Consumer Reports Many of the images making their way into home computers these days have been captured by a digital camera or camcorder, or digitized by the photo processor when the film was developed. Our tests of both types show that while flatbed scanners do differ significantly in accuracy when scanning color photographs, those with 1,200-dpi resolution don't necessarily produce better results.
All flatbed scanners work basically the same way.
Sensors pass beneath a plate of glass on which the document lies and convert light reflected from the original into an electronic signal, which is then digitized and sent to the computer. There, it can be processed with a specialized image-editing package that comes with scanners. The scanner's optical resolution is derived from the number of sensing elements that stretch horizontally across the scanning bar beneath the glass. Much of that hype is overkill, however, and should be ignored. The only kind of resolution that matters is optical resolution.