Hidden picture layout tool

The picture layout tool is a fantastic way to work with multiple images on a slide in order to move, resize, and even reshape them with consistent dimensions and ratios.

The picture layout option in the picture formatting ribbon allows you to convert your pictures to SmartArt graphics, which itself is a great way to arrange the images (and even add consistent text elements).

Taking it a step beyond SmartArt, you can then re-convert your objects back to pictures while they retain the shape and formatting.