The Kromskop was one of the earliest commercial applications of colour photography; it was invented by F.E. Ives and announced around 1896, it is described in his English patent of 1895 and in a US patent of 1894. At the time it was described as the Perfected Photochromoscope to distinguish it from earlier proposals from around 1890 and 1892¹.

In Britain the viewer was shown at a Camera Club meeting in January 1896 and at the February Royal Photographic Society meeting. There must have been some delay in manufacturing the viewer as the British Journal of Photography notes that it will be on sale from early 1897.

The viewer combines stereo images from three-colour separation transparencies called Kromograms, these are viewed through red, green and blue filters. A Kromogram comprises three monochrome transparencies printed from three-colour separation negatives which are taped together. The order being red image, blue image, green image with a label and caption between the red and blue images.

The red image lies horizontally on the top step of the viewer above a red filter, the blue image lies on the lower step above a blue filter, the green image stands vertically at the back of the viewer. The red and blue images are reflected into the eyepieces by transparent mirrors, these are coloured to absorb the light that they reflect to prevent a double image from the rear surface of the mirror, the mirror for the red image is coloured cyan/blue, that used for the blue filter is coloured green (the patent indicates a yellow filter). The green image is illuminated by a yellow reflector. As the mirror below the blue image is green there is no need for a green filter immediately in front of the green image.²

The viewer can be used in daylight, for some conditions a diffuser is used, this is hinged to the yellow reflector and laid across the steps. An artificial light was also available. The mirrors and image positions can be adjusted in the event that they become misaligned.

The Kromskop cost £5.0.0 and Kromograms cost 5/-. As well as the viewer and Kromogram images the Photochromoscope Syndicate sold a projector and a repeating back enabling photographers to produce their own Kromograms. A mono viewer was also produced called the Junior Kromskop.

In the 1895 patent alternative arrangements are described which include a viewer with three steps where each image is horizontal and one where the internal mirrors are at 22.5° rather than 45.

The company formed to promote the viewer in Britain - the Photochromoscope Syndicate was formed in 1896 or 97 and wound up in 1899. The Viewer was made in south London, whether this was for only the British market or world-wide sales is not clear, given that Ives was in Britain at the time the works in Clapham probably manufactured all the examples.

It is doubtful if anything about the Kromskop was unique; it is a well-designed and very well-made instrument that made colour photography available to the public. Ives must have considered that the fundamental design was more important and novel than it was, his dispute with B.J. Edwards and others carried out in the correspondence section of the British Journal of Photography continued for many weeks. The basic ideas incorporated in the Kromskop were anticipated by Charles Cros' work from the 1860s and fully described in 1879. Other similar viewers were described or patented by B.J. Edwards³ and Zinke (1893). This aspect is best described in Wall's History of Three-colour Photography. A similar looking viewer, though different in using only two images, was sold by Watson & Sons as the Kromaz.⁴