Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as "banding" in images. Dither is routinely used in processing of both digital audio and digital video data, and is often one of the last stages of audio production to compact disc.

Etymology

The term "dither" was published in books on analog computation and hydraulic controlled guns shortly after the war. The concept of dithering to reduce quantization patterns was first applied by Lawrence G. Roberts in his 1961 MIT master's thesis and 1962 article though he did not use the term ''dither''. By 1964 dither was being used in the modern sense described in this article.

In digital processing and waveform analysis

Dither is often used in digital audio and video processing, where it is applied to bit-depth transitions; it is utilized in many different fields where digital processing and analysis are used — especially waveform analysis. These uses include systems using digital signal processing, such as digital audio, digital video, digital photography, seismology, RADAR, weather forecasting systems and many more.

The premise is that quantization and re-quantization of digital data yields error. If that error is repeating and ''correlated'' to the signal, the error that results is repeating, cyclical, and mathematically determinable. In some fields, especially where the receptor is sensitive to such artifacts, cyclical errors yield undesirable artifacts. In these fields dither results in less determinable artifacts. The field of audio is a primary example of this — the human ear functions much like a Fourier transform, wherein it hears individual frequencies. The ear is therefore very sensitive to ''distortion,'' or additional frequency content that "colors" the sound differently, but far less sensitive to random noise at all frequencies.

Digital audio

In audio, dither can be useful to break up periodic limit cycles, which are a common problem in digital filters. Random noise is typically less objectionable than the harmonic tones produced by limit cycles.

In 1987, Lipshitz and Vanderkooy pointed out that different noise types, with different probability density functions, behave differently when used as dither signals, and suggested optimal levels of dither signals for audio.

In an analog system, the signal is ''continuous'', but in a PCM digital system, the amplitude of the signal out of the digital system is limited to one of a set of fixed values or numbers. This process is called quantization. Each coded value is a discrete step... if a signal is quantized without using dither, there will be quantization distortion related to the original input signal... In order to prevent this, the signal is "dithered", a process that mathematically removes the harmonics or other highly undesirable distortions entirely, and that replaces it with a constant, fixed noise level.

The final version of audio that goes onto a compact disc contains only 16 bits per sample, but throughout the production process a greater number of bits are typically used to represent the sample. In the end, the digital data must be reduced to 16 bits for pressing onto a CD and distributing.

There are multiple ways to do this. One can, for example, simply discard the excess bits — called ''truncation.'' One can also ''round'' the excess bits to the nearest value. Each of these methods, however, results in predictable and determinable errors in the result. Take, for example, a waveform that consists of the following values:

1 2 3 4 5 6 7 8

If we reduce our waveform by, say, 20% then we end up with the following values:

0.8 1.6 2.4 3.2 4.0 4.8 5.6 6.4

If we truncate these values we end up with the following data:

0 1 2 3 4 4 5 6

If we instead round these values we end up with the following data:

1 2 2 3 4 5 6 6

For any original waveform, the process of reducing the waveform amplitude by 20% results in regular errors. Take for example a sine wave that, for some portion, matches the values above. Every time the sine wave's value hit "3.2," the truncated result would be off by 0.2, as in the sample data above. Every time the sine wave's value hit "4.0," there would be no error since the truncated result would be off by 0.0, also shown above. The magnitude of this error changes regularly and repeatedly throughout the sine wave's cycle. It is precisely this error which manifests itself as distortion. What the ear hears as distortion is the additional content at discrete frequencies created by the regular and repeated quantization error.

A plausible solution would be to take the 2 digit number (say, 4.8) and round it one direction or the other. For example, we could round it to 5 one time and then 4 the next time. This would make the long-term average 4.5 instead of 4, so that over the long-term the value is closer to its actual value. This, on the other hand, still results in determinable (though more complicated) error. Every other time the value 4.8 comes up the result is an error of 0.2, and the other times it is –0.8. This still results in repeating, quantifiable error.

Another plausible solution would be to take 4.8 and round it so that the first four times out of five it rounded up to 5, and the fifth time it rounded to 4. This would average out to exactly 4.8 over the long term. Unfortunately, however, it still results in repeatable and determinable errors, and those errors still manifest themselves as distortion to the ear (though oversampling can reduce this).

This leads to the ''dither'' solution. Rather than predictably rounding up or down in a repeating pattern, what if we rounded up or down in a random pattern? If we came up with a way to randomly toggle our results between 4 and 5 so that 80% of the time it ended up on 5 then we would average 4.8 over the long run but would have random, unrepeating error in the result. This is done through dither.

We calculate a series of random numbers between 0.0 and 0.9 (ex: 0.6, 0.1, 0.3, 0.6, 0.9, etc.) and we add these random numbers to the results of our equation. Two times out of ten the result will truncate back to 4 (if 0.0 or 0.1 are added to 4.8) and the rest of the times it will truncate to 5, but each given situation has a random 20% chance of rounding to 4 or 80% chance of rounding to 5. Over the long haul this will result in results that average to 4.8 and a quantization error that is random — or noise. This "noise" result is less offensive to the ear than the determinable distortion that would result otherwise.

Audio samples:

Usage

Dither should be added to any low-amplitude or highly-periodic signal before any quantization or re-quantization process, in order to de-correlate the quantization noise with the input signal and to prevent non-linear behavior (distortion); the lesser the bit depth, the greater the dither must be. The results of the process still yield distortion, but the distortion is of a random nature so its result is effectively noise. Any bit-reduction process should add dither to the waveform before the reduction is performed.

Different types

RPDF stands for "Rectangular Probability Density Function," equivalent to a roll of a die. Any number has the same random probability of surfacing.

TPDF stands for "Triangular Probability Density Function," equivalent to a roll of two dice (the sum of two independent samples of RPDF).

Gaussian PDF is equivalent to a roll of a large number of dice. The relationship of probabilities of results follows a bell-shaped, or Gaussian curve, typical of dither generated by analog sources such as microphone preamplifiers. If the bit depth of a recording is sufficiently great, that noise will be sufficient to dither the recording.

Colored Dither is sometimes mentioned as dither that has been filtered to be different from white noise. Some dither algorithms use noise that has more energy in the higher frequencies so as to lower the energy in the critical audio band.

Noise shaping is a filtering process that shapes the spectral energy of quantization error, typically to either de-emphasise frequencies to which the ear is most sensitive or separate the signal and noise bands completely. If dither is used, its final spectrum depends on whether it is added inside or outside the feedback loop of the noise shaper: if inside, the dither is treated as part of the error signal and shaped along with actual quantization error; if outside, the dither is treated as part of the original signal and linearises quantization without being shaped itself. In this case, the final noise floor is the sum of the flat dither spectrum and the shaped quantization noise. While real-world noise shaping usually includes in-loop dithering, it is also possible to use it without adding dither at all, in which case the usual harmonic-distortion effects still appear at low signal levels.

Which types to use

If the signal being dithered is to undergo further processing, then it should be processed with TPDF dither that has an amplitude of two quantization steps (so that the dither values computed range from, say, –1 to +1, or 0 to 2). This is the lowest power ideal dither, in that it does not introduce noise modulation (constant noise floor) and completely eliminates the harmonic distortion from *quantization*. If colored dither is used at these intermediate processing stages then the frequency content can "bleed" into other, more noticeable frequency ranges and become distractingly audible.

If the signal being dithered is to undergo no further processing — it is being dithered to its final result for distribution — then colored dither or noise shaping is appropriate, and can effectively lower the audible noise level by putting most of that noise in a frequency range where it is less critical.

Digital photography and image processing

Dithering is a technique used in computer graphics to create the illusion of color depth in images with a limited color palette (color quantization). In a dithered image, colors not available in the palette are approximated by a diffusion of colored pixels from within the available palette. The human eye perceives the diffusion as a mixture of the colors within it (see color vision). Dithering is analogous to the halftone technique used in printing. Dithered images, particularly those with relatively few colors, can often be distinguished by a characteristic graininess, or speckled appearance.

Examples

Reducing the color depth of an image can often have significant visual side-effects. If the original image is a photograph, it is likely to have thousands, or even millions of distinct colors. The process of constraining the available colors to a specific ''color palette'' effectively throws away a certain amount of color information.

A number of factors can affect the resulting quality of a color-reduced image. Perhaps most significant is the color palette that will be used in the reduced image. For example, an original image (''Figure 1'') may be reduced to the 216-color "web-safe" color palette. If the original pixel colors are simply translated into the closest available color from the palette, no dithering occurs (''Figure 2''). Typically, this approach results in flat areas (contours) and a loss of detail, and may produce patches of color that are significantly different from the original. Shaded or gradient areas may appear as ''color bands'', which may be distracting. The application of dithering can help to minimize such visual artifacts, and usually results in a better representation of the original (''Figure 3''). Dithering helps to reduce color banding and flatness.

One of the problems associated with using a fixed color palette is that many of the needed colors may not be available in the palette, and many of the available colors may not be needed; a fixed palette containing mostly shades of green would not be well-suited for images that do not contain many shades of green, for instance. The use of an optimized color palette can be of benefit in such cases. An optimized color palette is one in which the available colors are chosen based on how frequently they are used in the original source image. If the image is reduced based on an optimized palette, the result is often much closer to the original (''Figure 4'').

The number of colors available in the palette is also a contributing factor. If, for example, the palette is limited to only 16 colors, the resulting image could suffer from additional loss of detail, and even more pronounced problems with flatness and color banding (''Figure 5''). Once again, dithering can help to minimize such artifacts (''Figure 6'').

{{Image gallery |lines=6 |width=260 |Dithering example undithered.png|frame|Figure 1. Original photo; note the smoothness in the detail. |Dithering example undithered web palette.png|frame|Figure 2. Original image using the web-safe color palette with no dithering applied. Note the large flat areas and loss of detail. |Dithering example dithered web palette.png|frame|Figure 3. Original image using the web-safe color palette with Floyd–Steinberg dithering. Note that even though the same palette is used, the application of dithering gives a better representation of the original. |Dithering example dithered 256color.png|frame|Figure 4. Here, the original has been reduced to a 256-color optimized palette with Floyd–Steinberg dithering applied. The use of an optimized palette, rather than a fixed palette, allows the result to better represent the colors in the original image. |Dithering example undithered 16color.png|frame|Figure 5. Depth is reduced to a 16-color optimized palette in this image, with no dithering. Colors appear muted, and color banding is pronounced. |Dithering example dithered 16color.png|frame|Figure 6. This image also uses the 16-color optimized palette, but the use of dithering helps to reduce banding. }}

Applications

Display hardware, including early computer video adapters and many modern LCDs used in mobile phones and inexpensive digital cameras, show a much smaller color range than more advanced displays. One common application of dithering is to more accurately display graphics containing a greater range of colors than the hardware is capable of showing. For example, dithering might be used in order to display a photographic image containing millions of colors on video hardware that is only capable of showing 256 colors at a time. The 256 available colors would be used to generate a dithered approximation of the original image. Without dithering, the colors in the original image might simply be "rounded off" to the closest available color, resulting in a new image that is a poor representation of the original. Dithering takes advantage of the human eye's tendency to "mix" two colors in close proximity to one another.

Some LCDs may use temporal dithering to achieve a similar effect. By alternating each pixel's color value rapidly between two approximate colors in the panel's color space (also known as Frame Rate Control), a display panel which natively supports 18-bit color (6 bits per channel) can represent a 24-bit "true" color image (8 bits per channel).

Dithering such as this, in which the computer's display hardware is the primary limitation on color depth, is commonly employed in software such as web browsers. Since a web browser may be retrieving graphical elements from an external source, it may be necessary for the browser to perform dithering on images with too many colors for the available display. It was due to problems with dithering that a color palette known as the "web-safe color palette" was identified, for use in choosing colors that would not be dithered on displays with only 256 colors available.

But even when the total number of available colors in the display hardware is high enough when rendering full color digital photographs, as those 15- and 16-bit RGB Hicolor 32,768/65,536 color modes, banding can be evident to the eye, especially in large areas of smooth shade transitions (although the original image file has no banding at all). Dithering the 32 or 64 RGB levels will result in a pretty good "pseudo truecolor" display approximation, which the eye cannot resolve as ''grainy''. Furthermore, images displayed on 24-bit RGB hardware (8 bits per RGB primary) can be dithered to simulate somewhat higher bit depth, and/or to minimize the loss of hues available after a gamma correction. High-end still image processing software, as Adobe Photoshop, commonly uses these techniques for improved display.

Another useful application of dithering is for situations in which the graphic file format is the limiting factor. In particular, the commonly-used GIF format is restricted to the use of 256 or fewer colors in many graphics editing programs. Images in other file formats, such as PNG, may also have such a restriction imposed on them for the sake of a reduction in file size. Images such as these have a fixed color palette defining all the colors that the image may use. For such situations, graphical editing software may be responsible for dithering images prior to saving them in such restrictive formats.

Algorithms

There are several algorithms designed to perform dithering. One of the earliest, and still one of the most popular, is the Floyd–Steinberg dithering algorithm, developed in 1975. One of the strengths of this algorithm is that it minimizes visual artifacts through an error-diffusion process; error-diffusion algorithms typically produce images that more closely represent the original than simpler dithering algorithms.

Dithering methods include: ''Thresholding'' (also average dithering): each pixel value is compared against a fixed threshold. This may be the simplest dithering algorithm there is, but it results in immense loss of detail and contouring. ''Random dithering'' was the first attempt (at least as early as 1951) to remedy the drawbacks of thresholding. Each pixel value is compared against a random threshold, resulting in a staticky image. Although this method doesn't generate patterned artifacts, the noise tends to swamp the detail of the image. It is analogous to the practice of mezzotinting.

''Patterning'' dithers using a fixed pattern. For every pixel in the image the value of the pattern at the corresponding location is used as a threshold. Neighboring pixels do not affect each other, making this form of dithering suitable for use in animations. Different patterns can generate completely different dithering effects.

* ''Halftone dithering'' looks similar to halftone screening in newspapers. This is a form of clustered dithering, in that dots tend to cluster together. This can help hide the adverse effects of blurry pixels found on some older output devices.

''Ordered dithering'' produces a cross-hatch pattern. This is a form of dispersed dithering. Because the dots don't cluster, the result looks much less grainy. Though simple to implement, this dithering algorithm is not easily changed to work with free-form, arbitrary palettes.

{| |- !(Original) !Threshold !Random !Halftone !Bayer (ordered) |- | | | | | |}

''Error-diffusion dithering'' is a feedback process that diffuses the quantization error to neighbouring pixels.

*Floyd–Steinberg dithering only diffuses the error to neighbouring pixels. This results in very fine-grained dithering.

*Jarvis, Judice, and Ninke dithering diffuses the error also to pixels one step further away. The dithering is coarser, but has fewer visual artifacts. It is slower than Floyd–Steinberg dithering because it distributes errors among 12 nearby pixels instead of 4 nearby pixels for Floyd–Steinberg.

*Stucki dithering is based on the above, but is slightly faster. Its output tends to be clean and sharp.

*Burkes dithering is a simplified form of Stucki dithering that is faster, but less clean than Stucki dithering.

{| |- !Floyd–Steinberg !Jarvis, Judice & Ninke !Stucki !Burkes |- | | | | |}

Error-diffusion dithering (continued):

*Sierra dithering is based on Jarvis dithering, but it's faster while giving similar results.

*Two-row Sierra is the above method modified by Sierra to improve its speed.

*Filter Lite is an algorithm by Sierra that is much simpler and faster than Floyd–Steinberg, while still yielding similar (according to Sierra, better) results.

*Atkinson dithering resembles Jarvis dithering and Sierra dithering, but it's faster. Another difference is that it doesn't diffuse the entire quantization error, but only three quarters. It tends to preserve detail well, but very light and dark areas may appear blown out.

**History

**Algorithm

Even toned screening is a patented modification of Floyd–Steinberg dithering intended to reduce visual artifacts, in particular to produce more even dot patterns in highlights and shadows.

{| |- !Sierra !Two-row Sierra !Sierra Lite !Atkinson |- | | | | |}

In optical fiber systems

Stimulated Brillouin Scattering (SBS) is a nonlinear optical effect that limits the launched optical power in fiber optic systems. This power limit can be increased by dithering the transmit optical center frequency, typically implemented by modulating the laser's bias input.

See also

Digital audio

Quantization (signal processing)

Anti-aliasing

Lossy data compression

References

External links

"Dither - Not All Noise Is Bad"

What is Dither? Article previously published in ''Australian HI-FI'' with visual examples of how audio dither sharply reduces high order harmonic distortion.

Other well-written papers on the subject at a more elementary level are available by:

Aldrich, Nika. "Dither Explained"

Both Nika Aldrich and Bob Katz are esteemed experts in the field of digital audio and have books available as well, each of which are far more comprehensive in their explanations:

Aldrich, Nika. "Digital Audio Explained"

Dither Vibration Example

More recent research in the field of dither for audio was done by Lipshitz, Vanderkooy, and Wannamaker at the University of Waterloo:

Stan Lipshitz

Category:Audio engineering Category:Digital signal processing Category:Computer graphic artifacts

ca:Tramat (informàtica) de:Dithering (Bildbearbeitung) fr:Tramage (informatique) ko:디더링 it:Dithering ja:ディザ pl:Dithering (grafika komputerowa) pt:Dither ru:Дизеринг sk:Dithering (počítačová grafika) uk:Дизеринг

Coordinates	12°2′36″N77°1′42″N
name	Fred Frith
background	non_vocal_instrumentalist
birth name	Fred Frith
birth date	February 17, 1949
birth place	Heathfield, Sussex, England
instrument	Guitar, violin, bass guitar, keyboards, percussion
genre	Avant-rock, experimental, free improvisation, contemporary classical
occupation	Musician, Composer,Professor of Composition
years active	1968–present
label	Caroline, Moers Music, Ralph, RecRec, Recommended, Fred, Tzadik, Winter & Winter
associated acts	Henry Cow, Art Bears, Massacre, Skeleton Crew, Keep the Dog, Chris Cutler, John Zorn
website	www.fredfrith.com }}

Fred Frith (born 17 February 1949) is an English multi-instrumentalist, composer and improvisor.

Probably best-known for his guitar work, Frith first came to attention as one of the founding members of the English avant-rock group Henry Cow. Frith was also a member of Art Bears, Massacre and Skeleton Crew. He has collaborated with a number of prominent musicians, including Robert Wyatt, Derek Bailey, The Residents, Lol Coxhill, John Zorn, Brian Eno, Lars Hollmer, Bill Laswell, Iva Bittová, the ARTE Quartett and Bob Ostertag. He has also composed several long works, including ''Traffic Continues'' (1996, performed 1998 by Frith and Ensemble Modern) and ''Freedom in Fragments'' (1993, performed 1999 by Rova Saxophone Quartet). Frith produces most of his own music, and has also produced many albums by other musicians, including Curlew, The Muffins, Etron Fou Leloublan and Orthotonics.

Frith is the subject of Nicolas Humbert and Werner Penzel's award-winning 1990 documentary film ''Step Across the Border''. He also appears in the Canadian documentary ''Act of God'', which is about the metaphysical effects of being struck by lightning. Frith has contributed to a number of music publications, including ''New Musical Express'' and ''Trouser Press'', and has conducted improvising workshops across the world. Frith's career spans over three decades and he appears on over 400 albums. He still performs actively throughout the world.

Currently Frith is Professor of Composition in the Music Department at Mills College in Oakland, California. He lives in the United States with his wife, German photographer Heike Liss, and their children, Finn Liss (born 1991) and Lucia Liss (born 1994).

Frith was awarded the 2008 Demetrio Stratos Prize for his career achievements in experimental music. The prize was established in 2005 in honour of experimental vocalist Demetrio Stratos, of the Italian group Area, who died in 1979. In 2010 Frith received an honorary doctorate from the University of Huddersfield in West Yorkshire, England in recognition of his contribution to music.

Frith is the brother of Simon Frith, a well-known music critic and sociologist, and Chris Frith, a psychologist working at University College London.

Biography

Frith was born in Heathfield in Sussex, England into a family where music was considered an essential part of life. He started violin lessons at the age of five and became a member of his school orchestra. But at 13 he switched to guitar after watching a group imitating a popular instrumental band at the time, The Shadows. He decided to learn how to play guitar and get into a band. Frith taught himself guitar from a book of guitar chords and soon found himself in a school group called The Chaperones, playing Shadows and Beatles covers. But when Frith started hearing blues music from the likes of Snooks Eaglin and Alexis Korner it changed his whole approach to the guitar, and by the time he was 15, The Chaperones had become a blues band. Frith's first public performances were in 1967 in folk clubs in the North of England, where he sang and played traditional and blues songs.

Besides the blues, Frith started listening to any music that had guitar in it, including folk, classical, ragtime and flamenco. He also listened to Indian, Japanese and Balinese music and was particularly drawn to East European music after a Yugoslav school friend taught him folk tunes from his home. Frith went to Cambridge University in 1967 where his musical horizons were expanded further by the philosophies of John Cage and Frank Zappa's manipulation of rock music. Frith graduated from Christ's College, Cambridge with a BA (English Literature) in 1970, and an MA (English Literature) in 1974, but the real significance of Cambridge for him was that that was where the seminal avant-rock group Henry Cow were formed.

Henry Cow

Frith met Tim Hodgkinson, a fellow student, in a blues club at Cambridge University in 1968. "We’d never met before, and he had an alto sax, and I had my violin, and we just improvised this ghastly screaming noise for about half an hour." But something clicked and recognizing their mutual open-minded approach to music, Frith and Hodgkinson formed a band there and then. They called it Henry Cow and they remained with the band until its demise in 1978. In the early 70's Fred's grey Morris Minor sported the band's heraldic logo, much to the amusement of boys at his dad's grammar school in York where he was the headmaster.

Frith composed a number of the band's notable pieces, including "Nirvana for Mice" and "Ruins". While guitar was his principal instrument, he also played violin (drawing on his classical training), bass guitar, piano and xylophone.

In November 1973, Frith (and other members of Henry Cow) participated in a live-in-the-studio performance of Mike Oldfield's ''Tubular Bells'' for the BBC. It is available on Oldfield's ''Elements'' DVD.

Guitar Solos

After Henry Cow's first album, Frith released ''Guitar Solos'' in 1974, his first solo album and a glimpse at what he had been doing with his guitar. The album comprised eight tracks of unaccompanied and improvised music played on prepared guitars. It was recorded in four days at the Kaleidophon Studios in London without any overdubbing.

When it was released, ''Guitar Solos'' was considered a landmark album because of its innovative and experimental approach to guitar playing. The January 1983 edition of ''Down Beat'' magazine remarked that ''Guitar Solos'' "... must have stunned listeners of the day. Even today that album stands up as uniquely innovative and undeniably daring." It also attracted the attention of some "famous" musicians, including Brian Eno, resulting in Frith playing guitar on two of Eno's albums, ''Before and After Science'' (1977) and ''Music for Films'' (1978).

In the mid-1970s, Frith contributed a series of articles to British weekly music magazine, New Musical Express entitled "Great Rock Solos of our Time". In them he analysed prominent rock guitarists of the day and their contribution to the development of the rock guitar, including Jimi Hendrix and Eric Clapton.

Post Henry Cow

While recording Henry Cow's last album, differences emerged between the group members over the album's content. Frith and Chris Cutler favoured song-oriented material, while Hodgkinson and Lindsay Cooper wanted purely instrumental compositions. As a compromise, Frith and Cutler agreed, early in 1978, to release the songs already created on their own album, ''Hopes and Fears'', under the name Art Bears (with Dagmar Krause). The instrumental material was recorded by Henry Cow on ''Western Culture'' later that year, after which the band split. The Art Bears trio continued purely as a studio group until 1981, releasing two more albums, ''Winter Songs'' in 1979 and ''The World as It Is Today'' in 1981.

During this time Frith also released ''Gravity'' (1980), his second solo album, recorded at Norrgården Nyvla in Uppsala, Sweden with Swedish group Samla Mammas Manna, and at the Catch-a-Buzz studio in Rockville, Maryland with United States band The Muffins. It showed Frith breaking free from the highly structured and orchestrated music of Henry Cow and experimenting with folk and dance music. "Norrgården Nyvla" was also the title of one of the tracks on the album and is considered one of Frith's most recognisable tunes.

New York

Towards the end of 1979 Frith relocated to New York City where he immediately hooked-up with the local avant-garde/Downtown music scene. The impact on him was uplifting: "... New York was a profoundly liberating experience for me; for the first time I felt that I could be myself and not try to live up to what I imagined people were thinking about me." Frith met and began recording with a number of musicians and groups, including Henry Kaiser, Bob Ostertag, Tom Cora, Eugene Chadbourne, Zeena Parkins, Ikue Mori, The Residents, Material, The Golden Palominos and Curlew. He spent some 14 years in New York, during which time he joined a few bands, including John Zorn's Naked City (in which Frith played bass) and French Frith Kaiser Thompson (consisting of John French, Frith, Henry Kaiser and Richard Thompson). Frith also started three bands himself, namely Massacre, Skeleton Crew and Keep the Dog.

Massacre was formed in 1980 with bassist Bill Laswell and drummer Fred Maher. A high energy experimental rock band, they toured the United States and Europe in 1980 and 1981, and released one album, ''Killing Time'' (1981), recorded at Martin Bisi's later-to-be historic studio in Brooklyn. Massacre split in 1981 when Maher left, but later reformed again in 1998 when drummer Charles Hayward joined. The new Massacre released three more albums.

Skeleton Crew, a collaboration with Tom Cora from 1982 to 1986, was an experimental group noted for its live improvisations where Frith (guitar, violin, keyboards, drums) and Cora (cello, bass guitar, homemade drums and contraptions) played a number of instruments simultaneously. They performed extensively across Europe, North America and Japan and released ''Learn to Talk'' in 1984. Zeena Parkins (electric harp and keyboards) joined in 1984 and the trio released ''The Country of Blinds'' in 1986. In October 1983 Skeleton Crew joined Duck and Cover, a commission from the Berlin Jazz Festival, for a performance in West Berlin, followed by another in February 1984 in East Berlin.

Frith formed Keep the Dog in 1989, a sextet and review band for performing selections of his extensive repertoire of compositions from the previous 15 years. The lineup was Frith (guitar, violin, bass guitar), René Lussier (guitar, bass guitar), Jean Derome (winds), Zeena Parkins (piano, synthesizer, harp, accordion), Bob Ostertag (sampling keyboard) and Kevin Norton (drums, percussion). Later Charles Hayward replaced Norton on drums. The group existed until mid-1991, performing live in Europe, North America and the former Soviet Union. A double CD, ''That House We Lived In'', from their final performances in Austria, Germany and Italy in May and June 1991, was released in 2003.

Other projects

During the 1980s, Frith began writing music for dance, film and theatre, and a number of his solo albums from this time reflect this genre, including ''The Technology of Tears (And Other Music for Dance and Theatre)'' (1988), ''Middle of the Moment'' (1995), ''Allies (Music for Dance volume 2)'' (1996) and ''Rivers and Tides'' (2003). Exploring new forms of composition, Frith also experimented with chance or accidental compositions, often created by building music around "found sounds" and field recordings, examples of which can be found on ''Accidental (Music for Dance volume 3)'' (2002) and ''Prints: Snapshots, Postcards, Messages and Miniatures, 1987-2001'' (2002).

As a composer, Frith began composing works for other musicians and groups in the late 1980s, including the Rova Saxophone Quartet, Ensemble Modern and Arditti Quartet. In the late 1990s, Frith established his own Fred Frith Guitar Quartet consisting of Frith, René Lussier, Nick Didkovsky and Mark Stewart. Their guitar music, varying from "tuneful and pretty, to noisy, aggressive and quite challenging", appears on two albums, ''Ayaya Moses'' (1997) and ''Upbeat'' (1999), both on Lussier's own Ambiances Magnétiques label.

The ex-Henry Cow members have always maintained close contact with each other and Frith still collaborates with many of them, including Chris Cutler, Tim Hodgkinson and Lindsay Cooper. Cutler and Frith have been touring Europe, Asia and the Americas since 1978 and have given dozens of duo performances. Three albums from some of these concerts have been released by Recommended Records. In December 2006, Cutler, Frith and Hodgkinson performed together at The Stone in New York City, their first concert performance since Henry Cow's demise in 1978.

In 1995 Frith moved to Stuttgart in Germany to live with his wife, German photographer Heike Liss and their children Finn and Lucia. Between 1994 and 1996, Frith was Composer-in-Residence at L’Ecole Nationale de Musique in Villeurbanne, France.

Frith relocated to the United States in 1997 to become Composer-in-Residence at Mills College in Oakland, California. In 1999 he was appointed the Luther B. Marchant Professor of Composition in the Music Department at Mills where he currently teaches composition, contemporary performance and improvisation. While he had never studied music in college, Frith's credentials of over forty years of continuous practice and self-discovery got him the position. He has, however, maintained that "most of my students are better qualified to teach composition than I am," and that he learns as much from them as they learn from him.

In March 1997 Frith formed the electro-acoustic improvisation and experimental trio Maybe Monday with saxophonist Larry Ochs from Rova Saxophone Quartet and koto player Miya Masaoka. Between 1997 and 2008 they toured the United States, Canada and Europe and released three albums. In March 2008 Frith formed Cosa Brava, an experimental rock and improvisation quartet with Zeena Parkins from Skeleton Crew and Keep the Dog, and Carla Kihlstedt and Matthias Bossi from Sleepytime Gorilla Museum, and The Norman Conquest. They toured Europe in April 2008 and performed at the 25th Festival International de Musique Actuelle de Victoriaville in Victoriaville, Quebec, Canada in May 2008.

==Equipment==

Guitars and playing technique

Fred Frith has used a number of different guitars, including homemades, over the years, depending on the type of music he is playing. For the more structured and refined music he has often used a Gibson ES-345, for example on his solo album, ''Gravity''. For the heavier "rock" sound, as in Massacre, he has used an old 1961 solid body Burns guitar, created by the British craftsman Jim Burns. On his landmark ''Guitar Solos'' album, Frith used a modified 1936 Gibson K-11 guitar (q.v. for details).

For Frith's early unstructured music, as with Henry Kaiser on ''With Friends Like These'', and his early table-top guitar solo performances, he used a homemade six- and eight-string double-neck guitar, created by a friend Charles Fletcher. Frith told ''Down Beat'' magazine in 1983: "It was the one and only guitar that he ever built ... he constructed it mainly out of old pieces from other guitars that I had, and for the body I think he used an old door." The possibilities offered by homemade instruments prompted Frith to start creating his own guitars, basically slabs of wood on which he mounted a pickup, a bridge, and strings stretched over metal screws. "The basic design of the instrument is supposed to be as rudimentary and flexible as possible," Frith said, "so I can use an electric drill to bore holes into the body of it to achieve certain sounds ... ."

Frith has used a variety of picks with his guitars, from traditional guitar picks to violin bows, drum sticks, egg beaters, paint brushes, lengths of metal chain and other found objects. Frith remarked: "It's more to do with my interest in found objects and the use of certain kinds of textures which have an effect on the string ... the difference between the touch of stone, the touch of glass, the touch of wood, the touch of paper — those kinds of basic elements that you're using against the surface of the strings which produce different sounds."

In a typical solo improvising concert, Frith would lay a couple of his homemade guitars flat on a table and play them with a collection of found objects (varying from concert to concert). He would drop objects, like ball bearings, dried beans and rice, on the strings while stroking, scraping and hitting them with whatever was on hand. Later he added a live sampler to his on-stage equipment, which he controlled with pedals. The sampler enabled him to dynamically capture and loop guitar sounds, over which he would capture and loop new sounds, and so on, until he had a bed of repeated patterns on top of which he would then begin his solo performance.

Effects and amplification

;Effect pedals:

Pro Co RAT Distortion Pedal

Boss FV-50L Volume Foot Controller

Boss RC20-XL Delay

DigiTech DigiTech Whammy 4

Line 6 DL4 Delay

EBow

;Amplification:

Fender Amplifiers

Step Across the Border

''Step Across the Border'' is an award winning 1990 documentary film on Fred Frith, written and directed by Nicolas Humbert and Werner Penzel, and released in Germany and Switzerland. It was filmed in Japan, Europe and the United States, and also features musicians René Lussier, Iva Bittová, Tom Cora, Tim Hodgkinson, Bob Ostertag and John Zorn.

Fred Records

In 2002, Fred Frith created his own record label, Fred Records to re-release his back catalogue of recordings and previously unreleased material. Frith also appears on several releases by Tzadik Records and Winter & Winter.

Compositions

Since the late 1980s, Fred Frith has composed a number of longer works. Here is a selection, the year indicating when they were composed. For a complete list, see Compositions by Fred Frith.

''The As Usual Dance Towards the Other Flight to What is Not'' (1989) – for four electric guitars

''Helter Skelter'' (1990) – for two sopranos, contralto and a large electric ensemble

''Stick Figures'' (1990) – for six guitars and two players

''Lelekovice'' (1991) – (for Iva Bittová) string quartet no. 1

''Stone, Brick, Glass, Wood, Wire'' (1992) – graphic scores for any number of players

''Freedom in Fragments'' (1993) – a suite of 23 pieces for saxophone quartet

''The Previous Evening'' (1993) – a tribute to John Cage for four clarinets, tapes, bass, footsteps, electric guitars, whirled objects and voice

''Elegy for Elias'' (1993) – for piano, violin and marimba

''Pacifica'' (1994) – a meditation for 21 musicians with texts by Pablo Neruda

''Seven Circles'' (1995) – for piano

''Impur'' (1996) – for 100 musicians, large building and mobile audience

''Shortened Suite'' (1996) – for trumpet, oboe, cello and marimba

''Back to Life'' (1997) – for trumpet, oboe, cello and marimba

''Traffic Continues: Gusto'' (1998) – for large ensemble with improvising soloists

''Landing for Choir'' (2001) – for Flamenco singer, cello, saxophone and samples

''Allegory'' (2002) – for string quartet and electric guitar

''Fell'' (2002) – for string quartet & electric guitar

''The Happy End Problem'' (2003) – for flute, bassoon, gu zheng, percussion, violin and electronics

''The Right Angel'' (2003) – for orchestra and electric guitar

''Save As'' (2005) – for cello and percussion

''Snakes and Ladders'' (2006) – for clarinet, electric guitar, piano, percussion, cello and double bass

''Episodes'' (2007) – for Baroque orchestra

''Water Stories'' (2007) – for clarinet, piano, percussion, violin, and cello

''For Nothing'' (2008) – for contralto and Baroque string quartet

Discography

Fred Frith appears on over 400 recordings: with bands, in collaboration with other musicians, solo, albums he produced for other bands and musicians, and albums featuring his composed work performed by others.

Films

1990 ''Step Across the Border'' – a 90 minute documentary on Fred Frith by Nicolas Humbert and Werner Penzel.

1991 ''Streetwise'' – a documentary by Charles Castella about Frith's work in Marseille with "unemployed rock musicians".

2000 ''Le Voyage Immobile'' – a documentary about Frith's trio with Louis Sclavis and Jean-Pierre Drouet for France 3 national TV.

2004 ''Touch the Sound'' – a documentary by Thomas Riedelsheimer about Scottish percussionist Evelyn Glennie and her collaboration with Frith.

2007 ''Attwenger Adventure'' – a documentary on Austrian folk-punk duo Attwenger by Markus Kaiser-Mühlecker, with special appearances by Frith rehearsing and performing live with Attwenger and Wolfgang "I-Wolf" Schlögl at Music Unlimited XX. in Wels, Austria.

2009 ''Act of God'' – a documentary by Jennifer Baichwal about the metaphysical effects of being struck by lightning, with music by Frith and others, and a segment showing Frith conducting an experiment to measure the effect of improvisation on brain waves.

Footnotes

External links

FredFrith.com ''Official homepage''.

Fred Frith biography ''FredFrith.com'' archive at the ''Internet Archive Wayback Machine''.

Fred Frith biography ''The Canterbury Website''.

Fred Frith interview ''Dan Warburton, Paris Transatlantic Magazine, March 1998''.

Fred Frith interview ''BBC Music'' archive at the ''Internet Archive Wayback Machine''.

Stage Effects Setup. ''All About Jazz''. .

Fred Frith discography.

Fred Frith interview at allaboutjazz.com

Category:1949 births Category:Living people Category:20th-century classical composers Category:21st-century classical composers Category:English guitarists Category:English violinists Category:English bass guitarists Category:English keyboardists Category:English composers Category:British film score composers Category:English experimental musicians Category:Free improvisation Category:Canterbury scene Category:Alumni of Christ's College, Cambridge Category:English multi-instrumentalists Category:People from Wealden (district) Category:Henry Cow members Category:The Golden Palominos members Category:Tzadik Records artists Category:Moers Music artists

de:Fred Frith es:Fred Frith fr:Fred Frith it:Fred Frith hu:Fred Frith nl:Fred Frith no:Fred Frith pl:Fred Frith pt:Fred Frith ru:Фрит, Фред fi:Fred Frith sv:Fred Frith