Some Notes on Sizing Images: Part 1, Resolution

One of the most common thing to do with photos is resize them, whether to get the ready for the web, fit them onto 4 x 6 standard prints, enlarge them, or even crop to improve the composition. And your ability to do any of these comes down to resolution and image size. Resolution refers to how many little digital dots you have in a given linear measure. For example, you might have 300 dots per inch (dpi) on a traditional print, or you might have 96 pixels per inch (ppi) for a screen display of an image. Here's an example of resolutions you'd need for some common uses:

Use	Resolution (in dpi/ppi)
Monitor viewing	96
Prints to be seen at a couple of feet	300
Prints to be seen at ten feet	60

The word resolution is clearly related to the word resolve, and that's the whole issue, as we'll see tomorrow.