NWE Help: Graphics: Intro: Raster and Vector Graphics

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The method used to create a graphic makes a big difference in the graphic's appearance and in its appropriateness for certain uses. This help page discusses the two most common ways to create graphics with a computer -- raster and vector -- and offers some guidelines on their use.

Raster, or bitmapped, graphics produce images as grids of individually defined pixels while vector graphics produce images using mathematically generated points, lines, and shapes. Until recently, raster ruled the roost on the World Wide Web, but the growing popularity of new vector-based web design programs such as Macromedia Flash is changing that. Currently, most web browsers require special plug-ins or external viewers to handle vector graphics, but a new format, SVG, promises to bring vector graphics to ordinary web pages soon. The W3C, the organization that sets standards for HTML, has standards for the SVG (scalable vector graphic) format, and popular browsers such as Netscape Navigator and Internet Explorer are have plug-ins that can allow readers to use SVG graphics.

So, how do you decide which method is appropriate for your graphics project? Here are some thoughts:

Raster

Until most browsers support the SVG format, raster is the way to go for web graphics. The dominant GIF and JPEG formats, and the increasingly popular PNG format, are raster graphics. Moreover, raster will remain the best mode for working with photographs and other images with complex and subtle shading.

Vector

The clean lines and smooth curves of vector graphics make them an obvious choice for logos, drawings, and other artwork that will appear in print. Also, the use of mathematical equations enables vector graphics to be scaled and manipulated repeatedly without distortion. The SVG format promises to deliver the same advantages to artwork on the web. In addition, vector artwork should require a lot less bandwidth than similar artwork in GIF format.