I wrote briefly more than two months ago at https://goo.gl/VxqVlx about the free PhotoScan app from Google. It uses your present cell phone to convert print photographs into high-quality digital images. I wrote:
PhotoScan is a new smartphone app used to “take a picture of your pictures.” That is, it will snap photos of all those old pictures you have stored in photo albums or in Fotomat envelopes. It will then create enhanced digital scans, with automatic edge detection, perspective correction, and smart rotation. Even better, it also automatically recognizes the four corners of the frame and displays circular overlays on each corner of the scanned image. You then point your phone camera at each circle, create a robust scan of the image, and PhotoScan gets to work from there.
I have used PhotoScan a number of times since I wrote the brief article. Now the How-To Geek web site has published a very detailed tutorial and has included lots of pictures showing how to get the most from PhotoScan.
If you have an interest in digitizing old family photographs, or even new ones, free of charge, you will want to read How to Digitize Old Photos with Your Smartphone at https://goo.gl/zqOb55.