In PowerPoint, you can use an easy trick to add emphasis to a specific area of a photo.
1. On the photo, circle the area that you want to emphasis with the circle or oval shape.
2. Then select both the shape and the photo itself. Be sure to select the photo first and then press CTRL and select the circle.
3. Under the Drawing Tools . . . Format menu, and on the far left select Merge Shapes . . . Fragment.
4. Then select the background photo and go to the Picture Tools . . . Format menu, and on the far left select Artistic Effects and choose a blurred version of the photo.