Black and white photography
Black and white photography is a special category of photography in which the real color lightness nuances of objects are fixed in an imaging process in achromatic gray value shades , including the extreme values black and white , in an image memory. Originally one spoke of a grayscale photo. Before the advent of color photography, the black and white process had no name; in the absence of alternatives, it was generally referred to as photography.
The light-dependent chemical changes on a coated surface and their use as image storage are now often referred to as “analog” photography in order to distinguish them from digital image recording processes. Digital photography combines photoelectric methods of image capture with storage techniques of electronic data processing . In addition to the various silver imaging processes and modern digital image recording, combinations of both methods are also used.
All photographic processes from the pioneering days of photography belong to the genre of "analog" black and white photography. Due to a simple duplication method, the photochemical silver image process with coated carrier plates made of glass finally established itself in 1871 and quickly developed into the first mass-widespread image medium in cultural history.
Concern and style
With its special ability to abstract minimalist motifs, the black and white process is particularly suitable for the artistic intensification of a picture statement in the sense of artistic photography . Especially in times of ubiquitous “colorful images”, which became popular in the 1970s, this sub-discipline is the medium of expression of many photographers of choice, whereby the basic photographic problems hardly differ from those of color photography. The focus of black and white photography is the reduction to structures, light and shadow and abstraction.
There is an irreconcilable contradiction between the two genres only in one decisive individual discipline: the central design factor of a good black and white photographic image is the motif and its effectively staged formal gray value dynamics; in color photography this is replaced by the design options of the color category, whereby observation, recognition and Evaluating photogenic color values and their photographic implementation place completely different demands on the photographer than the primarily formal thinking in terms of brightness nuances and their expressive implementation in graphic black and white.
Conventional black and white photography has lost its former importance and only plays a role in special marginal areas: in astrophotography and other areas of scientific photography , in special applications such as traffic monitoring, in long-term archiving, in artistic photography and for high-speed recordings .
In almost all methods of film-based black and white photography, a light-sensitive layer , which usually consists of tiny silver halide crystals in a gelatin layer , is applied to a transparent carrier material (glass plates, celluloid film, nitrate film, acetate film, polyester film) and then in a light-tight camera with the help of optical lenses or . pinhole exposed - while the photographic material stores the different light intensities by one of them triggered activation of the atomic structure, it creates a latent image . This initially invisible image is then made visible ( development ) with the exclusion of interfering light influences with a developer that contains a reducing agent as a chemically active substance , whereby the silver halides in the exposed image areas are reduced to finely divided, elemental silver in proportion to the extent of the light intensity. During the subsequent fixing process , the excess light-sensitive silver halide is removed and thus undesired further blackening is prevented. The resulting distribution of density of the fixed photographic emulsion normally corresponds to the inversion of the brightness values of the photographed object; the photographic image is a negative .
For the necessary inversion of the brightness values, a second beam path creates a latent positive image on light-sensitive material with the help of contact exposure or projection by means of an enlarger , which in turn creates the finished photographic top view image through development and fixation.
With the help of special development processes ( reverse development ), the tonal value distribution can also be reversed, the image result then corresponds to a positive top view or a slide suitable for projection .
Alternatively, there are chromogenic black and white films that work like a monochrome color negative film and can be developed anywhere in the standardized C-41 color process.
The invention of image generation with the help of an information-transmitting machine was tied to two basic requirements that had been known for a long time, but whose experimental combination was only put into practice by the Nièpce brothers: the optical principle of the camera obscura and the effects of light on light-sensitive substances. After the death of his brother Claude, after many years of tireless research , Joseph Nicéphore Nièpce succeeded for the first time in the direct generation and permanent storage of images in black-and-white brightness levels.
The heliography first mechanical image storage process was in 1826 by the self-taught Joseph Nicephore Nièpce with a camera obscura and light- asphalt invented as an image memory. These first heliographies required an exposure time of around eight hours and left a lot to be desired in terms of contrast and clarity.
August 19, 1839, is considered to be the real hour of birth of photography: the painter and theater decorator Louis Jacques Mandé Daguerre presented his further developed photomechanical process to the Parisian public, which he himself described as the daguerreotype.
The daguerreotype was the first practical photography process and was developed at the end of the 1830s. The resulting images were of high quality, but had the disadvantage, as positive, one-offs, that they could not be copied.
The pictures were created on silver-plated copper plates that were sensitized with iodine or bromine vapors. After exposing the plate in the camera, Daguerre succeeded in reversing the negative tonal values with the help of mercury vapor, which is deposited on the exposed areas.
Despite the cumbersome procedure and the not inconsiderable cost of the plates, the daguerreotype prevailed because of its remarkable results and was considered a reliable photographic process.
Calotype / Talbotype
In 1840 the Englishman William Henry Fox Talbot developed a process that he named calotype . A paper prepared with silver nitrate, acetic and gallic acid served as the image carrier. After exposure in the camera obscura, development was carried out with silver gallon nitrate and the sensitizing substances were washed out with sodium thiosulfate. Since the resulting image was a negative, any number of positive prints could be made in a reversal process.
The monochrome, grainy image result was much closer to a lithograph or a drawing than the high-contrast and high-precision image quality of a good daguerreotype.
The natural scientist Talbot had his process patented, demanded license fees and rigorously pursued patent infringements, which severely restricted further development and provoked the invention of other processes such as collodion and gelatine plates.
Collodion wet plate
The Englishman Frederick Scott Archer developed the “wetplate process” in 1851, with which, in the best case, exposure times of around one second could be achieved. For this purpose, collodion (cellulose treated in nitric acid is dissolved in ether and alcohol) was "iodized" with potassium iodide and then distributed evenly on a glass plate. The coated plate was made photosensitive with a silver nitrate solution and immediately exposed with a plate camera. Here, too, the resulting product was a negative, from which a contact print had to be made in a photocopy frame - which prompted Fox Talbot, the patent holder of the calotype, to file a lawsuit against Scott Archer, in which he ultimately succumbed in 1854 - the free use of the glass negative There were no longer any legal obstacles in the way. In Europe, the glass negative became widely accepted in the following years.
In contrast to the clearly "painterly" character of the calotypes , the new process was characterized by precise image sharpness and thus resembled the precise visual aesthetics of a daguerreotype.
Gelatin drying plate
The English doctor Richard Leach Maddox discovered the advantages of a gelatin-bromide-silver suspension in 1871 and was one of the pioneers of modern silver photography with his invention of the silver-bromide-gelatin dry plate he developed. The gelatine drying plates enabled the process of recording without the otherwise necessary wet chemistry and a corresponding darkroom for the sensitization of the image carrier - on top of that they were more sensitive to light than collodion plates and contributed considerably to the simplification and spread of the photographic craft, which in turn led to the beginning of industrial mass production led.
The gelatin dry plate process was the common photographic process from about 1871 through the 20th century. It was replaced by photographic film.
1868, the Americans invented John Wesley Hyatt , the celluloid , which as the support replaced the fragile glass plates because of its transparency and flexibility gradually and laid the foundation for modern film technology.
The American clergyman Hannibal Goodwin is the inventor of the celluloid-based roll film, which was patented in 1889. He led a lawsuit for years over patent priority with George Eastman, the founder of the Kodak company , which he was only guaranteed in 1898.
The flammable celluloid film was in 1901 for the first time through the carrier material cellulose acetate replaced, since 1908 it is mass produced and is the basis of modern safety film ( safety film- ). The production of the celluloid carrier material was discontinued at the end of 1950, except for the stored goods that were still processed and sold afterwards, it disappeared completely from the market. In contrast, the fact that films are easily flammable is still a rumor today.
Differences from color photography
Through the "translation" of colored reality into the reduced dimension of gray values and its extreme black and white expressions, black and white photography creates its own abstract visual aesthetic, which in many aspects of image design places different demands on the photographer than color photography that primarily works with color: Contrast and brightness nuances and their graphic relationships to one another are the central design categories of the black and white photographer - on the one hand they require a special photographic vision, on the other hand a special photographic-technical technique that actually only enables appropriate image results beyond any standardization.
The famous American photographer Ansel Adams (1902–1984) shot almost exclusively in black and white; he preferred this genre because he had greater control over the process (via the zone system ). “Actually,” says Adams, “I don't really like color photography. That's not my case. "
The production of a wet chemical black and white photograph in the home laboratory is not a difficult process with normal requirements, and it also requires far less equipment than the work in the color laboratory.
A particular advantage arises from the fact that there is an abundance of differently nuanced photographic papers on the market for black-and-white images , which allow precise reactions to technical details and photographic objectives.
Apart from the groups of PE paper (plastic-coated) and baryta paper (cardboard carrier), the papers mainly differ in the following areas:
- Gradation - the gradation of photographic papers or films describes their ability to reproduce the different brightness values of objects in the corresponding blackening densities, with the scale ranging from very softly nuanced to ultra hard materials for extreme effects where you can hardly find gray tones in the blackening zones - On top of that there are fixed gradation papers, each with a single gradation, and multi-grade papers, which enable gradation control from soft to hard via the light color of the enlarger.
- Color - in addition to white paper backing, there are slightly warm to strongly chamois colored nuances.
- Surface - high gloss, matt, deep matt, silk gloss, dull matt, rasterized
- Grammage - the weight per unit area ranges from almost paper thin (135 g / m²) to extra thick cardboard (260 g / m²)
- Blackening tone - from warm black to cool black
Different types of drying also make interesting effects possible, some papers can be dried on linen, they then take on the structure of the fabric. If glossy papers are dried in the air rather than on the glossy film of the drying machine, the result is a matt gloss.
The importance of black and white photography in the mass business has declined significantly over the past few decades. An exception are the chromogenic black and white films , which are developed in Process C-41 . This is the usual process for color images today, and laboratories do not distinguish these films from color films.
Assembly of black and white films
In photography, packaging refers to the recording format and the commercial length of photographic film material.
The dominant suppliers of black and white films today are still the companies Kodak and Ilford , which produce classic films and C-41 films (classification of B / W negative films from Ilford ). In Eastern Europe, China and Russia, black and white films are also produced to a significant extent, but these are mainly used on their domestic markets. Almost the entire market for cheap or company label films is produced at Ilford.
35mm films (35 mm films, 135 format), roll films and sheet film material that are primarily reserved for professional photography are still in use today. Black and white films can be stored in a cool place for several years past the expiry date, but you have to expect a flattening of the gradation, a decrease in the film speed and an increase in the background fog.
With the introduction of roll films , it was possible for the first time to change negative material in daylight. Until then, it was only possible to equip the camera with light-sensitive material in the darkroom .
The classic roll film is the 120 film, which with an image width of 60 mm for various length formats still sets the standard for professional studio photography today . Length formats with the 120 film are 45 mm ( Mamiya and Pentax ), 60 mm square (mainly Rolleiflex , their replicas, Pentacon SIX and Hasselblad ) and 90 mm (rare, various manufacturers).
The numbering of the roll film formats goes back to the American film producer KODAK who produced the most diverse roll film formats since 1895 and zuordnete them for clarity numbers starting with the number 101 for the oldest roll film 9 by 9 cm (3 1 / 2 x 3 1 / 2 inch) began. The 120 roll film was released in 1901 for the recording format 2 1 / 4 × 3 1 / 2 inch (6 x 9 cm) and for over 100 years, is still available. This film has a continuous light protection paper on the back, which on the one hand protects the actual film strip from incidence of light and, on the other hand, with the simplest cameras without frame counter and film transport gears, with the help of printed frame numbers via a red-colored window on the back of the camera, both the number of frames and the correct positioning of the film strip in front of the picture stage are visible .
In 1965 the long version of the 120 roll film, the 220 film with twice the film length, was published, which was required by many professional photographers. Since the film strip had to fit on the standardized 120 roll film spool, a short strip of paper was used as light protection to reduce the winding diameter only at the beginning and at the end. As a result, the possibility of using this film material was limited to special types of cameras with switchable frame counters and film transport gears, which were mainly found in the professional sector.
35mm films were first developed for the cinema. At the end of the 1920s, Oskar Barnack developed the first applications for the photographic use of the 35 mm material, from which the Leica M series emerged.
35 mm film (135 format) is still the standard material in film-based photography today. These films are 35 mm wide, so the format designation "135" can come from it.
Usual assemblies are:
- 135-36 - standard format with 36 exposures
- 135-27 - three more pictures than 135-24, only sold by AGFA as a means of promoting sales
- 135-24 - 24 shots
- 135-12 - twelve shots
Black and white negative material is also available by the meter in 35 mm format - this allows you to flexibly adjust the film requirements to different situations.
A few cameras were able to expose images in “half format”, which resulted in twice the image yield, but also in a significantly poorer quality of the images due to the smaller negative format of only 17 × 24 mm. The best-known representatives were the Yashica Samurai or the cameras of the PEN series from Olympus. Half-format cameras are practically no longer represented on the market today.
In addition to the standard 35mm film, there have been various cassette films in the past, e.g. B. with the designation "126" (Kodak-Instamatic with the square format 28 × 28 mm) or "110" (the pocket film in the format 13 × 17 mm) as well as currently still available special formats for large picture photography (common formats are 9 × 12 cm, 13 × 18 cm and 18 × 24 cm) and the miniature film format 8 × 11 mm for the Minox cameras (see film types ).
In 1996, the five major manufacturers in the photo industry brought out the APS format, which was somewhat smaller than 35 mm film, for reasons of market strategy , which combined some handling advantages with the film cartridges and, in addition to various format options, provided magnetic coding of the film strip with data transfer properties. For the APS format, Nikon even launched a completely newly developed SLR camera, the Nikon Pronea. But it wasn't until 1998 that black and white negative film was available in the new format, and the film industry quickly compensated for the format disadvantage of APS films compared to 35 mm film with improved emulsions .
There have always been a small number of special films on the market for special photographic tasks; black and white infrared film is a well-known representative . Since it is very unstable due to its heat-sensitive sensitizing dyes, storage and transport are time-consuming. If the film is exposed through steep edge filters that block out the visible spectrum , the long-wave infrared component is used almost exclusively for image generation. The resulting shifts in tonal value create a typical IR alienation, which is responsible for the peculiar image effect.
The best-known 35 mm black and white film with real IR sensitization and high basic sensitivity was the Kodak HIE, which even made the tripod, which is mandatory for IR photography, superfluous: Coarse silver grain and significant overexposure due to the lack of a protective halo layer ensured the special IR image aesthetics - meanwhile the production of this material has been stopped.
Since secure and long-term digital storage of valuable data sets is associated with considerable problems, high-resolution, orthochromatically sensitized b / w microfilms are still of great importance for efficient, scaled-down imaging of valuable and irreplaceable archive data. For this reason, all major manufacturers (Kodak, Agfa-Gevaert, Ilford) continue to supply microfilm material in a wide variety of configurations, even in the 'digital age'.
Particularly high demands are made of black and white traffic surveillance films, as they serve to secure evidence (driver recognition) even under complicated lighting conditions. Because of the risk of glare for the driver, the recording is only 'flashed' through a red filter with medium density, which requires increased red sensitization compared to panchromatic b / w normal film. High exposure latitude, higher sensitivity and appropriate fine grain are part of the requirement profile of these films. An example from the series of such special films is the Ilford SFX200, which is also available on the regular film market as a pseudo infrared film and can be used in pictorial photography with interesting image results.
For aerial photography , highly specialized black and white image capture films are still produced today, which are mainly used in the areas of cartography , surveying , hydrology and military reconnaissance. Similar to the traffic surveillance films , these materials are sensitized in a panchromatic manner (with an extended red area).
Line films or lith films are particularly rapidly reacting photochemical film materials which, in cooperation with lith developers, produce halftone black and white image areas without gray scale gradations; they are mainly used in printing and repro technology.
Black and white sensitometry
The sensitometry is a central research discipline in the SW photography because it as a research object, the interactions of light and photographic emulsion qualitatively and quantitatively describes and ambitious photographer allows predictions about the reaction behavior of a film material in a concrete image situation.
The image-critical properties of a black and white photographic layer are its general sensitivity and its spectral sensitivity . The aim of spectral sensitivity (color sensitivity) is to sensitize the photographic material to those light colors that lie outside of its own absorption area.
In terms of color sensitivity, a distinction is made between the following types of emulsion:
- Unsensitized materials are pure silver bromide layers that only respond to UV , blue and blue-green.
- Orthochromatic materials are red-blind; their sensitization ends at about 600 nm wavelength (about light color orange).
- Panchromatic materials are sensitized to all visible colors.
- Superpanchromatic materials have a particularly pronounced preference for red, which is rendered too lightly compared to the primary color green.
In almost all modern panchromatic black and white films, the reproduction of the brightness values is largely matched to the brightness perceived by the eye - only the blue reproduction is usually too bright for all brands. Nevertheless, subtly differentiated and characteristic differences in the gray value nuances of the films from different film manufacturers are among the exclusive features of the film-based ones Black and white photography that can only be copied very imperfectly by digital means.
The size of the silver halide crystals responsible for the graininess is approximately 0.1 to 2 micrometers . Film material with low sensitivity normally has a thin photographic layer and also relatively small, uniform crystal structures - highly sensitive black and white material always consists of several individual layers on top of one another, the light-sensitive crystals of which are considerably larger and which also have an irregular size distribution. If the light penetrates through these grain layers, it is scattered in all directions, so evenly blackened negative areas have a more or less uneven graininess, the extent of which can be specifically controlled as a photographic design element.
Image influencing options
Compared to digital photography, the photographer's technical possibilities to influence the finished image result are only very limited - decisions made in the image creation process can hardly be corrected in the negative-positive process, and completely impossible in black and white slide photography with reversal film. A planned, effective use of the available influencing factors presupposes a well-founded knowledge of their possibilities and their limits, but also technical and manual skills as well as visual empathy and special photographic vision.
Influencing the image during the recording process
The choice of a suitable film, its sensitometric properties, together with an appropriate development that is appropriate to the type and subject, is a central design element in black and white photography. Highly sensitive films show a rather clear film grain and a flat gradation with very different gray values, low- sensitivity films behave exactly the other way around - especially the grain structure of the film can be planned with suitable motifs towards an interesting image effect.
Light control with lens filters
The intensity and spectral composition of the light (light color) in a photographic situation ultimately determine the extent of the blackening distribution on a photographic layer. The lighting effect can be controlled with the help of various types of filters in the beam path of the imaging lens of the camera.
In film-based black and white photography, precise gray value control can only be carried out before the actual film exposure; in contrast to the highly differentiated manipulation options of digital image processing, subsequent correction in the analog positive process can only be carried out to an extremely limited extent. By using monochrome colored filter disks in different filter densities in front of the taking lens, areas of visible light are filtered out, which results in a changed distribution of blackness on the exposed film, which in the positive process results in a different gray tone reproduction.
Precondition for the success of a planned control of the blackening distribution on the film is precise knowledge of the absorption behavior of the color filters used, the light color situation of ambient light and reflected object light during photography and the reaction behavior ( sensitization ) of the negative and positive material used.
In principle, filters allow their own color to pass unhindered, the complementary color is blocked more or less depending on the filter density - i.e. H. In the finished positive, the areas in the intrinsic color of the tone value filter used are lighter in gray value, the areas of the complementary colors in gray value are darker than without the color filter, here are some striking examples:
- Yellow : darkens a blue sky and increases the contrast of the clouds.
- Green : very strongly differentiates the green tones present in nature, red tones (lips in human portraits ) are darkened.
- Red : A landscape in sunshine appears to be illuminated by the full moon due to the strong blocking effect of the red glass . Any atmospheric haze that may be present is strongly suppressed. The blue sky becomes much darker, clouds appear (mostly) more clearly than in reality. Skin tones appear waxy, skin imperfections are suppressed, but red lips are also greatly lightened and blend in with light skin.
There are also a variety of other filter colors such as yellow-green and orange filter glasses, with which the effects described above can be combined or weakened. In contrast, the use of blue filter glasses in black and white photography has hardly any meaning.
UV filters , actually UV blocking filters , are colorless or slightly yellowish colored filters that are intended to keep high levels of overexposure UV light away from the film, especially in winter and in high mountains. So-called skylight filters have a somewhat stronger effect than UV filters, but they change the color temperature.
Polarization filters influence the level of oscillation of the light waves. A distinction is made between linear polarizing filters and circular polarizing filters. The linear polarizing filter cannot be used with many modern SLR cameras as it falsifies the values for exposure metering and autofocus .
Polarization filters enable the removal of unwanted non-metallic reflections and, under certain circumstances, a significant increase in contrast . Depending on the direction in which you are looking, the blue sky is more or less polarized. This can be darkened with a polarizing filter so that clouds stand out strongly. Similar to a neutral density filter, a polarizing filter always has a light attenuating effect, since the ambient light is usually not polarized, but only the waves of the "correct" alignment can pass a polarizing filter, and so only a portion of the available light reaches the film. Depending on the motif and the angle of rotation, the exposure time may need to be increased by two to four times. You can already see the effect of a polarizing filter if you just turn the filter in front of your eye.
Neutral density filter
Neutral density filters - also known as gray filters - reduce the passage of light without changing the light color. They can therefore also be used in color photography. Due to their light attenuation, the filters enable longer exposure times or larger apertures to be used. This means that deliberately planned motion blurs or shallow depths of field can be implemented. This technique is often used when recording rivers or 'water features'.
Since most mirror lens lenses do not have an adjustable diaphragm, neutral density filters are the only way to reduce the amount of light entering.
A wide range of effect filters can also be used in black and white photography, but when it comes to the dosage, they are particularly dependent on the photographer's sure taste: starting with blur or soft focus lens covers to star effects (four-fold, six-fold, eight-fold light stars) to A wide variety of effects can be created through to prismatic effects.
Influencing the image in the laboratory
A type-specific and targeted development of the exposed black and white film is a fundamental quality parameter for the desired image result. In laboratory practice, the planned contrast control via the development technology is of particular importance, whereby the development time is mainly used as a control parameter: in principle, an extension of the development time increases the negative contrast, a shortening of the development time leads to a reduction in the contrast .
Basically, the contrast behavior of a negative depends on the sensitometric film properties, the brightness range (the contrast ) of the object of the picture, the exposure and the development of the film.
The developer activity is controlled by the dilution by means of a so-called equalization development and, if the development time is greatly extended, a more balanced negative is created in which the image is built up from the shadows. The density of the lights only increases with a greatly extended development time. Since an extension factor similar to the Schwarzschild effect must be taken into account when the developer solution is diluted, the dilution factor is always slightly smaller than the extension of the development time. Two-stage developers , in which the first stage contains the actual developer substances, the second stage the necessary alkalis and stabilizing additives, are particularly suitable for contrast-compensating development .
In a second light passage comes from the developed see-negative using a contact frame or an enlarger on a photo paper a latent exposed positive regulatory picture that also only developed for visualizing and fixed needs. The main options for influencing the image result are outlined below.
Manipulations of the paper exposure
The extremely different distribution of density of a highly differentiated black-and-white negative can only very rarely be transformed into an effective top-view positive with a single exposure dose - in contrast to the production of a positive contact copy , the amount of light responsible for the blackness intensity can be dosed differently with the help of a special process in individual parts of the image when using an enlarger . These include in particular the techniques of 'light retouching' such as partial post-exposure or dodging .
The dodging or re-exposure is done with templates or the hands in the light cone of the enlarger - to avoid clearly visible blackening transitions, the shadow-generating tools must be constantly moved slightly. With appropriate training and the necessary skill, imperceptibly flowing transitions are created in the different blackening zones of the finished image.
The lith printing process - not to be confused with the lith development of black and white film material - is an extremely effective black and white positive laboratory technique that works with conventional graphic high-contrast lith positive developers in extremely strong dilution, especially chlorine or silver containing chlorine It requires bromide silver photo paper without embedded developer substances and produces highly interesting, monochrome image structures as a result. In a process known as infectious development , the positive developer, initially strongly slowed down by the high dilution, together with a targeted overexposure and partial development of the photo paper - without additional laboratory manipulations such as the subsequent toning process - generates monochrome picture tones that depend on various laboratory parameters and the specific selection of one suitable photo paper includes a wide range of colors from about medium brown to delicate ocher yellow. This creates a completely different interpretation of a normal black and white negative; Lit enlargements are photographic images with very peculiarly nuanced, monochrome color stimuli, with rich, grainy blacks and finely modulated lights with rather less pronounced mid-tones.
With the classic toning process , a monochrome coloring of the picture substance of finished pictures can be achieved. Wet-chemical post-treatment with various metal salt solutions changes the normally black image silver and forms colored compounds, with different image effects resulting in each case.
The simplest manipulation of brown tones is not actually a toning: it is rather a coloring of the image carrier of a finished black and white print with the stable dye particles of black tea, whereby the black silver image remains unchanged.
The picture example is an original black and white photo, the brown tone manipulation was made on the computer and roughly represents the effect that can also be achieved in the darkroom. Depending on the prevailing taste of the time, they were used more or less frequently in the history of photography.
Due to the interference-sensitive processing process, faulty image areas in the finished image often cannot be avoided - valuable and complex photographic images are therefore often retouched . Scratches from mechanically damaged negatives as well as dust particles when enlarging cause dark or light imperfections in the finished print, which can be made almost invisible through technically complex retouching work.
The demands on qualified retouching that arise here require basic knowledge, suitable retouching aids and a good dose of skill: the areas to be retouched must be adapted to the photo paper used in terms of their image tone and surface effect, and the gray value of their tonal surroundings must be added.
Black and white digital photography
Digital cameras made specifically for black and white photography are almost exclusively intended for remote sensing . The tonal range (the number of different shades of gray) is more important than a colored image. In satellite meteorology and geology , satellite images from different channels are often "colored" and combined. This creates colored RGB images that make it easier to interpret the image .
Many commercially available digital cameras support modes in which the images are saved in grayscale or different monochrome representations. In most cases, however, a subsequent conversion of color images to black and white images is preferable, as automatic conversions such as simple conversion to grayscale rarely work optimally. Better results can be achieved with manual methods using channel mixers, with which the proportion of red, green and blue channels can be precisely influenced. Imitating the properties of orthochromatic or orthopanchromatic black and white films by means of digital image processing is only possible to a limited extent.
An exception in the area of digital medium format photography is the Achromatic digital back from Phase One . This back is based on the color-sensitive model P45 +, but has been reduced by the Bayer filter and the IR cut filter. The Achromatic is therefore particularly suitable for IR, black and white and industrial photography. Since May 2012, Leica has also had a pure black and white 35mm camera in its range, the Leica M Monochrom .
Pictures that are mostly black and white and contain some color are called colorkey, the process itself is called keying . With the widespread use of digital image editing, it has become very easy to produce black and white photos with color elements. In doing so, part of the image that is converted from color to black and white remains colored. The subsequent coloring of black and white photos is also much easier with digital image processing than the time-consuming toning of photo-chemical photo papers in the positive laboratory.
- ↑ Adams in Color ; ed. by Harry Calahan; Little, Brown and Company, Boston 1993, blurb
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