What is a Vectorized Image?

On a computer, there are two basic methods for representing visual data: dots and geometry. The method of using dots to tell each pixel where to go is known as bitmap imaging, but it’s more commonly referred to as raster graphics. Vector or vectorized graphics is a method that uses geometrical formulas.

Vectorized images were popular in the past because they used much less memory than raster images. Because they could be represented with only a few lines of mathematics rather than a detailed description of where each pixel had to appear, most of the earliest graphical computers used graphics that were characterized long arcs, circles, and other simple geometrical shapes. Vectorized images became less common in most applications as computers advanced and memory became less of an issue, and raster images took their place. Vectorized graphics, on the other hand, are still around and are experiencing a resurgence in popularity for a variety of reasons.

Vectorized images use a mathematical formula to describe every aspect of their shape. Consider a simple shape, such as a circle, to see how useful this can be. In a raster image, a 100-pixel-wide circle must be used to store the locations of each of the pixels in a 1,000-pixel area. Because only those 1,000 pixels were described, pixelization would appear if you zoomed in on that image.

A simple mathematical formula would describe the radius of the circle and the fact that it is a true circle on a vectorized image, and the processor could calculate the rest. Not only is there less information to deal with, but if you zoom in on the image, the smooth line will remain because the processor will continue to calculate the arc of the circle. This makes it much easier to manipulate vectorized images, such as growing or shrinking them, twisting and bending them without losing quality. It also means that vectorized images will appear as higher-resolution graphics on higher-resolution monitors, whereas raster graphics have a maximum resolution beyond which no noticeable improvement can be seen.

Vectorized images are widely used in computer-aided design, as well as many rendered images for movie special effects and, increasingly, computer animation. Vectorized images are used in the popular Flash format, which allows for much higher resolution in smaller files than traditional raster graphics, making them ideal for Internet applications and movies.

Automated raster to vector conversion is a field of computer intelligence that is constantly evolving. Many programs try to automate the process of converting a raster graphic – such as a painting or photograph – into a vectorized version, which can then be more easily manipulated and, in many cases, is smaller in file size. Many vector-image programs, such as Freehand, have a Trace tool that automates this process, and there are a variety of specialized applications available, each with its own set of advantages and disadvantages.