The Basics of Image Resolution: Video 101

The following lesson was created by Vimeo for its Vimeo Video School. It's used here with permission. Look for a new lesson each week.

Image resolution is an important term when it comes to making and watching videos. If you go to an electronics store you'll be bombarded with information about how every gizmo and gadget is HD, Full HD, even HD 3-D. Let's dig a little deeper and learn what all the fuss is about.

Many factors determine the quality of an image, but for the purpose of this lesson we're going to focus on just one aspect: resolution. At its most basic level, resolution is a measure of how many pixels an image contains. Pixels are the tiny little squares that make up a digital image. Each minuscule square is like a piece of puzzle, by itself it doesn't do much, but collectively all the pixels combine to form an image.

As an example let's look at a simple image, like the Vimeo icon below. From left to right you'll see that as we add more pixels or increase the resolution, the image gets sharper and more detailed.

Typically resolution is expressed as the image's length (in pixels) times its height (in pixels.) So if someone says their camera records video at 1280 by 720 resolution, what they're saying is that it records a rectangular image that is 1,280 pixels wide and 720 pixels tall.

Let's review some common resolutions you'll encounter with online video. There's 640x480 which is commonly referred to as standard definition (or SD), 1280x720 which is the minimum for what's called high definition (or HD), and finally 1920x1080 which is sometimes mentioned as full HD. Keep in mind that all of these terms are relative and as technology advances HD will include higher and higher resolutions. Often when referring to a certain resolution, a person will only refer to the image's height. For example, if you overhear someone say "my camera shoots video at 1080", what they mean is that it records video at 1920x1080 resolution. Below is a chart showing the relative sizes of these common display resolutions (note that these images are not to scale.)

Resolution is important when you're shooting and editing video. More pixels doesn't always equal a better image, but it helps to understand some of the numbers that get thrown around when gadget aficionados get together.

Ready for more? Learn all about tripods or view more lessons at the Vimeo Video School.

Guest Post's article first appeared on OnlineVideo.net