increase quality

[phil_4_69]

I have the iso file of a DVD which I recently backed up but the problem is that the original DVD wasnt the best quality. the file is only 1.5 gig, with no compression at all. I also have the original dvd. Is there anyway i can enhance the quality since i still have roughly 3 gigs to add until the disc would be full?
Again, ihave the original dvd and the iso file on my comp.
Any info would be greatly appreciated
thanks in advance

[UncasMS]

you might be able to increase the film quality using certain filters via avisynth

this way for example grainy sources could be smoothed or colors could be changed slightly etc