The Compare view in Lightroom 2 can be very helpful for quickly sorting through your images to identify the best image in a given group. If you want to compare all images currently visible on the Filmstrip, keep only one image selected and then click the Compare view button below the preview area in the Library module. If you want to review only a subset of the images on the Filmstrip, select the range of images you want to compare before clicking the Compare view button. Now the image on the left is the "Select" image, meaning the one you currently think is the best (though initially that may obviously not be the case). The image on the right is the "Candidate" image, meaning the one you need to review to determine if it's better than the Select image. If you like the Candidate image better, you can click the Swap button below the preview to keep the same pair of images displayed but switch them between Select and Candidate. Or you can click the Make Select button to make the Candidate image become the Select image, and replace the Candidate image with the next on the list in the Filmstrip (causing the existing Select image to no longer be displayed). You also can use the left and right arrows to navigate among the available Candidate images. When you've gone through all the images, click Done, and the current Select image will be displayed alone in the preview area.