An image consisting of data (specifically a set of elements) defined on an n-dimensional regular grid that has the potential for display. These elements are referred to as pixels. The pixels in different images may represent a variety of types of information, such as temperature, pressure, velocity, terrain height, or tissue density. The regular grid is frequently over a two-dimensional space but can be three-dimensional, and even four-dimensional if sampling over time is also included. See also image processing.