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An object colour's Commission Internationale de l'Éclairage XYZ coordinates can change when it is viewed under different illuminants. The set of XYZ coordinates for all object colours, which is called the object-colour solid, likewise varies under different illuminants. This article shows that, despite these changes, some properties are invariant under illuminant transformations. In particular, as long as the illuminant is nowhere zero in the visible spectrum, optimal colours take the same Schrödinger form, and no two optimal colours are metameric. Furthermore, all object-colour solids have the same shape at the origin: they all fit perfectly into the convex cone (which we will call the spectrum cone) generated by the spectrum locus. The spectrum cone, itself, does not vary when the illuminant changes. The object-colour solid for one illuminant can be transformed into the solid for another illuminant, by an easily visualized sequence of expansions and contractions of irregular rings, called zones. © 2012 Wiley Periodicals, Inc. Col Res Appl, 39, 179-187, 2014 [ABSTRACT FROM AUTHOR]

A new algorithm for calculating the metamer mismatch volumes that arise in colour vision and colour imaging is introduced. Unlike previous methods, the proposed method places no restrictions on the set of possible object reflectance spectra. As a result of such restrictions, previous methods have only been able to provide approximate solutions to the mismatch volume. The proposed new method is the first to characterize precisely the metamer mismatch volume for any possible reflectance. [ABSTRACT FROM PUBLISHER]

In the field of the conservation-restoration of paintings, the retouching intervention is a critical act during which a metamerism phenomenon can easily be created in the blue hues. This research suggests an alternative to this problem. Indeed, it is possible to find some current pigments which have a similar spectral composition to traditional pigments usually used by the ancient painters and so, this option would reduce the risk of creating a metamerism.

The article observes that the evolution of digital motion picture technology has afforded advancement in image quality, content distribution and artistic options for contemporary filmmakers. It suggests that multispectral motion imaging promises to solve fundamental issues of color inconsistency and inaccuracy associated with observer metamerism. The article also comments that multispectral imaging promises to expand useful color gamut in video applications in a controlled manner.

Light emitting diode (LED) with its long lifetime of up 100,000 h has been receiving keen interest as there has been a rapid increase in luminous efficacy of LED recently. One interesting feature of LED is that its spectral power distributions can be easily controllable by regulating electric circuits to LED. Therefore, the same colour from LED can have quite different spectral power distribution due to metamerism. This is important as spectral power distribution is a key factor that can affect human circadian rhythm and subjective responses to changes with different spectral power distribution under the same illuminance level. The study aims to explore the energy saving potentials of LED lighting system by modulating spectral power distributions. The wavelength controllable LED system was developed in the previous study and was used in this study. Dynamic building simulations were carried out in order to quantify the total energy use including energy demands for lighting, cooling and heating indoors. Our study indicates that subjects would tend to feel brighter under red-colour emphasizing spectral power distribution, as compared to their perception under blue-colour. Also, simulation results indicate that total energy consumption can be reduced by 38% by changing spectral power distribution without sacrificing subjects’ visual comfort. [ABSTRACT FROM AUTHOR]

Animals have been described as segmented for more than 2,000 years, yet a precise definition of segmentation remains elusive. Here we give the history of the definition of segmentation, followed by a discussion on current controversies in defining a segment. While there is a general consensus that segmentation involves the repetition of units along the anteriorposterior (a-p) axis, long-running debates exist over whether a segment can be composed of only one tissue layer, whether the most anterior region of the arthropod head is considered segmented, and whether and how the vertebrate head is segmented. Additionally, we discuss whether a segment can be composed of a single cell in a column of cells, or a single row of cells within a grid of cells. We suggest that 'segmentation' be used in its more general sense, the repetition of units with a-p polarity along the a-p axis, to prevent artificial classification of animals. We further suggest that this general definition be combined with an exact description of what is being studied, as well as a clearly stated hypothesis concerning the specific nature of the potential homology of structures. These suggestions should facilitate dialogue among scientists who study vastly differing segmental structures. [ABSTRACT FROM AUTHOR]

Early coelomic development in the abbreviated development of the sea urchin Holopneustes purpurescens is described and then used in a comparison with coelomic development in chordate embryos to support homology between a single arm of the five-armed radial body plan of an echinoderm and the single bilateral axis of a chordate. The homology depends on a positional similarity between the origin of the hydrocoele in echinoderm development and the origin of the notochord in chordate development, and a positional similarity between the respective origins of the coelomic mesoderm and chordate mesoderm in echinoderm and chordate development. The hydrocoele is homologous with the notochord and the secondary podia are homologous with the somites. The homology between a single echinoderm arm and the chordate axis becomes clear when the aboral to oral growth from the archenteron in the echinoderm larva is turned anteriorly, more in line with the anterior-posterior axis of the early zygote. A dorsoventral axis inversion in chordates is not required in the proposed homology. [ABSTRACT FROM AUTHOR]

The article discusses the study which investigates the illuminant metamerism's potential presence through measurements of digital and inkjet halftone proofs using metamerism index. The study provides printed proofs and samples from four printing organizations of four color process work which adheres to the specification defined by IDEAlliance GRACoL 7. Results show that continues tone inkjet proofs exhibits illuminant metamarism when compared to proofing technologies of digital halftone.

- A control sequence gives the intensities of the primaries for a pixel of a display device. The display gamut, i.e., the set of all the colors that a display can produce, is a zonohedral subset of CIE XYZ space and contains both boundary and interior colors. Displays with four primaries or more exhibit metamerism, in which different control sequences produce colors that appear identical to an observer. This paper shows mathematically that, provided no three primaries are linearly dependent, metamerism can only occur for interior colors. When there are four or more primaries, metamers can always be found for interior colors. A color on the gamut boundary, by contrast, is only produced by a unique control sequence. The proof used for displays can be extended to object-color solids, to show that optimal colors, which are on the boundary of an object-color solid, have unique reflectance functions. [ABSTRACT FROM AUTHOR]

- In a display with more than three primaries (called a multi-primary display), a color can be expressed as multiple combinations (called control sequences) of primaries. This paper presents an algorithm for assigning control sequences that preserves current assignments when further primaries are added. These control sequences are cal led extensible. It is shown that the gamut of any number of primaries is a zonohedron, which can be dissected into parallelepipeds. Control sequences are assigned within each parallelepiped. The current parallelepipeds remain when more primaries are added, so the current assignments are preserved. Multi-primary displays can also cause unwanted metamerism and make continuous color scales appear discontinuous. The algorithm avoids these problems. When viewed through natural filters, such as yellowed ocular lenses, multi-primary displays can sometimes make two different colors appear identical. If the primaries satisfy the Binet-Cauchy criterion, which is always the case when all primaries are monochromatic, then these spurious matches are avoided. [ABSTRACT FROM AUTHOR]

Data on the molecular and genetic basis of animal development, and on genome sequences, have been challenging our established assumptions about animal evolution for the last decade. Recent such data in animals of particular phylogenetic importance beg us to take another look at whether similarities in developmental and genetic mechanisms in current animals are the product of a common inheritance (homology) or convergent evolution (analogy). The evolution of segmentation, in particular whether segmentation and metameric bodies have arisen just once or several times in evolution, is a prime concern. Segmentation and metamerism are striking developmental and body organisations that exist, in varying degrees, in many complex animals, but the traditional view holds that this is the result of convergent evolution. Here, I review recent palenotological and developmental information and conclude that a metameric body plan is not only a likely ancestral character of bilaterian animals, but also a possible trigger for the Cambrian explosion in body morphology and complexity. This conclusion is supported by the phylogenetic distribution and prevalence of metameric phyla in the Cambrian, and the similarity of the genomes and segmentation mechanisms across current bilaterian phyla. [ABSTRACT FROM AUTHOR]

Forty three metameric pairs, which refers to the pair of coloured samples were obtained by comparison, shade-adjustment, and redyeing of 660 self shades dyed with direct, azoic, vat, and reactive dyes. The pairs were regrouped shadewise and ranked visually in increasing order of metamerism. Spearman's rank correlation coefficients were calculated between 11 measures of metamerism and the visual metameric ranking under three illuminants A, D65, and TL84 in pairs. The present work, showed that indices based on ΔL*, Δa*, Δb* differ under two illuminants, both unmodified and modified by Berns-Billmeyer performed best among the existing indices. The differences of colour constancy indices showed good correlation with the degree of metamerism in some cases, and this maybe utilized for developing newer indices of metamerism. [ABSTRACT FROM AUTHOR]

Metamerism is a phenomenon where two or more colored items with different colorant chemistries appear to the observer to be the same color. Those differences should result in different UV-visible spectra. Additionally, the literature on color science states that metameric samples will have spectra that intersect at three or more loci. Metameric samples of blue textile fibers, which were created using different coloring agents or different relative concentrations of the coloring agents, were studied to demonstrate that they could be differentiated by obtaining their spectra between 350 and 800 nm using UV-visible microspectrophotometry. However, while some of the metameric samples tested did intersect at three or more loci, others did not intersect at all. In the spectra that did intersect, no correlation was found between either the dye chemistries or the relative component concentrations. [ABSTRACT FROM AUTHOR]

The article focuses on the factors to consider in analyzing the genetic and physical structure of animals like the snakes and centipedes. Animal segmentation helps in determining the changes in their bodies when develop through the evolutionary lineages. Results of various researches show indications that snakes differ from centipedes in various aspects including their growth rate and body structures.

Abstract: The Ten-a gene of Drosophila melanogaster encodes several alternative variants of a full length member of the Odz/Tenm protein family. A number of Ten-a mutants created by inexact excisions of a resident P-element insertion are embryonic lethal, but show no pair-rule phenotype. In contrast, these mutants, and deficiencies removing Ten-a, do enhance the segmentation phenotype of a weak allele of the paralog gene odz (or Ten-m) to the odz amorphic phenotype. Germ line clone derived Ten-a − embryos display a pair-rule phenotype which phenocopies that of odz. Post segmentation eye patterning phenotypes of Ten-a mutants establish it as a pleiotropic patterning co-partner of odz. [Copyright &y& Elsevier]

Summary: Objectives: The purpose of this study was to determine the metameric color differences between resin composites and dentin. Methods: Spectral reflectance and color of five shades of one brand of resin composite were measured according to the CIELAB color scale relative to the standard illuminant D65, A and F2. Average values of human dentin were used as the optical properties of dentin. Color differences between resin composite and dentin relative to three illuminants were calculated, and ratio of values by the illuminant (A/D65 and F2/D65) was calculated. Ratios of changes in hue angle of resin composites by illuminant over those of dentin were compared. Results: In curves of spectral reflectance, three of five shades made more than three crossing points with dentin indicating a metameric effect. Color differences between resin composite and dentin was changed when illuminant were changed from daylight (D65) to incandescent light (A) or fluorescent light (F2). Ratios of value between resin composite and dentin by the illuminant were 0.74–0.98. Color difference relative to D65 was larger than those for illuminants A and F2. Differences in hue angle (value relative to illuminant A-that to D65) of resin composites were in the range from −10.1 to −7.2 (−13.8 to −14.0 in dentin), and those between F and D65 were 2.6–5.2 (−3.9 to −2.8 in dentin). Significance: Changes in optical properties of resin composites relative to the different illuminants were different from those of dentin; therefore this inconsistency should be considered in shade matching of resin composites. [Copyright &y& Elsevier]

Much is understood of how quantitative aspects of image structure are measured by V1 simple cells, but less about how qualitative structure is determined from these measurements. We review Geometric Texton Theory (GTT) that aims to describe this step from quantitative to qualitative. GTT proposes that qualitative feature categories arise through consideration of the maximum likelihood (ML) explanations of image measurements. It posits that a pair of output vectors of an ensemble of co-localised neurons signal the same feature category if and only if the corresponding ML explanations are qualitatively similar. We present mathematical and empirical results relevant to GTT for the limited case of measurement by 1D filters of up to 2nd order. The mathematical results identify the simplest explanations for measurements by such filters, while the empirical results identify the ML. We find that the ML explanations are not the most simple under any of the definitions of simple that we examined. However, the ML explanations do have properties predicted by GTT. In particular they change rapidly and qualitatively for certain narrow regions of measurement space, while remaining qualitative stable between those transition regions. Three feature categories arise naturally from the data: light bars, dark bars and edges. The results are consistent with GTT. [ABSTRACT FROM AUTHOR]

There appears to be a need for a reliable method for quantification of tooth colour and analysis of shade. Therefore, the primary objective of this study was to show the applicability of graphic software in colour analysis and secondly to investigate the reliability of commercial shade guides produced by the same manufacturer, using this digital technique. After confirming the reliability and reproducibility of the digital method by using self-assessed coloured images, three shade guides of the same manufacturer were photographed in daylight and in studio environments with a digital camera and saved in tagged image file format (TIFF) format. Colour analysis of each photograph was performed using the Adobe Photoshop 4·0 graphic program. Luminosity, and red, green, blue (L and RGB) values of each shade tab of each shade guide were measured and the data were subjected to statistical analysis using the repeated measure ANOVA test. The L and RGB values of the images taken in daylight differed significantly from those of the images taken in studio environment (P < 0·05). In both environments, the luminosity and red values of the shade tabs were significantly different from each other (P < 0·05). It was concluded that, when the environmental conditions were kept constant, the Adobe Photoshop 4·0 colour analysis program could be used to analyse the colour of images. On the other hand, the results revealed that the accuracy of shade tabs widely being used in colour matching should be readdressed. [ABSTRACT FROM AUTHOR]

This paper develops a wide-band multi-spectral space for color representation with Aitken PCA algorithm. This novel mathematical space using the broad-band spectra matching method aims at improving the accuracy of color representation as well as reducing costs for processing and storing multi-spectral images. The results show that the space can present our experimental original spectral spaces (i. e. Munsell color matt and DIN-6164 color chips) with high efficiency, and that the spanning space with three eigenvectors can present the original space at more than 98% CSCR, and when 5 eigenvectors are used it can cover almost the whole original spaces. [ABSTRACT FROM AUTHOR]

This article deals with cationization of cotton during mercerization and its effects on trichromatic vat dyeing. If cationization is carried out during the after-treatment, regardless of cotton pretreatment, the reaction takes place on the surface and blocks cellulose groups, subsequently resulting in uneven coloration. However, when cationization is carried out with an epihalohydrin during the mercerization process, new cellulose is formed in which the cationic compound is uniformly distributed and trapped between cellulose chains, resulting in uniform coloration after the dyeing process. The reaction time for the process during mercerization is 24 h, thus a more favorable process was researched. Based on electrokinetic analysis, it was found that 5 h was sufficient for the reaction with 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTAC). The cationization of cotton contributed to the processes of vat dyeing. The change in charge upon cationization resulted in very high adsorption of vat-dye anions, indicating that ionic bonding occurred in addition to van der Waals forces. The color depth improved by more than 10 times. It should be emphasized that the colors with higher chroma and targeted color hue, especially in trichromatic dyeing, were obtained on cationized cotton, in contrast to standard cotton fabrics. The color differences obtained under the different light sources indicate the occurrence of metamerism. Considering the color fastness to laundering, vat-dyed cationized fabrics of all colors may be used in hospitals or other environments where high hygiene and oxidative bleaching are required. [ABSTRACT FROM AUTHOR]

Vertebrate segmentation, the process that generates a regular arrangement of somites and thereby establishes the pattern of the adult body and of the musculoskeletal and peripheral nervous systems, was noticed many centuries ago. In the last few decades, there has been renewed interest in the process and especially in the molecular mechanisms that might account for its regularity and other spatial-temporal properties. Several models have been proposed but surprisingly, most of these do not provide clear links between the molecular mechanisms and the cell behaviours that generate the segmental pattern. Here we present a short survey of our current knowledge about the cellular aspects of vertebrate segmentation and the similarities and differences between different vertebrate groups in how they achieve their metameric pattern. Taking these variations into account should help to assess each of the models more appropriately., (Copyright © 2021. Published by Elsevier B.V.)

Thirty-six manubriosternal composites from skeletally immature cadavers were examined morphologically and radiographically. Sternebral ossification followed certain patterns. The manubrium (first sternebra) usually had one primary ossification center and one or two smaller centers. These usually were caudad to the major center (longitudinally bifid). The second sternebra invariably had only one ossification center. The third and fourth sternebrae had latitudinal (right-left) bifid ossification centers, undoubtedly a result of the original formation of the sternum from two longitudinal mesenchymal anlagen. Occasionly the fourth sternebra exhibited longitudinally bifid ossification. The usual pattern was ossification of four sternebrae, although a fifth was intermittently present. The xiphisternum (not a true sternebra) was infrequently ossified. [ABSTRACT FROM AUTHOR]

The migration pathways and spatial distribution of neural crest cells largely depend on the embryonic architecture. At the preotic level in the chick embryo, cephalic crest adhere to even-numbered rhombomeres proximally, and populate each pharyngeal arch distally, thus prefiguring the morphology of the branchiomeric nerves. This distribution pattern is possible because of the absence of somites in the head. In the postotic region, however, somites and pharyngeal arches coexist at the same axial level. The caudalmost cephalic crest cell population, the circumpharyngeal crest cells, are derived from the postotic crest and their distribution covers the entire innervation areas of cranial nerves IX and X. In their proximal migration pathway, circumpharyngeal crest cells can exist along the dorsolateral pathway only where somites are absent. They divert around the occipital somites rostrally, making an arc that represents the caudal limit of the dorsolateral pathway of cephalic crest cells, or the head/trunk interface at the paraxial level. Ventrally, the circumpharyngeal crest cells localize in postotic pharyngeal arches as well as in an arc-shaped ridge, called the circumpharyngeal ridge. Since the circumpharyngeal ridge represents the caudal limit of the pharynx, it indicates the head/trunk interface at the level of the lateral body wall. These two interfaces of reverse orientation make an S-shaped, head/trunk interface together. Several structures unique to this region develop in this interface. Since the rhombomeric compartmentalization is distinct only in higher vertebrates, the rhombomere-dependent segregation of cephalic crest cells is more likely to be a secondary feature of the vertebrate head. The topographical configuration of the vertebrate crest cell distribution pattern does not support the idea that the vertebrate head evolved as a specialized trunk, but rather supports the idea that two distinct methods of segmental patterning have evolved in rostral and caudal parts of the vertebrate body, which resulted in the head and trunk, respectively. Postotic crest is located at the intermediate level between the trunk and the head, giving rise to both the cephalic and trunk crest cells. Its cephalic components circumpharyngeal crest cells, are distributed only rostral to the S-shaped interface. [ABSTRACT FROM AUTHOR]

Plant morphology, including morphogenesis, remains relevant to practically all disciplines of plant biology such as molecular genetics, physiology, ecology, evolutionary biology and systematics. This relevance derives from the fact that other disciplines refer to or imply morphological concepts, conceptual frameworks of morphology, and morphological theories. Most commonly, morphology is equated with classical morphology and its conceptual framework. According to this, flowering plants and certain other taxa are reduced to the mutually exclusive categories of root, stem (caulome) and leaf (phyllome). This ignores the fact that plant morphology has undergone fundamental conceptual, theoretical and philosophical innovation in recent times. These changes, when recognized, can fundamentally affect research in various disciplines of plant biology. They may even change the questions that are asked and thus may affect the direction of future research. If, for example, plant diversity and evolution are seen as a dynamic continuum, then compound leaves can be seen as intermediate between simple leaves and whole shoots. Recent results in molecular genetics support this view. Phylogenetically, this could mean that compound leaves are the result of developmental hybridization, i.e. partial homeosis. Many other examples are given to illustrate the relevance and potential impact of basic conceptual and theoretical innovations in plant morphology.Copyright 1997 Annals of Botany Company [ABSTRACT FROM AUTHOR]

Control of color takes on a new meaning when considered as a part of a method to differentiate products. The basics of color and color perception are reviewed. Legal issues concerning the use and misuse of color as a trademark are explored. [ABSTRACT FROM AUTHOR]

The diverse inflorescence morphology of species in the Pithecellobium-complex is shown to be a result of: 1) the organization of the components of the inflorescence and their relative positions; 2) the hierarchical relationship of the axes of the inflorescences and the position they assume in total tree architecture; and 3) heterochronic development of the components of the inflorescence. It is shown that the typological system of nomenclature of inflorescences leads to false assumptions of homology and therefore must be discarded. The morphology of inflorescences is discussed in terms of metamerism, and the term Repeating Growth Unit (RGU) is introduced and is defined as the smallest complete sequence of metamers produced by a meristem. A module is defined as the sequence of RGUs produced by a meristem. An inflorescence is defined as that sequence of metamers in an RGU which participates in the production and/or presentation of flowers and fruit. Heterochrony, proleptic and sylleptic buds, and shoot dimorphism are discussed and their role in modifying inflorescence morphology in the Pithecellobium-complex is illustrated. Examples from the Pithecellobium-complex are provided which demonstrate the various modifications of the inflorescence that result from the interaction of these various phenomena. [ABSTRACT FROM AUTHOR]

This is the second of a two-part review on the measurement of color and color differences. It was written to be part of a technical handbook on AATCC test methods. It presents the theoretical background on color that is needed to understand fully the color evaluations included in the AATCC test methods. The Gray Scale for Color Change and the AATCC Chromatic Transference Scale are discussed in detail. Certain special aspects of color, including whiteness, fluorescence, iridescence, flare, metamerism and color mixing are reviewed. [ABSTRACT FROM AUTHOR]

Instrumental shade sorting of textile samples offers the advantages of consistency and a simple shade order system. A special purpose computer, integral with a unique, four-filter tristimulus colorimeter, has been developed to suit the specific requirements of textile production shade sorting. Samples may be evaluated under llluminant A and/or C conditions, to uniform visual appearance difference tolerances, regardless of hue, saturation or lightness. The human engineering considerations and design concept of the instrument system are briefly discussed, as is the simple procedure for programming the computer for the evaluation task. Mill experience with the instrumental shade sorting system indicates excellent agreement with visual judgment with greatly improved uniformity of classification. Economic advantages gained through reduced customer complaints and improved process feedback information is discussed in detail. [ABSTRACT FROM AUTHOR]

This paper discusses the practical use of a computer for color matching. The author describes his experience with instrumental color measurement and matching since 1954. Problems involved in computerizing a dye system are presented, with an emphasis on practical application. [ABSTRACT FROM AUTHOR]

The concept of metamerism and its definition is discussed briefly in terms of the spectral reflectance characteristics of colored materials, the spectral power distribution of the illuminant and the color-matching properties of the observer's eyes. Various ways of defining a degree of metamerism are explained and methods outlined that are potentially useful to specify the degree of metamerism. The Colorimetry Committee of the Commission Internationale de l'Eclairage (CIE) is currently studying several methods with the view to arriving at one or more that are suitable for practical applications and can be recommended internationally. [ABSTRACT FROM AUTHOR]

We have isolated the stable as well as the metastable tautomers of 1-deazapurine in the solid state by exploiting principles of supramolecular selectivity in the context of cocrystal design. [ABSTRACT FROM AUTHOR]

The spread of digital photographic cameras (predominantly of D-SLR type) during the last decade has opened new possibilities to the investigators of work of arts, having now a tool not only to document the conservation state of a work of art but also to examine in the invisible spectrum (such as in Infrared or Ultraviolet) or to collect and analyze information in the visible spectrum in new ways. This is the case of the present work, which presents some results obtained on building, calibrating and testing a system using a commercial digital camera (a Nikon D300 D-SLR) that showed to be possible, entirely on the visible spectrum, to capture hyperspectral images composed of 28 bands, between 420 nm and 690 nm, in steps of 10 nm (22 bands are directly captured with the system and 6 are interpolated), a number of bands superior to many other multispectral and hyperspectral imaging systems built with more complex and expensive hardware. Compared to a reference spectroradiometer (Photoresearch PR650) using a standard 24 color chart ColorChecker X-Rite, the proposed system showed good results, indicating that it presents an accuracy good enough to many of the new and promising uses in hyperspectral imaging. It showed average values for RMSE (Root Mean Square Error) of 3,4% and 99,3% for GFC (Goodness-of-Fit-Coefficient); the colorimetric precision of the system presented values for color differences equations of 6,0968 units for ΔE , 3,8228 units for ΔE and 3,6794 units for ΔE ; the tested metameric indices showed values of 1,1457, 1,2410, 0,8078 and 0,7777 for iluminant pairs "D65,A" and "D65,F2", all quantified in terms of color differences equations ΔE and ΔE , respectively. The possibility of capturing images in more bands than the traditional three channels color models (the RGB model, commonly used on digital camera's sensors), opens new possibilities, because this type of data contains reflectance values (data independent of the type of illuminant) and in an higher number of wavelength bands. This type of data is more colour accurate than conventional photography and it is not susceptible to colours metamerism, a frequent problem with trichromatic reproduction systems. With the present work we have shown some of the possible applications of hyperspectral imaging. In a practical case using a XVI Century painting (Triptico de Pentecostes de Miragaia, Porto) and a XX Century work of Art (O Cabouqueiro, by Julio Pomar) observing and analyzing individual isolated bands in certain wavelengths of the visible spectrum, allowed us to detect alterations in paintings, areas with repainting, reintegration, under drawings and other type of information, traditionally only possible to obtain using invisible radiation imagery. Using adequate software programs it was possible to virtually test the appearance of the work of art in different types of illuminants or light sources, preventing more time-consuming experiences or, in both situations, avoiding submitting the work of art to unnecessary stress or more destructive radiations. [ABSTRACT FROM AUTHOR]