Fig 1.
Schema of progress from physical variables through psychophysical variables and color attributes to 3-dimensional color and its maximum 6 color attributes.
The attributes are lightness, brightness, hue, saturation, chroma, colorfulness, labeled l, b, h, s, c, f. Three groups of similar attributes each relate to one of 3 color dimensions, i.e., lightness/ brightness, hue, or chromaticness. One attribute represents one dimension at a time. The 3-D object color shown here has attributes l,h,c. The 9 possible effects of 3 psychophysical variables on 3 color attributes are shown as 9 dashed lines (see Table 1). If saturation applied, dashed lines would meet on “s” rather than “c”. The 3-D color solid (showing 4 of many hue planes) shows effects of raising Luminance Y (from 0.06Y to 0.3Y), roughly doubling both lightness/Value (3 to 6) and chroma (Figs III-VI(6.6.1) of [2],and Fig. 5.1 of [4]).
Table 1.
Class I effects (total 18), each consisting of one psychophysical variable (of a total 3) on one color attribute (of a total 6), listed by the effect name and its abbreviation in parentheses, for all modes of appearance.
Table 2.
Classification of the effects of 3 psychophysical variables on a maximum 6 color attributes for all modes of appearance by singles, pairs, and triplets of psychological variables and of color attributes.
Table 3.
Class II effects of single psychophysical variables on pairs of color attributes for all modes of appearance (i.e., total six color attributes).
Table 4.
Class VI effects of paired psychophysical variables on triplets of the six color attributes.
Fig 2.
Graphs of the Luminance-on-hue (or Bezold-Brucke) effect for the no-contrast mode (labeled as LhN) and for the contrast mode (LhC), each for two subjects and illuminant D65; after Pridmore [20].
The ordinate shows the wavelength shift (nm) of the hue attribute. The curves are similar but LhN is shifted to shorter dominant wavelength by 10–25 nm.
Fig 3.
Munsell (solid line) and NCS (dashed) data for the Luminance-on-hue (no-contrast) effect; after Hunt [35].
Dash-dot line: Pridmore [20] data for Lh (no-contrast) effect as in Fig. 2. Dotted line: Mean of the three curves; the curve is labeled LhN to indicate the no-contrast mode.
Fig 4.
Five data sets of constant-hue loci, reflecting the Purity-on-hue (or Abney) effect in the CIE 1931 diagram for illuminant C (open circle).
Some curvatures are exaggerated and some loci slightly shifted for clarity. Data sets differ in some parameters. Ph (contrast mode) effect is shown for Munsell data (samples at equal luminance), NCS data (equal blackness 0 s), Pridmore data [9] (equal luminance, mean of 31 subjects), MacAdam data [25] (equal brightness, mean of 2 subjects), and Ayama data [26] (equal brightness to 100 td reference white, mean of 2 subjects). The latter three data sets derive from different CIE diagrams or different light sources, so their loci are approximated by normalising them to center on illuminant C. Inset Table: Approximate nulls in dominant wavelength nm for the 5 data sets, plus that for Robertson [8] (mean of 3 subjects). Only nulls about 570–590 nm (yellow) and 450 nm-565 c (violet) are common to most sets.