Simulations from additive mosaic systems.

The additive processes most difficult to simulate or to copy, and retain the screen character of the original. The Dufay process images reversal originals or negative-positives, using a reseau of red, green and blue areas each providing a tiny separation record of that part of the scene, are very difficult to copy. The dyes appear to be reasonably stable and seem not to have faded in up to sixty years. Eastman Internegative is often used to make a colour internegative and thence a colour print and this is usually disappointing to anyone who has seen an original projected. The originals, even Dufay prints from Dufay negative are dark and of a very low screen brightness but very saturated. Modern subtractive dyes have difficulty in achieving the high saturations of the original reseau, and perhaps all subtractive systems, per se, will have this problem. Certainly, a modern telecine unit can translate a Dufay image into a far better video representation of the original than any film.

The best approach for all mosaic or lenticular additive colour systems is to copy them onto reversal print film stock such as 16mm Ektachrome Print Film. The higher that usual contrast compensates for some of the lost saturation and the black areas have a higher density that colour print film.

Many mosaic and lenticular and ruled screen systems were used to make documentary film of relatively important events in the 1920’s and early 1930’s and probably were quite dramatic records of those events in their original format. Some were copied to make more easily distributed versions, onto whatever “colour” system was available, with the result that archives contain some extremely confusing prints. British Realita ruled screen film, and Dufay was printed onto two-colour print film such as DuPont Duplicoat or Eastman Duplitised Film or onto Kodachrome print film, even onto Technicolor, with the result that the original is almost unrecognisable.

In the British Pathe collection newsreels were made from many film origins and important images reused in later issues. Sometimes the edge printing comes through - Raycol can be read on the edge of a two-colour print coated with orange dye on one side and blue-cyan on the other and a bright blue, variable density, sound track [presumably a Cinecolor print or similar], or Dufay can be seen on the edge of a early unmasked Gevacolor negative. More often, the origin is simply obscure, and some so unsharp that the reseau or ruled lines are gone.