Have you ever tried to use a photo you found online in a presentation or document and it looks blurry? Or tried to order a print of an image and the website tells you the file isn’t high enough quality?

Understanding image resolution can help you avoid those problems.

(Lookout, we’re going to get a bit technical up in here today!)

It boils down to this: photographs are constructed using a fixed number of colored pixels. Photos are measured in pixels per inch (ppi) which indicates how many pixels there are, indicating the level of detail that’s contained within them. The more ppi your image contains, the higher the quality of the digital image.

For example: a 1-inch by 1-inch image at 300ppi equals 300 individual squares of color. Likewise, an 18 by 24-inch image at 300ppi contains 129,600 squares of color. Keep in mind that more pixels means a much bigger file size.

Now let’s say you want to take that 1-inch image and print it as a 3-inch square picture (triple the size). Since there is only a fixed number of pixels, the computer has to take its best guess as to what colors should fill in the gaps. It’s called interpolation, and it’s what causes an image to appear blurry when it’s enlarged. The computer really has no way of knowing what colors to fill in the gaps with.