Chromogenic print

Photographic print made using a chromogenic process
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.

Developing color by using oxidized developers was first suggested by German chemist Benno Homolka who, in 1907, successfully developed insoluble indigo blue and red dyes on a latent image by oxidizing indoxyl and thio indoxyl respectively. He additionally noted these developers could create beautiful photographic effects. The following year he filed a patent listing various color developers and dye couplers, which have historically been used in Agfachrome and are still in use today in Fujichrome Velvia and Provia, and Ektachrome. In spite of this, Fischer never created a successful color print due to his inability to prevent the dye couplers from moving between the emulsion layers. This first solution to this problem was found by Agfa workers Gustav Wilmanns and Wilhelm Schneider, who created a print made of three layers of gelatin containing subtractive color dye couplers made of long hydrocarbon chains, and carboxylic or sulfonic acid. This turned the dye couplers into micelles which can easily be scattered in the gelatin while loosely tethering to it. :698 Agfa patented both the developer for this print and its photographic process, and promptly developed and released in 1936 Agfacolor Neu, the first chromogenic print, which was a color print film that could be developed using a transparency. Kodak too worked to solve the issue of the dye couplers movement, and found a different solution. They used ionic insoluble carbon chains which were shorter than Agfa's for their dye couplers, which were suspended within droplets of water in the gelatin layers of the print. Due to their simple development process and their cheap price, chromogenic printing became wildly popular in amateur photography, and by the 1960s it overtook black and white printing in the amateur photofinishing market. In 1955, Kodak introduced a chromogenic paper named "Type C", which was the first color negative paper Kodak sold to other labs and individual photographers. Although the paper's name was changed to "Kodak Ektacolor Paper" in 1958, the terminology "Type C Print" persisted, and has become a popular term for chromogenic prints made from negatives still in use today, and Stephen Shore. Their works, and those of many others, caused chromogenic prints to become the preferred medium for contemporary photography by the 1990s. Plastic chromogenic "papers" such as Kodak Duratrans and Duraclear are used for producing backlit advertising and art.

A reversal film chromogenic print, also known as a Type R print, is a positive to positive photographic print made on reversal type color photographic paper. Fujifilm, Kodak, and Agfa have historically manufactured paper and chemicals for the R 3 process, a chromogenic process for making Type R prints. as of 2008, all of these companies have ceased to produce Type R paper, although Fujifilm still has some stocks remaining. Another positive to positive process was Ilfochrome, formerly Cibachrome, in use until 2012. This is sometimes also referred to as a Type R process. Ilfochrome was a dye destruction process, with materials, processing, and results quite different from the R 3 process.

A digital chromogenic print, sometimes known as digital Type C print, Lambda print or LightJet print, is a chromogenic print made from a digital file rather than a negative, and exposed using digital exposure systems such as the Durst Lambda, Océ LightJet and ZBE Chromira. The LightJet and the Lambda both use RGB lasers to expose light sensitive material to produce a latent image that is then developed using conventional silver based photographic chemicals. The Chromira uses light emitting diodes (LEDs) instead of lasers. All of the aforementioned printers utilize ICC color profiles to achieve color and density accuracy and also to correct paper sensitivity errors. The same technology can also be used to produce digital silver gelatin bromide black and white prints.