This book has been produced in response to an insistent demand from color workers for exhaustive information on the many forms of research that have developed the various color processes of photography into the usable condi tion in which they are'found today. This subject was covered very completely by Professor Wall up to the time of the publication of his famous book, The History of three-color Photography, in 1925. But the demand for that work was so great that it has long been out of print and its information is no longer generally available. Even if it were, color photography has progressed so rapidly in the past twenty years that information as of that date could tell no more than half the story of today.
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