Quantitative Estimates of Saturation*

Abstract

Scales relating saturation to clorimetric purity have been derived from magnitude estimations for red (W29) and green (W65) test stimuli of 4° and 1.50 subtense. Scales based on homochromatic comparisons at several luminance levels follow a power-law form, with exponents ranging from 1.80 to 2.30. There is evidence that saturation scales for red and green light differ in slope, with the red scale being of consistently higher slope than the green. This difference is demonstrated clearly by heterochromatic saturation matches for a large number of clorimetric purities, but is not substantiated by magnitude estimations utilizing heterochromatic comparisons. It is suggested that observers are not able to apply a ratio definition of saturation in making quantitative comparisons of heterochromatic stimuli by the method of magnitude estimation, and that real differences between saturation scales for differing hues may be masked by the adoption of median magnitude estimations as a quantitative index of perceived saturations.

On saturation and related parameters following Guth's ATD colour‐vision model

“…Regarding the dependence of saturation on colorimetric purity at constant luminance, the experimental results [15][16][17]21,53 can be fitted, for any colour, with a power function whose exponent depends on dominant wavelength and luminance. Our calculations [ Fig.…”

Model of saturation and brightness: Relations with luminance

“…[26][27][28][29][30] For flicker luminance, where linear relations apply, saturation S of any pc is modeled as the product of its p c and the relative saturation S , of its dominant wavelength: [26][27][28][29][30] For flicker luminance, where linear relations apply, saturation S of any pc is modeled as the product of its p c and the relative saturation S , of its dominant wavelength:…”

“…Saturation decreases in some unknown proportion to pc. [26][27][28][29][30] For flicker luminance, where linear relations apply, saturation S of any pc is modeled as the product of its p c and the relative saturation S , of its dominant wavelength:…”

Quantitative judgments of color: The square root rule

“…saturation alone is changed by blending the colored paper with the appropriate gray. Therefore, recent studies have used gray and colored papers (Galifret, 1959;Panek & stevens, 1966), or, if luminous stimuli were used rather than reflecting pigments, the total brightness was kept constant as the proportion of colored light was changed (Onley et al, 1963;Holmberg, 1964Holmberg, , 1965Indow & Stevens, 1966). However, changing only one of the stimulus aspects governing response does not necessarily allow us to eliminate the influence of those other qualities which are kept constant.…”