What is your final output? Is a print on a printer? If so, you need to understand that each component in your workflow has a different range of possible color depth -- your camera, scanner, display (monitor), printer, paper and so on. Color workflow is a science that must be applied no matter what computer, software, or components being used.
If your "final output" is to a gif, jpeg, PNG, PDF, etc, what are you color management settings in Photoshop? Are you converting to the correct color mode and assigning an appropriate color profile before outputting?