purist way to create cd/dvd images?

Of all the searching I have done in looking for a way to create perfect 1:1 cd/dvd images for every disc I could come across, I haven't found one. Nero seemed to be working well, but I have found a few discs that it won't image.

In January before I left for school, I was going to start a thread asking how to do this, but didn't get around to it. I did have someone tell me though that the best way to do this is from a Linux console. That is all I remember.

Does anyone know anything about accomplishing this from a Linux console or by any other means? I am sure there must be a way to read a disc bit by bit and record it to an image.

I don't know how Nero does it, but k3b might work where Nero doesn't.

Otherwise, I haven't tried this myself, but you might be able to literally write a program that reads byte by byte. Might be an interesting experiment.