FIRST RESULTS OF PROCESSING DIGITIZED V-PLATES TAKEN WITH THE TAUTENBURG 2m SCHMIDT TELESCOPE

The process of treatment of about 500 digitized plates has started in MAO NAS of Ukraine. Plates were taken with the Tautenburg 2m Schmidt telescope in 1963-1989. Linear dimensions of plates are 24x24 cm with a working field of 3.3x3.3 degrees and a scale of 51.4 "/ mm. Astronegatives were digitized on the Tautenburg Plate Scanner in five strips with linear dimensions of 5 400x23 800 px. The software developed in MAO NAS of Ukraine for the image processing of these scans takes into account the horizontal overlap and the vertical offset of strips. The photometric range of fixed objects is 12 magnitudes, around V = 7 m - 19 m , due to the separation of objects into faint and bright parts by their images’ diameters. Positions of stars and other fixed objects are obtained in the GAIA DR2 reference system. Magnitudes are defined in the V-band of the Johnson color system. The resulted positional accuracy defined from 180 plates’ processing is σ RA,DEC = 0.10"for both coordinates, photometric error on the whole range of magnitudes is σ V = 0.14 m . The convergence of resulted magnitudes with ones from photoelectric standards’ data is 0.19 m . In parallel with image processing and plate data reduction, the search for minor planets’ images was carried out. Nine positions and magnitudes of 4 asteroids registered on the plates obtained in 1963-1965 were defined and used for further analysis.

Real-Time Application of Computer Graphics Improvement Techniques Using Hyperspectral Textures in a Virtual Reality System

In virtual reality technology, it is necessary to develop improvements and apply new techniques that allow rapid progress and innovative development. Nowadays, virtual reality devices have not yet demonstrated the great potential they could develop in the future. One main reason for this is the lack of precision to represent three-dimensional scenarios with a similar solvency to what our visual system obtains from the real world. One of the main problems is the representation of images using the RGB color system. This digital colorimetry system has many limitations when it comes to representing faithful images. In this work we propose to develop a virtual reality environment incorporating hyperspectral textures into a virtual reality system. Based on these hyperspectral textures, the aim of our scientific contribution is to improve the fidelity of the chromatic representation, especially when the lighting conditions of the scenes and its precision are relevant. Therefore, we will present the steps followed to render three-dimensional objects with hyperspectral textures within a virtual reality scenario. Additionally, we will check the results obtained by applying such hyperspectral textures by calculating the chromaticity coordinates of known samples.

Análise da eficácia de dentifrícios clareadores e seus efeitos na superfície dental: um estudo in vitro

Tooth whitening can be performed at the dental office, at-home or upon the use of OTC (Over-the-Counter) products. Among the latter, there are whitening toothpastes that promise to bleach and to prevent tooth staining. Objectives: (1) to investigate the bleaching and abrasive potential of different whitening dentifrices to enamel; and (2) to evaluate the effect of Oral-B 3D White Perfection® (Oral-B) toothpaste in preventing staining. Materials and Methods: Bovine enamel samples were stained and brushed for 14 days with water (negative control) or with different products: Colgate Total 12® (control), Oral-B, Sensodyne Branqueador Extra Fresh® (Sensodyne), and Colgate Luminous White Advanced® (Colgate). Oral-B was also tested before and after staining. The samples were tested by their color (spectrophotometer) and surface roughness (profilometer). Color change (ΔDE00) was calculated using the CIEDE2000 color system. The data were analyzed using Kruskal-Wallis, SNK, and Mann-Whitney tests (ɑ=5%). Results: The negative control showed the lowest ΔE00 (p

What is the “opposite” of “blue”? The language of colour wheels

© Society for Imaging Science and Technology 2019 A color wheel is a tool for ordering and understanding hue. Different color wheels differ in the spacing of the colors around the wheel. The opponent-color theory, Munsell's color system, the standard printer's primaries, the artist's primaries, and Newton's rainbow all present different variations of the color wheel. I show that some of this variation is owing to imprecise use of language, based on Berlin and Kay's theory of basic color names. I also show that the artist's color wheel is an outlier that does not match well to the technical color wheels because its principal colors are so strongly connected to the basic color names.

What is the “opposite” of “blue”? The language of colour wheels

© Society for Imaging Science and Technology 2019 A color wheel is a tool for ordering and understanding hue. Different color wheels differ in the spacing of the colors around the wheel. The opponent-color theory, Munsell's color system, the standard printer's primaries, the artist's primaries, and Newton's rainbow all present different variations of the color wheel. I show that some of this variation is owing to imprecise use of language, based on Berlin and Kay's theory of basic color names. I also show that the artist's color wheel is an outlier that does not match well to the technical color wheels because its principal colors are so strongly connected to the basic color names.

Suppression of Luminance Contrast Sensitivity by Weak Color Presentation

The results of psychophysical studies suggest that color in a visual scene affects luminance contrast perception. In our brain imaging studies we have found evidence of an effect of chromatic information on luminance information. The dependency of saturation on brain activity in the visual cortices was measured by functional magnetic resonance imaging (fMRI) while the subjects were observing visual stimuli consisting of colored patches of various hues manipulated in saturation (Chroma value in the Munsell color system) on an achromatic background. The results indicate that the patches suppressed luminance driven brain activity. Furthermore, the suppression was stronger rather than weaker for patches with lower saturation colors, although suppression was absent when gray patches were presented instead of colored patches. We also measured brain activity while the subjects observed only the patches (on a uniformly black background) and confirmed that the colored patches alone did not give rise to differences in brain activity for different Chroma values. The chromatic information affects the luminance information in V1, since the effect was observed in early visual cortices (V2 and V3) and the ventral pathway (hV4), as well as in the dorsal pathway (V3A/B). In addition, we conducted a psychophysical experiment in which the ability to discriminate luminance contrast on a grating was measured. Discrimination was worse when weak (less saturated) colored patches were attached to the grating than when strong (saturated) colored patches or achromatic patches were attached. The results of both the fMRI and psychophysical experiments were consistent in that the effects of color were greater in the conditions with low saturation colors.