Okay,
Cirkutz made a little utility, the Mini Image Ripper, that will take any safedisc 2 image and rip all data out, leaving only the copy protection info. Now this will not work for all titles, but it does work for at least Battlefield 1942, since I tested it myself. Go to
Cirkutz's homepage, and click on the top link for the Mini Image Ripper, you can then download it. If you have trouble downloading, disable any download accelerators. If I used Getright, it couldn't find the file, but without Getright I didn't have any problem ten minutes ago. The tool itself is really simple to use, it will make a file with the .mir extension, just load that in Alcohol120% and see if you can still play the game. If you can, it's now safe to delete the old image files, or compress them with winrar and put them on cdr as a backup. You might have to switch to 'showing all files' to select the .mir file in Alcohol120%.
Oh, and the compressing of the image files is just so they take up their original amount of space. If you make image files, those are always ~100Mb bigger than the original data, so most games require these image files to be compressed in order to still fit on the same number of cds as the original data...