by Julieanne Kost
When a layer is larger than the canvas size (maybe you dropped a larger file into a smaller composite), Photoshop keeps track of the information beyond the visible canvas. This provides added flexibility if the image needs to be repositioned. However, when working with really large files (for example when I create my digital illustrations, each layer is 24 x 24 inches at 300 ppi and the files often reach greater than 1.5GB very quickly). In order to keep my file size down, as soon as I am certain that I will not change my mind and reposition the image, I choose Select > All and then Image > Crop. This crops any extraneous information beyond the visible canvas size (which is typically significant for my images as I photograph in a 2:3 aspect ratio but my final images are 1:1). Of course you do loose some flexibility so make sure that you are happy with each layer’s position before cropping!