I used to be facinated by old photographic processes. I believe that using filters to make b+w shots that will later be recombined has been around for a long time. While RGB color theory has been around for only a century or so, artists have know for many hundreds of years that you can combine several printing plates, one for each color you want, and print them one on top of another. Many of the early photograhic processes like the gum-dichoromate types allowed printing in various colors using actual artist pigments fairly easy.
What really amazed me was the orignal Technicolor technique. Orignally Technicolor used a special camera that held three reels of film running at the same time. Look here for a picture of one of these cameras http://www.technicolor.com/aboutus/his1930.html. Each reel recorded for one primary color. They must have used some sort of clever prism followed by filters. These three film reels would be processed, and then used to make film that would absorb dye depending on the amount of exposure that had occured. One reel is dyed for each of the primaries. The dye is then transferred by physical contact to one reel of film combining the colors. Imagine trying to keep everything in register. Think of all this the next time you watch Gone With The Wind! I believe Technicolor still uses some aspects of the orginal technique. Kodak still has dye-transfer materials for making what amounts to photos on paper using three black and white negatives. A neat thing about the dye-transfer process is that you end up with a photo done in dyes that are very nice looking and fairly stable. Another payoff to doing things this way was the control you could get by adusting the dyes for each color. Amazingly, there was a time before Photoshop, when they still managed to make excellent photos!
Slashdot Mirror
I used to be facinated by old photographic processes. I believe that using filters to make b+w shots that will later be recombined has been around for a long time. While RGB color theory has been around for only a century or so, artists have know for many hundreds of years that you can combine several printing plates, one for each color you want, and print them one on top of another. Many of the early photograhic processes like the gum-dichoromate types allowed printing in various colors using actual artist pigments fairly easy.
What really amazed me was the orignal Technicolor technique. Orignally Technicolor used a special camera that held three reels of film running at the same time. Look here for a picture of one of these cameras http://www.technicolor.com/aboutus/his1930.html. Each reel recorded for one primary color. They must have used some sort of clever prism followed by filters. These three film reels would be processed, and then used to make film that would absorb dye depending on the amount of exposure that had occured. One reel is dyed for each of the primaries. The dye is then transferred by physical contact to one reel of film combining the colors. Imagine trying to keep everything in register. Think of all this the next time you watch Gone With The Wind! I believe Technicolor still uses some aspects of the orginal technique. Kodak still has dye-transfer materials for making what amounts to photos on paper using three black and white negatives. A neat thing about the dye-transfer process is that you end up with a photo done in dyes that are very nice looking and fairly stable. Another payoff to doing things this way was the control you could get by adusting the dyes for each color. Amazingly, there was a time before Photoshop, when they still managed to make excellent photos!