Perl Graphics Programming

Vector Graphic File Formats

Vector graphics are not represented by a fixed matrix of pixels, but by a collection of points and instructions for connecting those points. Whereas raster graphics cannot be scaled without losing or resampling the image data, vector graphics may be rendered at any scale without a loss of quality.

When we talk about vector graphics, we are actually referring to vector graphic file formats. Vector-based display devices (such as oscilloscopes or the old Vectrex video game console) are rare these days. All of the images that we cover in this book become rasterized in the end, whether it is by the display software, video card, or printer.

The two vector image formats that are of interest to us here are the open standard SVG format (Scalable Vector Graphics) and Macromedia’s SWF format (Shockwave/Flash). You might argue that PostScript and PDF are also vector formats, since each typically defines lines and curves as a series of points and control points. However, nothing in the PostScript language description restricts it to using only vector graphics. You could, for example, craft a well-formed PostScript document in which each page is represented as a raster graphic. PostScript and PDF are more properly defined as high-level document formats, as we shall see later in the chapter.

At first glance, you might think of SVG (described in Chapter 6) and SWF (described in Chapter 8) as competing graphics formats. The two are very different beasts, actually. The overriding ...