From the earliest days of photography, people yearned for a means of reproducing color. By the middle 1800s a great deal of theoretical and practical work had evolved into an understanding of the primary colors. However, film emulsions, though sensitive to colored light, produced only black and white results.
Frederic Ives was an American scientist and inventor of considerable talent. Among his 70 odd patents was the invention of the halftone process, know the ubiquitous means of reproducing photographs in offset printing of books, magazines and newspapers. He had a particular interest in photography, and so he applied his talents to photographic color reproduction.
Ives knew, by using prisms and mirrors, the color spectrum could be broken down into its primary components of red, green and blue. He cleverly devised a camera system which recorded each of the three primary colors on its own photographic plate. Filters were used to ensure only one specific primary color was recorded on each of three plates.
To see a color composite, it was then necessary to recombine the three primary color images. Although each of the camera's recorded images was itself black and white, they each held a unique record of one primary color. If you study each plate, you will see they are definitely not identical. By viewing each plate through an appropriately colored filter, and merging those three images, we reconstruct the full color original.
Marketed as the Kromskop, Ives viewer essentially reversed the process of the camera. The views, composed of three black and white images held together by fabric tape, was draped over a viewer. Diffused white light was then used to illuminate the three images through a set of red, green and blue color filters. Careful alignment of the photos and viewer internals provided a merged color image to the eye. The system works, but as with modern offset printing, color registration is an issue. All the pieces had to be very carefully aligned.
Its no simple task to bring the three colors together. As illustrated, it took a complex arrangement to reflect and align the component colors. At the top is a red filter. Light from this image was reflected by the cyan filter visible in the photo of the opened viewer front. The next step down is a blue filter. Light from this image was reflected off a green filter but, passed through the cyan filter. Light from the bottom vertically mounted image passes through a green filter, and then through both a diagonal green and cyan filters before arriving at the viewing lenses.
Open front of viewer shows the cyan filter. Alignment between the diagonal cyan and green filters was factory set. The pair could then be moved fore and aft, by means of a brass adjusting screw on the left, to set vertical alignment of the red image. Any other alignment issues would be dealt with by wiggling the red and blue images. The green sat down in a pair of vertical slots and was therefore pretty much fixed in position.
My viewer is missing two components. On the front there are mounts for the missing viewing hood. This would be convenient, but is not critical. What is important is the missing opal glass diffuser. Originally it rested on the top of the reflecting mirror and lay over the top of the viewer. Opal glass provides extremely even light dispersion. This is critical to color balance. If any one of the three primary colors is too bright or too dark, the image takes on an overall color cast. This is one of many downsides to the three image viewing process.
The Kromskop viewer was perhaps little more than a short lived novelty. However, three color photography, cinematography and three color projection were concepts of far reaching significance. Processes such as Cinemascope relied on three color imaging well into the 1960s. The primary color negatives were only recombined when a full color print was made. Today, television and digital projection still rely on combining the three distinct primary colors into a single full color image. Before the advent of color emulsions and CRT phosphors, the Kromskop was the only way to view a color photograph.
This is (as best I can represent it on a sMacintosh monito r) what one sees in a Kromskop. This view was scanned from the Kromograph above. Each image was laid into an RGB color channel. One could do a great deal of color manipulation. While I have fixed a significant vertical alignment problem, I believe the color balance difference between the two frames is accurate. The right hand frame is also softer in all three images segments. This may have been a camera problem. The colors are as true as I can achieve compared to standing out in the sun with the viewer. I'm working on making a new diffuser and will readjust this image if things look different when the diffuser is fitted.