example, you can make your work look like a pencil drawing by going to Effects -> Pencil in Paint.Net.
Set the compression of the exported JPG file to allow for good image quality and definition. Choose a JPG quality of 85 to 95%. The definition of the exported file should be at least 300 dots per inch for a magazine, meaning that a 4-by-3-inch illustration in a magazine needs a digital image that is at least 1,200-by-900 pixels.
The powerful functions offered by FOSS drawing programs can not only help you to present your digital artworks, but can also help you to improve your artistic skills and improve your visibility in the art world.