What are vector graphics?
A vector graphic is made up of points, lines, curves, and shapes or polygons, which are all based on mathematical equations. Inkscape uses these objects and can convert them into paths. A path is a line with a start and end, which are also calculated with a mathematical equation. These paths are not limited to being straight—they can be of any shape, size, and even encompass any number of curves. When you combine them, they create drawings, diagrams, and can even help create certain fonts.
How does this all relate to vector-based graphics? Vector-based graphics aren't made up of pixels. Since they are resolution-independent, you can make them larger (by scaling) and the image quality will stay the same, lines and edges stay clean, and the same images can be used on items as small as letterheads or business cards, blown up to be billboards, or used in high-definition animation sequences. This flexibility, often accompanied by smaller file sizes, makes vector graphics ideal—especially in the world of Internet, computer displays of varying resolution, and hosting services for web pages. Inkscape can help in the navigation of those waters of vector graphics and is a tool that can be invaluable when designing for the digital world as well as print.
These characteristics make vector graphics very different from JPEGs, GIFs, or BMP images—all of which are considered raster or bitmap images, made up of tiny squares called pixels or bits. If you magnify these images, you will see that they are made up of a grid (or bitmap), and if magnified further, they will become blurry and grainy as each pixel with bitmap square's zoom level grows larger.
As stated earlier in the chapter, many programs and applications are similar to Inkscape and can open vector graphics. Some can only open these files for viewing purposes and others can edit them.
Other applications typically used for page layout, but which can open and manipulate vector graphics include Scribus, Quark Xpress, and Adobe InDesign. Scribus is unique in that it is also open source (as Inkscape is) and can even import SVG files (the file type Inkscape uses) and manipulate them. The other programs can open, import, place, scale, and distort .eps files, a vector graphic file type, but unfortunately cannot create or otherwise modify vector graphics.
To create vector graphics, you will use illustration programs like Inkscape—which this book is about—or other programs like Adobe Illustrator, Adobe Freehand Corel Draw, Freehand, XARA Xtreme, or Serif DrawPlus. These programs all have native file formats, but allow you to export your graphics as .eps or .svg files, as needed. What is different about these applications than those for page layout is that you start with a completely blank document that allows you to fully design or draw what you would like, whereas the page layout application focuses on full page layouts.
In the previous section, it was noted that .eps, an Encapsulated Post Script file, is a common vector graphic format—or open format—that can be read by most applications that open and/or create vector graphics. However, there are other file formats that are also considered vector-graphic compatible. These include Inkscape's .svg format, Adobe Illustrator (.ai), Adobe Freehand (.Fhx), and Adobe Flash files, which are mostly vector data and are considered proprietary formats, tied more directly to the prospective software that can open them.
There are a number of other proprietary graphic file formats which can include vector graphics within them as well as rasterized (or bitmap) graphics. These include:
Also note that .eps files are basically the same files a Post Script laser printer uses. Both file types are developed by Adobe and are the foundation of the Adobe PDF format.