Exposure latitude is the extent to which a light-sensitive material can be overexposed or underexposed and still achieve an acceptable result.
This measure is used for digital and analogue processes, e.g. optical microlithography or
photography
Photography is the visual art, art, application, and practice of creating durable 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 i ...
.
Details
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 electronic industry.
...
to radiation and defines the
process window The process window is a graph with a range of parameters for a specific manufacturing process that yields a defined result. Typically multiple parameters are plotted in such a graph with a central region where the process behaves well, while the out ...
where the photolithographic process can vary within (e.g. how well it compensates for spatial non-uniformities of the illumination). In the case of
photography
Photography is the visual art, art, application, and practice of creating durable 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 i ...
, 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 (abbrevi ...
tends to have very little latitude, while colour
negative film
In photography, a negative is an image, usually on a strip or sheet of transparent plastic film, in which the lightest areas of the photographed subject appear darkest and the darkest areas appear lightest. This reversed order occurs because t ...
has considerably more. Digital sensors vary.
It is not to be confused with
dynamic range
Dynamic range (abbreviated DR, DNR, or DYR) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of signals, like sound and light. It is measured either as a ratio or as a base- ...
, 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.
See also
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Contrast ratio
The contrast ratio (CR) is a property of a display system, defined as the ratio of the luminance of the brightest shade (white) to that of the darkest shade (black) that the system is capable of producing. A high contrast ratio is a desired aspe ...
References
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Photographic techniques
Science of photography
Film and video technology