Efficacy and Validity of Percutaneous Transhepatic Gallbladder Drainage as a Bridge to Surgery for Octogenarian and Older Patients With Acute Cholecystitis: A Single-Center Retrospective Observational Study in Japan.

Background: Japan currently has a super-aged society, with a rapid increase in elderly patients in need of medical care. Determining treatment strategies for acute cholecystitis (AC) in very elderly patients with various comorbidities is often difficult. Although percutaneous cholecystostomy (PC) is a less-invasive treatment option, its impact on subsequent surgery remains debatable.

How many surfaces can you distinguish by color? Real environmental lighting increases discriminability of surface colors.

Color supports object identification. However, two objects that differ in color under one light can appear indiscriminable under a second light, a phenomenon known as illuminant metamerism. Past studies evaluated the frequency of illuminant metamerism only under single, uniform illuminants.

A deep new look at color.

Bowers et al. counter deep neural networks (DNNs) as good models of human visual perception. From our color perspective we feel their view is based on three misconceptions: A misrepresentation of the state-of-the-art of color perception; the type of model required to move the field forward; and the attribution of shortcomings to DNN research that are already being resolved.

Color and gloss constancy under diverse lighting environments.

When we look at an object, we simultaneously see how glossy or matte it is, how light or dark, and what color. Yet, at each point on the object's surface, both diffuse and specular reflections are mixed in different proportions, resulting in substantial spatial chromatic and luminance variations. To further complicate matters, this pattern changes radically when the object is viewed under different lighting conditions.

Task-dependent extraction of information from videos of iridescent and glossy samples.

We present an exploratory study on iridescence that revealed systematic differences in the perceptual clustering of glossy and iridescent samples that was driven by instructions to focus on either the material or the color properties of the samples. Participants' similarity ratings of pairs of video stimuli, showing the samples from multiple views, were analyzed using multidimensional scaling (MDS), and differences between the MDS solutions for the two tasks were consistent with flexible weighting of information from different views of the samples. These findings point to ecological implications for how viewers perceive and interact with the color-changing properties of iridescent objects.

Modeling surface color discrimination under different lighting environments using image chromatic statistics and convolutional neural networks.

We modeled discrimination thresholds for object colors under different lighting environments [J. Opt. Soc.

Invariant categorical color regions across illuminant change coincide with focal colors.

Are there regions in a color space where color categories are invariant across illuminant changes? If so, what characteristics make them more stable than other regions? To address these questions, we asked observers to give a color name to 424 colored surfaces, presented one at a time, under various chromatic illuminants. Results showed a high degree of categorical color constancy, especially under illuminants that occur in the natural environment. It was also shown that surfaces selected as a focal color (the best example of a color category) are more resistant to illuminant change than nonfocal color samples.

Hyperspectral characterization of natural lighting environments.

Lights are primary drivers of some crucial biological functions including vision and regulation of circadian rhythm. To understand the light exposure pattern that we experience in a daily life, many past studies measured the spectral composition of natural daylight and artificial lighting. The aim of this book chapter is to introduce a novel method to characterize directional spectral variation in natural lighting environments.

Spectral measurement of daylights and surface properties of natural objects in Japan.

We present a spectral dataset of daylights and surface reflectances and transmittances of natural objects measured in Japan. Daylights were measured under the sun and under shadow from dawn to dusk on four different days to capture their temporal spectral transition. We separately measured daylight spectra at five different locations (including an open space and a forest) with minimum time difference to reveal whether a local environment alters daylight spectra reaching the ground.

Luminosity thresholds of colored surfaces are determined by their upper-limit luminances empirically internalized in the visual system.

We typically have a fairly good idea whether a given object is self-luminous or illuminated, but it is not fully understood how we make this judgment. This study aimed to identify determinants of the luminosity threshold, a luminance level at which a surface begins to appear self-luminous. We specifically tested a hypothesis that our visual system knows the maximum luminance level that a surface can reach under the physical constraint that a surface cannot reflect more light than any incident light and applies this prior to determine the luminosity thresholds.

Human color constancy based on the geometry of color distributions.

The physical inputs to our visual system are dictated by the interplay between lights and surfaces; thus, for surface color to be stably perceived, the influence of the illuminant must be discounted. To reveal our strategy to infer the illuminant color, we conducted three psychophysical experiments designed to test our optimal color hypothesis that we internalize the physical color gamut under various illuminants and apply the prior to estimate the illuminant color. In each experiment, we presented 61 hexagons arranged without spatial gaps, where the surrounding 60 hexagons were set to have a specific shape in their color distribution.

Explaining #theShoe based on the optimal color hypothesis: The role of chromaticity vs. luminance distribution in an ambiguous image.

The image of #theShoe is a derivative image of #theDress which induces vastly different color experiences across individuals. The majority of people perceive that the shoe has grey leather with turquoise laces, but others report pink leather with white laces. We hypothesized #theShoe presents a problem of color constancy, where different people estimate different illuminants falling onto the shoe.

Hyperspectral environmental illumination maps: characterizing directional spectral variation in natural environments.

Objects placed in real-world scenes receive incident light from every direction, and the spectral content of this light may vary from one direction to another. In computer graphics, environmental illumination is approximated using maps that specify illumination at a point as a function of incident angle. However, to-date, existing public databases of environmental illumination specify only three colour channels (RGB).

The Neon Fruit Illusion: A Fresh Recipe for Colour Science Demonstrations.

At this year's European Conference on Visual Perception, we debuted a novel colour science demonstration-and visual illusion-for the Un mare di illusioni exhibition. Under carefully curated lighting conditions, cycling through different illuminant spectra, certain fruits and vegetables appear to glow and dim in an unchanging environment. Encouraged by the positive reactions it received, and the numerous and specific questions from conference delegates, we here describe what this illusion is, why we believe it may work, and how this particular low-cost setup may be assembled and demonstrated for the amazement of your friends, students, and members of the public.

Discrimination of spectral reflectance under environmental illumination.

Color constancy is the ability to recover a stable perceptual estimate of surface reflectance, regardless of the lighting environment. However, we know little about how observers make judgments of the surface color of glossy objects, particularly in complex lighting environments that introduce complex spatial patterns of chromatic variation across an object's surface. To address this question, we measured thresholds for reflectance discrimination using computer-rendered stimuli under environmental illumination.

Color Constancy in Two-Dimensional and Three-Dimensional Scenes: Effects of Viewing Methods and Surface Texture.

There has been debate about how and why color constancy may be better in three-dimensional (3-D) scenes than in two-dimensional (2-D) scenes. Although some studies have shown better color constancy for 3-D conditions, the role of specific cues remains unclear. In this study, we compared color constancy for a 3-D miniature room (a real scene consisting of actual objects) and 2-D still images of that room presented on a monitor using three viewing methods: binocular viewing, monocular viewing, and head movement.

Understanding individual differences in color appearance of "#TheDress" based on the optimal color hypothesis.

We performed a theoretical analysis based on our optimal color hypothesis to explain why "#TheDress" image had a different color appearance for different observers (observer-dependent perception). We then carried out an experiment to test the hypothesis derived from the aforementioned theoretical analysis. In the optimal color hypothesis, the visual system picks the optimal color distribution that provides the best fit to the luminance distribution at a scene.

No effects of surround complexity on brown induction.

A yellow stimulus turns brown when it is made sufficiently darker than its surroundings. Most previous studies have used simple contiguous surround stimuli to induce brown, so we know little about how brown induction may be controlled by more distant and more complex surround features. We begin to address this issue by varying the complexity of two configurations of achromatic surround stimuli.

Effects of surrounding stimulus properties on color constancy based on luminance balance.

The visual system needs to discount the influence of an illuminant to achieve color constancy. Uchikawa et al. [J.

Dichoptic perception of brown.

Two experiments assessed mechanisms underlying brown induction by presenting a foveal target disk and concentric annular surround stimuli that varied in contrast relative to larger backgrounds. Stimuli were presented under monocular, binocular, and dichoptic viewing conditions. Observers adjusted the luminance of the target disk to a criterion brown level.

Influence of surround proximity on induction of brown and darkness.

A bright white surround makes a yellow long-wavelength target look both browner and darker. We explored the parallel between these two types of induction by examining their dependence on the proximity of the bright surround to the target at two different time scales with 27 ms and 1 s stimulus durations. We assessed (a) brown induction by adjustment of target luminance to perceptual brown and yellow boundaries and (b) darkness induction by a successive matching procedure.