Paper backdrops are a staple within any studio setup as they offer a wide range of colors at a reasonable price.
The downside, however, is that the paper becomes dirty easily, manifesting with scuffs, smudges, grime, and other distractions that will be picked up by the camera.
To simply clean up your backgrounds, this useful tutorial by Anita Sadowska will have your paper backdrops polished in no time.
Steps Shown in the Video:
1.) With your image open in Photoshop, Duplicate the Layer using keyboard shortcut Command + J (Ctrl + J on PC).
2.) Select your background using your preferred method. In this example, the Magic Wand tool is used, set to Add to Selection, Point Sample, Tolerance at 29, Anti-alias, and Contiguous. Click around your subject, then switch to the Lasso Tool, also set to Add to Selection, to quickly pick up any remaining parts of the background.
3.) Go to Filter, Noise, and select Median. Choose the Radius that shows the dirt disappearing, which was 25 in the tutorial, click OK, and your paper background will now be remarkably cleaner!
Source: Anita Sadowska