Toronto. Once monochrome images were successfully captured by Daguerre and Fox Talbot and announced in January 1839, the holy grail of photography became capturing life in full colour. Beyond experimental processes, and hand colouring, this goal wasn’t reached as a marketable process until the next century.
Two basic colour schemes were identified. Firstly, the additive process where layers of red, green and blue light combined to create colour. We are most familiar with this process today in our TV screens, smartphone, tablets, computer monitors, etc.
Secondly there was the subtractive process usually a Cyan, Magenta and Yellow with some times black and grey tossed in the mix. This is most common today in computer, newspaper and magazine printing. The old style film days most recently showed additive processes in colour slides and subtractive processes in colour negatives (often an orange filter was tossed in the mix as well to shift the colour balance.)
In 1861, James Clerk Maxwell demonstrated the additive process by recording the red, green, and blue components of a tartan ribbon on three separate glass plates using filters. The fact his experiment even worked was pure serendipity. Glass plates of the day were totally insensitive to the rather low energy of red waves. However, the red tones of the ribbon Maxwell used also reflected the much stronger ultra violet light waves which were the second harmonic of the reds.
Eventually in 1903 the Lumiere Brothers successfully created extremely slow colour plates called Autochromes using randomly dyed potato starch layered on a monochrome glass plate. The coloured starch layer acted as a filter for both taking and viewing the image. It wasn’t until Kodak released Kodachrome in the 1930s that colour photography took off. Kodachrome actually used the more light sensitive subtractive process and colour reversal to create colour slides. A separate process using similar steps was released by Agfa in Europe. Skipping the reversal development led to colour negatives which dominated the world of film before the digital era washed across the globe.