Dominant wavelength, color

Another method of expressing color is in terms of luminance, dominant wavelength, and excitation purity. These latter are roughly equivalent to the three recognizable attributes of color lightness, hue, and saturation. Lightness is associated with the relative luminous flux, reflected or transmitted. Hue is associated with the sense of redness, yellowness, blueness, and so forth. Saturation is associated with the strength of hue or the relative admixture with white. The combination of hue and saturation can be described as chromaticity. 

Achromatic colors are white, black, and gray. Black and gray differ from white only in their relative reflection of incident light. The purples are nonspectral chromatic colors. All other colors are chromatic for example, brown is a yellow of low lightness and low saturation. It has a dominant wavelength in the yellow or orange range. 

The strontium formulation shows a reasonably high red color purity as can be seen from the chromaticity diagram in Fig. 2.19a. The color purity (pe) of a visible flare with the chromaticity (x, y) is its difference from the illuminant s white point relative to the furthest point on the chromaticity diagram with the same hue (dominant wavelength for monochromatic sources) where (x , y ) is the chromaticity of the white point and (x7, y7) is the point on the perimeter whose line segment to the white point contains the chromaticity of the stimulus. 

Fig. 3-3. Color designation in the CIE-Yxy system. Colors lie within the solid lines resembling a shoe sole. Colors within that plane may be given either by the Cartesian coordinates x and y, or by the dominant wavelength, [nm], and the excitation purity, Pg. The lightness, Y, is normal to the plane. (Scheinost and Schweitmann 1999 with permission)...

Hue hyii [ME hewe, fr. OE htw, akin to ON hy plant down. Gothic hiwi form] (before 12c) n. The speciflc quality distinguishing one color from other, such as yellow, red, or blue (color, character, and dominant wavelength) Blue, green, red, etc. White, black, and grays possess no hue. 

In the Flame Tests for Metals movie eChapter 6.3) the characteristic color of the flame is produced by emissions at several visible wavelengths, with the most intense spectral lines dominating the color. For instance, the most intense visible lines in the spectrum of lithium occur at 671 nm. (a) What color is light of this wavelength ... 

The hue is a color attribute associated with the dominant wavelength in a mixture of light waves that represent the dominant color as perceived by an observer when an object is considered to be red, orange, or yellow, the hue is being specified. The chroma defines the color s strength. It is measured in numbered steps starting at one with weak colors having low chroma values (Plataniotis and Venetsanopoulos 2000). 

Chroma The deviation of the color from gray. Pure spectral colors such as red and violet have high saturation. Saturation refers strength of the dominant wavelength or hue. Pink and red have the same hue but differing saturation. 

Passive satellite measurements of reflected intensity at visible wavelengths allow mapping of ocean color. Ocean color is dominated by the amount of chlorophyll and phaeopigments present, which in turn can be related to primary productivity. Ocean color is also an important indicator of the presence or absence of nutrients and various physical oceanographic phenomena. 

Neutrals. Black, white, and gray are the three neutrals or noncolors, which are not part of the color wheel. A neutral, when used beside a color, intensifies the color. Black and white, if not used properly, can dominate a composition. We see black when no electromagnetic radiation reaches our eyes we see white when all the wavelengths in the electromagnetic spectrum reach our eyes. 

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