Certified Professional Photography Glossary CPP Glossary Terms. Definitions are from The Focal Encyclopedia of Photography (3rd Edition) and Photography by London, Stone and Upton (10th and 11th edition).

Certified Professional Photography Glossary CPP Glossary Terms. Definitions are from The Focal Encyclopedia of Photography (3rd Edition) and Photography by London, Stone and Upton (10th and 11th edition). Aliasing - Low and medium resolution computer imaging systems display normally smooth edges as jagged edges. These jaggies are known as aliasing. It may result from undersampling the spatial frequency, or when the detail exceeds the display ability of the monitor. Ambient Light - The light that already exists where a photograph is to be made, as opposed to light brought in by the photographer. Often implies a relatively dim light. Also called ambient light or exisiting light. Angle of View - Angle subtended at the center of the entrance pupil of the lens by the subject field or area delineated by the image format of the camera. Generally, the value for the diagonal extent is quoted, this being the largest for the horizontal, vertical, and diagonal dimensions of a rectangular or square format. For an aberration-free lens of focal length "f" and format dimension "k", the corresponding angle of view "W" is given by W= 2 tan -1 (k/2f). It normally is equal to the corresponding angle subtended at the format by the emergent rays, except in the case of lenses that have pincushion or barrel distortion, such as fisheye types. Aperture - The size of the lens opening through which light passes. Aperture Priority - A mode of automatic exposure in which the photographer selects the aperture and the camera sets the shutter speed that will produce the correct exposure. Aspect Ratio - The width to height proportions of an image format, commonly used in motion picture photography and video. The aspect ratio for conventional motion pictures is 1.33 to 1, but wide-screen aspect ratios range from 1.8 to 1 to 3 to 1. Available Light - The light that already exists where a photograph is to be made, as opposed to light brought in by the photographer. Often implies a relatively dim light. Barn Doors - Opaque flaps attached to the edges of a light and used to control light spread, for shading effects in the set, and to keep flare-causing light from entering the camera. Two, with one on each side, or four with additional top and bottom flaps, are typically used. The flaps are hinged and blackened so the light spread can be continuously restricted. An open-face fixture may cast a double-edged shadow, one from the lamp and a less-distinct one from the reflector. Barrel Distortion - A lens aberration or defect that causes straight lines to bow outward, away from the center of the image. Bit - The smallest unit of information useable by a computer, indicated by a 1, or a 0, describing one of two conditions- on or off. Broad Lighting - Portrait lighting in which the main light illuminates the side of the face turned toward the camera. Butterfly Lighting - Portrait lighting in which the main source of light is placed high and directly in front of the face. Byte - A unit of digital data containing 8 bits. Calibration - To adjust the output of a digital device, such as a computer monitor, to match a predefined standard. Chromatic Aberration - A lens defect that bends light rays of different colors at different angles and therefore focuses them on different planes. Color Balance - 1. A film's or a sensor's response to the colors of a scene. 2. The reproduction of colors in a color print, alternatable during image editing or darkroom color printing. Color Space - Three-dimensional representation of colors. Color Temperature - A numerical description of the color of light measured in degrees Kelvin (K). Colorimeter - An instrument for measuring colors. Visual colorimeters are sometimes used in research work, but practical colorimetry is usually carried out with photoelectric instruments in which the light from the sample is passed through three filters onto a photoelectric detector. Compression - A means of reducing the file size for a digital image in order to reduce storage requirements or transmission speed across networks. Continuous Tone - Describes an image with a smooth gradation of tones from black through grays or colors to white. Contrast - The difference in darkness or density between one tone and another. Cookie - A thin opaque sheet with a pattern of irregularly shaped and positioned holes. When held in front of a light source, a dappled highlight and shadow pattern is cast on a backdrop or other surface. Typically used so that light appears to have been filtered through trees outside a window. The edges of the cookie should be irregular, and not straight-edged, to avoid angular shadows that revel the use of an effect tool. Depth of Field - The area between the nearest and farthest points from the camera that are acceptably sharp in an image. Diffusion - Scattered, not all coming from the same direction. For example, sunlight on a cloudy day. DPI - Dots per inch: a measure of the resolution of a digital printer or photomechanical halftone. The number of dots or points that can be printed or displayed by a device. DSLR - Digital Single-Lens Reflex Dynamic Range - The difference between the lightest and darkest (or highest and lowest) values in a scene or image. Sometimes, in the zone system, called subject brightness range. Environmental portraiture - Kind of portraiture in which the loose composition of an image provides information about where the subject lives and the conditions it survives in. Exposure - 1. The act of letting light fall on a light-sensitive material. 2. The amount of light reaching the light-sensitive material;specifically, the intensity of light multiplied by the length o