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Dynamic range

Dynamic range (abbreviated DR, DNR,[1] or DYR[2]) 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-10 (decibel) or base-2 (doublings, bits or stops) logarithmic value of the ratio between the largest and smallest signal values.[3]

For other uses, see Dynamic range (disambiguation).

Electronically reproduced audio and video is often processed to fit the original material with a wide dynamic range into a narrower recorded dynamic range that can more easily be stored and reproduced; this processing is called dynamic range compression.

Specifies the ratio of a maximum level of a , such as power, current, voltage[43] or frequency, to the minimum detectable value of that parameter. (See Audio system measurements.)

parameter

In a , the ratio of the overload level (the maximum signal power that the system can tolerate without distortion of the signal) to the noise level of the system.

transmission system

In systems or devices, the ratio of maximum and minimum signal levels required to maintain a specified bit error ratio.

digital

Optimization of bit width of digital data path (according to the dynamic ranges of signal) can reduce the area, cost, and power consumption of digital circuits and systems while improving their performance. Optimal bit width for a digital data path is the smallest bit width that can satisfy the required signal-to-noise ratio and also avoid overflow.[45][46][47][48]

[44]

In electronics dynamic range is used in the following contexts:


In audio and electronics applications, the ratio involved is often large enough that it is converted to a logarithm and specified in decibels.[43]

Music[edit]

In music, dynamic range describes the difference between the quietest and loudest volume of an instrument, part or piece of music.[49] In modern recording, this range is often limited through dynamic range compression, which allows for louder volume, but can make the recording sound less exciting or live.[50]


The dynamic range of music as normally perceived in a concert hall does not exceed 80 dB, and human speech is normally perceived over a range of about 40 dB.[28]: 4 

are used to decrease the dynamic range of scene luminance that can be captured on photographic film (or on the image sensor of a digital camera): The filter is positioned in front of the lens at the time the exposure is made; the top half is dark and the bottom half is clear. The dark area is placed over a scene's high-intensity region, such as the sky. The result is more even exposure in the focal plane, with increased detail in the shadows and low-light areas. Though this does not increase the fixed dynamic range available at the film or sensor, it stretches usable dynamic range in practice.[55]

Graduated neutral density filters

overcomes the limited dynamic range of the sensor by selectively combining multiple exposures of the same scene in order to retain detail in light and dark areas. Tone mapping maps the image differently in shadow and highlights in order to better distribute the lighting range across the image. The same approach has been used in chemical photography to capture an extremely wide dynamic range: A three-layer film with each underlying layer at one hundredth (10−2) the sensitivity of the next higher one has, for example, been used to record nuclear-weapons tests.[56]

High-dynamic-range imaging

Photographers use dynamic range to describe the luminance range of a scene being photographed, or the limits of luminance range that a given digital camera or film can capture,[52] or the opacity range of developed film images, or the reflectance range of images on photographic papers.


The dynamic range of digital photography is comparable to the capabilities of photographic film[53] and both are comparable to the capabilities of the human eye.[54]


There are photographic techniques that support even higher dynamic range.


Consumer-grade image file formats sometimes restrict dynamic range.[57] The most severe dynamic-range limitation in photography may not involve encoding, but rather reproduction to, say, a paper print or computer screen. In that case, not only local tone mapping but also dynamic range adjustment can be effective in revealing detail throughout light and dark areas: The principle is the same as that of dodging and burning (using different lengths of exposures in different areas when making a photographic print) in the chemical darkroom. The principle is also similar to gain riding or automatic level control in audio work, which serves to keep a signal audible in a noisy listening environment and to avoid peak levels that overload the reproducing equipment, or which are unnaturally or uncomfortably loud.


If a camera sensor is incapable of recording the full dynamic range of a scene, high-dynamic-range (HDR) techniques may be used in postprocessing, which generally involve combining multiple exposures using software.

Loudness war

High dynamic range

High-dynamic-range imaging

Highlight headroom

Range fractionation

Spurious-free dynamic range

Audible dynamic range (online test)

Steven E. Schoenherr (2002). . Recording Technology History. Archived from the original on 2006-09-05.

"Dynamic Range"

Vaughan Wesson (October 2004). . Archived from the original on 2004-12-21.

"TN200410A - Dynamic Range"