Light can be added to a scene where none existed before just as if you were adding light at the time of shooting. Realistic lighting and shadow is introduced using digital versions of the entire gobo libraries created by Gamproducts and Rosco.
Adobe Photoshop CS5 and up (64 Bit Only)
Adobe Photoshop Elements 13 and up (Non-app store version)
Apple Photoshop Lightroom 3 and up
Apple Aperture 3