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Encyclopedia > Dynamic range

Dynamic range is a term used frequently in numerous fields to describe the ratio between the smallest and largest possible values of a changeable quantity. The term Dynamic range may mean: Dynamic range, Dynamic range is a term used frequently in numerous fields to describe the ratio between the smallest and largest possible values of a changeable quantity. ... Image File history File links Broom_icon. ... A ratio is a quantity that denotes the proportional amount or magnitude of one quantity relative to another. ...

Contents

Dynamic range and human perception

The human senses of sight and hearing have a very high dynamic range. A person is capable of hearing (and usefully discerning) anything from a quiet murmur in a soundproofed room to the sound of the loudest rock concert. A difference like this can be 100dB which represents a difference in energy of 10,000,000,000. Equally a person can see objects in starlight (although colour differentiation is reduced at low light levels) or in bright sunlight, even though on a moonless night objects receive 1/1,000,000,000 of the illumination they would on a bright sunny day: that is a dynamic range of 90 dB. A person cannot perform these feats of perception at both extremes of the scale at the same time. The eyes take time to adjust to different light levels and the dynamic range of the human eye without any adjustment of the pupil is only approximately 30 dB. The instantaneous dynamic range of human audio perception is similar, so that, for example, a whisper cannot be heard in loud surroundings. Nevertheless, a good quality audio reproduction system should be able to reproduce accurately both the quiet sounds and the loud; and a good quality visual display system should be able to show both shadow details in nighttime scenes and the full brightness of sunny scenes. This does not cite any references or sources. ... The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power) relative to a specified or implied reference level. ... Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they reflect or emit. ...


In practice it is difficult to achieve the full dynamic range seen by human beings using electronic equipment, since most electronic reproduction equipment is essentially linear rather than logarithmic like human perception. Electronically reproduced audio and video often uses some trickery to fit original material with a wide dynamic range into a narrower recorded dynamic range that can more easily be reproduced: this is dynamic compression. For example a good quality LCD display has a dynamic range of around 1000, or 30 dB


Was the previous line an error? Dynamic Range (dB) = SNR (dB) = 20*Log10 (RMS Full-scale/RMS Noise) Dynamic range formula 20*Log10(1000) = 60. While power doubles every 3dB, dynamic range doubles every 6dB.


(commercially the dynamic range is often called the "contrast ratio" meaning the full on/full off contrast ratio). When showing a movie or a game such a display is able to show both shadowy nighttime scenes and bright outdoor sunlit scenes, but in fact the level of light coming from the display is much the same for both types of scene (perhaps different by a factor of 10). Knowing that the display does not have a huge dynamic range, the program makers do not attempt to make the nighttime scenes millions of times less bright than the daytime scenes, but instead use other cues to suggest night or day: a nighttime scene will contain duller colours and will often be lit with blue lighting, which reflects the way that the human eye sees colours at low light levels. The contrast ratio is a measure of a display system, defined as the ratio of the luminosity of the brightest color (White) to that of the darkest color (black) that the system is capable of producing. ... Normalised absoption spectra of human rod (R) and cone (S,M,L) cells. ...


Examples of usage

Audio

Audio engineers often use dynamic range to describe the ratio of the loudest possible undistorted sound to the quietest or to the noise level, say of a microphone or loudspeaker. In digital audio, the maximum possible dynamic range is given by the audio bit depth (see signal-to-noise ratio). Dynamic range of an audio device is also sometimes referred to as the dynamic window. An Audio Engineer is a person recording, editing, manipulating, mixing and mastering sound by technical means. ... “Microphones” redirects here. ... This article or section needs copy editing for grammar, style, cohesion, tone and/or spelling. ... This article does not cite its references or sources. ... Signal-to-noise ratio (often abbreviated SNR or S/N) is an electrical engineering concept defined as the ratio of a signal power to the noise power corrupting the signal. ...


To mathematically determine a dynamic range you must add the headroom to the signal to noise ratio OR take the difference between the ceiling and noise floor of an audio device. For example, if the ceiling of a device is 10 dB and the floor is 3 dB then the dynamic range is 7 dB, since 10-3 = 7.


Since the early 1990s it has been recommended by several authorities including the Audio Engineering Society that measurements of dynamic range be made with an audio signal present. This avoids questionable measurements based on the use of blank media, or muting circuits.


Electronics

Electronics engineers apply the term to: This article is about the engineering discipline. ...

In audio and electronics applications, the ratio involved is often so huge that it is converted to a logarithm and specified in decibels. The factual accuracy of this article is disputed. ... In physics, power (symbol: P) is the rate at which work is performed or energy is transferred. ... In electricity, current refers to electric current, which is the flow of electric charge. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. ... It has been suggested that Audio quality measurement be merged into this article or section. ... In telecommunications a transmission system is a system that transmits a signal from one place to another. ... Overload can refer to: Electrical overload, a situation where an electrical machine or system is subjected to a greater load than it was designed for. ... In telecommunication, signalling (or signaling) has the following meanings: The use of signals for controlling communications. ... A distortion is the alteration of the original shape (or other characteristic) of an object, image, sound, waveform or other form of information or representation. ... In telecommunication, noise level is the noise power, usually relative to a reference. ... A digital system is one that uses discrete values (often electrical voltages), especially those representable as binary numbers, or non-numeric symbols such as letters or icons, for input, processing, transmission, storage, or display, rather than a continuous spectrum of values (ie, as in an analog system). ... In telecommunication, an error ratio is the ratio of the number of bits, elements, characters, or blocks incorrectly received to the total number of bits, elements, characters, or blocks sent during a specified time interval. ... Logarithms to various bases: is to base e, is to base 10, and is to base 1. ... The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power) relative to a specified or implied reference level. ...


Music

In music, dynamic range is the difference between the quietest and loudest volume of an instrument, part or piece of music. In modern recording, this range is often limited through audio level compression, which allows for louder volume, but can make the recording sound less exciting or live[1]. Popular music typically has a dynamic range of 6 to 10 dB, with some forms of music having as little as 1 dB or as much as 15 dB.[1] // Music is an art form consisting of sound and silence expressed through time. ... A musical instrument is a device constructed or modified with the purpose of making music. ... As a noun, a part is a section of a greater whole. ... Audio level compression, also called dynamic range compression, volume compression, compression, limiting, or DRC (often seen in DVD player settings) is a process that manipulates the dynamic range of an audio signal. ... Popular music is music belonging to any of a number of musical styles that are accessible to the general public and are disseminated by one or more of the mass media. ...


Photography

Main article: Exposure range

Photographers use exposure range as a synonym for the luminosity range of a scene being photographed; the light sensitivity range of photographic film, paper and digital camera sensors; the opacity range of developed film images; the reflectance range of images on photographic papers. In photography, exposure range is one of several types of dynamic range: The Light sensitivity range of photographic film, paper, or digital camera sensors. ... Photography [fәtɑgrәfi:],[foʊtɑgrәfi:] is the process of recording pictures by means of capturing light on a light-sensitive medium, such as a film or electronic sensor. ... In photography, exposure range is one of several types of dynamic range: The Light sensitivity range of photographic film, paper, or digital camera sensors. ... Synonyms (in ancient Greek, συν (syn) = plus and όνομα (onoma) = name) are different words with similar or identical meanings. ...


Metrology

In metrology, such as when performed in support of science, engineering or manufacturing objectives, “dynamic range” refers to the range of values that can be measured by a sensor or metrology instrument. Often this dynamic range of measurement is limited at one end of the range by saturation of a sensing signal sensor or by physical limits that exist on the motion or other response capability of a mechanical indicator. The other end of the dynamic range of measurement is often limited by one or more sources of random noise or uncertainty in signal levels that may be described as the defining the sensitivity of the sensor or metrology device. When digital sensors or sensor signal converters are a component of the sensor or metrology device, the dynamic range of measurement will be also related to the number of binary digits (“bits”) into which any analog measurement quantities are converted to create digital numeric values. For example, a 12-bit digital sensor or converter can only provide a dynamic range in which the ratio of the maximum measured value to the minimum measured value is limited to 4096-to-1. For the Irish mythological figure, see Naoise. ... See: Sensitivity (electronics) Sensitivity (human) Sensitivity (tests) For sensitivity in finance, see beta coefficient This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...


Metrology systems and devices may use several basic methods to increase their basic dynamic range. These methods include averaging and other forms of filtering, repetition of measurements, nonlinear transformations to avoid saturation, etc. In more advance forms of metrology, such as multiwavelength digital holography, interferometry measurements made at different scales (different wavelengths) can be combined to retain the same low-end resolution while extending the upper end of the dynamic range of measurement by orders of magnitude. Digital holography refers to the science and the process of acquiring three-dimensional signals that enable the high-definition measurement of the surface dimensions of an object or an assembly of objects, and in which multi-wavelength optical imaging interferometry is employed to allow the surface shape to be measured... It has been suggested that Optical interferometry be merged into this article or section. ...


Others

High Dynamic Range Imaging is an emerging field in computer graphics which seeks to represent light levels (either measured or synthesised) as an open-ended range of absolute values, rather than as a simple ratio of 'full' brightness. This allows more accurate and realistic renderings. In computer graphics and cinematography, high dynamic range imaging (HDRI for short) is a set of techniques that allow a far greater dynamic range of exposures than normal digital imaging techniques. ...


Standard Operating Level: A specified reference level. In recording applications, standard operating level is defined as O VU = + 4 dBm.

  1. ^ Katz, Robert (2002). "9", Mastering Audio. Amsterdam: Boston, 109. ISBN 0240805453. 

  Results from FactBites:
 
Dynamic range - Wikipedia, the free encyclopedia (486 words)
Dynamic range is a term used frequently in numerous fields to describe the ratio between the smallest and largest possible values of a changeable quantity.
In music, dynamic range is the difference between the quietest and loudest volume of a instrument, part or piece of music.
Photographers use dynamic range as a synonym for the luminosity range of a scene being photographed; the light sensitivity range of photographic film, paper and digital camera sensors; the opacity range of developed film images; the reflectance range of images on photographic papers.
Dynamic range, 24 bit vs 36 bit (1299 words)
Dynamic range is not a major consideration for scanning photo prints, because prints themselves are very limited, but it is very important when scanning film.
An intensity range of 100:1 is a density range of 2.0, and 1000:1 is a range of 3.0.
The greater dynamic range extends the signal into low fl levels where the noise is. To be effective, the electronics must be improved greatly to reduce the noise.
  More results at FactBites »

 
 

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