Measurement of the brightness, hue, and saturation produced by three different narrow spectral bands having dominant wavelengths of 500, 580, and 660 mμ, was made with intermittent inputs having a rate of 9.8 cps. The PCF (pulse-to-cycle fraction) was , and the luminance ranged from 3319 candles/ft2 down to 0.3 candle/ft2. At the higher luminance levels, the 500-mμ waveband produced the greatest brightness; the 660-mμ waveband, the lowest; and the 580-mμ waveband, an intermediate effect. As luminance decreased, the three bands finally became about equally effective around 30 candles/ft2. A range of 200 to 30 candles/ft2 manifested the greatest brightness index. Whereas brightness was above expectations under some conditions, it fell below expectations under others.
The intermittent inputs also produced hue changes and desaturation. Only the 500-mμ band produced large desaturation. When the 660-mμ waveband was used and when luminance was high, hue shifts were toward colors expected of the shorter wavelengths. Only one subject experienced hue shifts for the 580-mμ band; three of the four subjects obtained hue shifts for the 500-mμ band. The results here were complex.
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