Photoshop is, believe it or not, mostly based off of techniques that photographers did in the darkroom years ago and eventually evolved into a full design platform. Years ago, it was common place for burning and dodging to happen in the darkroom, so was gradient work, saturation work, etc.
Lynda.com did a video highlighting this stuff. They cite things like Bridge being a contact shoot and how film photographers never thought that it would change the way that they worked. In fact, Photoshop and its other programs do pretty much everything that the darkroom can–even smart upscaling, which is comparable to using an enlarger to get a bigger print of an image.
Their video on all the darkroom techniques is after the jump.
Via ISO 1200