Agfacontour Professional was (as of 2002 not anymore produced
) a special emulsion sheet film which, after exposure and development in the Agfacontour developer, produced direct
equidensities.
Agfacontour was introduced in 1970 by
Agfa-Gevaert
Agfa-Gevaert N.V. (Agfa) is a Belgian-German multinational corporation that develops, manufactures, and distributes analogue and digital imaging products, software, and systems. It has three divisions:
* Agfa Graphics, which offers integrated pre ...
to produce equidensities by a direct, one-developing-step process.
Until then equidensities had to be obtained using one of the following techniques:
*The most popular method to obtain equidensities was the ''One-Film'' technique, better known as
Sabattier effect
The Sabatier effect, also known as pseudo-solarization (or pseudo-solarisation) and erroneously referred to as the Sabattier effect, is a phenomenon in photography in which the image recorded on a negative or on a photographic print is wholly o ...
(a.k.a. Pseudosolarization).
*Another technique, making tonal extractions on high-contrast film, was called the ''Two-Film'' technique (negative-positive process): from a negative 3-5 different exposures were made on ultra high-contrast
lith-films. These 3-5 positives were then copied again on ultra high-contrast lith-film to obtain negatives with virtually no grey tones. Then one positive and a negative from a different set were sandwiched together in register to obtain one specific equidensity. Using the same shuffling, the other positives were combined with the negatives to resulting in 2-4 equidensity series.
*Although there are other techniques such as the ''Scattered-light'' technique or ''Electronic (video)'' techniques, thy are less important for obtaining equidensity series.
Each of these techniques had its drawbacks of which reproducibility and extensive work involvement were undoubtedly the most important ones.
Therefore the researchers at Agfa-Gevaert set up a workgroup to develop a film that enables the use of equidensitometry with the following, principal evaluation methods of an information-carrier
[Agfacontour Professional in Wissenschaft und Technik, C. Sauer, Agfa-Gevaert AG Druckschrift nr. 152, 1. Auflage 1974 (in German)]
# A
Black and white
Black-and-white (B&W or B/W) images combine black and white in a continuous spectrum, producing a range of shades of grey.
Media
The history of various visual media began with black and white, and as technology improved, altered to color. ...
extract of a precisely controllable range of densities
# A breakdown into separate, distinctive density ranges which could be created in a manageable manner by colorizing or using
Halftone
Halftone is the reprographic
Reprography (a portmanteau of ''reproduction'' and ''photography'') is the reproduction of graphics through mechanical or electrical means, such as photography or xerography. Reprography is commonly used in catal ...
screens
# Distance measurement of similar densities, called isodensities (especially in cases of density gradients)
# Information clarification/reduction in the presence of chaotic density distribution and density gradients
The Agfacontour film contained two special emulsions with each different spectral sensitivity.
* By using color filters (yellow or magenta) during the exposure one could respectively narrow or widen the width of the equidensity.
* By varying the exposure one could change the density in the image that showed on Agfacontour as equidensity.
Although the material exhibited very low sensitivity (long exposures were necessary) the results were very reproducible and second order equidensities were sharp and clear, something that with pseudo-solarization was almost impossible to achieve without special procedures.
The
Gamma
Gamma (uppercase , lowercase ; ''gámma'') is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter re ...
of the material was very high (approx. above 7.0), power of resolution was 40 lines/mm
Since the introduction of
Photo editing software
In computer graphics, graphics software refers to a program or collection of programs that enable a person to manipulate images or models visually on a computer.
Computer graphics can be classified into two distinct categories: raster graphic ...
, altering
curves
A curve is a geometrical object in mathematics.
Curve(s) may also refer to:
Arts, entertainment, and media Music
* Curve (band), an English alternative rock music group
* ''Curve'' (album), a 2012 album by Our Lady Peace
* "Curve" (song), a 20 ...
into U-curves also produces equidensities.
![Cow Agfacontour, chromogenic development of equidenities serie](https://upload.wikimedia.org/wikipedia/commons/7/73/Cow_Agfacontour%2C_chromogenic_development_of_equidenities_serie.jpg)
For the image at the right a darkroom process was used that encompassed the production a serie of equidensities of the negative, enlarged on Agfacontour Professional sheetfilm. Each sheet was then copied onto lith film and developed in lith developer. Each copy was then developed in a chromogenic developer. All colored lith films were then put together in register and a positive print on color paper was made.
See also
* Agfa Publication Department, ''Agfacontour Professional in Photographics''. Leverkusen, 1970
Agfacontour Film on archive.org* Solf, Kurt Dieter (Februar 1973). "Äquidensitenfilm". ''Fotografie''. Frankfurt am Main: Fischer Taschenbuch Verlag GmbH. pp. 111–118. .
* Mass, H. "Agfacontour Professional in der Praxis." Phototechnik und Wirtschaft (1971) Nr.2, p 39
* Myšák, F "The Evaluating of Autoradiographs by Means of the Film Agfacontour Professional"
References
{{reflist
Photographic films
Products and services discontinued in 2002