A type of digital object that is created from the digitization of still image (textual documents and photographs) originals. A still image is data in which a grid or raster of picture elements (pixels) has been mapped to represent a visual subject, e.g., the page of a book or a photograph. The term raster data is often contrasted with vector data, in which geometrical points, lines, curves, and shapes are based upon mathematical equations, thus creating an image without specific mapping of data to pixels. [From theFADGI Glossary] Bit-depth, spatial resolution, and color encoding, for example, are all important characteristics of still images. Raster images can be stored in a variety of data formats, such as TIFF (.tif).

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