What are raster images?

A raster image is simply an image made up of tiny pixels of color. Depending on the size of the image there will be hundreds, or even thousands of different pixels placed together in the right way to form the image you see.

In the following raster image, you can see that at normal size it looks great, and there is lots of different shading. However, the right-hand side shows that when you zoom into this image using Prezi, you will start to see the individual pixels that make up the shaded areas. This degrades the quality of the image when viewed at this size.

The preceding image has been saved as a PNG (Portable Network Graphics) file using the much loved Adobe Photoshop.

Some other raster graphics editors you could use to create raster images are: