We're talking big big big files here. I have a one gigabyte file which represents a 720 pixel by 480 pixel image size capture of a Betacam original tape segment lasting only about 5 minutes. It's beautiful and clear, but it's trapped on my AV speed drive because I can barely squeeze it onto a JAZ removable cartridge. Most software which operates capture systems offers you a pallette of compression schemes. If you compress the file when saving, you're going to lose image.
Fuzzy originals become worse when compressed.
Some software hasn't a clue what you need. Other stuff is helpful or will handle plug in software to help with the transitions. However, most plug in technology is developed to get graphic files into video and not video files into graphic formats. Long before you play the tape into the computer you should have had the kind of meaningful conversation with your graphics professional you would normally have with your spouse concerning family planning. They may ask that you capture as big and deep a picture as you can afford so that they later can reduce it, enhance it, and then compress it.