This is the introduction to Film Masking and Color Reproduction. It is a historical view of this subject and is it not necessary to view this part in order to start the masking section. It is just an informative lesson on the history of color separation and the invention of masking as a remedy to color correction.
Note that densitometers should be available at darkroom rental facilities as well as conventional photo labs (if they are still in business).
Update -
8/26/2018 - Just wanted to add a note. I state in this video that film masking was suggested by a person named "Arnold" back in 1898. He thought of a method to make a film mask in order to correct the inherent deficiency of the cyan pigments and dyes used in color printing. This was the origin of color masking.
Just recently I was re-reading Beaumont Newhall's "The History of Photography" and in his section on Alfred Stieglitz he writes (page 103) that "he began to push technique beyond the accepted limits." Then he writes that "Stieglitz worked out ingenious techniques for controlling the contrast and tone of the lantern slide by chemical means, and for expanding the range of values by the use of a mask, or as he called it, "compensating cover glass."
Since he learned from H. W. Vogel, the famous photo-chemist who had invented orthochromatic emulsion, one can imagine that Stieglitz learned his technique from Vogel. This was in the 1880s and that predates Arnold's suggestion of using film masks to correct color. So apparently film masking was invented prior to 1898.

свернуть