I have kind of an exceptionally large photography and digital image collection, plenty of images I use for general use, image editing, studying and many other purposes. I am wondering what is the best way to keep such a high volume of images safe and stop them from degrading on my hard drive. So far I have been keeping them on my PC but also every couple weeks I back them all up on an External Hard Drive. Is this a good method? If I defragment any of the hard drives will this decrease overall image quality? How can I keep up the images quality when i am constantly having to save them, load them, overwrite them and such?