Color Space of Normally Sighted and Color-Deficient Observers Reconstructed from Color Naming

1996 ◽  
Vol 7 (5) ◽  
pp. 311-317 ◽  
Author(s):  
Galina V. Paramei
Keyword(s):  
Color Space ◽  
Three Dimensional ◽  
Spherical Model ◽  
Color Discrimination ◽  
Color Naming ◽  
Three Dimensions ◽  
Color Spaces ◽  
Experimental Procedure ◽  
Additional Information ◽  
Necessary And Sufficient

An experimental procedure based on the color-naming method introduced by Boynton, Schafer, and Neun (1964) was used to study the color appearance of equiluminant spectral stimuli in observers with congenital red-green color deficiencies, as well as in normal trichromats Subjects' responses (choice of one or more labels from the set red, yellow, green, blue, and white) were converted to numeric scores, which were used to estimate subjective differences between pairs of colors Individual subjects' matrices were processed by means of multidimensional scaling As in the direct rating of color dissimilarities in normal trichromats (Sokolov & Izmatlov, 1983) and color-deficient observers (Paramei Izmatlov, & Sokolov, 1991), these indirectly obtained measures yielded a color space in which three dimensions appear to be necessary and sufficient The dimensions are interpreted as evidence for red-green, blue-yellow, and achromatic (saturation) subsystems Based on the color-naming technique, three-dimensional spaces were reconstructed for the color-deficient observers These results were compared with those obtained by Helm (1964) It is argued that retaining more than one (blue-yellow) dimension in the color spaces of such observers provides additional information indicating preservation of residual red-green discrimination accompanied by finer discrimination of chroma than in normal trichromats The spherical model of color discrimination developed for normal trichromats (Izmatlov & Sokolov, 1991) is shown to be valid for color-deficient subjects as well and may be useful as a framework for differentiating protan and deutan types of color deficiency Colornaming functions, which seem not to reveal a differentiation between protans and deutans, provide results from which this differentiation can be extracted in reconstructed color spaces

scholarly journals On the forces that cable webs under tension can support and how to design cable webs to channel stresses

2019 ◽  
Vol 475 (2223) ◽  
pp. 20180781 ◽  
Author(s):  
Guy Bouchitté ◽  
Ornella Mattei ◽  
Graeme W. Milton ◽  
Pierre Seppecher
Keyword(s):  
Linear Programming ◽  
Convex Hull ◽  
Structural Engineering ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Finite Dimensional ◽  
Necessary And Sufficient

In many applications of structural engineering, the following question arises: given a set of forces f 1 ,  f 2 , …,  f N applied at prescribed points x 1 ,  x 2 , …,  x N , under what constraints on the forces does there exist a truss structure (or wire web) with all elements under tension that supports these forces? Here we provide answer to such a question for any configuration of the terminal points x 1 ,  x 2 , …,  x N in the two- and three-dimensional cases. Specifically, the existence of a web is guaranteed by a necessary and sufficient condition on the loading which corresponds to a finite dimensional linear programming problem. In two dimensions, we show that any such web can be replaced by one in which there are at most P elementary loops, where elementary means that the loop cannot be subdivided into subloops, and where P is the number of forces f 1 ,  f 2 , …,  f N applied at points strictly within the convex hull of x 1 ,  x 2 , …,  x N . In three dimensions, we show that, by slightly perturbing f 1 ,  f 2 , …,  f N , there exists a uniloadable web supporting this loading. Uniloadable means it supports this loading and all positive multiples of it, but not any other loading. Uniloadable webs provide a mechanism for channelling stress in desired ways.

scholarly journals A Quantitative Method for Estimation of Quality of Screens Color

2018 ◽  
pp. 39-46
Author(s):  
O. Kupko
Keyword(s):  
Visual Perception ◽  
Color Space ◽  
Three Dimensional ◽  
Dimensional Case ◽  
Two Dimensional ◽  
Color Spaces ◽  
Human Visual Perception ◽  
Insufficient Amount ◽  
History Of ◽  
The Difference

The history of the issue on creation of uniform color spaces is analyzed. It is noted that the calculations based on the results of spectral measurements do not adequately correspond to the human visual perception. For all existing color spaces, it has been proposed to create a uniform metric, a me­thod for determining the length, area and volume in the corresponding spaces, one that corresponds to the human visual perception. The metric is based on MacAdam ellipses, that is, on the threshold perception of the difference in colors. For each point of any color space (two or three measurements) is determined the area of space around each point, within which a person is not able to fix the difference in color. The area is characterized by either an ellipse (two-dimensional case) or an ellipsoid (three-dimensional case). To characterize an ellipse, it is necessary to have three parameters — two axes and the angle of slope. To characterize an ellipsoid, it is necessary to have five parameters — three axes and two angle of slope. The number of sections along a line, along a plane, or in a volume is a measure of length, a plane, or in a volume and sets a metric. The connection of the existing systems for determining color and visual perception of a person is carried out using scales. Scales associate the length, area or volume of any color system with a person’s visual perception. The scale depends on the point of space and the direction in which the movement takes place. As a result, a large number of scales (more than the number of colors, because it is necessary to know the angles of inclination of the ellipses) are needed, which must be agreed by the international community. To use this amount of data and for the corresponding calculations, it is necessary to have an agreed international calculation procedure. It is established, that as a result of the development of computing technology, a large amount of data and a large amount of computation are not a significant obstacle. The obstacle is an insufficient amount of consistent data, that is, it is necessary to perform additional measurements and approvals to determine the areas of space around each point of the color space within which a person is not able to fix the difference in color. A schematic diagram of the measurements and the equipment with the help of which it is possible to carry out the corresponding measurements are proposed. Estimates of the greatest labour intensity of such works are carried out. It is determined what is the most important part of these works is possible to carry out within a few years. For two-dimensional spaces (x, y and u, v), using the results of the classical work of McAdam, we determined the scales for connecting the lengths and areas in these spaces with the visual perception of the human eye. The directions in which the scales are largest or smallest are determined. For these two directions there are given scales that relate the distances and areas of the spaces (x,y and u,v) with the human visual perception. It is noted, that the work on creating the metrics has a clear phased structure, some parts of the work, i.e.: the development of software and programming, the development of stabilized radiation sources, the development of comparing tools and experimental research can be carried out independently. Conclusions and suggestions are made.

scholarly journals Communicating in Three Dimensions

2019 ◽  
Vol 3 (1) ◽  
pp. 100-116
Author(s):  
Adam Rabinowitz
Keyword(s):  
Three Dimensional ◽  
3D Models ◽  
Three Dimensions ◽  
Scientific Models ◽  
Additional Information ◽  
Public Consumption ◽  
3D Documentation ◽  
New Research

After excavating the Praedia of Iulia Felix at Pompeii in 1755, architect Karl Weber published the building with an axionometric illustration that showed the remains in three-dimensional perspective. In doing so, Weber communicated additional information about the form of the building in a manner that was both visually accessible to a lay audience and sufficiently “scientific” for a scholarly one. By contrast, digital 3D documentation methods in current archaeological practice can reinforce a division between “scientific” models intended for internal consumption by the project that produces them, and external communication in the form of lower-quality online digital displays. Using recent fieldwork at the Greek colonial site of Histria in Romania as a case-study, this paper explores the space between high-resolution contextualized 3D documentation used only by an internal audience and down-scaled, decontextualized 3D content designed for public consumption. In particular, it explores whether measurable 3D models derived from photogrammetrical capture are useful in communicating excavation results to non-specialists – and if so, in what ways. It presents several scenarios for the role of high-quality 3D documentation in both formal and informal scholarly communication, and discusses the potential for the reuse of such documentation to answer new research questions.

scholarly journals Usage-related variation in the referential range of blue in marketing context

2015 ◽  
Vol 22 (1) ◽  
pp. 20-43 ◽  
Author(s):  
Alena V. Anishchanka ◽  
Dirk Speelman ◽  
Dirk Geeraerts
Keyword(s):  
Frequency Analysis ◽  
Color Space ◽  
Three Dimensional ◽  
Color Naming ◽  
Cognitive Approach ◽  
Related Factors ◽  
Product Categories ◽  
Individual Product ◽  
The Individual ◽  
Internal Variation

The paper explores language-internal variation in the referential meaning of the lexical form blue. Taking a usage-based cognitive approach, we analyze the referential range of blue in several marketing contexts from a semasiological and an onomasiological perspective. The study develops an interdisciplinary method that combines frequency analysis with mapping of the referent distributions in the three-dimensional CIELab color space. It is argued that the observed referential variation in blue is influenced by usage-related factors such as availability of the referents, diversity of color naming strategies and onomasiological competition between lexical forms in the individual product categories.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

Color Space Transformation using Neural Networks

2019 ◽  
Vol 2019 (1) ◽  
pp. 153-158
Author(s):  
Lindsay MacDonald
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Color Space ◽  
Reflectance Spectra ◽  
Network Architectures ◽  
Color Spaces ◽  
Natural Materials ◽  
Space Transformation ◽  
Color Space Transformation

We investigated how well a multilayer neural network could implement the mapping between two trichromatic color spaces, specifically from camera R,G,B to tristimulus X,Y,Z. For training the network, a set of 800,000 synthetic reflectance spectra was generated. For testing the network, a set of 8,714 real reflectance spectra was collated from instrumental measurements on textiles, paints and natural materials. Various network architectures were tested, with both linear and sigmoidal activations. Results show that over 85% of all test samples had color errors of less than 1.0 ΔE2000 units, much more accurate than could be achieved by regression.

Extension of the Spatial PDI Model to Three Dimensions

1997 ◽  
Vol 84 (1) ◽  
pp. 176-178
Author(s):  
Frank O'Brien
Keyword(s):  
Population Density ◽  
Dimensional Space ◽  
Finite Lattice ◽  
Three Dimensional ◽  
Upper Bounds ◽  
Three Dimensions ◽  
Lower And Upper Bounds ◽  
Density Index ◽  
Three Dimensional Space

The author's population density index ( PDI) model is extended to three-dimensional distributions. A derived formula is presented that allows for the calculation of the lower and upper bounds of density in three-dimensional space for any finite lattice.

scholarly journals Free partition functions and an averaged holographic duality

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Nima Afkhami-Jeddi ◽  
Henry Cohn ◽  
Thomas Hartman ◽  
Amirhossein Tajdini
Keyword(s):  
Partition Function ◽  
Spectral Gap ◽  
Central Charge ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Partition Functions ◽  
General Constraints ◽  
Dimensional Gravity ◽  
Holographic Duality

Abstract We study the torus partition functions of free bosonic CFTs in two dimensions. Integrating over Narain moduli defines an ensemble-averaged free CFT. We calculate the averaged partition function and show that it can be reinterpreted as a sum over topologies in three dimensions. This result leads us to conjecture that an averaged free CFT in two dimensions is holographically dual to an exotic theory of three-dimensional gravity with U(1)c×U(1)c symmetry and a composite boundary graviton. Additionally, for small central charge c, we obtain general constraints on the spectral gap of free CFTs using the spinning modular bootstrap, construct examples of Narain compactifications with a large gap, and find an analytic bootstrap functional corresponding to a single self-dual boson.

scholarly journals The Application of Machine Learning for Cultivar Discrimination of Sweet Cherry Endocarp

Agriculture ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 6
Author(s):  
Ewa Ropelewska
Keyword(s):  
Sweet Cherry ◽  
Color Space ◽  
Geometric Parameters ◽  
Geometric Features ◽  
Color Spaces ◽  
Discriminative Models ◽  
Sweet Cherries ◽  
Rgb Color Space ◽  
Cultivar Discrimination ◽  
Color Channels

The aim of this study was to evaluate the usefulness of the texture and geometric parameters of endocarp (pit) for distinguishing different cultivars of sweet cherries using image analysis. The textures from images converted to color channels and the geometric parameters of the endocarp (pits) of sweet cherry ‘Kordia’, ‘Lapins’, and ‘Büttner’s Red’ were calculated. For the set combining the selected textures from all color channels, the accuracy reached 100% when comparing ‘Kordia’ vs. ‘Lapins’ and ‘Kordia’ vs. ‘Büttner’s Red’ for all classifiers. The pits of ‘Kordia’ and ‘Lapins’, as well as ‘Kordia’ and ‘Büttner’s Red’ were also 100% correctly discriminated for discriminative models built separately for RGB, Lab and XYZ color spaces, G, L and Y color channels and for models combining selected textural and geometric features. For discrimination ‘Lapins’ and ‘Büttner’s Red’ pits, slightly lower accuracies were determined—up to 93% for models built based on textures selected from all color channels, 91% for the RGB color space, 92% for the Lab and XYZ color spaces, 84% for the G and L color channels, 83% for the Y channel, 94% for geometric features, and 96% for combined textural and geometric features.

Turbulent three-dimensional dielectric electrohydrodynamic convection between two plates

2012 ◽  
Vol 696 ◽  
pp. 228-262 ◽  
Author(s):  
A. Kourmatzis ◽  
J. S. Shrimpton
Keyword(s):  
Spatial Data ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Energy Budgets ◽  
Turbulent Regime ◽  
Scalar Flux ◽  
Wide Range ◽  
Scalar Variance

AbstractThe fundamental mechanisms responsible for the creation of electrohydrodynamically driven roll structures in free electroconvection between two plates are analysed with reference to traditional Rayleigh–Bénard convection (RBC). Previously available knowledge limited to two dimensions is extended to three-dimensions, and a wide range of electric Reynolds numbers is analysed, extending into a fully inherently three-dimensional turbulent regime. Results reveal that structures appearing in three-dimensional electrohydrodynamics (EHD) are similar to those observed for RBC, and while two-dimensional EHD results bear some similarities with the three-dimensional results there are distinct differences. Analysis of two-point correlations and integral length scales show that full three-dimensional electroconvection is more chaotic than in two dimensions and this is also noted by qualitatively observing the roll structures that arise for both low (${\mathit{Re}}_{E} = 1$) and high electric Reynolds numbers (up to ${\mathit{Re}}_{E} = 120$). Furthermore, calculations of mean profiles and second-order moments along with energy budgets and spectra have examined the validity of neglecting the fluctuating electric field ${ E}_{i}^{\ensuremath{\prime} } $ in the Reynolds-averaged EHD equations and provide insight into the generation and transport mechanisms of turbulent EHD. Spectral and spatial data clearly indicate how fluctuating energy is transferred from electrical to hydrodynamic forms, on moving through the domain away from the charging electrode. It is shown that ${ E}_{i}^{\ensuremath{\prime} } $ is not negligible close to the walls and terms acting as sources and sinks in the turbulent kinetic energy, turbulent scalar flux and turbulent scalar variance equations are examined. Profiles of hydrodynamic terms in the budgets resemble those in the literature for RBC; however there are terms specific to EHD that are significant, indicating that the transfer of energy in EHD is also attributed to further electrodynamic terms and a strong coupling exists between the charge flux and variance, due to the ionic drift term.

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