Back to the drawing board

Producing a creative drawing on paper tends to be a two-stage process, first sketching the defining lines in black (‘inking’) and then filling in this framework with colour (‘colouring’). The first truly mainstream program to attempt to translate this creative drawing process to a computer environment was Adobe Illustrator in 1987. Based on Adobe’s PostScript technology, Illustrator – and its subsequent competitors such as CorelDRAW and Macromedia FreeHand – builds up drawings by tracing out mathematically defined vectors or paths. Applying a stroke to an open-ended path turns it into a line, while filling a closed path produces a coloured shape, and given a stack of stroked and/or filled paths you have all you need to reproduce any illustration, technical drawing, graphic design or even text-based layout. It is an efficient system and one that has become second nature to generations of computer artists.

Back to the drawing board

Second nature maybe, but no-one could say that drawing with vectors is truly natural. Compared to the simple creative freedom of sketching on paper, the whole process of drawing onscreen is awkward and indirect (despite important advances, such as freehand tools and digitising tablets) and further limitations are imposed by the underlying vector architecture. For creative drawing, you often want lines that are fluid and expressive, but that is not possible with stroked paths that are inherently uniform along their length. Again, advances such as vector brushes that treat each stroke as a filled path can radically improve the end results – Creature House’s Expression deserves special mention in that respect – but still no-one would claim they were as natural as pens and pencils.

It is not just the computer equivalent of inking that’s confining, as the situation is worse when it comes to colouring. Traditional artists expect to simply fill in the holes in the sketched framework, but on a computer that proves impossible for areas that have been produced by overlapping and intersecting lines – as far as the program’s concerned, there is not any shape to fill. Fill algorithms need a single, and ideally, closed boundary path to work to, and multiple open paths do not provide one. This means that to apply colour to a hand-drawn vector sketch, you will first have to recreate the areas that you want to fill in as objects.

Ultimately, it is possible to recreate any drawing using vectors, including hand-drawn illustrations, but you will have to construct its apparently spontaneous appearance by laboriously defining the shape of each separate coloured region as a closed path (and even do the same for each inked stroke if these aren’t to be of uniform width). In other words, the fundamental unit of a vector-drawing program is not the sketched line but the defined shape, which explains why almost all vector-originated artwork looks so clearly artificial and computer-generated. In fact, it would be hard to devise any system less like the creative freedom of pen on paper, both in terms of process and results. As a result, programs such as Illustrator and FreeHand have always failed the one group of users they were designed to help: freehand illustrators.

But there is an alternative: namely, to use bitmaps rather than vectors. Each of today’s major bitmap editors, such as Adobe Photoshop and Corel Painter, provides far more responsive and realistic interactive drawing tools, and, of course, bitmap programs offer another unbeatable advantage in that you can draw your sketch on real paper and then scan in the result. Even better, by creating a new layer on top of your scanned quick sketch, you can use it as the basis for final inking using the bitmap editor’s brushes.

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