Abstract

The best practical test of color vision is the printed polychromatic, typified by the Ishihara. Its flaw is that, being calibrated to a standard illuminant which is required for actual testing, it becomes undependable with deviations from this standard. In practice the standard is rarely provided, because it requires special artificial installations which are rarely available or even appreciated as a necessity. Hence, improper illumination is the rule rather than the exception, and accounts for the passing of 50 percent of color defectives in the Navy, for example. The present report, the first of a projected series, discusses solely the basic technical aspects of a new polychromatic printed test for red-green deficiency which retains stability and diagnostic integrity under a range of illumination far wider than that encountered in testing under natural or artificial sources, from minus-blue to 14,000°K. With this, testing may be done in disregard of composition of illuminant. Thus a source of error is eliminated which has seriously impaired the utility of what is otherwise the most desirable type of practical test.

© 1948 Optical Society of America

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References

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  1. Dean. Farnsworth, “A survey of methods in administering pseudo-isochromatic test plates for color vision,” , Medical Research Laboratory, U. S. Submarine Base, New London, Connecticut, November6, 1943.
  2. While the data in this paper are confined to the given range, it will be shown in a subsequent report that in practical performance the inks maintain diagnostic integrity at color temperatures far below that of Illuminant A.
  3. Color Measurement Laboratory, Massachusetts Institute of Technology, Handbook of Colorimetry (The Technology Press, Cambridge, Massachusetts, 1936); and J. Opt. Soc. Am. 34, 636 (1944), Table IIIa, last column.
  4. This ink lies just outside the boundary of the zone in which the other five lie. In a subsequent paper dealing with the design and validation of the test plates the expedient by which this minor difficulty has been resolved will be presented.
  5. F. H. G. Pitt, “Characteristics of dichromatic vision,” Medical Research Council, Report of the Committee on the Physiology of Vision XIV; , London, 1935, pp. 47–49; also Deane B. Judd, “Facts of color-blindness,” J. Opt. Soc. Am. 33, 304–305 (1943).
  6. The expedient by which these two minor difficulties have been resolved will also be discussed in the report that is to follow. It may suffice here to say that as long as it is possible to make groupings of pairs of approximately equal brightness (within 1 percent of each other), the deviants mentioned offer no obstacles.
  7. Preliminary work has also been done toward a polychromatic printed test for blue-deficiency which shall remain stable under wide fluctuations of illumination. The principle is identical, but with the blue test the specific problem lies in reducing the red component to the vanishing point instead of so reducing the blue component as in the present red-green test.

Farnsworth, Dean.

Dean. Farnsworth, “A survey of methods in administering pseudo-isochromatic test plates for color vision,” , Medical Research Laboratory, U. S. Submarine Base, New London, Connecticut, November6, 1943.

Pitt, F. H. G.

F. H. G. Pitt, “Characteristics of dichromatic vision,” Medical Research Council, Report of the Committee on the Physiology of Vision XIV; , London, 1935, pp. 47–49; also Deane B. Judd, “Facts of color-blindness,” J. Opt. Soc. Am. 33, 304–305 (1943).

Other (7)

Dean. Farnsworth, “A survey of methods in administering pseudo-isochromatic test plates for color vision,” , Medical Research Laboratory, U. S. Submarine Base, New London, Connecticut, November6, 1943.

While the data in this paper are confined to the given range, it will be shown in a subsequent report that in practical performance the inks maintain diagnostic integrity at color temperatures far below that of Illuminant A.

Color Measurement Laboratory, Massachusetts Institute of Technology, Handbook of Colorimetry (The Technology Press, Cambridge, Massachusetts, 1936); and J. Opt. Soc. Am. 34, 636 (1944), Table IIIa, last column.

This ink lies just outside the boundary of the zone in which the other five lie. In a subsequent paper dealing with the design and validation of the test plates the expedient by which this minor difficulty has been resolved will be presented.

F. H. G. Pitt, “Characteristics of dichromatic vision,” Medical Research Council, Report of the Committee on the Physiology of Vision XIV; , London, 1935, pp. 47–49; also Deane B. Judd, “Facts of color-blindness,” J. Opt. Soc. Am. 33, 304–305 (1943).

The expedient by which these two minor difficulties have been resolved will also be discussed in the report that is to follow. It may suffice here to say that as long as it is possible to make groupings of pairs of approximately equal brightness (within 1 percent of each other), the deviants mentioned offer no obstacles.

Preliminary work has also been done toward a polychromatic printed test for blue-deficiency which shall remain stable under wide fluctuations of illumination. The principle is identical, but with the blue test the specific problem lies in reducing the red component to the vanishing point instead of so reducing the blue component as in the present red-green test.

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Figures (13)

Fig. 1
Fig. 1

Family of spectrophotometric curves showing percent spectral reflectance of the six inks.

Fig. 7
Fig. 7

Change of trichromatic coefficients of the six inks with change of illumination.

Fig. 8
Fig. 8

Change of luminous reflectance of six inks with change of illumination.

Tables (3)

Tables Icon

Table I The specifications of the six inks of the Illuminant-Stable Color Vision Test for red-green deficiency.

Tables Icon

Table II Percent spectral reflectance of the six selected inks.

Tables Icon

Table III Trichromatic coefficients and percent luminous reflectance for each of the six inks under various illuminants. From these trichromatic coefficients Figs. 2A to 7, inclusive, have been plotted. From the corresponding luminous reflectances Fig. 8 has been plotted.