to superimpose colours

накладати (одну річ на іншу)

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1) класти, накладати ( одну річ на іншу)

2) фoтo вдруковувати; робити подвійне експонування

3) (on, upon) накладати ( відбиток); додавати, привносити

SUBJECT AREA: Photography, film and optics

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The son of a tax collector, Ducos du Hauron began researches into colour photography soon after the publication of Clerk Maxwell's experiment in 1861. In a communication sent in 1862 for presentation at the Académie des Sciences, but which was never read, he outlined a number of methods for photography of colours. Subsequently, in his book Les Couleurs en photographie, published in 1869, he outlined most of the principles of additive and subtractive colour photography that were later actually used. He covered additive processes, developed from Clerk Maxwell's demonstrations, and subtractive processes which could yield prints. At the time, the photographic materials available prevented the processes from being employed effectively. The design of his Chromoscope, in which transparent reflectors could be used to superimpose three additive images, was sound, however, and formed the basis of a number of later devices. He also proposed an additive system based on the use of a screen of fine red, yellow and blue lines, through which the photograph was taken and viewed. The lines blended additively when seen from a certain distance. Many years later, in 1907, Ducos du Hauron was to use this principle in an early commercial screen-plate process, Omnicolore. With his brother Alcide, he published a further work in 1878, Photographie des Couleurs, which described some more-practical subtractive processes. A few prints made at this time still survive and they are remarkably good for the period. In a French patent of 1895 he described yet another method for colour photography. His "polyfolium chromodialytique" involved a multiple-layer package of separate red-, green-and blue-sensitive materials and filters, which with a single exposure would analyse the scene in terms of the three primary colours. The individual layers would be separated for subsequent processing and printing. In a refined form, this is the principle behind modern colour films. In 1891 he patented and demonstrated the anaglyph method of stereoscopy, using superimposed red and green left and right eye images viewed through green and red filters. Ducos du Hauron's remarkable achievement was to propose theories of virtually all the basic methods of colour photography at a time when photographic materials were not adequate for the purpose of proving them correct. For his work on colour photography he was awarded the Progress Medal of the Royal Photographic Society in 1900, but despite his major contributions to colour photography he remained in poverty for much of his later life.

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