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PRIME COLOR, INCORPORATED |
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DISCOVERIES Below is a table of Thornton
discoveries, At
the bottom of the page is an overview of the discovery
A. If white light, of a given target chromaticity, is composed by mixing three spectral lights in proper proportion, both its luminous efficiency and its CIE Color Rendering Index (when considered together) maximize in the neighborhood of CRI = 80 when: (a) the wavelengths of the spectral lights fall near 450 nm, 540 nm, and 610 nm and (b) target chromaticities fall near those of daylights or Planckian radiators from about 2850 K to 6800 K. Here, most of the visible spectrum is empty; yet CRI is higher than that of most commercial lamplights. JOSA January 1971. Any artificial illumination of thirty years ago was ideally simultaneously maximized for lumens per watt of lamplight, and color-rendering (CRI). Astonishingly, this happens when the white light is composed of spectral colors (narrow spikes of pure color) at the “prime color” wavelengths. Most of the spectrum of such light is, then, empty. B. White light
of the preceding paragraph, composed of a mixture of spectral lights at 450 nm,
540 nm, and 610 nm, has a gamut of coloration appreciably larger, even, than
that of average daylight of the same chromaticity. JOSA February 1972. Intuition
suggests that white light composed of three spikes of color, leaving its
spectrum almost empty, cannot possibly render illuminated objects in brighter
colors than in daylight itself. C The
chromaticity of an element in any visual scene is established with minimum power
input to the eye when light from the element is composed of a mixture of
spectral colors near 450, 540, and 610 nm. JOSA March 1972. So have your TV
set emit only the three prime colors, or have the illumination on your
illuminated scene composed only of them, and you will be expending minimum
power. D.Three-color response of the normal human visual system
consists of well-separated channels peaking near 450, 540, and 610 nm. . JOSA
March 1972. The corresponding
three (visual) spectral sensitivities had been unknown. They are the basis of
the color matching functions of the CIE Standard Observers, and are responsible
for the visual brightness seen per watt of each of the spectral colors. E. Illumination
composed of a mixture of three different spectral lights near 430, 530,
and 660 nm (illumination more purple in color than average daylight) yields a
color gamut about three times that of average daylight (useful in applications
requiring maximum color-discriminating capability). Journal of the Illuminating
Engineering Society October 1973. In such illumination, the surroundings are
surrealistically colorful. F. Following a suggestion of Professor David Wright (1944),
the three intersections typical of pairs of spectral power distributions of
visually-matching lights are shown to point accurately at the three peaks of
spectral sensitivity of the normal human visual system.
Journal of Color and Appearance 1973. This understanding of the
significance of such intersections contributed a solid foundation to the
“prime colors.” G. Brightness ( beta b
) and acceptability of coloration
(Color Preference Index CPI ) are
more useful metrics than traditional “lumen output” and “Color Rendering
Index.” Journal of the Illuminating Engineering Society October 1974. The new metrics are considerably more meaningful to human
seeing than the traditional measures. By “brightness” is meant perceived
brightness of a scene, per lighting-watt per square meter on the scene.
The new metrics can be simultaneously optimized in artificial illumination.
Conversely, lumens (rather than brightness) and Color Rendering Index ( rather
than Color Preference Index) cannot be optimized simultaneously. H. The design of safety-colors (used in traffic, around
radioactive materials, etc.) that show their designated warning colors even in
poor illumination. Journal of the Illuminating Engineering Society January 1977.
Spectral reflectance of safety
colors of the new design is peaked at the prime colors, so that, whatever the
illumination, the visual color of the safety-color materials remains the same. I. A Brightness Meter, utilizing four spectral inputs, that assesses visually-perceived brightness of any scene far better than does a Lumen Meter, with only the “luminosity” input of the oldfashioned footcandle meter. Journal of the Illuminating Engineering Society October 1980. 1950 Thesis on scintillation counter. Graduated 1951. Dad, President of Whitney club. 1951 GE labs (5 years) (GE was already a ‘big deal’--made first diamonds in corporation) Mike O and Dad---Ge---Electron Physics—cathode ray tubes w/ phosphor layer---electroluminescence—wrote paper “electroluminescence in zinc sulfide’ Ferd Williams upstairs, with handpicked crew as his light group—didn’t like or invite Dad to join—Dad a lost sheep 1965-Until that time, NOONE CARED about HOW THE LIGHT LOOKED!! No intrest in brightness or color rendition. This was the first time anyone cared about the human visual system. Arc and incandescent—you can’t fashion the spectral composition, so no one was concerned with doing that in fluorescents. Prime Color also colored the illuminated item the way the human visual system wantd and expected to see it. Preferred color-rendering. 1967-These 3 prime colors were found to match the normal observer’s visual system. Made any desired color illumination by mixing 3 colors. Fluorescent lamps were made to make certain color—white. Two parallel, related tracks of research started:
PCI discovered that they were set up wrong. They measure color relationships/colors themselves.
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