Abstract

A 4° square, two-part photometric field, symmetrical about a vertical division and viewed through a pupil 3 mm in diameter, is illuminated in both parts by artificial sunlight at a constant brightness of about 3 or 4 millilamberts (retinal illumination, 70 to 90 photons) with a surrounding field of about 0.5 millilambert. Homogeneous light is added to one-half, and sunlight simultaneously subtracted so that the field remains matched in brightness. Two adjustments of the mixture are made: (1) the least purity perceptible with certainty (p_max), and (2) the greatest imperceptible purity (p_min). The purity of these mixtures is then measured, increased accuracy being obtained by measuring a known large multiple of the homogeneous brightness. Values of p_max and p_min have been obtained as a function of the wave-length of the homogeneous component; these values are reported in detail, and some discussion of their interpretation is given.

© 1938 Optical Society of America

Chromaticity Sensibility to Wave-Length Difference as a Function of Purity*

E. P. T. Tyndall
J. Opt. Soc. Am. 23(1) 15-24 (1933)

Apparatus for the Determination of Color in Terms of Dominant Wave-Length, Purity and Brightness*

Irwin G. Priest
J. Opt. Soc. Am. 8(1) 173-200 (1924)

Photometric Relationships Between Complementary Colors*

David L. MacAdam
J. Opt. Soc. Am. 28(4) 103-111 (1938)

Hue Sensibility to Dominant Wave-Length Change and the Relation Between Saturation and Colorimetric Purity

Dorothy Nickerson and Walter C. Granville
J. Opt. Soc. Am. 30(4) 159-162 (1940)

The Blackening of Photographic Plates by Long Wave-Length X-Rays, II

F. R. Hirsh
J. Opt. Soc. Am. 28(12) 463-465 (1938)