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	MacAdam ellipse - Wikipedia, the free encyclopedia
		In the study of the perception of color, a MacAdam ellipse is the region on a chromaticity diagram which contains all colors which are indistinguishable, to the average human eye, from the color at the center of the ellipse.
		MacAdam Ellipses (observer PGN) plotted on the CIE 1931 xy chromaticity diagram.
		It was found by MacAdam, however, that all of the matches made by the observer fell into an ellipse on the CIE chromaticity diagram, which is a standard method of displaying chromaticity.
	en.wikipedia.org /wiki/MacAdam_ellipse (635 words)

	[No title]
		On the level macadamized road in ordinary repair the force which the horse has to put forth to draw a load may be taken as one-thirtieth of the load.
		Macadam Roads.—The thickness to be given to a road made altogether of broken stone will depend on the traffic it is in-tended for.
		In a macadamized street pitched or paved water channels are required to prevent the wash of the surface water from undermining the kerb.
	encyclopedia.jrank.org /correction/edit?locale=en&content_id=57019 (8659 words)

	ROADS AND STREETS - LoveToKnow Article on ROADS AND STREETS
		Macadam Roads.The thickness to be given to a road made altogether of broken stone will depend on the traffic it is intended for.
		Various special preparations of petroleum and other oils have been introduced as palliatives, but the most promising treatment for existing macadam roads consists in distributing tar by hand or machine over the surface, care being taken to make the application in fine weather when the roads are dry.
		WateringOn macadamized roads in Great Britain watering is only good for the road itself when the materials are of a very sillcious nature and in dry weather.
	31.1911encyclopedia.org /R/RO/ROADS_AND_STREETS.htm (7556 words)

	A model of color non-linearities (Site not responding. Last check: 2007-10-06)
		We have choosen a perceptual space LMS defined by Smith & Pokorny to represent the MacAdam ellipses.
		Alpha is calculated in order to fit each ellipse of the model with the MacAdam's ellipses.
		Second, as model fit well MacAdam data, we can said that the first stage of photreception is mostly responsible of non linearity in opposite with other model such Guth which take into account color opposition layer.
	lcavwww.epfl.ch /~alleysso/Publication/ecvp97.html (868 words)

	What is color consistency? \| Light Sources and Color \| Lighting Answers \| NLPIP
		A number of researchers, most notably D.L. MacAdam, showed that a just noticeable difference (JND) in the colors of two lights placed side-by-side was about three times the standard deviation associated with making color matches between a reference light and a test light (MacAdam 1942, Wyszecki and Stiles 1982).
		MacAdam also argued that these JNDs form an elliptical pattern of "constant discriminability" in chromaticity space, centered on the chromaticity of a reference light.
		The American National Standards Institute (ANSI) has formalized six, 4-step MacAdam ellipses, centered on specific chromaticity coordinates, for T8, T10, T12 and some CFL fluorescent lamps (ANSI 2000); these are shown in Figure 9.
	www.lrc.rpi.edu /programs/nlpip/lightinganswers/lightsources/whatisColorConsistency.asp (2180 words)

	Color vision loss in patients treated with chloroquine (Site not responding. Last check: 2007-10-06)
		The central point in each ellipse represents the background chromaticity and each data point (crosses) is a color discrimination threshold, between the background color and one of the tested colors.
		Horizontal ellipses tilted towards the red or green vertices of the color triangle in the diagram correspond to protan or deutan losses, respectively, while ellipses pointing to the blue extremity correspond to tritan losses.
		MacAdam’s ellipses obtained in patients treated with chloroquine were enlarged in comparison with those measured in age-matched controls (Figures 1 and 2).
	www.abonet.com.br /abo/665/abo66501.htm (3256 words)

	MacAdam
		History: In the early 1940's Dr. David MacAdam tested the threshold sensitivity of the eye to chromaticity differences in the matching of colored lights.
		MacAdam found that the threshold could be described with ellipses on the chromaticity diagram.
		MacAdam Ellipses help to define the boundary on the Chromaticity Diagram where color will start to appear dissimilar from the ideal.
	www.kruschwitz.com /macadam.htm (214 words)

	ADAMAS GEMOLOGICAL LABORATORY & ADAMAS ADVANTAGE GEMOLOGICAL AND APPRAISAL SOFTWARE
		Superimposed on this plot are the closest one sigma and three sigma MacAdam uncertainty ellipses.
		The MacAdam ellipses are one of color sciences reference points, empirically derived through testing, estimating human repeatability in color matching, which is the essence of diamond color grading.
		Of particular interest is that the 1 sigma MacAdam ellipse shown is both the closest, centered at [.305,.323 ] on the chromaticity diagram, and the smallest of the 25 ellipses within the CIE diagram.
	www.adamasgem.org /sas2000.html (1468 words)

	[No title]
		The results of a comparison of unit ellipses in constant luminosity/luminous reflectance planes in an X, Z diagram indicate the following: MacAdam color matching error ellipses are tilted about 10 degrees toward the neutral point in quadrants 1 and 3; away from the neutral point in quadrant 3 and placed vertically in quadrant 4.
		Wyszecki-Fielder color matching ellipses follow the same pattern except that in the fourth quadrant ellipses are rotated up to 45 degrees toward the neutral point.
		Ellipses pointing toward the neutral point of the diagram imply another, more complex process of generating the unit ellipse.
	www.iscc.org /aic2001/abstracts/oral/Kuehni.doc (1878 words)

	What Color is it?
		MacAdam shows that the colors of all objects with such spectra have the same dominant wavelength (580.1 nm) and differ only in purity.
		The chromaticity of the point closest to Illuminant C was (x, y) = (0.305, 0.323), at which the long semiaxis of the ellipse that represents the standard deviation of visual color matches was 0.0023, and the short semiaxis was 0.0009 in length.
		This is consistent with MacAdam's statement that the first visually detectable step from white corresponds to 0.2 to 0.7excitation purity, depending on the wavelength.
	mintaka.sdsu.edu /GF/explain/optics/color/color.html (9793 words)

	The Teufel colors
		In conventional cone space (MacLeod and Boynton 1979) these colors form an ellipse situated on a plane of equal luminance.
		Such ellipses were described first by MacAdam (1942) plotting his results in CIE space.
		Optical Society of America, Washington D.C. MacAdam DL (1942) Visual sensitivities to color differences in daylight.
	www.kyb.tuebingen.mpg.de /ki/people/wehrhahn/htcw/htcw.htm (726 words)

	[No title] (Site not responding. Last check: 2007-10-06)
		The ellipses are known as MacAdam ellipses after their inventor.
		The ellipses at the top are larger than those at the bottom of the figure, and that they rotate as they move up.
		This means that the magnitude of the difference in x, y coordinates is a poor guide to the difference in color.
	www.cs.stevens.edu /~elli/classes/cs558/Notes/color_files/TextMostly/Slide12.html (64 words)

	handprint : the geometry of color
		Projected to the MacAdam limits for that lightness, I estimate the lightness increases were in the range of 20% to 50% for all hues.
		MacAdam took the novel approach of asking subjects to match exactly a test light with a mixture of primary lights, then used the margin of error in primary mixtures accepted as a match across repeated test runs to define the perceptual minimal limits of color difference.
		MacAdam's approach stimulated several efforts to devise isotropic color spaces or uniform color scales (UCS) that are perceptually equal in all dimensions and in all combinations of brightness/lightness, hue and chromatic intensity.
	www.handprint.com /HP/WCL/color2.html (15174 words)

	Completed Research \| Solid State Lighting \| Programs \| LRC
		The American National Standards Institute (ANSI) specifies a 4-step MacAdam ellipse—a region plotted on a color space diagram showing where colors are perceived to be the same—as the color-tolerance criterion for certain types of fluorescent lamps.
		2-step MacAdam ellipse — For applications where the white LEDs (or white LED fixtures) are placed side-by-side and are directly visible, or when these fixtures are used to illuminate an achromatic (white) scene.
		4-step MacAdam ellipse — For applications where the white LEDs (or white LED fixtures) are not directly visible, or when these fixtures are used to illuminate a visually complex, multicolored scene.
	www.lrc.rpi.edu /programs/solidstate/completedProjects.asp?ID=65 (577 words)

	Ask a Color Scientist!
		Instead the data for each ellipse are tabulated in the original paper (D.L. MacAdam, Visual sensitivities to color differences in daylight, J. Opt.
		The MacAdam limits are a definition of a theoretical maximal color gamut for object colors.
		In fact the MacAdam limits are far beyond any realizable object colors since they were computed, by David MacAdam, from theoretical reflectance curves that were equal to either zero or 100% at every wavelength (with a maximum of 2 transitions).
	www.cis.rit.edu /mcsl/outreach/faq.php?catnum=2 (12767 words)

	Lab color space - QuickSeek Encyclopedia (Site not responding. Last check: 2007-10-06)
		Therefore only a few representations of some horizontal "slices" in the model are enough to conceptually visualize the whole gamut, assuming that the luminance would be represented on the vertical axis.
		CIE 1976 Lab* is based directly on the CIE 1931 XYZ color space as an attempt to linearize the perceptibility of color differences, using the color difference metric described by the MacAdam ellipse.
		The non-linear relations for L, a, and b* are intended to mimic the logarithmic response of the eye.
	labcolorspace.quickseek.com (702 words)

	FAQ
		Samples with a DE(CMC) less than 1.0 fall within the ellipse, and samples with a D E(CMC) greater than 1.0 fall outside the ellipse.
		The CMC color difference equation is designed so that you can adjust the tolerance ellipse axes to put more or less emphasis on lightness and chroma.
		The signal from the eye is just a signal; it becomes meaningful only after it has been processed in the brain.
	www.prism.to /glossary.htm (1756 words)

	PROTECTING VISIBILITY (Site not responding. Last check: 2007-10-06)
		A great deal of experimental work has been done on color discrimination thresholds, which are of critical importance to the pain and dye related industries.
		On the chromaticity diagrams, these thresholds take the form of small ellipses of colors just distinguishable from a given color (Figure 2-8).
		Each ellipse is the locus of standard deviation in repeated small-field color matching.
	capita.wustl.edu /CAPITA/CapitaReports/ProtectingVisibility/Chapter2/Chapter2.htm (7388 words)

	2005 (Site not responding. Last check: 2007-10-06)
		We used the Trivector test, a short version used for rapid screening, and the Ellipses test which determine a MacAdam ellipse.
		A correlation between duration of DM and color vision loss was also found for the CCT results in the protan (r=.48; p=.028) and tritan (r=.60; p=.003) axes of the Trivector test and in the MacAdam ellipse area (r=.53; p=.015).
		Metabolic control (glucose level at the test time and glycosylated hemoglobin, HbA) and time of diabetes of the patients were correlated with their visual data.
	www.usp.br /ip/laboratorios/visual/arvo2005.htm (1610 words)

	EDCS Reference Manual
		Asphalt, asphaltic concrete, tar macadam, or bitumen bound macadam (including any of these types with concrete ends).
		The <> of the semi-major axis of the error ellipse at the of a stroke of .
		The <> of the semi-minor axis of the error ellipse at the of a stroke of .
	www.sedris.org /sdk_4.0.1/src/lib/edcs/docs/dictionary/EAC_L.htm (4080 words)

	Home > Hollister, CA, California Yellow Pages, Classifieds, Real Estate, Business, Schools, Library and Jobs (Site not responding. Last check: 2007-10-06)
		It would be desirable if a distance on a chromaticity diagram corresponded to the degree of difference between two colors.
		The idea of measuring the difference between two colors was developed by D.L. MacAdam and summarized in the concept of a MacAdam ellipse.
		Based on the work of MacAdam, the CIELuv color space was developed in 1960 and was later replaced by the CIELab color space, both of which were designed to have an equal distance in the color space correspond to equal differences in color, as measured by MacAdam.
	www.hollistercaus.com /info/CIE_1931_color_space (2486 words)

	MacAdam David L David Lewis 1910 Correspondence with Selig Hecht, Parry Moon, and others concerning optics and color, ... (Site not responding. Last check: 2007-10-06)
		MacAdam David L David Lewis 1910 Correspondence with Selig Hecht, Parry Moon, and others concerning optics and color, 1943-1964.
		Correspondence with Selig Hecht, Parry Moon, and others concerning optics and color, 1943-1964.
		One Physics Ellipse, College Park, MD 20740, USA
	www.aip.org /history/catalog/icos/4330.html (86 words)

	PHYSICS AND CHEMISTRY (Site not responding. Last check: 2007-10-06)
		Ellipse is the MacAdam locus of colors just noticeably different from source C. (Adapted from Middleton, 1952.)
		MacAdam D.L. (1942) Visual sensitivities to color differences in daylight.
		Excerpted in Sources of Color Science, D.L, MacAdam, Ed., MIT Press, Cambridge, 1970.
	capita.wustl.edu /CAPITA/capitareports/AerosolCourse/RadiativeTransfer.html (3749 words)

	Extract: Pilgrimage to Fátima 1999 (Site not responding. Last check: 2007-10-06)
		Following a night of pelting rain, we leave the spa early beneath a leaden sky.
		A procession slowly describes a virtual ellipse through the assembly.
		White-clad clerics and a few laymen form the vanguard, holding aloft national flags and banners of religious orders and lay organizations that sparkle in the brilliant sunlight.
	www.marshillreview.com /extracts/brooks.shtm (6618 words)

	CVNet: CVNet - summary of responses; Colored spot detectibility
		and were not well represented by the ellipse [MacAdam's] used to describe
		Abstract: "Color-discrimination ellipses derived from the variability of
		ellipses do not vary significantly in shape with chromaticity, observer, or
	www.visionscience.com /mail/cvnet/1998/0285.html (1254 words)

	San Francisco State University :: The Poetry Center
		Lewis MacAdams introduces Blaser and Ebbe Borregaard, in the Barbary Coast Room, SFSU.
		Lewis MacAdams introduces Borregaard and Robin Blaser, at SFSU.
		Otis Brown has written a weekly jazz, sports, and cooking column for the Philadelphia Drummer, has worked in Philly with his thirty piece jazz band, and has written the book Gus Gates After Boneless Chicken and Little Boys.
	www.sfsu.edu /~poetry/archives/b.html (3930 words)

	Fall 2004 Center for History of Physics Newsletter
		This year we also are grateful for donations of collections of photographs from Peter Trower of Luis Alvarez; Wolf Prize recipient François Englert of himself; Ken Ford of himself; Charlotte F. Fischer of Douglas Hartree; Dr. and Mrs.
		John F. Kielkopf with John R. Hale of Edwin Hubble; Ellen Ryndina of Lev Landau; Keith MacAdam of his father and former Optical Society of America president David MacAdam, and Emmanuel Rashba of various Russian physicists.
		American Institute of Physics, One Physics Ellipse, College Park, MD 20740-3843.
	www.aip.org /history/newsletter/fall2004/recentacq.htm (1632 words)

	Student Abstracts: ORNL - Physics
		All of these algorithms are combined into a single, customizable program with a Windows Graphical User Interface written in Borland C++.
		The program is designed to keep the color difference within a 1-step MacAdam ellipse, the minimum amount of color difference perceivable by the human eye.
		The use of a genetic algorithm will also allow future researchers to easily redefine the criteria for determining the optimal filter.
	www.scied.science.doe.gov /scied/Abstracts2001/ORNLphys.htm (1736 words)

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