1. A machine readable medium storing an image-viewing application for execution by at least one processing unit, the image-viewing application comprising sets of instructions for: calculating an average aspect ratio of a plurality of images for display in an image viewing area, wherein a first image in the plurality of images has a first aspect ratio and a second image in the plurality of images has a second, different aspect ratio; determining a number and size of regions of the image viewing area for displaying the plurality of images, the regions having the calculated average aspect ratio, wherein each image is for display in a different one of the regions; and displaying the plurality of images in the regions of the image viewing area, each displayed image having a same visual weighting, wherein the first image is displayed at the first aspect ratio and the second image is displayed at the second aspect ratio.