...that I haven't sent anyone to http://www.scantips.com/ for information recently.
This is a great source of information for anyone just starting to get into image processing whether they are starting from a scanner or using images from a digital camera.
I think the plain english explanations of confusing subjects and similar terms are among the best available on the web.
Many of the scanner tools he explains operate exactly the same way in the image editors we all use.
I also think his explanation of files formats is one of the easiest to understand.
I know the site helped me a great deal when I was starting a few years ago.