What is a raster graphic?
A raster graphic is made of a grid of small squares known as pixels. Photographs must be raster graphics in order to show shades of colors. Adobe Photoshop is the recommended software to create and save a high-quality photo as a .tif file. Raster images are resolution-dependent—that is, they contain a fixed number of pixels. Resolution is measured in Dots-Per-Inch, also known as DPI. To get a good quality printed image, the number of dots should be at least 300 DPI. Below this number, the edges will appear fuzzy and rough. It is not recommended to use the raster format for logos.