To eliminate or at least minimize, color differences between devices, you can use a color management system. Color management systems use a standard, device-independent color model, such as CIELab. Images are associated with a profile, which contain information about the input and/or output devices. Thus, if images are to be output on a specific device, it will be associated, or “tagged”, with a profile for that device. Of course, the same goes for text or line-art. For more information on device-independent color, see the online Adobe Acrobat Guide.