Back to the drawing board
The benefits of bitmaps when colouring your original sketch or scan are just as clear. Since, by default, each bitmap canvas is a single layer, it is possible to fill any enclosed area simply by clicking in it with the Paint Bucket tool. A bitmap editor cannot ‘see’ shapes any more than a vector drawing program can, but instead works like the Magic Wand tool, by replacing colours similar to the pixel that you clicked on – that means you need to apply anti-aliasing or feathering to the fill to avoid jaggy fringes around anti-aliased lines. This lets you apply flat colours, gradients or patterns to your artwork in seconds, or slightly longer if you remove unwanted gaps, stray pixels and anti-aliasing.
With such superior inking and colouring, it looks like game, set and match to the bitmap editor. So perhaps Illustrator and its ilk ought to forget about creative drawing entirely and concentrate its efforts on logo design and technical drawing, where precision is more important than expression. It is certainly true that for painterly works built around subtle brushwork and continuous tones, bitmaps are the way to go. However, for the typical creative illustration built from clearly defined lines and areas of colour, vector handling still proves unbeatable. It all comes down to the underlying nature of vectors.
To begin with, the object-based nature of vector design provides extraordinary creative control – once you have applied a stroke or a fill in a bitmap editor, your changes are pretty much permanent, whereas in a vector drawing everything remains infinitely and instantly fine-tunable. In other words, you can keep redrawing and reformating your lines and shapes until you find the effect you are looking for. And with advanced features such as Illustrator’s gradient meshes, multifill styles and non-destructive effects, the extra control offered by vector handling leads to new creative possibilities.
As well as absolute control, vectors provide absolute quality. Since each vector path is a mathematical function rather than an array of pixels, it is intrinsically resolution-independent, which enables it to be scaled to any size without loss of quality. Crucially this also means that, unlike bitmap images whose output resolution is determined by the half-tone screen (see RW79) and so typically 150 lines per inch or less, the black lines in a vector drawing can be output at the maximum device resolution. Since a PostScript typesetter can output at over 1,500 dots per inch, the resulting lines are as crisp as text on the page, and you will not need bitmap-based anti-aliasing to fool the eye into seeing smoothness – at that resolution lines are smooth.
Tracing the way
What we are seeing here is a spectrum with the freedom and expression of pen on paper at one end and the quality and control of vector drawing at the other, and bitmap editing falling close to the middle. Obviously, the ideal would be to combine the strengths of all three. Scanning and reworking hand-drawn artwork takes care of integrating paper and bitmap workflows, so what is needed is a way to then turn edited bitmaps into vectors – and the obvious solution is tracing.
I still remember my excitement when GEM Artline first introduced the ability to place a partially greyed-out bitmap into your layout, which you were then expected to manually trace using the path-based drawing tools. Sounds crude, but do not knock it: this manual, line-by-line approach meant that you can swap between stroked paths and filled paths as appropriate and that the artwork is kept as clean and editable as possible. Nowadays, you will even find dedicated Illustrator add-ons such as LogoSpruce, designed to make this bitmap redrawing process and its end results as smooth as possible.