Tristimulus Coordinates Research Articles

Changes in myoglobin content in pork Longissimus thoracis muscle during freezing storage

In this study, pork Longissimus thoracis muscle was used, which was frozen in a chamber and thawed under controlled conditions. The color profile and the surface myoglobin were evaluated. A thermal analysis was performed by modulated differential scanning calorimetry (MDSC), and Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR-ATR). It was found that there were important effects in myoglobin due to the freeze-thawing process in parameters such as pH, luminosity (L*), and chroma values, as well as in activation energies (Ea) and denaturation enthalpy (ΔH) between myoglobin forms. In raw meat, it was found that there was a greater proportion of deoxymyoglobin, and in frozen-thawed samples, metmyoglobin was the most abundant form, indicating that are significant effects which are correlated with the changes in tri-stimulus coordinates and with the thermal and chemical parameters in pork meat.

Silicon-based microhole arrays for spectral tuning of white light emitted from InGaN nanocolumns grown by molecular-beam epitaxy

In this paper, the molecular beam epitaxy of InGaN nanocolumns on silicon-based microhole arrays has been investigated experimentally. A low-cost method has been designed, which contains the processes of photolithography and wet etching. Tuning uniform microhole arrays show the ability in modulating the luminescence spectra of InGaN nanocolumns, which could lead to the modulation of tristimulus coordinates and correlated color temperatures. Due to the shadow effect, it is found that the size of microholes and the area of flat Si surface have more obvious effects, while the configuration of microhole arrays has limited effect on the modulation of peak wavelength.

Innovative Industrial Displays with Enhanced Gamut of a Colorful Image of Three Components

The task how to define tristimulus coordinates of the screen gamut in xy-plane with color formation scheme of three components is being studied. To solve this task is practically important to improve the manufacturing technological process of the screen production in order to make screens which are capable of reproducing more colors. Some screen profiles with enhanced color reproduction have been made for the most popular standards of the white color.

Tristimulus analysis for sensors set with either positive or negative sensitivities—determination of the relative concentration of an analyte in a binary mixture

We consider the general case of a set of three sensors that show a response proportional to analyte concentration and apply tristimulus analysis to represent the set of responses as tristimulus coordinates in a two-dimensional representation. These coordinates are a signature of the analyte and can be used for analyte identification. We extend the tristimulus analysis for cases where the sensors may present either positive or negative sensitivities, a situation in which the usual tristimulus analysis has limitations. We propose a different approach, taking the coordinates where the tristimulus vector crosses the unitary radius spherical shell, taking the angular coordinates as signature of the analyte. We also consider the case of binary mixtures and derive the set of equations that can be used to determine the relative concentration of each one of the analytes in the binary mixture from the tristimulus coordinates of the mixture.

Low-cost and high-color-quality white light emitting diodes based on CdSe/ZnS quantum dots

Low-cost and high-color-quality white light emitting diodes (WLEDs) have been realized based on CdSe/ZnS colloidal quantum dots (QDs). CdSe/ZnS QDs with different diameters and emission wavelengths were used as phosphors and coated on the unpackaged blue InGaN/GaN LED chips, the emission of QDs and the unabsorbed LED light collectively contribute to the white light generation. Drop-coating and layer-by-layer assembly techniques were used to integrate QDs on the LED chips. Comparison of the experimental results, we found layer-by-layer assembly method with larger QDs at the bottom were the suitable method to generate controllable white light emission. Using this easy and low cost method, WLED samples were fabricated using QD mixtures with one (‘single’), or two (‘dual’) emission wavelengths. High-quality warm WLED were obtained with a correlated color temperature of CCT = 3778 K, tristimulus coordinates of (x, y) = (0.36, 0.28) and color rending index of CRI = 80.8.

Colorimetry: Choice of colorimetric parameters for chromophore concentration measurements

The problem of choice of tristimulus color coordinates which uniquely depend on chromophore concentration in an investigated material has been considered. A theoretical study shows that there are no simple analytical formulas for such dependences, and the majority of tristimulus coordinates of various color spaces: RGB, CIE (XYZ), CIE (L*a*b*), CIE (L*C*H*), HSB, and CMYK poorly correlate with the concentration of molecules responsible for color. However, analysis of published papers on this subject provides abundant evidence showing that at least one tristimulus coordinate of the CIE (L*a*b*) color space, specifically L* (lightness), is related to chromophore concentration C by a simple, steadily descending exponential function. The empirical formula L* = L*(C) can be successfully applied for instrumental treatment of experimental colorimetric data for the determination of chromophore concentrations.

White light generation by resonant nonradiative energy transfer from epitaxial InGaN/GaN quantum wells to colloidal CdSe/ZnS core/shell quantum dots

We propose and demonstrate white-light-generating nonradiative energy transfer (ET) from epitaxial quantum wells (QWs) to colloidal quantum dots (QDs) in their close proximity. This proof-of-concept hybrid color-converting system consists of chemically synthesized red-emitting CdSe/ZnS core/shell heteronanocrystals intimately integrated on epitaxially grown cyan-emitting InGaN/GaN QWs. The white light is generated by the collective luminescence of QWs and QDs, for which the dot emission is further increased by 63% with nonradiative ET, setting the operating point in the white region of CIE chromaticity diagram. Using cyan emission at 490 nm from the QWs and red emission at 650 nm from the nanocrystal (NC) luminophors, we obtain warm white light generation with a correlated color temperature of Tc = 3135 K and tristimulus coordinates of (x,y) = (0.42, 0.39) in the white region. By analyzing the time-resolved radiative decay of these NC emitters in our hybrid system with a 16 ps time resolution, the luminescence kinetics reveals a fast ET with a rate of (2 ns)-1 using a multiexponential fit with χ 2 = 1.0171.

Voicing documentation of a pipe organ

The paper begins with a brief presentation on the Parisian organ landscape, and then focuses on sound documentation of the historical organ of Sainte Elisabeth (Suret 1853, 3 keyboards and pedal, 40 stops, about 2500 pipes). Calibrated recordings of all the notes have been performed inside and outside the organ case, using several microphone positions. The methodology proposed by Pollard (J. Acoust. Soc. Am. 106(1), July 1999, 360‐370) is extended and applied to sound analysis for all the notes of the instrument. The analogies between the proposed sound description (or “voicing quality,” described in terms of sharpness, loudness, tristimulus coordinates, transient building, and spectral centre of gravity) and human voice quality description are discussed. Both voicing of individual pipes and voicing of the instrument are analysed. “Voicing of the instrument” means voicing variations of the pipes for different notes or registers of a same stop, for different stops of a same division, and for different divi...

Dual-color emitting quantum-dot-quantum-well CdSe-ZnS heteronanocrystals hybridized on InGaN∕GaN light emitting diodes for high-quality white light generation

We report white light generation by hybridizing green-red emitting (CdSe)ZnS∕CdSe (core)shell/shell quantum-dot-quantum-well heteronanocrystals on blue InGaN∕GaN light emitting diodes with the photometric properties of tristimulus coordinates (x,y)=(0.36,0.30), luminous efficacy of optical radiation LE=278lm∕W, correlated color temperature CCT=3929K, and color-rendering index CRI=75.1. We present the photometric analysis and the quantum mechanical design of these dual-color emitting heteronanocrystals synthesized to achieve high-quality white light when hybridized on light emitting diodes. Using such multicolor emitting heteronanocrystals facilitates simple device implementation while providing good photometric properties.

Color-converting combinations of nanocrystal emitters for warm-white light generation with high color rendering index

Warm-white light emitting diodes with high color rendering indices are required for the widespread use of solid state lighting especially indoors. To meet these requirements, we propose and demonstrate warm-white hybrid light sources that incorporate the right color-converting combinations of CdSe∕ZnS core-shell nanocrystals hybridized on InGaN∕GaN LEDs for high color rendering index. Three sets of proof-of-concept devices are developed to generate high-quality warm-white light with (1) tristimulus coordinates (x,y)=(0.37,0.30), luminous efficacy (LE)=307lm∕W, color rending index (CR)=82.4, and correlated color temperature (CCT)=3228K; (2) (x,y)=(0.38,0.31), LE=323lm∕W, CRI=81.0, and CCT=3190K; and (3) (x,y)=(0.37,0.30), LE=303lm∕W, CRI=79.6, and CCT=1982K.

Hybrid white light sources based on layer-by-layer assembly of nanocrystals on near-UVemitting diodes

We present the design, growth, fabrication, integration and characterization of alternativehybrid white light sources based on the controlled layer-by-layer assembly of nanocrystalson UV-emitting nitride diodes for adjustable white light parameters. We hybridizeCdSe/ZnS core–shell nanocrystals of different sizes (1.9–3.2–5.2 nm) on InGaN/GaN LEDsas a near-UV excitation source at 383 nm for efficient pumping. The first deviceincludes layer-by-layer assembly of dichromatic cyan- and red-emitting nanocrystals(λPL = 504–615 nm) leading to the tristimulus coordinates(x = 0.37,y = 0.46); the second device uses the trichromatic combination oflayer-by-layer hybridized cyan-, yellow- and red-emitting nanocrystals(λPL = 504–580–615 nm),yielding (x = 0.38,y = 0.48). Such layer-by-layer hybridization offers the advantages of precisely controllingindividual nanocrystal film thicknesses and order in addition to concentrations. Byutilizing such multiple combinations of nanocrystals in the assembly, the lightparameters are well controlled and adjusted. Leveraging rapidly advancing UVtechnology into efficient lighting with nanocrystal based color conversion, it iscritical to develop and demonstrate hybrid light sources on UV pumping platforms.

Precise Measurement of Concentration of Blood Glucose from the Tristimulus Values Obtained from the Colour of the Assay in the Course of Clinical Diagnosis

Blood chemical tests carried out in the conventional clinical instruments such as Colorimeter and Spectrophotometer, measure the concentration of the Blood substances such as Glucose, Non-protein nitrogen substances like Amino acids, Peptides, Urea waste and Uric acid, Lipids such as Cholesterol and Triglycerides, Proteins, Enzymes and Steroids, etc. The concentration of these Complex substances appearing in the Blood serum can be analyzed based on colour reactions.This research paper attempts to find an alternative to the 5 decades old Colorimetry based measurement technique. Methods in vogue are fraught with anomalies and deviations because they require a highly monochromatic source; also they possess measurement complexity especially in the non-linear region of the reagent solution. For example, Linearity prevails in the Blood Glucose measurement if the Blood Glucose in the serum is less than 500 mg/dl. As the Colour concentration of the assay increases with that of the Blood chemical in the serum, it is clear that the Wavelength of the Colour of the assay reasonably remains constant irrespective of the concentration of Blood chemical and the variation is only in the saturation of the colour.In the proposed system, the colour image of the assay is captured by a Digital camera connected with a Computer and the RGB data of the colour pixel in that image is converted to its equivalent Tristimulus coordinates (XYZ) and then to Chromaticity coordinates (xyz) of the Chromaticity diagram in conformance with the International Commission on Illumination, CIE 1931, standards of colour space. From the Chromaticity coordinates, the saturation of the colour of the assay can be calculated.The saturations of the colour thus obtained for various known concentrations of Blood chemical are fit into a Polynomial equation of degree ‘m’ This Polynomial equation yields the unknown concentration of the Blood Glucose in the test sample against the saturation of the colour that is calculated from the RGB data. Measurement error is less when the order of polynomial equation is high. As the higher order polynomial equation refines values even in the non-linear region viz., beyond 400 mg/dL, the results obtained from this proposed method are fairly precise. Moreover this proposed method overcomes the shortcomings in the existing system such as requirement of Monochromatic source, Colour development restrictions in the assay (Usually Pink or Purple is preferred).

Nanocrystal-based hybrid white light generation with tunable colour parameters

We present the hybridization of CdSe/ZnS core–shell nanocrystals (NCs) on InGaN/GaN based blue/near-UV LEDs to generate light widely tunable across the visible spectral range and especially within the white region of the CIE (1931) chromaticity diagram. We report on the design, growth, fabrication and characterization of these hybrid NC-LEDs. In 26 NC-LED samples, we experimentally show the effect of the NC concentration and NC film thickness on tuning the colour properties of the generated light (tristimulus coordinates, colour rendering index and correlated temperature) and further compare layer by layer assembly and blending of NCs for integration in LEDs. With greatly tunable colour properties, these hybrid white light sources hold promise for future lighting and display applications.

White light generation using CdSe/ZnS core–shell nanocrystals hybridized withInGaN/GaN light emitting diodes

We introduce white light generation using CdSe/ZnS core–shell nanocrystals of single,dual, triple and quadruple combinations hybridized with InGaN/GaN LEDs.Such hybridization of different nanocrystal combinations provides the ability toconveniently adjust white light parameters including the tristimulus coordinates(x,y), correlated colourtemperature (Tc) andcolour rending index (Ra). We present the design, growth, fabrication and characterization of our whitehybrid nanocrystal-LEDs that incorporate combinations of (1) yellow nanocrystals(λPL = 580 nm) on ablue LED (λEL = 440 nm) with (x,y) = (0.37,0.25), Tc = 2692 K andRa = 14.69; (2) cyan and rednanocrystals (λPL = 500 and620 nm) on a blue LED (λEL = 440 nm) with (x,y) = (0.37,0.28), Tc = 3246 K andRa = 19.65; (3) green, yellow and rednanocrystals (λPL = 540, 580 and620 nm) on a blue LED (λEL = 452 nm) with (x,y) = (0.30,0.28), Tc = 7521 Kand Ra = 40.95; and (4) cyan, green, yellow and red nanocrystals(λPL = 500, 540, 580 and 620 nm)on a blue LED (λEL = 452 nm) with (x,y) = (0.24,0.33), Tc = 11 171 Kand Ra = 71.07. These hybrid white light sources hold promise for future lighting and display applicationswith their highly adjustable properties.

The CIELAB reversal in calibration and verification

A CIELAB anomaly, in which smaller spectrophotometric errors at all wavelengths lead to larger CIELAB differences, is identified. It is shown that the reversal can occur throughout tristimulus space and is colorimetrically important during calibration procedures. Three numerical examples of the reversal, using data from the BCRA tiles, are given. The reversal cannot be attributed entirely to metamerism, which itself may cause large spectrophotometric error leading to small CIELAB difference. The effect is compounded by the nonlinearity of CIELAB relative to tristimulus coordinates. A recommendation for avoiding the reversal is offered. © 2004 Wiley Periodicals, Inc. Col Res Appl, 30, 66–68, 2005; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/col.20076

Root contrast enhancement for measurement with optical scanner-based image analysis

Fine roots (diameter <0.30 mm) account for about 80% of total root length in many species but are often underestimated owing to their small size and near transparency. We have assessed a technique for rapid and accurate estimation of root length when using image analysis. To allow the collection of clear images, several stains were tested to determine when staining is beneficial. Plants of six species (barley (Hordeum vulgare L.), maize (Zea mays L.), oat (Avena sativa L.), soybean (Glycine max (L.) Merr.), strawberry (Fragaria × ananassa), and wheat (Triticum aestivum L.)) were grown for either 3 or 5 weeks after emergence. Roots of five woody species (honey locust (Gleditsia triacanthos L.), Norway maple (Acer platanoides L.), red ash (Fraxinus pennsylvanica Marsh.), silver maple (Acer saccharinum L), and hackberry (Celtis occidentalis L.)) were collected outdoors. Stains were evaluated over a range of concentrations and for three staining times. Root variables were measured with WinRHIZO, an interactive scanner-based image analysis system. Two approaches were used: (i) measuring specific amounts of roots at several stain concentrations and contrasting the results with an unstained control and (ii) measuring unstained roots, recovering the roots, staining them and measuring them again. The tristimulus coordinates (L*a*b*) of unstained root colour were measured by spectrophotometer to determine if root colour might be used as an indicator as to whether or not staining improved the image contrast. Staining improved image contrast and substantially increased measured root length estimates for species with low root contrast (maize, barley, and wheat), gave small improvements for hackberry, Norway maple, and honey locust, but had no effect on other species. Staining for 10 min was sufficient to maximally enhance the image contrast of species with a high proportion of fine roots. Tristimulus coordinates indicated that differences among species correlated with the distribution of root diameter. Establishing whether staining of root samples is required should be accomplished before any study of root systems with a high proportion of fine roots is undertaken.Key words: root measurement, staining, imaging analysis, root colour measurement, stains.

Addition of sugars influences color of oil-in-water emulsions.

The influence of glucose, fructose, lactose, and glycerol on the color and appearance of surfactant-stabilized oil-in-water emulsions containing a red dye was investigated. A stabilized (Tween-20) oil-in-water emulsion was diluted into sugar solutions to give a range of oil droplet and sugar concentrations. Tristimulus coordinates (L, a, b) and reflectance spectra were measured using a spectrophotometer. With increasing sugar concentration, reflectance spectra shifted to lower reflectance values. Tristimulus coordinates were reduced by approximately 50% for emulsions containing high concentrations of sugar. Adding fructose to emulsions reduced L, a, b values more significantly than adding glucose, lactose, or glycerol. Tristimulus coordinates remained constant when the temperature was raised from 20 to 80 degrees C. The experimental results were explained in terms of the change of relative refractive index at the water-oil interface. The results have important implications for the food industry as they offer a new means to control and optimize the color of food emulsions.

Tonal portrait of a pipe organ

Measurement techniques are described that enable the steady state tone color (timbre) of a musical instrument to be quantified. The system is applied to sounds from the pipe organ in the Great Hall of Sydney University. A one-third octave normalized loudness spectrum that is independent of pitch is derived for each set of notes from selected ranks of pipes. From the normalized spectrum, sharpness and tristimulus coordinates are computed, the latter being independent of both pitch and loudness. Measurements made on different ranks of pipes or made at different times are compared with the aid of spectrum dissimilarity and tristimulus diagrams.

Prediction of Food Emulsion Color Using Light Scattering Theory

ABSTRACTA theoretical model was developed to predict spectral reflectance and color of emulsions from droplet (radius and concentration) and dye (absorption spectra and concentration) characteristics. The Rayleigh‐Gans‐Debye theory of light scattering was used to calculate the scattering cross‐section, absorption cross‐section and asymmetry factor of droplets. These values were used to calculate spectral reflectance of an emulsion based on Kubelka‐Munk theory. The tristimulus coordinates (L, a, b) of an emulsion were calculated from its spectral reflectance using color matching functions. Predictions were in good agreement with experimental measurements on oil‐in‐water emulsions containing a red food dye. The theory may be useful for optimization of emulsion appearance.

Influence of Droplet Size and Concentration on the Color of Oil-in-Water Emulsions

The influence of droplet size (0.2−15 μm) and concentration (0−20 wt %) on the turbidity and color of n-hexadecane oil-in-water emulsions containing a blue food dye has been investigated. Emulsion turbidity was maximum for droplets with diameters of ∼2 μm (at 650 nm). Colorimetry measurements of the tristimulus coordinates (L,a,b) of emulsions indicated that they became less light, more green, and more blue as droplet size increased and more light as droplet concentration increased. Sensory analysis showed emulsions became lighter and less blue as droplet size decreased and droplet concentration increased. The observed behavior can be explained in terms of the scattering and absorption of light by emulsions. Our results show that food emulsion appearance can be optimized by carefully controlling droplet characteristics, such as size and concentration. Keywords: emulsion; color; turbidity; droplet size; droplet concentration; light scattering