Images in print media represent a series of overlapping dots that should create an illusion of more colors. When you scan such a photo you can usually discover a moire pattern. A moire pattern results from incorrect screen angles of overprinting halftones.
You can try to avoid moire at the scanning stage. Sometimes a well-chosen scan angle can produce a remarkable effect. However, if you deal with a scanned image you have only one method of moire suppression at your disposal - apply image processing techniques.
On the photo below you can see a scan of a music CD cover. Moire is visible.
Noise Buster AI will process the image using the default settings.