If you have a blank area surrounding your image, you can use Photoshop’s TRIM command to crop it away with one fell swoop.

Open an image with white space around it. Go to IMAGE > TRIM. You will see a dialog box that gives you choices on how the trim will be applied. Accept the default settings and click OKAY. The photo will be close cropped automatically. Photoshop will make the overall image as small as it can without cutting out non-white areas of the image.