I think 3-Strip Technicolor films deserve as much of nostalgia’s warm embrace as vinyl records. Webcams and mp3s are completely ubiquitous, but their predecessors (and distant ancestors) still hold a certain charm. So, for Eric Rosenthal’s Digital Imaging class I created a few digital images using a process similar in spirit to that of old Technicolor films.
As the name suggests, a 3-strip film process is one in which the red, green and blue component images are recorded onto three separate sheets of black & white film. Actually the first version of this process, innovated by Technicolor in 1916, was a two-color system (red and green). The basic idea is the same for both systems: an image enters the camera’s lens and passes through a beam-splitter. The beam-splitter is directed towards two or three color filters, through which the component beams pass onto a film emulsion. Naturally, this process made for a bulky camera and used 2x or 3x as much film stock as a B&W film. Nonetheless, it was an incredible innovation and Walt Disney and others quickly put it to good use. This, of course, was later replaced by color film that allowed the color components to be layered on top of one another on a single sheet of film. In the digital era, this 3-strip idea found new life. Many high-quality digital motion picture cameras still use 3 component image sensors and a beam-splitter. These are commonly called 3CCD cameras.
To imitate this process, I set up my camera on a steady tripod and obtained three sheets of color filter material: red, green and blue. As Eric told us, the color filters that are generally used in digital image sensors tend not to be rich, saturated reds, greens and blues, but instead more pastel so as to not produce true color separations and instead have some channel blending at the sub-pixel level. In this process, I used saturated filters that I hoped would produce stark color separations. I put the camera on a timer and shot a very still scene (an empty room) three times in succession, each time with a new color filter in front of the lens. I repeated this process twice and the second time included a gray card in the shot so that I could do some calibration later. Here are the results:
The bottom image is much better than the top. This is largely because the gray card allowed me to better calibrate but also because the original component exposures for the bottom image are better. Overall, the color accuracy to the original scene is pretty good and could certainly be fine-tuned further with more extensive testing.