As long as there is no fault with media (eg corrupted files, scratch on DVD) it won't make any difference to the image quality what media it is stored on. In other words, a given file is the same whether it has been stored on a flash drive, hard drive or DVD. And as many files as you wish can be copied at once using Explorer or burned to a DVD in one session, it makes no difference.
The file format (the type of file that has been saved) can affect the image quality under some circumstances. What is the existing file format?
I use .TIF files when I want to maintain image quality. They are much larger than, for example, .JPG files.
However an important thing to understand is that if you are just copying
the file to another location, there will be no change
to the image quality, regardless of its format. So if they're .JPG files, and you just burn them off to a DVD, then copy them back onto the computer when it's restored to operation, the images will still be exactly the same. In this case there would be no advantage in using another file format.
If they are important and/or difficult to replace, it would be best though to have more than one copy in case of a disaster. If you have them on both a DVD and a flash drive for example, if the flash drive is lost, you still have the DVD. Any storage medium can fail, be lost or stolen etc.
cause loss of image quality is re-saving
a format like .JPG after the image is modified in something like Photoshop. Say you re-size an image and crop it so it looks neat, then save it again as a .JPG. There will be a loss of image quality as it's re-compressed. That's when it's best to start with an uncompressed format like .TIF, and once all processing and re-saving is completed and the image is in its final state, it can then be saved as a .JPG or similar compressed file in order to be much smaller. That way there's only one compressing process that loses quality.
Edited by Platypus, 25 January 2010 - 12:17 AM.