Color Spreading Research Articles

Transparency: Relation to Depth, Subjective Contours, Luminance, and Neon Color Spreading

The perception of transparency is highly dependent on luminance and perceived depth. An image region is seen as transparent if it is of intermediate luminance relative to adjacent image regions, and if it is perceived in front of another region and has a boundary which provides information that an object is visible through this region. Yet, transparency is not just the passive end-product of these required conditions. If perceived transparency is triggered, a number of seemingly more elemental perceptual primitives such as color, contour, and depth can be radically altered. Thus, with the perception of transparency, neon color spreading becomes apparent, depth changes, stereoscopic depth capture can be eliminated, and otherwise robust subjective contours can be abolished. In addition, we show that transparency is not coupled strongly to real-world chromatic constraints since combinations of luminance and color which would be unlikely to arise in real-world scenes still give rise to the perception of transparency. Rather than seeing transparency as a perceptual end-point, determined by seemingly more primitive processes, we interpret perceived transparency as much a 'cause', as an 'effect'. We speculate that the anatomical substrate for such mutual interaction may lie in cortical feed-forward connections which maintain modular segregation and cortical feedback connections which do not.

Effects of luminance contrast on color spreading and illusory contour in the neon color spreading effect.

The present study examined whether color spreading and illusory contours in the neon color spreading effect of Ehrenstein figures are governed by different mechanisms. In the experiment, Ehrenstein figures with colored crosses inserted in the central gaps were used. There were three luminance conditions: the luminance of the Ehrenstein figures was lower than, the same as, or higher than the luminance of the background. In each condition, 16 trials (2 sets of instructions X 8 repetitions) were conducted in a random order. Subjects were required to adjust the luminance of the colored crosses according to one of the two sets of instruction given before each trial. One was to adjust the upper and lower thresholds in the luminance of the colored crosses such that their color was seen to spread out of the crosses. The other was to adjust the thresholds such that circular illusory contours were visible. It was found that illusory contours disappeared and the color spreading remained when the crosses and the Ehrenstein figures were in or nearly in isoluminance or when the Ehrenstein figures and the background were in isoluminance. These results suggest that color spreading and illusory contours are governed by different mechanisms.

A BV photographic study of the southern open cluster NGC 6259

A BV photographic survey of NGC 6259 indicates that the cluster has a color-magnitude diagram similar to M11. Both clusters are found to have main-sequence turnoffs with color spreads significantly larger than expected from the photometric errors. A true modulus for both clusters of (m - M)0 = 11.5 is obtained, along with reddening estimates E(B - V) of 0.44 for M11 and 0.68 for NGC 6259. 30 refs.

Discontinuities along lines: Psychophysics and neurophysiology

If a segment of a line differs in luminance or color from the rest of the line, three illusory phenomena may be perceived: a reduction in contrast of the line segment relative to the background, subjective contours running perpendicularly to the ends of the line segment, and spread of color or brightness surrounding the line segment. All three phenomena cause a perceptual enhancement of the line discontinuity. Their psychophysical properties and possible neurophysiological correlates in the visual cortex are discussed. Contrast reduction has characteristics similar to end-stopped neuronal responses. Subjective contours elicit orientation-specific neuronal responses in areas 17 and 18. Neon color and brightness spreading may be mediated by "dot-responsive" cells in area 19.

The modern metric system on postage stamps

Many countries have issued postage stamps that display various aspects of the metric system. This article includes a beautiful color spread depicting these stamps.

Deep CCD Photometry of Omega Centauri

This paper presents a color magnitude diagram for the enigmatic cluster ω Centauri (NGC 5139 = C1328 − 472) tracing the main sequence down to V ~ 21.5. The spread in color on the upper main sequence is confirmed as intrinsic to the cluster. The CCD observations were made using the SAAO 1 m telescope with the UCL CCD camera and the RGO CCD camera at the prime focus of the AAT.

Self-regulated cooling flows in elliptical galaxies and in cluster cores - Is exclusively low mass star formation really necessary?

A self-consistent treatment of the heating by supernovae associated with star formation in a spherically symmetric cooling flow in a cluster core or elliptical galaxy is presented. An initial stellar mass function similar to that in the solar neighborhood is adopted. Inferred star-formation rates, within the cooling region - typically the inner 100 kpc around dominant galaxies at the centers of cooling flows in XD clusters - are reduced by about a factor of 2, relative to rates inferred when the heat input from star formation is ignored. Truncated initial mass functions (IMFs) are also considered, in which massive star formation is suppressed in accordance with previous treatments, and colors are predicted for star formation in cooling flows associated with central dominant elliptical galaxies and with isolated elliptical galaxies surrounded by gaseous coronae. The low inferred cooling-flow rates around isolated elliptical galaxies are found to be insensitive to the upper mass cutoff in the IMF, provided that the upper mass cutoff exceeds 2 M solar mass. Comparison with observed colors favors a cutoff in the IMF above 1 M solar mass in at least two well-studied cluster cooling flows, but a normal IMF cannot be excluded definitively. Models for NGC 1275 support a young (less than about 3 Gyr) cooling flow. As for the isolated elliptical galaxies, the spread in colors is consistent with a normal IMF. A definitive test of the IMF arising via star formation in cooling flows requires either UV spectral data or supernova searches in the cooling-flow-centered galaxies.

Postage stamps as a teaching tool in chemistry

A full color spread in this article shows the many stamps that depict: emergence of chemistry as a science; metric system, atoms, molecules, and ions; stoichiometry; energy relationships in chemical systems; gases, liquids, and solids; electronic structures of atoms; chemical bonding; nuclear chemistry; geochemistry; organic chemistry; biochemistry; and laboratory apparatus, equipment, techniques, and instrumentation.

Electrochemistry of Prussian Blue Films on Metal and Semiconductor Electrodes

The electrochemical properties of Prussian blue films on Pt and spark anodized n‐type electrodes were investigated. Evidence for four redox states for Prussian blue was obtained. While the oxidation of Everitt's salt to Prussian blue involves the high spin iron atoms, the oxidation of Prussian blue to Berlin green and Berlin green to Prussian yellow involves the low spin hexacyanoferrate groups. The Prussian blue/Everitt's salt redox system ( vs. SCE) is the most stable and reversible couple. The diffusion coefficients for reduction and oxidation of this redox couple are, respectively. The photoelectrochromic behavior of Prussian blue on semiconductor electrodes is discussed. The films deposited on have short‐circuit memory, and lateral color spreading through the film is slow. A light addressable electrochromic display is described.

Neural dynamics of form perception: Boundary completion, illusory figures, and neon color spreading.

Neural dynamics of form perception: Boundary completion, illusory figures, and neon color spreading.

Neural dynamics of form perception: Boundary completion, illusory figures, and neon color spreading.

Abstract A real-time visual processing theory is used to analyse real and illusory contour formation, contour and brightness interactions, neon color spreading, complementary color induction, and filling-in of discounted illuminants and scotomas. The theory also physically interprets and generalizes Land's retinex theory. These phenomena are traced to adaptive processes that overcome limitations of visual uptake to synthesize informative visual representations of the external world. Two parallel contour sensitive processes interact to generate the theory's brightness, color, and form estimates. A boundary contour process is sensitive to orientation and amount of contrast but not to direction of contrast in scenic edges. It synthesizes boundaries sensitive to the global configuration of scenic elements. A feature contour process is insensitive to orientation but sensitive to both amount of contrast and to direction of contrast in scenic edges. It triggers a diffusive filling-in of featural quality within perceptual domains whose boundaries are determined by completed boundary contours. The boundary contour process is hypothesized to include cortical interactions initiated by hypercolumns in Area 17 of the visual cortex. The feature contour process is hypothesized to include cortical interactions initiated by the cytochrome oxydase staining blobs in Area 17. Relevant data from striate and prestriate visual cortex, including data that support two predictions, are reviewed. Implications for other perceptual theories and axioms of geometry are discussed.

The neon color effect in the ehrenstein pattern: Dependence on wavelength and illuminance

The neon color effect can be described as an illusory spread of color surrounding colored lines embedded in certain line gaps. The effect is seen in the Ehrenstein pattern if colored crosses are added to the central gaps so as to connect the inner tips of the pattern. Experiments were conducted to explore the dependence of this neon color effect on the wavelength and retinal illuminance of the inducing lines. The following results were obtained: (1) neon color effects are strong when the wavelength of the crosses is in the short- (< 480 nm) or long-wave part of the spectrum (> 620 nm) and the wavelength of the Ehrenstein pattern is in the middle-wave part (500–580 nm). Effects are weak or absent when the crosses and the pattern have similar wavelengths. (2) The neon color effect is just detectable when the ratio between the retinal illuminances of the Ehrenstein pattern and the crosses ranges from 0.1 to 0.8. The neon color effect is maximal at illuminance ratios ranging from 0.8 to 8. (3) The strength of the neon color effect is independent of the illuminance level of the crosses if the illuminance ratio to the Ehrenstein pattern is maintained.

Colored neon flanks and line gap enhancement

When a colored line connects two black (or differently colored) lines across a gap, colored neon flanks are seen on either side of it. These flanks extend over gap sizes of 50 min arc foveally and are not explained by Bezold-type assimilation. They may be elicited by black lines as short as 6 min arc adjoining the colored line at each end. To maximize these flanks, the black and colored lines must appear linearly continuous. Nonaligned junctions weaken the effect and an angular tilt of more than 40 deg destroys it. In this and other respects, (local) neon flanks are similar to van Tuijl's (global) neon color spreading (1975). Both phenomena have analogs in brightness perception. We propose that neon spreading is a lateral extension of neon flanks across the empty space between them, and discuss similarities of these effects with other brightness illusions (Schumann, Prandtl, Ehrenstein). For this group of illusions the term “line gap enhancement” is introduced to imply perceptual enhancement of changes in brightness and/or color along lines. Correspondences between the psychophysical properties and structural prerequisites for line gap enhancement on one hand and neuronal response properties of end-zone inhibited (hypercomplex) cortical cells on the other are discussed.

Neon color spreading, partially delineated borders, and the formation of illusory contours.

Neon color spreading, partially delineated borders, and the formation of illusory contours.

On the Low Temperature Damage in Rice Seedling : I. Effects of low temperature on the seedling growth, discoloration and chloroplast strycture of leaf blades in japonica × indica rece variety "Tongil"

Ajaponica X indica rice variety Tongil was treated with various low temperatures in phytotrons under natural light to investigate the discoloration processes of leaves experimentally. The results obtained are summarized as follows: 1. Leaf number did not increase at 15°/10°C (day/night), but increased gradually with increase of temperature, while, the length of leaf blades and sheaths which were at grand growth period was markedly shortened under low temperature. The increase in plant height of seedling was inhibited under low temperature over 6 days. 2. Leaf color changed to light green, yellow or brown when treated below 20°/15°C, and brown color spread over whole leaf blade at 15°/10°C. 3. Chlorophyll content of leaf blades began to decrease at the 3rd day under low temperature (17°/12°C), and markedly decreased at the 9th day. 4. Chloroplasts treated by low temperatures contained larger starch grains in size and amount and more lipid globules, and also thylakoid membranes were some-what distended and disordered. 5. Under normal temperatures the mean sectional areas of chloroplasts in meso-phyll cells were about 2.4 times greater than in bundle sheath cells, but under lower temperatures they decreased to 1.7 times mostly due to a grcat expanding of the chloro-plasts in bundle sheath, resulting from a much deposition of starch grains. 6. Under normal temperatures the chloroplasts of the mesophyll cells close to both the adaxial and abaxial epidermis contained less starch grains compared to those at the central portion, but under lower temperatures the chloroplasts at the abaxial side contained more starch grains than those of the adaxial side.

The Influence of Rotation on Horizontal Branch Stars and on RR Lyrae Pulsational Properties

The occurrence of rotation in Globular Cluster stars has been suggested (see e.g. Renzini 1977) as a mechanism producing the observed colour spread in actual Horizontal Branches. If this is the case, canonical results on evolutionary properties of HB stars have to be revisited in order to account for rotation-driven structural variations: faster Main Sequence rotators delay the He flash increasing the mass-size Mc of the He core at the flash and loosing a greater amount of mass during the Red Giant stage.

The range of V - R colors for a cluster of E and S0 galaxies as a function of redshift

The expected (V - R) color distribution for a centrally condensed, relaxed cluster of E and S0 galaxies has been calculated as a function of redshift. Because of the differences in the ultraviolet spectra of E and S0 galaxies, which are correlated with absolute magnitude, the spread in (V - R) colors for such a cluster becomes increasingly wide for increasing redshift. This effect becomes pronounced for redshifts of 0.4 and beyond. Thus evidence for the color evolution of cluster galaxies will be seen as an additional broadening of the color distribution.

Neon color spreading and structural information measures.

This article presents a study on Van Tuijl’s (1975) neon effect. The neon effect can be described as an illusory spreading of color around the colored elements of an otherwise black line pattern. The observer has a strong impression of colored light projected onto a lattice of black lines. The hypothesis is advanced that the neon effect will only result if the structural relationships between black and colored line elements in the pattern are such that a neon interpretation is the most efficient interpretation that can be given of the pattern. The necessity of this approach to the neon phenomenon emanates from the inadequacy of alternative, more simple, explanations, such as aberrations of peripheral perceptual mechanisms or the presence in the pattern of easily definable stimulus features. To subject the hypothesis proposed above to experimental test, a precise quantification of its central concept, the efficiency of pattern interpretations, is needed. To that end, Leeuwenberg’s (1971) coding language for sequential patterns is introduced. By means of the coding language, pattern interpretations can be represented in a pattern code, the length of which is inversely proportional to the efficiency of the interpretation coded. Several possible interpretations of color differences between the elements of line patterns are discussed, and it is shown how the efficiency of each of them can be determined. Next, in two experiments, the efficiency of the neon interpretationrelative to that of alternative interpretations of color differences in line patterns is varied, by manipulating the structural relations between black and colored line elements, and the dependency of the neon effect on the relative efficiency of the neon interpretation is demonstrated. Implications of the findings are discussed.

A new visual illusion: Neonlike color spreading and complementary color induction between subjective contours

A new visual illusion is described as a neonlike spreading of color between subjective contours. Spreading of an actually present color as well as spreading of a complementary color appear to be possible. Spreading of brightness can be demonstrated also. Two related classes of illusions are mentioned and some indications of central factors involved in the effect are discussed.

Selection of cultivars for soft wheat quality. 1. Tests for softness in flour

Cultivars are not always placed in the same order in respect of soft wheat quality when grain from different trials is examined. This is largely because the relative importance of the underlying components varies from place to place and from year to year. The hydrophilic components-damaged starch, protein, and fibrous material-are the principal features limiting soft flour quality as they affect water absorption, flour colour, and cookie spread. Of the tests most commonly applied to flour, the water absorption as measured by the Brabender Farinograph appears to provide the most useful single test for soft flour quality.