Joly Color Screen (1894-95)

John Joly, 1911. Image from The Royal Dublin Society.

In 1894, a Dublin physicist by the name of John Joly, patented the Joly Color Screen. This glass screen consisted of thin red, blue, and green filtered stripes that could be positioned in between the lens and the plate. This allowed all colors to be recorded on a single piece of film, as opposed to the need for the three primary colors to be recorded as three separate images. The negative was then attached to and viewed through a similar glass screen, reproducing natural colors. However, common to the other color additives of the time period, there was some loss of film resolution. To view the image without the distraction of the lines, some distance is required. The texture of the screen is also invisible when placed on a lantern slides, a method that can be seen in the extensive collection of John Joly botanical slides located at the National Library of Ireland.

The George Eastman House website offers a more detailed and scientific explanation of the process:

"A piece of glass ruled in parallel lines, -red, yellow and blue alternately; the lines being extremely fine, and composed of transparent material, is interposed immediately in front of the plate when making a negative. Suppose the original subject contains patches of red, yellow, blue, black, and white. The red rays will pass through the red transparent line and act upon the silver immediately behind it; but the blue and red lines, allowing no red to pass, will preserve the plate from light action. The blue rays will penetrate the blue lines, and attack the silver behind those lines, and the yellow rays will pass through the yellow lines. The white part of the subject, reflecting light which contains red, yellow, and blue rays, will secure action under all three sets of lines. The black, on the other hand, reflects no light to affect the silver. 

From this negative a transparent positive is made; and in order to see this in its natural colors it is only necessary to place behind it a color-screen, such as was used in making the original negative. It is, of course, necessary that the lines that were under the original red shall now come under the red again, and so on. Where there is clear glass, light will shine through the red, yellow, and blue lines equally. The parts of the picture that represented pure red, will have transparency under the red lines, but a dense deposit under the blue and yellow. Pure strong secondary colors will be represented by transparency under both their primaries; and impure colors will be represented by greater or lesser opacity, according to the amount of red, yellow, and blue that they reflected, to affect the plate." (The George Eastman House)

Image from Museum of the History of Science.

(If you look closely, you can see the screen lines.)

JOHN JOLY. Arum Lily and Anthuriums, 1898. 
Joly process print. Kodak Museum, Harrow, England. From A World History of Art.

While the Joly Color Screen did not see great fame, it did help usher in a new era of commercially produced and affordable color film, and is seen as the precursor to the Dufaycolor, by Louis Dufay, which was produced and sold until the 1940s.



References

"Color Photography - Early Years, Additive Color Systems, Subtractive Color Systems" by Jon Kapecki:  http://encyclopedia.jrank.org/articles/pages/1223/Color-Photography.html

Encylopedia: http://www.encyclopedia.com/topic/John_Joly.aspx

History of Art: History of Photography: http://www.all-art.org/history658_photography6-3.html

The George Eastman House: http://notesonphotographs.org/index.php?title=Ward,_H._Snowden_and_Catharine_Weed_Ward,_eds._%22In_Colors_of_Nature:_Dr._Joly's_Process.%22