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Dye transfer is a continuous-tone color photographic printing process. It was used to print Technicolor films, as well as to produce paper colour prints used in advertising, or large transparencies for display.
The use of dye imbibition for making full-color prints from a set of black-and-white photographs taken through different color filters was first proposed and patented by Charles Cros in 1880. [1] It was commercialized by Edward Sanger-Shepherd, who in 1900 was marketing kits for making color prints on paper and slides for projection. [1]
Imbibition printing was initially in monochrome. The basic underlying principle is that bichromate development of a silver gelatine photographic emulsion (not strictly a real chemical emulsion) results in the gelatine being differentially tanned or hardened in proportion to the exposure received, and blackening obtained. When washed in hot water a relief gelatine image is obtained which is then immersed in a dye bath, washed off in a 3% acetic acid solution (one liter for a 16 x 20 inch print to remove excess dye) then to the 1% acetic acid holding bath. Photographic paper was removed from the conditioner (mordant bath) and matrix was rolled into contact with photographic paper consisting of a paper base, a baryta coating to improve light reflectance and a gelatine coating without the light-sensitive silver salts in regular photographic bromide paper. The gelatine absorbs dye from the matrix (which is the same size as the print). Finally, the print is dried between blotters, or by heat.
The colour process depends on superimposing three images in the subtractive colours: cyan, magenta and yellow in exact register, facilitated by means of register pins mounted at the edge of a glass rolling bed, using a purpose designed punch to make holes at the edge of the matrix films. As three matrices are required for each print, which are the same size as the print, the process is relatively expensive. Colour separation negatives together with their high contrast highlight masks that keep specular highlights clear from fogging over by exposing the contrast reducing masks through them.
Technicolor introduced dye transfer in its Process 3, introduced in the feature film The Viking (1928), which was produced by the Technicolor Corporation and released by Metro-Goldwyn-Mayer. Technicolor's two previous systems were an additive color process and a physically problematic subtractive color process, the latter requiring two prints cemented together back-to-back. Process 3 used an imbibition process pioneered by the Handschiegl color process, which had been created in 1916 for Cecil B. DeMille's feature film Joan the Woman (1917). Technicolor further refined the imbibition dye transfer process in its Process 4, introduced in 1932, which employed three simultaneously filmed negatives. [2]
In the 1940s, this process was popularized by the work of Jeannette Klute at Eastman Kodak for general-purpose graphic arts work, but not for motion picture work, which remained exclusive to Technicolor (and for which Eastman Kodak was manufacturing Technicolor's light-sensitive camera and printing films, including the "blank receiver" film, on an exclusive basis, but not Technicolor's dyes), and is sometimes referred to by such generic names as "wash-off relief printing" and "dye imbibition" printing. The graphic arts process requires making three printing matrices from three colour separation negatives made from a colour transparency original or at one time directly in a large format camera fitted with a sliding plate holder or film holder (to minimize camera movement when changing regular plate holders). The matrices, which are relief gelatine images on a film support (one for each subtractive primary color) absorb dye in proportion to the optical densities of the gelatin relief image. Successive placement of the dyed film matrices, one at a time, "transfers" each primary dye by physical contact from the matrix to a mordanted, gelatin-coated paper. It took a technician one whole day to produce one print. Firstly, three colour separation negatives were made using three high contrast highlight masks to produce three contrast reducing and colour correction unsharp masks. The unsharp masks were made with an oblique light source (and a clear film as a spacer, the contact frame exposed while rotating on a gramophone turntable. The original was either a miniature 6 x 6 cm or 35 mmm colour transparency, or else a large format 5 x 7 or 8 x 10 inch colour transparency. Three separation negatives were made on panchromatic film exposing the colour transparency through a red, green and blue filter that would eventually print in the subtractive dyes: cyan, magenta and yellow respectively. The red separation negative was exposed onto panchromatic film through the red unsharp mask. The green separation negative was also exposed through the red unsharp mask. The blue separation negative was exposed through the green unsharp mask. The purpose of the contrast reducing masks was to reduce the contrast range of the original transparencies to a level that could be handled by reflected copy material. By swapping the masks, colour correction was achieved to compensate for deficiencies in the dyes. The 8 x 10 separation negatives were placed in an enlarger to expose the printing matrices. These were developed in plastic developing trays, and when fixed were washed in hot water to remove unexposed gelatin. After drying in a room with a fan heater each matrix was placed in a dye bath: the red matrix in cyan; the green matrix in magenta, and the blue matrix in yellow dye. Before being rolled into contact with the mordanted paper with a gelatine surface, the first matrix was lifted out of the cyan dye bath and allowed to drain until the stream of dye broke into drops. It was then placed into a plastic developing dish and one litre of 3% acetic acid. The dish was vigorously rocked back and forth and right to left from side to side to wash off the dye on the surface of the matrix. The matrix was lifted clear of the solution once so as to allow the acetic acid solution to reach the back of the matrix film. To facilitate registration, a special punch with pairs of matching register pins: one round on the left and a squarish pin on the right; both pins mounted at the edge of a glass rolling bed. The paper was placed on the glass rolling bed gelatine surface up. The matrix held by one short edge high in the air while the left (round) hole fitted onto the register pin, and then the right (squarish) hole pressed down onto the pin. Then a rubber roller is taken and the matrix firmly rolled away from the operator into contact with the paper which is kept in a pile in a conditioning bath. The dye is absorbed by the paper for one minute after which the matrix is picked up by the farthermost corners and peeled off the paper. The same procedure is followed for the magenta and yellow matrices.
While technicolor live action movies ended in 1954, the dye-transfer process would continue to be used for another twenty years for films shot with the single-negative Eastmancolor process. [3]
In 1994, Eastman Kodak stopped making all materials for this process. The dyes used in the process are very spectrally pure compared to normal coupler-induced photographic dyes, with the exception of the Kodak cyan. The dyes have excellent light and dark fastness. The dye transfer process possesses a larger color gamut and tonal scale than any other process, including inkjet. Another important characteristic of dye transfer is that it allows the practitioner the highest degree of photographic control compared to any other photochemical color print process. A peculiar advantage of the process was that skilled dye transfer retouchers would use the same dyes the image was printed with to fill in blank white spaces between two or three separate colour photographs such as a background shot (rocks and a waterfall) one or more human figures, and more often than not a product shot (a cigarette pack) to produce a "strip in". Using the same dyes for photographically printing the images and for retouching meant that colour matching by eye would not show up differently when rephotographed.
Photographic processing or photographic development is the chemical means by which photographic film or paper is treated after photographic exposure to produce a negative or positive image. Photographic processing transforms the latent image into a visible image, makes this permanent and renders it insensitive to light.
Photographic paper is a paper coated with a light-sensitive chemical formula, like photographic film, used for making photographic prints. When photographic paper is exposed to light, it captures a latent image that is then developed to form a visible image; with most papers the image density from exposure can be sufficient to not require further development, aside from fixing and clearing, though latent exposure is also usually present. The light-sensitive layer of the paper is called the emulsion. The most common chemistry was based on silver halide but other alternatives have also been used.
In the processing of photographic films, plates or papers, the photographic developer is one or more chemicals that convert the latent image to a visible image. Developing agents achieve this conversion by reducing the silver halides, which are pale-colored, into silver metal, which is black when in the form of fine particles. The conversion occurs within the gelatine matrix. The special feature of photography is that the developer acts more quickly on those particles of silver halide that have been exposed to light. When left in developer, all the silver halides will eventually be reduced and turn black. Generally, the longer a developer is allowed to work, the darker the image.
In photography, a negative is an image, usually on a strip or sheet of transparent plastic film, in which the lightest areas of the photographed subject appear darkest and the darkest areas appear lightest. This reversed order occurs because the extremely light-sensitive chemicals a camera film must use to capture an image quickly enough for ordinary picture-taking are darkened, rather than bleached, by exposure to light and subsequent photographic processing.
In art, craft, and engineering, masking is the use of materials to protect areas from change, or to focus change on other areas. This can describe either the techniques and materials used to control the development of a work of art by protecting a desired area from change; or a phenomenon that causes a sensation to be concealed from conscious attention.
The gelatin silver process is the most commonly used chemical process in black-and-white photography, and is the fundamental chemical process for modern analog color photography. As such, films and printing papers available for analog photography rarely rely on any other chemical process to record an image. A suspension of silver salts in gelatin is coated onto a support such as glass, flexible plastic or film, baryta paper, or resin-coated paper. These light-sensitive materials are stable under normal keeping conditions and are able to be exposed and processed even many years after their manufacture. The "dry plate" gelatin process was an improvement on the collodion wet-plate process dominant from the 1850s–1880s, which had to be exposed and developed immediately after coating.
An enlarger is a specialized transparency projector used to produce photographic prints from film or glass negatives, or from transparencies.
A contact print is a photographic image produced from film; sometimes from a film negative, and sometimes from a film positive or paper negative. In a darkroom an exposed and developed piece of film or photographic paper is placed emulsion side down, in contact with a piece of photographic paper, light is briefly shone through the negative or paper and then the paper is developed to reveal the final print.
Photographic printing is the process of producing a final image on paper for viewing, using chemically sensitized paper. The paper is exposed to a photographic negative, a positive transparency , or a digital image file projected using an enlarger or digital exposure unit such as a LightJet or Minilab printer. Alternatively, the negative or transparency may be placed atop the paper and directly exposed, creating a contact print. Digital photographs are commonly printed on plain paper, for example by a color printer, but this is not considered "photographic printing".
Photogravure is a process for printing photographs, also sometimes used for reproductive intaglio printmaking. It is a photo-mechanical process whereby a copper plate is grained and then coated with a light-sensitive gelatin tissue which had been exposed to a film positive, and then etched, resulting in a high quality intaglio plate that can reproduce detailed continuous tones of a photograph.
C-41 is a chromogenic color print film developing process introduced by Kodak in 1972, superseding the C-22 process. C-41, also known as CN-16 by Fuji, CNK-4 by Konica, and AP-70 by AGFA, is the most popular film process in use, with most, if not all photofinishing labs devoting at least one machine to this development process.
Color printing or colour printing is the reproduction of an image or text in color.
Sun printing may refer to various printing techniques which use sunlight as a developing or fixative agent.
Cinecolor was an early subtractive color-model two-color motion picture process that was based upon the Prizma system of the 1910s and 1920s and the Multicolor system of the late 1920s and the 1930s. It was developed by William T. Crispinel and Alan M. Gundelfinger, and its various formats were in use from 1932 to 1955.
A carbon print is a photographic print with an image consisting of pigmented gelatin, rather than of silver or other metallic particles suspended in a uniform layer of gelatin, as in typical black-and-white prints, or of chromogenic dyes, as in typical photographic color prints.
The Handschiegl color process produced motion picture film prints with color artificially added to selected areas of the image. Aniline dyes were applied to a black-and-white print using gelatin imbibition matrices.
Gum printing is a way of making photographic reproductions without the use of silver halides. The process uses salts of dichromate in common with a number of other related processes such as sun printing.
A chromogenic print, also known as a C-print or C-type print, a silver halide print, or a dye coupler print, is a photographic print made from a color negative, transparency or digital image, and developed using a chromogenic process. They are composed of three layers of gelatin, each containing an emulsion of silver halide, which is used as a light-sensitive material, and a different dye coupler of subtractive color which together, when developed, form a full-color image.
Color motion picture film refers both to unexposed color photographic film in a format suitable for use in a motion picture camera, and to finished motion picture film, ready for use in a projector, which bears images in color.
Technicolor is a series of color motion picture processes, the first version dating back to 1916, and followed by improved versions over several decades.