Raster and Vector Graphics

There are many different formats for computer graphics, but almost all can be divided into two types: vector and raster graphics. Most people are familiar with raster graphics, which store pictures as a collection of pixels of different colors. But there is another important class of file formats with some advantages over raster graphics, the vector file formats. These store pictures as a collection of objects or as instructions for drawing a particular type of picture. Let's take a look at these two types of formats.

Raster Graphics

Raster formats include GIF, PNG, JPEG, and TIFF. Files in these formats store pictures as a rectangular grid of colored (or black and white) pixels. These are the types of graphics your digital camera stores: the camera records the color it sees at many different points inside a rectangle and writes those colors to a file. Raster formats are easy to display and manipulate. Many programs can view these files, including web browsers. Microsoft Paint, which has come with Windows for at least 20 years, can edit some raster formats. Paint is a very simple program, but there are much more sophisticated programs, like Adobe Photoshop and the GNU Image Manipulation Program, for editing raster graphics. One disadvantage of raster formats is that they can't be scaled very well. For example, if you take a picture with a one megapixel camera and try to blow up the picture to portrait size, the resulting image will look pixelated and unattractive.

Vector Graphics

Popular vector formats include PDF, SVG, and Postscript/EPS. Files in these formats store pictures as a collection of shapes and directions on how to color and combine them, or as instructions on how to draw a picture. For this reason, they can be scaled to be very large or very small with no degradation in quality. Vector graphics are often used for page layout for books and magazines and for illustrations to go in these types of publications. These files take a little bit more work to view, so you may need a special program to see them. Here are some different programs for opening SVG files and opening EPS files. In addition to being scalable, vector graphics usually take up less room to store. They are a bit more difficult to create, however.