The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
Cecilia Kopuchian - One of the best experts on this subject based on the ideXlab platform.
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Short-wavelength visual sensitivity and sexual differences in plumage Colouration of ovenbirds (Aves: Furnariinae)
Journal of Ornithology, 2021Co-Authors: Ana S. Barreira, Muir D. Eaton, Elisabet Vilacoba, Pablo L. Tubaro, Cecilia KopuchianAbstract:Ovenbirds represent a clade of exclusively Neotropical birds that are exceptionally diverse, despite their rather dull, melanin-based plumage. In general, sexes are considered monomorphic in size and Colour, but several authors have reported females of some species within this family as being slightly paler than their conspecific counterparts. Our aim was to assess levels of sexual dichromatism in a set of ovenbird species representing a diversity of genera and plumage patterns; Furnarius rufus, Phleocryptes melanops, Synallaxis spixi and Schoeniophylax phryganophilus. For each species, we quantified sexual differences in brightness and Colouration among 8–10 different plumage regions through modelling avian Perceptual Colour-Space distances. To best inform our visual modelling parameters, we successfully sequenced the SWS1 gene fragment (associated with short-wavelength, including ultraviolet, visual sensitivity in birds) for one species, P. melanops, and found it possessed an amino acid sequence consistent with the VS-type SWS1 visual system. This provides further evidence supporting the presence of VS-sensitive opsin in ovenbirds. Among all four species, females were consistently brighter than males in at least one plumage patch, but chromatic Colour differences between sexes were significant only for the throat patches of Schoeniophylax phryganophilus. Overall, we interpret ovenbirds to exhibit very low levels of sexual dichromatism, manifest mainly by achromatic Colour differences.
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Short-wavelength visual sensitivity and sexual differences in plumage Colouration of ovenbirds (Aves: Furnariinae)
Journal of Ornithology, 2021Co-Authors: Ana S. Barreira, Muir D. Eaton, Elisabet Vilacoba, Pablo L. Tubaro, Cecilia KopuchianAbstract:Visuelle Sensitivität für kurzwelliges Licht und Geschlechtsunterschiede in der Gefiederfärbung von Töpfervögeln (Aves: Furnariidnae) Töpfervögel repräsentieren eine Klade von ausschließlich neotropischen Vögeln, die trotz ihres eher einfachen, melaninbasierten Gefieders außergewöhnlich vielfältig sind. Im Allgemeinen werden die Geschlechter in Größe und Farbe als monomorph angesehen. Jedoch berichteten mehrere Autoren, dass Weibchen einiger Arten innerhalb dieser Familie etwas blasser gefärbt sind als ihre männlichen Artgenossen. Unser Ziel war es, den Grad des Geschlechtsdichromatismus in einer Reihe von Töpfervogelarten zu beschreiben, die eine Vielfalt von Gattungen und Gefiedermustern repräsentieren: Furnarius rufus, Phleocryptes melanops, Synallaxis spixi und Schoeniophylax phryganophilus. Für jede Art quantifizierten wir die Geschlechtsunterschiede in der Gefiederhelligkeit und -färbung innerhalb acht bis zehn unterschiedlicher Gefiederregionen anhand der Modellierung der vom Vogel wahrnehmbaren räumlichen Distanz der Farbabstände. Um unsere visuellen Modellparameter bestmöglich zu bestimmen, sequenzierten wir erfolgreich das SWS1-Genfragment (assoziiert mit visueller Sensitivität für kurzwelliges, einschließlich ultraviolettes, Licht bei Vögeln) für eine Vogelart, P. melanops , und fanden heraus, dass es eine Aminosäurensequenz besitzt, die mit dem visuellen System VS-Type SWS1 übereinstimmt. Dies ist ein weiterer Beweis für das Vorhandensein von VS-sensitivem Opsin bei Töpfervögeln. Bei allen vier Arten waren die Weibchen in mindestens einer Gefiederregion durchweg heller als die Männchen, aber chromatische Farbunterschiede zwischen den Geschlechtern waren nur für den Kehlfleck bei S. phryganophilus signifikant. Zusammenfassend lässt sich feststellen, dass Töpfervögel ein sehr geringes Maß an Geschlechtsdichromatismus aufweisen, der sich hauptsächlich anhand achromatischer Farbunterschiede äußert. Ovenbirds represent a clade of exclusively Neotropical birds that are exceptionally diverse, despite their rather dull, melanin-based plumage. In general, sexes are considered monomorphic in size and Colour, but several authors have reported females of some species within this family as being slightly paler than their conspecific counterparts. Our aim was to assess levels of sexual dichromatism in a set of ovenbird species representing a diversity of genera and plumage patterns; Furnarius rufus , Phleocryptes melanops , Synallaxis spixi and Schoeniophylax phryganophilus . For each species, we quantified sexual differences in brightness and Colouration among 8–10 different plumage regions through modelling avian Perceptual Colour-Space distances. To best inform our visual modelling parameters, we successfully sequenced the SWS1 gene fragment (associated with short-wavelength, including ultraviolet, visual sensitivity in birds) for one species, P. melanops , and found it possessed an amino acid sequence consistent with the VS-type SWS1 visual system. This provides further evidence supporting the presence of VS-sensitive opsin in ovenbirds. Among all four species, females were consistently brighter than males in at least one plumage patch, but chromatic Colour differences between sexes were significant only for the throat patches of Schoeniophylax phryganophilus . Overall, we interpret ovenbirds to exhibit very low levels of sexual dichromatism, manifest mainly by achromatic Colour differences.
Winfried Boxleitner - One of the best experts on this subject based on the ideXlab platform.
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h2si a new Perceptual Colour Space
International Conference on Digital Signal Processing, 2013Co-Authors: Michael Nolle, M Suda, Winfried BoxleitnerAbstract:In this paper we introduce a new Colour Space which is equipped with a metric that shares many properties with the human perception of Colour, and we derive its the most important geometric properties. The new Colour Space is well suited for algorithmic purposes, as we demonstrate with the `Eigen' Colour decomposition of images.
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DSP - H2SI - A new Perceptual Colour Space
2013 18th International Conference on Digital Signal Processing (DSP), 2013Co-Authors: Michael Nolle, M Suda, Winfried BoxleitnerAbstract:In this paper we introduce a new Colour Space which is equipped with a metric that shares many properties with the human perception of Colour, and we derive its the most important geometric properties. The new Colour Space is well suited for algorithmic purposes, as we demonstrate with the `Eigen' Colour decomposition of images.
Ana S. Barreira - One of the best experts on this subject based on the ideXlab platform.
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Short-wavelength visual sensitivity and sexual differences in plumage Colouration of ovenbirds (Aves: Furnariinae)
Journal of Ornithology, 2021Co-Authors: Ana S. Barreira, Muir D. Eaton, Elisabet Vilacoba, Pablo L. Tubaro, Cecilia KopuchianAbstract:Ovenbirds represent a clade of exclusively Neotropical birds that are exceptionally diverse, despite their rather dull, melanin-based plumage. In general, sexes are considered monomorphic in size and Colour, but several authors have reported females of some species within this family as being slightly paler than their conspecific counterparts. Our aim was to assess levels of sexual dichromatism in a set of ovenbird species representing a diversity of genera and plumage patterns; Furnarius rufus, Phleocryptes melanops, Synallaxis spixi and Schoeniophylax phryganophilus. For each species, we quantified sexual differences in brightness and Colouration among 8–10 different plumage regions through modelling avian Perceptual Colour-Space distances. To best inform our visual modelling parameters, we successfully sequenced the SWS1 gene fragment (associated with short-wavelength, including ultraviolet, visual sensitivity in birds) for one species, P. melanops, and found it possessed an amino acid sequence consistent with the VS-type SWS1 visual system. This provides further evidence supporting the presence of VS-sensitive opsin in ovenbirds. Among all four species, females were consistently brighter than males in at least one plumage patch, but chromatic Colour differences between sexes were significant only for the throat patches of Schoeniophylax phryganophilus. Overall, we interpret ovenbirds to exhibit very low levels of sexual dichromatism, manifest mainly by achromatic Colour differences.
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Short-wavelength visual sensitivity and sexual differences in plumage Colouration of ovenbirds (Aves: Furnariinae)
Journal of Ornithology, 2021Co-Authors: Ana S. Barreira, Muir D. Eaton, Elisabet Vilacoba, Pablo L. Tubaro, Cecilia KopuchianAbstract:Visuelle Sensitivität für kurzwelliges Licht und Geschlechtsunterschiede in der Gefiederfärbung von Töpfervögeln (Aves: Furnariidnae) Töpfervögel repräsentieren eine Klade von ausschließlich neotropischen Vögeln, die trotz ihres eher einfachen, melaninbasierten Gefieders außergewöhnlich vielfältig sind. Im Allgemeinen werden die Geschlechter in Größe und Farbe als monomorph angesehen. Jedoch berichteten mehrere Autoren, dass Weibchen einiger Arten innerhalb dieser Familie etwas blasser gefärbt sind als ihre männlichen Artgenossen. Unser Ziel war es, den Grad des Geschlechtsdichromatismus in einer Reihe von Töpfervogelarten zu beschreiben, die eine Vielfalt von Gattungen und Gefiedermustern repräsentieren: Furnarius rufus, Phleocryptes melanops, Synallaxis spixi und Schoeniophylax phryganophilus. Für jede Art quantifizierten wir die Geschlechtsunterschiede in der Gefiederhelligkeit und -färbung innerhalb acht bis zehn unterschiedlicher Gefiederregionen anhand der Modellierung der vom Vogel wahrnehmbaren räumlichen Distanz der Farbabstände. Um unsere visuellen Modellparameter bestmöglich zu bestimmen, sequenzierten wir erfolgreich das SWS1-Genfragment (assoziiert mit visueller Sensitivität für kurzwelliges, einschließlich ultraviolettes, Licht bei Vögeln) für eine Vogelart, P. melanops , und fanden heraus, dass es eine Aminosäurensequenz besitzt, die mit dem visuellen System VS-Type SWS1 übereinstimmt. Dies ist ein weiterer Beweis für das Vorhandensein von VS-sensitivem Opsin bei Töpfervögeln. Bei allen vier Arten waren die Weibchen in mindestens einer Gefiederregion durchweg heller als die Männchen, aber chromatische Farbunterschiede zwischen den Geschlechtern waren nur für den Kehlfleck bei S. phryganophilus signifikant. Zusammenfassend lässt sich feststellen, dass Töpfervögel ein sehr geringes Maß an Geschlechtsdichromatismus aufweisen, der sich hauptsächlich anhand achromatischer Farbunterschiede äußert. Ovenbirds represent a clade of exclusively Neotropical birds that are exceptionally diverse, despite their rather dull, melanin-based plumage. In general, sexes are considered monomorphic in size and Colour, but several authors have reported females of some species within this family as being slightly paler than their conspecific counterparts. Our aim was to assess levels of sexual dichromatism in a set of ovenbird species representing a diversity of genera and plumage patterns; Furnarius rufus , Phleocryptes melanops , Synallaxis spixi and Schoeniophylax phryganophilus . For each species, we quantified sexual differences in brightness and Colouration among 8–10 different plumage regions through modelling avian Perceptual Colour-Space distances. To best inform our visual modelling parameters, we successfully sequenced the SWS1 gene fragment (associated with short-wavelength, including ultraviolet, visual sensitivity in birds) for one species, P. melanops , and found it possessed an amino acid sequence consistent with the VS-type SWS1 visual system. This provides further evidence supporting the presence of VS-sensitive opsin in ovenbirds. Among all four species, females were consistently brighter than males in at least one plumage patch, but chromatic Colour differences between sexes were significant only for the throat patches of Schoeniophylax phryganophilus . Overall, we interpret ovenbirds to exhibit very low levels of sexual dichromatism, manifest mainly by achromatic Colour differences.
Michael Nolle - One of the best experts on this subject based on the ideXlab platform.
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h2si a new Perceptual Colour Space
International Conference on Digital Signal Processing, 2013Co-Authors: Michael Nolle, M Suda, Winfried BoxleitnerAbstract:In this paper we introduce a new Colour Space which is equipped with a metric that shares many properties with the human perception of Colour, and we derive its the most important geometric properties. The new Colour Space is well suited for algorithmic purposes, as we demonstrate with the `Eigen' Colour decomposition of images.
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DSP - H2SI - A new Perceptual Colour Space
2013 18th International Conference on Digital Signal Processing (DSP), 2013Co-Authors: Michael Nolle, M Suda, Winfried BoxleitnerAbstract:In this paper we introduce a new Colour Space which is equipped with a metric that shares many properties with the human perception of Colour, and we derive its the most important geometric properties. The new Colour Space is well suited for algorithmic purposes, as we demonstrate with the `Eigen' Colour decomposition of images.
Anna Montesanto - One of the best experts on this subject based on the ideXlab platform.
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content based image retrieval using a metric in a Perceptual Colour Space
International Conference on Image Analysis and Processing, 2005Co-Authors: Guido Tascini, Anna MontesantoAbstract:The aim of the present work is building an evaluation method for the similarity between Colour hues. The method is defined by studying the attribution process, by human subjects, of Colour hue couple to similarity classes (from ‘very similar' to ‘little similar'). From the study of these categorical judgements it is derived that the relation between the hue and the Colour similarity is ‘not-isometric' and greatly depends on the Colour category. This result allows to extract representative functions for the three Colour of the subtractive system: Red, Yellow, Blue. Besides we used a new method for segmenting the Colour, based on the similarity with the main Colours. Our method defines a quaternary tree structure, named ‘Similarity Quad-Tree'; it is capable of extracting, from the whole image, the belonging degree to the Red, Yellow and Blue Colours and their similarity with the reference Colour. The check on the method applicability has given good results both: in the user satisfaction and in the computation. The approach may be viewed as a simple and fast indexing method.
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Non-isometric Colour similarity
Journal of Vision, 2005Co-Authors: Anna Montesanto, Maria Pietronilla Penna, Guido TasciniAbstract:This paper presents the findings obtained in an experimental study of metric underlying the Perceptual Colour Space. Previous studies evidenced that, in tasks of evaluation of Colour similarity, the subjects don't refer to the most general category of “Colour”, but rather rely on the introduction of subordinate categories containing all variations of a Colour. Besides, categories related to different Colours can sometimes overlap. This forces to conclude that perception of Colour variations is not isometric, but is rather weighed in different ways for different Colours.\ud \ud In order to detect the metric of Colour Space we performed an experiment with multiple conditions within the subjects, designed to determine the form of the function that ties the independent variable (tonality of Colour) with the dependent variable (similarity judgement). To each subject we presented simultaneously a pair of images, the target one and another differing from the target only for its Colour (a suitable perturbation of the tonality). The subject task was to rate the similarity of the second image with the target. The frequency distribution of similarity judgments for each Colour gave a qualitative description of how the different Colours are represented at the cognitive level. We applied to the observed frequencies a unidimensional scaling procedure to obtain a precise measure of the distance between the variation steps for each Colour. We were allowed to choose a single dimension because we limited the study only to the variation of tonality. The scaling was applied separately to each Colour scale.\ud \ud The results showed that different Colours were associated to different measure scales. Besides, once chosen a particular Colour, its measure scale itself was depending on the direction of variation chosen for its tonality during the experimental presentation. We can conclude that the geometry of Colour Space looks very complicated and not reducible to familiar mathematical concepts
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ICIAP - Content based image retrieval using a metric in a Perceptual Colour Space
Image Analysis and Processing – ICIAP 2005, 2005Co-Authors: Guido Tascini, Anna MontesantoAbstract:The aim of the present work is building an evaluation method for the similarity between Colour hues. The method is defined by studying the attribution process, by human subjects, of Colour hue couple to similarity classes (from ‘very similar' to ‘little similar'). From the study of these categorical judgements it is derived that the relation between the hue and the Colour similarity is ‘not-isometric' and greatly depends on the Colour category. This result allows to extract representative functions for the three Colour of the subtractive system: Red, Yellow, Blue. Besides we used a new method for segmenting the Colour, based on the similarity with the main Colours. Our method defines a quaternary tree structure, named ‘Similarity Quad-Tree'; it is capable of extracting, from the whole image, the belonging degree to the Red, Yellow and Blue Colours and their similarity with the reference Colour. The check on the method applicability has given good results both: in the user satisfaction and in the computation. The approach may be viewed as a simple and fast indexing method.