You can use a Mac's default image-viewing program, Preview, to resize any image or multiple images at once. Here's how to resize images on a Mac.

There are two easy ways to resize an image in Photoshop. Photoshop is an editor by Adobe that lets you create designs and easily edit images.

To manually crop a picture in Microsoft Word, Excel, or PowerPoint, select it, and in the Picture Format tab on the ribbon, click the top half of the split "Crop" button.

Learn GIMP - you won't regret it. I'm a GIMP expert, and I've got 10 tips for getting productive faster with this great Photoshop alternative.