When collecting digital photographs and other imagery for a printed piece, it is important to understand resolution. Digital images are made up square dots called pixels. Each pixel represents the color of a small part of an image. The more pixels you have in an image the smoother and more realistic the image will appear. Resolution refers to the density of pixels in an image. Low resolution images have lines that look jagged and you can actually see the individual pixels that make up the image. High resolution images have many more pixels. That means that each pixel makes up a much smaller part of the image – making them so small that they become invisible
How much resolution you need is determined by the size the image will appear when printed. If you’re only going to print 2 inch thumbnails of your images, than you don’t need a lot of resolution. But if you’re printing a picture of a landscape that you want to blow up to three feet tall, then you want as much resolution as you can get.
The resolution needed to view an image well on your computer screen is much lower than what is needed for a printed piece. One good rule is to make sure your photo appears on your screen at 3 times the size at which you plan to print it.
Adapted from “Basics: Understanding Resolution” by Jim McGee, www.vividlight.com