We have already shown you how you can apply picture fills as slide backgrounds — all the picture format options which can be applied on a picture also works for a picture background. Unfortunately, once you apply Office 2013’s Service Pack 1, many of the picture format options for picture backgrounds stop working. Until future updates restore the options back, you can follow the workaround explained on this page — all within PowerPoint 2013.
Explore a workaround for pictures backgrounds in PowerPoint 2013 for Windows.

