Australian National Film and Sound Archive
The new gaps were bleached and dyed red, resulting in a colour filter mosaic, known as a réseau, consisting of alternating green and blue squares between red lines, and having roughly one million colour filter elements per square inch. Less saturated tints, and non-primary colours such as orange, yellow, and purple, along with neutral grays and white, are reproduced by various proportions of red, green, and blue light blending together in the viewer's eye due to the tiny size and close spacing of the individual elements. For example, intensely red objects are represented by transparent areas behind the red filter elements and opaque areas behind the green and blue elements. The ink was removed, and new ink lines were printed at a 90-degree angle to the blue and green lines. After a final ink removal and the application of an isolating varnish, the same side of the film base was coated with a panchromatic black-and-white photographic emulsion. When exposed to light through the base and its réseau, the bit of emulsion behind each colour element recorded only the amount of light of that primary colour striking the film at that point. A very thin coating of collodion on one side of the film base was dyed blue, printed with closely spaced fine lines using a water-repelling greasy ink, and bleached. This content has been g enerated with the help of GSA Content Generator Demoversion !
Australian National Film and Sound Archive. Dufaycolor - The Spectacle of Reality and British National Cinema, a recent article on the process and the history of its use. Color Photography - Dufaycolor, a 1938 article on the process. Roll films for colour snapshots followed in 1935 and remained popular with some amateurs until manufacture ceased in the late 1950s. They were cheaper than the more sophisticated film types, some of which, especially Kodachrome, were not available in the sizes used by typical snapshot cameras, and amateur darkroom enthusiasts could process Dufaycolor at home almost as easily as black-and-white film. Dufaycolor's filter layer was of the geometric type, but its proprietary manufacturing process produced an unusually fine-patterned mosaic. John Joly independently reinvented the concept in 1894 and attempted to commercialise it, but the first successful product based on this idea, the Autochrome plate, did not reach the market until 1907. Several competing mosaic colour screen plate products soon appeared, including Louis Dufay's Dioptichrome plate, but the Autochrome plate remained by far the most popular. Most competing products employed a coarser geometric pattern created by one of the many methods devised and patented during that era.
These plate and film products differed substantially only in the means used to manufacture the colour mosaic layer and its resulting pattern and fineness. The photographic reproduction of natural colour by means of a black-and-white photograph taken and viewed through a mosaic of tiny colour filters was an idea first patented and published by Louis Ducos du Hauron in the late 1860s, but the incomplete colour sensitivity of contemporary photographic materials made it impractical at that time. Autochrome's mosaic was a random array of dyed potato starch grains, too small to be individually visible without a microscope. Typical modern LCD video displays work similarly, combining a backlit black-and-white image layer with an array of hair-thin red, green, and blue vertical filter stripes. Both Dioptichrome and Dufaycolor worked on the same principles as the Autochrome process, but achieved their results using a layer of tiny colour filter elements arrayed in a regular geometric pattern, unlike Autochrome's random array of coloured starch grains.
In very early years, different arrangements of the same colours were used, the lines being green or blue instead of red and sometimes intersecting the other colours diagonally. The same principle operates with intensely green or blue objects. The clear spaces created were then dyed green. Louis Dufay's interests were purchased by British paper manufacturing firm Spicers in 1926, which then funded research to produce a workable colour motion picture film. Although less expensive than other colour films, Dufaycolor was still expensive compared to black-and-white film. Dufaycolor on Timeline of Historical Film Colors, a comprehensive bibliography, many photographs of historical Dufaycolor films, patents, and links. Dufaycolor was normally a reversal film which was processed to produce the final positive image, instead of a negative, on the original film. Small-gauge home movie films were also unique original positives, but to facilitate use for theatrical motion pictures, which required the production of numerous identical positive prints, a two-step negative-positive 35 mm version was introduced. Medium and large format cut films for professional use were also made. In the case of still photographs, the result, known as a diapositive or transparency, was usually viewed directly by means of a backlight, but it could also be bound up between cover glasses or mounted in a small frame for use in a projector, in which form it was commonly called a slide.
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