The Photoshop Lightroom 4 Software For Mac And Windows from Adobe is a complete photo management and editing suite for Mac OS X and Windows. Ideal for enthusiasts and professionals alike, Lightroom takes a nondestructive approach to photo editing, leaving the original files unmolested. All your adjustments and edits are stored in a database and applied to an image on the fly, so that you'll always be able to go back to the original image. This enables you to execute as many post-processing adjustments on a photo as you'd like, without making permanent changes to the original image.