Color may be defined as each distinguishable variation on an image produced by a multitude of combinations of hue, value and chroma. Many factors influence the tone or color of objects or features recorded on photographic emulsions. But, if there is not sufficient contrast between an object and its background to permit at least detection, there can be no identification. Some authors state that interpreters can distinguish at least 100 times more variations of color on color photography than shades of gray on black and white photography. 2.3.1.2 Resolution - Resolution is defined as the ability of the entire photographic system, including lens, exposure, processing, and other factors, to render a sharply defined image.
Resolution is one of the most difficult concepts to address in image analysis.
There are resolution targets that help to determine this when testing camera lenses for metric quality. Photo interpreters often talk about resolution in terms of ground resolved distance, the smallest normal contrast object that can be detected and identified on a photo. In the use of size as a diagnostic characteristic both the relative and absolute sizes of objects can be important. The Pentagon building in Washington is a diagnostic shape. Man-made features have straight edges that natural features tend not to.