A color magic lantern slide made using the process invented in 1900 by Edward Sanger-Shepherd, a scientific instrument maker in London. Separation negatives were taken through red, green and blue filters and developed using the standard process. The negative taken through the red filter was printed to a glass plate, with the resulting black and white image converted to greenish-blue using a Sanger-Shepherd converting solution. The remaining negatives were contact printed on celluloid film coated with bichromated gelatin. The gelatin hardened where exposed to light; the unhardened gelatin was then washed away to leave a relief (Pénichon 2013, 128–131). The reliefs corresponding to the green and blue filters were stained in a pink and a yellow dye bath, respectively. The resulting celluloid images were superimposed on the glass plate and the layers were bound together (Sanger-Shepherd 1900, 4–6).

The initial color separations could be made using a standard camera to take three separate photographs, swapping color filters in between. Sanger-Shepherd also sold a special camera back that would hold a longer glass plate in a frame with the filters mounted side by side in front of the plate. The frame was slid sideways between photographs to take the three pictures. A more expensive option was a camera that would take all three pictures at once, enabling color photography for more dynamic scenes (Sanger-Shepherd 1907, 11).