Working with digital image data, especially photorealistic representations, requires considerations of quality and size. Anyone looking to reproduce graphic information of this kind must make a decision regarding resolution. What factors are involved, and how high or low should it be? This text explains how to determine resolutions that need to be set in scanning programs or digital cameras, for example. The resolution determination leads to considerations about the media used, the purpose of application, the devices employed, and the output quality and size, and is presented in detail for various contexts, such as private and professional printed materials, screen and projector presentations, internet, multimedia, and video applications, as well as text recognition and vectorization. For existing image data, it is necessary to check and possibly adjust the resolution afterwards.