As the graphical pillars of Adobe’s Creative Suite, Photoshop and Illustrator now offer state-of-the-art vector- and bitmap-based handling, but things weren’t always like this. Back in 1992, when I first laid my hands on them – both just recently ported to the Windows platform – things were very different. To begin with, there was no meaningful integration and the two programs were presented as opposites, best kept far apart. Either you were an Illustrator vector user or a Photoshop bitmap user and ne’er the twain should meet…
Moreover, the applications themselves were far from the creative powerhouses of today. In particular, even by its fourth release, Illustrator’s creative formatting options were way below dismal: you could apply flat CMYK or pantone-specified colours, uniform-width lines either solid or dashed, and, er, that was about it. The reason usually given for this poverty of creative options was that Illustrator was a vector application, and if you wanted to get creative you should be using the bitmap-based Photoshop. This didn’t wash because Illustrator’s biggest rival on the PC, CorelDRAW, simply didn’t have these same limitations and could happily mix imported bitmaps and vector objects, filled with bitmaps and effects like advanced graduated transparency. Other programs – notably Xara and Macromedia Fireworks – took these features further still to build naturalistic bitmap-based images from vector-based roots.
The bottom line is that although vectors and bitmaps are very different beasts, if you want to get artistic they’re best combined. In fact, all graphics are rasterised eventually for output to bitmap-based screens or printers, and all manual input originally starts off as a vector – how else does your PC understand mouse or pen movements except by turning them into vector paths along which a brush’s pixel-based effects are applied? So why did those early versions of Illustrator so studiously avoid all bitmap handling? The answer is that Illustrator isn’t just any vector application but a PostScript-based vector application.
PostScript is Adobe’s seminal Page Description Language, devised back in 1984, which describes typefaces as scalable outlines to enable resolution-independent output. The shapes that make up each letterform don’t require any formatting more fancy than a solid fill, hence PostScript’s creative capabilities were rudimentary. Even so, they could still be used for more than just text – and the first Mac-only release of Illustrator in 1987 was Adobe’s way of extending PostScript to handle graphics. Illustrator files were effectively self-contained, “encapsulated” PostScript files that could be output directly to a PostScript device.
If PostScript explains Illustrator’s original creative weakness, it also provided the program with its greatest strength – because the absence of bitmaps and bitmapped effects allowed Illustrator to completely avoid rasterising its output the way its more creative rivals had to, Illustrator files could be saved as vector-only EPS (Encapsulated PostScript) that could then be incorporated in a layout within a DTP program. Only when finally output from the DTP application does the embedded EPS file need to be rasterised at the maximum resolution of the PostScript output device – absolutely crucial for high-resolution imagesetting. This also explains why early Illustrator was restricted to those flat CMYK fills, necessary for clean and reliable colour separation onto printing plates for four-colour process printing presses. For high-resolution, colour-separated commercial print, Illustrator’s creative limitations were, in fact, strengths.