Seeing Before/After Versions in Lightroom
Sometimes, seeing before/after views can be a big help when you’re making edits in Photoshop Lightroom, and seeing them side-by-side as you edit can be even more helpful. Lightroom gives you a number of different view options, depending on your personal preferences and the physical orientation of the photo you’re editing.
When you’re working on a photo in the Develop module and want to see what the original, unedited version of your photo looked like (the "before" photo), just press the Backslash key (\) to toggle between the before and after views. The word Before appears in the lower-right corner of the Preview area—it’s circled in red in Figure 1.