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.

It's easy to resize a layer in Photoshop, and you'll need to if you want to manipulate the size of text or images. Here's how to do it.

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.