The next time you forward an image to your communications person or a magazine editor, have a heart. Even though publication professionals often can make something wonderful with very little raw material, they can’t create a story where there isn’t one, and they can’t publish a beautiful centerfold image from the thumbnail you pulled off the Web.
Pixels per inch (ppi) are a unit of measure. Simply put, this unit defines how much color data is crammed into each inch of your digital image.
• On the Web, an image can look clear even if it has a very low resolution; a Web standard is 72 ppi.
• To print, an image would preferably be 300 ppi or more. In rare instances, you may get away with 150 ppi; however, 72 ppi looks hideous.
Here are 2-by-3-inch pictures displayed at the same screen size. Image A is 72 ppi and B is 300 ppi.
The difference is obvious
Always start with high-resolution images, because it’s easy to make an image smaller, but often impossible to make it larger. Low-resolution images look fuzzy and pixilated when you enlarge them, because they lack any color data for previously nonexistent pixels.
To demonstrate, look at this example. On the left, we start with a magnified look at a black and white, 2-by-2 pixel image.
Then, we use Photoshop to double the image size to 4-by-4 pixels. Photoshop uses the original black and white-colored pixels to approximate color for the new pixels. The intention is to mimic the nearest pixel colors, so that the image retains smooth color transitions as it’s stretched to a new larger size. The results, however, introduce
coloring nothing like the original image.