I've been reading some old books on color printing and color
photography, and I found some interesting stuff, so I thought I'd
post some excerpts here. The books are:

[Yule]
Principles of Color Reproduction, by J. Yule
(Wiley, 1967)
A very technical book about color printing, including a full
discussion of the Neugebauer equations and the masking equations,
photographic masking, and halftone dot structures. You can skip
the math and still get a lot out of it, though. Also contains a
brief description of early electronic scanners. Yule worked for
Kodak Research Labs in Rochester.

[Billmeyer & Saltzman]
Principles of Color Technology, by Fred Billmeyer & Max Saltzman
(ISBN 0-471-03052-X, 2nd ed, 1981)
A book about specifying color in industry (for things like paint,
plastics, and textiles). Heavy emphasis on metamerism. Nothing
specifically about printing or photography, but worth reading
anyway.

[Hunt]
The Reproduction of Color, by R. Hunt
(ISBN 0-85242-356-X, 1957, 3rd ed 1975)
Mostly about photography, but also covers television and color
printing. Odd mixture of topics, but there is some good stuff
here. Hunt worked for Kodak Research Labs in Harrow, England.

[Sipley]
A Half Century of Color, by Louis Sipley
(Macmillan, 1951)
A book about the history of color printing and color photography,
up to 1950. Many color inserts, made from original printing
plates. Before Kodachrome, color photography was very difficult
and expensive, so it was more suited to printing (where the costs
could be spread over many copies) than to making individual
photographs to hang on a wall.

[Coote]
The Illustrated History of Color Photography, by Jack Coote
(ISBN 0-86343-380-4, 1993)
Another book about the history of color photography. Includes
discussion of the various Technicolor processes, automatic
snapshot-printing machines, and film-coating machines. Many
historic color photographs.