Multiplying factors of some photographic correction filters are calculated by means of the addition law and are found in fair agreement with the practical figures given by the manufacturers. The improvement of color rendering by the correction filters is calculated in the same way; it is very considerable. It is shown, that each filter can be characterized by three “improvement-factors,” indicating the improvement of the green, yellov, and red colors, respectively. The improvement-factors are—in contradistinction to the multiplying factors—nearly independent of the color-sensitivity of the emulsion. It is argued that green correction filters are not generally useful, whereas (hypothetical) pale orange filters should yield the best possible color rendering.
A. VAN KREVELD, "Improvement of Photographic Color Rendering by Correction Filters," J. Opt. Soc. Am. 36, 412-412 (1946)