Image quality will vary depending on what option you decide to use when backing up the DVD. When you strip out the extras, and stick with just one language and no subtitles, the quality is pretty much an exact replica of the original (there will still be some compression if the movie takes a lot of storage space). When you copy the entire disc, including the extras, the image quality can take quite a nosedive, especially if it's a DVD9 disc.



Link: Viper's Lair