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Automatic computing color meter - Patent 4247202 The tristimulus values X, Y, Z and the chromaticity coordinates x, y of the sample with respect to the CIE standards for luminance and chromaticity values are produced for accurate color measurement. The tristimulus values, by definition, are as follows: ##EQU2## expressed in units such that Y is numerically equivalent to the luminous reflectance value of the sample or target 14. The tristimulus values having these functions included in their numerator term (electronically as automatic gain controls) would be essentially independent (to a first order) of the spectral change from an initially calibrated source. www.freepatentsonline.com /4247202.html   (9126 words)

Calculating Tristimulus values   (Site not responding. Last check: 2007-10-10) Tristimulus values are the amounts of three primaries that specify a colour stimulus. The CIE 1931 tristimulus values are called X, Y, and Z. Tristimulus values can be calculated if the reflectance spectrum of a sample is known. CIE XYZ tristimulus values can be calculated by the integration of the reflectance values R(l), the relative spectral energy distributions of the illuminant E(l), and the standard observer functions x(l), y(l), and z(l). www.radioqualia.net /illata/bibliotheca/cscience/s9.html   (156 words)

GCA_Color_Theory The tristimulus space and the usual chromaticity diagrams don't have uniform scales and this is in colorimetry a big problem, either cognitive that practical. Tristimulus space is based on the cone activation and it depends on the electromagnetic radiation entering into the eye, therefore it needs first to introduce the fundamental properties of the electromagnetic radiations concerning colorimetry. In this case the tristimulus values are denoted by the foot-index 10, that regards the size of the visual field. www.fis.unipr.it /~fermi/PagInternet_English/GCA_Color_Theory.html   (3993 words)

Prism Instruments Canada - Your Source for Colour Measurement Basically, it is a measure of how opaque a substance is. It is the ratio of Y tristimulus for the sample measured over a fl substrate divided by Y tristimulus for the sample measured over a white substrate, expressed as a percentage: These values are simply tristimulus values and chromaticity coordinates and represent the absolute values displayed when FMC-2 is selected. Tristimulus values are numbers that represent how the human visual system responds to a given colour. www.prism.to /glossary.htm   (1777 words)

Theory Tristimulus values are the amounts of three primaries that specify a color stimulus. Secondly, the imaginary primaries were chosen such that the Y tristimulus value was directly proportional to the luminance of the additive mixture. Thus, all possible sets of tristimulus values can be represented in a two-dimensional plot of two of these chromaticity coordinates and by convention x and y are always used. www.ihara-group.com /color/theory4.html   (2250 words)

[No title] When using tristimulus data to describe a color, the illuminant and observer must also be defined. Tristimulus values are not, therefore, absolute values characteristic of a sample, but relative values dependent on the method used to obtain them. Approximations of CIE tristimulus values may be obtained from measurements made on a tristimulus colorimeter that gives measurements generally normalized to 100. www.xrite.com /support_doc.aspx?SupportID=2907&Type=d   (4141 words)

PDS - Terminology C The ratios of each of the three tristimulus values X, Y and Z in relation to the sum of the three: designated as x, y and z respectively. The ratios of each of the tristimulus values of a colour to the sum of the tristimulus values. Tristimulus values, chromaticity co-ordinates and luminance value, or other colour-scale values, used to designate a colour numerically in a specified colour system. www.pdsconsulting.co.uk /Glossary/C.htm   (1851 words)

F.A.Q. The CIE (Commission International de l'Eclairage) has established standards for the measurement of visible light as it relates to the "standard human eye response." This so called standard observer curve was first established in 1931 (see figure 1a). From this curve, the tristimulus values for accurately defining a color are obtained. The X, Y, Z tristimulus system is based on the assumption that every color is a combination of three primary colors; red, green and blue. ledproductstore.com /colorimetry.htm   (651 words)

Tristimulus - Wikipedia, the free encyclopedia The tristimulus values of a test color are the amounts of the three primary colors in a three-component color model needed to match that test color. The tristimulus values are most often given in the CIE 1931 color space, in which they are denoted X, Y, and Z. By analogy with the above, tristimulus parameters for audio have been proposed and used, based on the strengths of the harmonics in a sound. en.wikipedia.org /wiki/Tristimulus   (194 words)

Sample Technical Definition   (Site not responding. Last check: 2007-10-10) A colorimeter is a machine that measures the way an object either reflects or transmits light across the visible spectrum, and records the values which correlate with the way the human eye sees color. There are two types of colorimeters: the tristimulus colorimeter and the spectrophotometric colorimeter. TRISTIMULUS COLORIMETERS The first type of colorimeter is the tristimulus colormeter, which uses four color filters to approximate color matching functions. www.engl.niu.edu /wac/techdef1.html   (220 words)

Calculating tristimulus (XYZ) values   (Site not responding. Last check: 2007-10-10) Tristimulus.xls is a spreadsheet for calculating tristimulus (XYZ) values from spectral reflectance or spectral transmission data. You then replace the spectral reflectance data in column G with the values for the colour for which you want to find the tristimulus values or chromaticity coordinates. Because the values of the matching functions are very low at the ends of the visible spectrum, this will not normally have a significant effect on the final XYZ values. www.digitalcolour.org /understanding/Tristimulus.htm   (382 words)

Color Perception In modern color measurement the CIE tristimulus values are probably the most important. That mixture may be specified by three numbers X,Y,Z called tristimulus values. Nevertheless, the tristimulus values X,Y,Z uniquely represent a perceivable hue, and different combinations of light wavelengths which gives the same set of tristimulus values will be indistinquishable in chromaticity to the human eye. hyperphysics.phy-astr.gsu.edu /hbase/vision/colper.html   (620 words)

Colorimetry 2.5.4   (Site not responding. Last check: 2007-10-10) The trichromatic system of colorimetry recommended by the CIE in 1931 is used internationally for specifying the colour of light or of illuminated objects. The colour of any radiation is specified by three tristimulus values X, Y, Z which represent the amounts of three standard reference stimuli (X), (Y), (Z) which if mixed together by optical superposition would produce the same sensation of light and colour for an observer with normal colour vision. The colour of a reflecting surface is specified in terms of the tristimulus values X, Y, Z of the radiation reflected when the surface is illuminated with radiation of specified spectral power distribution P( www.kayelaby.npl.co.uk /general_physics/2_5/2_5_4.html   (976 words)

Tristimulus Colorimetry   (Site not responding. Last check: 2007-10-10) Tristimulus methods, which generate three values to describe the color of an object, provide a more descriptive and precise measurement based on the complete spectral content of the transmitted radiation. The spectral transmission is measured continuously from 350-750 nm, at flow rates of up to 4 liters per minute, and the tristimulus L*a*b* color values are determined. This calculation converts the CIE tristimulus color measurement to the equivalent visual color rating. www.novachembv.com /color.htm   (493 words)

Digital Prepress and Printing   (Site not responding. Last check: 2007-10-10) In particular, they are given by an integral transform X = òPlx(l)dl where Pl is the spectral power curve for the color being evaluated and x(l) is the color matching function for the x tristimulus color. Similar expressions for Y and Z are given in terms of y(l) and z(l). (blue-yellow) are defined in terms of the X, Y and Z tristimulus values. www.wmich.edu /~ppse/prepress/pp16.htm   (348 words)

Planar Systems | Display Innovation You Depend On - The ratios of each of the three tristimulus values X, Y, and Z in relation to the sum of the three: designated as x, y, and z respectively. A supplementary observer for a larger angle of 10° was adopted in 1964. (3) One of the CIE chromaticity coordinates calculated as the fraction of the sum of the three tristimulus values attributable to the Z value. www.planar.com /Support/Glossaries.html   (2011 words)

Professor David M Howard - tristimulus project   (Site not responding. Last check: 2007-10-10) The tristimulus analysis for audio groups the harmonics into three as follows: the fundamental, mid-frequency harmonics (2nd to 4th harmonics), and hi frequency harmonics (5th harmonic and above). The objective of the project was to turn the tristimulus representation into a timbre controller for sound synthesis, with pitch and volume being controlled via a MIDI synthesiser. All sounds were created using the tristimulus synthesiser and these were pieced together to form the composition using an audio editor. www-users.york.ac.uk /~dmh8/tristimulus.htm   (240 words)

[No title] Tristimulus response functions are either calculated from spectral-irradiance data or measured directly and used to calculate parameters representing colour. The tristimulus responses are correlated because they depend on the same spectral information. In this paper we derive and confirm the correlation coefficients between the tristimulus response functions. stacks.iop.org /0026-1394/36/477   (199 words)

[No title] The color matching functions are the tristimulus values of the equal energy spectrum as a function of wavelength. Separate sets of three color matching functions are specified for the 2° Standard Observer and the 10° Supplementary Standard Observer. Tristimulus values determined based on the color matching functions home.wanadoo.nl /paulschils/10.00.htm   (382 words)

Research (Inseong Kim) A convert masking matrix was calculated from the R,G,B densities and the X,Y,Z tristimulus values, which were measured by a colorimeter. The average color difference D E between converted X,Y,Z tristimulus values and measured X,Y,Z tristimulus values was obtained. A masking matrix was calculated to convert R,G,B densities into the X,Y,Z tristimulus values with consideration of non-uniformity of the light source. www.stanford.edu /~inseong/INSEONG/research.html   (535 words)

Thesis These two sets of tristimulus values are referred to as corresponding colors. Instead of visually recording the data under a second set of viewing conditions, input the values for the first viewing condition into the model, and depending on how good the model is, and the output should be an accurate prediction of the second set of tristimulus values. A chromatic-adaptation model can be converted to a chromatic-adaptation transform by using the forward model for one set of viewing conditions and the inverse of the second set of viewing conditions. www.cis.rit.edu /research/thesis/bs/2000/ochs/thesis.htm   (1930 words)

CIE 1931 color space - Wikipedia, the free encyclopedia A specific method for associating three numbers (or tristimulus values) with each color is called a color space: the CIE XYZ color space is one of many such spaces. In the CIE XYZ color space, the tristimulus values are not the S, M, and L stimuli of the human eye, but rather a set of tristimulus values called X, Y, and Z, which are also roughly red, green and blue, respectively. The corresponding XYZ tristimulus values for a color with a spectral power distribution I(λ) would then be given by: en.wikipedia.org /wiki/CIE_1931_color_space   (2863 words)

Color models at AllExperts The human tristimulus space has the property that additive mixing of colors corresponds to the adding of vectors in this space. This makes it easy to, for example, describe the possible colors (gamut) that can be constructed from the red, green, and blue primaries in a computer display. The CIE-xyz color space is a prism, as opposed to the cone-shaped tristimulus space above. en.allexperts.com /e/c/co/color_models.htm   (1677 words)

Cleaning Consultancy Delft bv. - Delft - The Netherlands - Apparatuur The Tristimulus Reflection Analyzer TRA2000 is a portable instrument for measuring whiteness, stain removal and tristimulus reflection of textile and other materials. The Tristimulus Reflection Analyzer (TRA) is a portable instrument for measuring whiteness, stain removal and tristimulus reflection of textile and other materials. This new version of the TRA can easily be operated, and can be used independent of external power supply. www.ccd.nl /html/uk/producten/apparatuur/tra.htm   (314 words)

PDTristimulus (PDFBox-0.7.4-dev-20070118 API) A tristimulus, or collection of three floating point parameters used for color operations. This will set the x value of the tristimulus. This will set the y value of the tristimulus. www.pdfbox.org /javadoc/org/pdfbox/pdmodel/graphics/color/PDTristimulus.html   (158 words)

PDS - Terminology XYZ 1) One of the three CIE tristimulus values; the red primary. 1) One of the three CIE tristimulus values, equal to the luminous reflectance or transmittance; the green primary. Making the image or image part become larger (zooming in) or smaller (zooming out) as it appears on the monitor. www.pdsconsulting.co.uk /Glossary/XYZ.htm   (265 words)

PDGamma (PDFBox-0.7.4-dev-20070118 API) This will set the b value of the tristimulus. This will set the g value of the tristimulus. This will set the r value of the tristimulus. www.pdfbox.org /javadoc/org/pdfbox/pdmodel/graphics/color/PDGamma.html   (185 words)

glossary Ratio of each of a set of tristimulus values to their sum. The tristimulus values of monochromatic stimuli of equal radiant power. The temperature of the Planckian radiator whose radiation has the same chromaticity as that of a given stimulus. www.cs.rit.edu /~ncs/color/glossary.htm   (508 words)

E2022-01 Standard Practice for Calculation of Weighting Factors for Tristimulus Integration 1.1 This practice describes the method to be used for calculating tables of weighting factors for tristimulus integration using custom spectral power distributions of illuminants or sources, or custom color-matching funtions. In the latter case, a correction for the influence of bandpass on the resulting tristimulus values is built in to the tristimulus integration through the weighting factors. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. www.astm.org /DATABASE.CART/HISTORICAL/E2022-01.htm   (201 words)

handprint : do "primary" colors exist? The negative tristimulus values indicate that the primary must be mixed with the target light — primarily R with "blue green" and most "blue" spectral hues and G with extreme "violet" hues. To avoid confusion, the primary lights are denoted with a capital R, and the tristimulus value of the light, the relative quantity required in a color match at each wavelength, with a lowercase r(λ). To obtain coordinates for a two dimensional chromaticity diagram, the effect of luminance on the tristimulus values is made constant, which is done by normalizing the values. www.handprint.com /HP/WCL/color6.html   (13986 words)

ASTM D 6045 Standard Test Method for Color of Petroleum Products by the Automatic Tristimulus Method - IHS, Inc This test method covers the automatic determination of color of a wide variety of petroleum products such as undyed motor and aviation gasoline, aviation turbine fuels, naphthas, kerosine, pharmaceutical white oils, diesel fuel oils, heating oils, and lubricating oils by the automatic tristimulus method. This test method correlates to Test Method D 156 and Test Method D 1500 as calculated by the instrumentation. IHS been in business for more than 45 years and employ more than 2,300 people around the world. engineers.ihs.com /document/abstract/CIGSGBAAAAAAAAAA   (424 words)

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