In the world of 2D digital art, there are two major categories of graphics — bitmaps and vectors — yet so far we have focused only on the bitmap side of the house. Today I’ll try to correct that oversight with an introduction to vector graphics.
If you’ve ever used Photoshop or Corel Painter, or even MS Paint, you have used a bitmap graphics program. They’re sometimes called “paint” programs, or “image editing” programs. With a bitmap application, you are creating, changing, and deleting the pixels that make up the image. Pixels are what you see on the screen, those tiny little squares of color. It’s pretty easy to understand what’s going on with bitmap applications. Take a look at the icons on your computer screen. Each one is made up of hundreds of dots, or pixels. Like this:
The advantage of bitmap applications is how they mimic their real-world counterparts, the pencil and the paintbrush. The disadvantage is that bitmap images don’t scale up very well. They look very “pixellated” once you enlarge them past 300% or so. Also, digital artifacts begin to show up at higher zooms. For this reason, we say that bitmaps are resolution dependent: how good they look depends on the resolution used to display and print them. Bitmaps are collections of dots.
Vector graphics, on the other hand, are resolution independent. They are files containing coordinates, positions, curve information, and other information that are displayed as pixels (or dots on paper) when translated by a vector graphics program. (That last sentence is the one I’ve been trying not to write, but I can’t think of a better way to say it. This stuff is not easy to explain!) Think of a vector file as a mathematical description of how the computer should render a picture. The computer can draw that picture as large as you’d like, and it will still look razor sharp. One example of this kind of scalable vector object is a font. The font is described once and the computer shows it to you at whatever font size you specify. The letters stay sharp and clear whatever size you choose.
The disadvantage of vector graphics is that they are not good at creating realistic, shaded, and detailed artwork. This is beginning to change, as vector programs become more sophisticated, and bitmap programs begin to incorporate vector graphics abilities (such as the Pen tool in Photoshop and Painter). Here’s a typical example of a vector illustration. As you can probably tell, it is made up of many small areas of flat color, along with a few subtle gradients to suggest volume in the face.
Drawing with a vector tool takes some getting used to. It’s a bit like laying out pieces of spaghetti and pushing them around into shapes, then filling them in with color. It’s also quite a bit like printmaking, with individual flat areas of color combining to make up an image.
The main tool you use is called a Pen tool, but it’s not much like a real ink pen. Drawing with the pen tool is a matter of creating, moving, and deleting points (known as anchor points), some of which have built-in “handles” which affect the curve of the line as it enters and leaves the anchor point. As you can tell, it’s a very non-intuitive way of drawing. However, as the example at the top of the page shows (created with a free program called Inkscape), with hard work and dedication, amazing results are possible. I imagine that the yellow sports car took hundreds of hours to create.
Vector Graphics Programs
The industry standard, especially in the print and web graphics fields, is Adobe Illustrator. It’s quite expensive, costing more than $500, and perhaps the hardest vector program to learn and use. There are some free alternatives, including:
- Inkscape is a free, open-source vector graphics program. You can see a screenshot of Inkscape at the top of this article. Runs on Linux, Mac, and Windows.
- Raven, just released by Aviary, is the first web-based vector drawing program. It runs in your browser, and looks just like a high-end application installed on your computer. It looks very nice, but so far lacks any documentation.
- Karbon14 is a free vector drawing program, part of an office suite.
- Xara Xtreme is a Linux-only open-source release of Xara. The commercial version of Xara runs only on Windows.
In addition to Adobe Illustrator, there are these commercial programs, as well:
- ACD Canvas – Windows only
- CorelDRAW – Windows only
- Intaglio – Mac only
- Lineform – Mac only
- Xara – Windows only, but there is an open source version available for Linux (see above).