Lightness and Brightness and Other Confusions
Lightness and Brightness and Other Confusions
Lightness and Brightness and Other Confusions
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Yellow +b*<br />
60<br />
50<br />
40<br />
Hue<br />
30<br />
20<br />
10<br />
-60 -50 -40 -30 -20 -10<br />
Green -a*<br />
10<br />
20<br />
30<br />
40<br />
50<br />
60<br />
Red +a*<br />
-10<br />
-20<br />
-30<br />
-40<br />
-50<br />
-60<br />
Blue -b*<br />
100<br />
90<br />
80<br />
70<br />
60<br />
50<br />
h<br />
<strong>Lightness</strong> (L*)<br />
40<br />
30<br />
Hue<br />
20<br />
10<br />
0<br />
10 20 30 40 50 60<br />
Chroma (C*)<br />
Figure 20. The L*C*h* colour space is a cylindrical variation of the spherical<br />
CIELAB space. The hue angle (indicating hue) rotates counter-clockwise<br />
from +a (red = 0˚). The chroma increases outwards from the central axis<br />
(grey scale = 0 chroma).<br />
Chromaticness <strong>and</strong> chromaticity<br />
Chromaticness is often given the same definition as chromaticity, i.e. the hue<br />
<strong>and</strong> saturation of a colour regarded independent of its brightness. The Collins<br />
English Dictionary still gives chromaticness as “the attribute of colour that<br />
involves both hue <strong>and</strong> saturation” (Collins 2000). Billmayer <strong>and</strong> Saltzman<br />
give chromaticness as follows: “Finally, when taken together, the hue <strong>and</strong><br />
saturation of a perceived colour are called its chromaticness”. In their book<br />
The Science of Color The optical Society of America’s Committee on Colorimetry<br />
defined chromaticness as follows: “Chromaticness consists of hue <strong>and</strong><br />
87