Exposure latitude is the extent to which a light-sensitive material can be

exposed Expose, exposé, or exposed may refer to: News sources * Exposé (journalism), a form of investigative journalism * '' The Exposé'', a British conspiracist website * '' Exeposé'', a student-run newspaper of the University of Exeter Film and TV ...

(overexposed or underexposed) and still achieve an acceptable result. It is relevant to both digital and analogue processes such as

photolithography Photolithography (also known as optical lithography) is a process used in the manufacturing of integrated circuits. It involves using light to transfer a pattern onto a substrate, typically a silicon wafer. The process begins with a photosensiti ...

and

photography Photography is the visual arts, art, application, and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is empl ...

Applications

In the case of optical microlithography this value statistically describes the response of a

photoresist A photoresist (also known simply as a resist) is a light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface. This process is crucial in the electronics industry. T ...

to radiation and defines the process window where the photolithographic process can vary within (e.g. how well it compensates for spatial non-uniformities of the illumination). In the case of

, an artistic case, the measurement of exposure latitude is, by definition dependent on both personal aesthetics and artistic intentions, somewhat subjective. However, the relative differences between media are generally agreed upon:

reversal film In photography, reversal film or slide film is a type of photographic film that produces a positive image on a transparent base. Instead of negatives and prints, reversal film is processed to produce transparencies or diapositives (abbrevia ...

tends to have very little latitude, while colour negative film has considerably more. Digital sensors vary. It is not to be confused with

dynamic range Dynamics (from Greek δυναμικός ''dynamikos'' "powerful", from δύναμις ''dynamis'' " power") or dynamic may refer to: Physics and engineering * Dynamics (mechanics), the study of forces and their effect on motion Brands and ent ...

, the range of light intensities a medium can capture simultaneously. A recording medium with greater dynamic range will be able to record more details in the dark and light areas of a picture. Latitude depends on dynamic range. If the same scene can be recorded using less than the full brightness range available to the medium, the exposure can be shifted along the range without losing information in the shadows or highlights. Greater exposure latitude allows one to compensate for errors in exposure while retaining quality. In radiography, exposure latitude and dynamic range are equivalent. It is the range of exposures that can be recorded as useful densities on a radiographic film for interpretation. In film-screen radiography, exposure latitude range from 10:1 to 100:1. In digital chest radiography, exposure latitude can more than 100:1. In computed radiography, the exposure latitude can reach 10,000:1. High X-ray beam energy will increase the exposure latitude. High intrinsic subject contrast, as in chest radiography, requires wide latitude to differentiate various tissues in the mediastinum and lesions in the lungs. Low intrinsic subject contrast, as in mammography, requires narrow latitude to increase contrast between the different breast tissues or any lesion within them.

References

{{photo-stub Photographic techniques Science of photography Film and video technology

Applications

See also

References