Color Correspondences in Chemosensation
Alan R. Hirsch in Nutrition and Sensation, 2023
Before we go any further, it is important to introduce some basic concepts from the field of color perception research. Color is defined as a perceptual response to the visible spectrum of light (the distribution of light power as a function of the wavelength) reflected or emitted by the surface of an object. This signal interacts in the eye with the L, M, and S cones in the retina, these names referring to the long-, middle-, and short-wavelength sensitive cones, respectively. These signals are then ultimately transmitted to the visual cortex by the optic nerve (Zeki 1993). Eventually, the human observer assigns a color to this signal. Such arguments have led some researchers to suggest that color is not an intrinsic property of the surface of an object, since if the light source changes, so too does the color of its surface (Melendez-Martinez, Vicario, and Heredia 2005; Shepherd 2012). The perception of color, then, is a complex phenomenon that depends on the properties of an object in a given illumination environment, the characteristics of the perceiving eye and brain, and the angle of illumination and viewing.
Treatment Planning for Successful Whitening
Linda Greenwall in Tooth Whitening Techniques, 2017
There are three dimensions of color: hue, chroma, and value (Miller 1987). Hue is the pigment—most commonly called the color. Chroma denotes the strength or concentration of a hue and may also be referred as the color saturation. Value is the relative whiteness or blackness of a color and is a qualitative assessment of the gray component. Value is independent of hue or chroma; in dental shade matching, it is the most important of the three dimensions of color. Value should be selected first. Rearrangement of the color guide from the lightest to the darkest shade is recommended to avoid distractions. Hue selection should be undertaken next. The basic hue can be best seen in the middle and cervical thirds. Chroma variations can be perceived within the same tooth. The cervical third usually has a higher chroma and a more saturated hue than the middle third. The incisal third often has a lower value when compared with the middle and cervical thirds.
MemoryBox
Paul A. Rodgers in Design for People Living with Dementia, 2022
To counter the loss of physical dexterity in users, all media selections were aligned horizontally and positioned towards the base of the screen for easy and comfortable access. In a trial by Jin et al. (2007), zero spacing between selections reported the lowest accuracy and preference among participants. Therefore, media tiles were spaced 10 mm apart. According to Bernard et al. (2001), older people perceive sans serif fonts more easily than serif fonts. When presenting text to the elderly on a screen, a minimum font size of 14 points should be considered, as individual characters at this size are easier to perceive. Based on this knowledge, MemoryBox employed a 30-point sans serif font. MemoryBox consisted of a black background to provide contrast to the media tiles which used four colours spaced evenly on a colour wheel (referred to as “tetrad colours”). Complementary colours (colours at opposite ends of a colour wheel) were placed next to each other (blue–orange, green–pink), dividing analogous ones (colours next to each other on a colour wheel: blue–green, orange–pink), to make them easier for older people to perceive and differentiate.
The intraocular staining potential of anthocyanins and their retinal biocompatibility: a preclinical study
Published in Cutaneous and Ocular Toxicology, 2018
Lan-Hsin Chuang, An-Lun Wu, Nan-Kai Wang, Kuan-Jen Chen, Laura Liu, Yih-Shiou Hwang, Ling Yeung, Wei-Chi Wu, Chi-Chun Lai
Anthocyanins are well-known compounds with beneficial effects on human health, and research in many fields has revealed their antioxidant and cytoprotective properties. However, few studies have examined their surgical application and ocular protection capacity. In the present study of five natural anthocyanin dyes, three dyes (Del, Peo, and Lut) exhibited efficacy and safety in vitro and in vivo. Photoimpact software was used to quantitatively analyse the colour levels with the RGB colour model to characterize the different anthocyanin dyes at different concentrations. In theory, red, green, and blue are the three additive primary colours. Photoimpact software is based on the RGB colour model, the name of which is derived from the initials of these three primary colours. According to the additive colour model, red, green, and blue light are added together in different ways to represent a broad array of colours. Furthermore, for numeric representations, each colour is expressed as an RGB triplet (r, g, and b), each component of which ranges from zero to a defined maximum value. With the creative application of anthocyanins to ocular tissue, all three dyes showed darker and different staining colours with lower RGB triplet values that also differed from the colour of ICG staining the lens capsule and ILM on the retinal surface, as indicated by the Photoimpact software. Since the colour of the human fundus is yellowish red, the blue colour of Del recommended it as the preferred dye to show the contrast and it is presumed to be similar to TB or BBG for vitreoretinal surgery.
Effects of Hatha yoga on cognitive functions in the elderly: a cross-sectional study
Published in Libyan Journal of Medicine, 2022
Souad Baklouti, Asma Aloui, Hana Baklouti, Nizar Souissi, Mohamed Jarraya
The French adaptation of the Victoria Stroop test [26] is based on Strauss et al.’s instructions [27]. Twenty-four stimuli were presented on three 35.5 × 10 cm cards, each containing six rows of four items. Four colors were used: blue, green, yellow, and red. Card 1 (C) consisted of colored bars (Color task), card 2 (M) displayed words written in different colors (Word task), and card 3 (I) presented color names written in a different color (e.g. the word ‘yellow’ was printed in red) (Color-Word task). Words and color bars were ordered horizontally on the cards. Participants completed three tasks. Firstly, they were required to read the names of the colors given on card 1. Then, they were asked to read the colored words on card 2. In the final task, they were asked to name the color used for each colored word displayed on card 3. The third task is considered as an ‘interference’ task because it reflects the extent to which participants are able to ‘shift perceptual set to conform to changing demands’ [28]. Participants were required to respond as rapidly as possible.
Low dose-rate irradiation with [3H]-labelled valine to selectively target hypoxic cells in a human colorectal cancer xenograft model
Published in Acta Oncologica, 2018
Stine Gyland Mikalsen, Lars Tore Gyland Mikalsen, Joe Alexander Sandvik, Eva-Katrine Aarnes, Siri Fenne, Kjersti Flatmark, Heidi Lyng, Nina Frederike Jeppesen Edin, Erik Olai Pettersen
Hypoxia was automatically identified through the following steps: A correction for vignetting was performed for each individual frame, using a least-square parabolic fit to the frame with all saturated (stained) pixels replaced by neighbouring values using morphological reconstruction. Following this, pixels that were dark, saturated and red were identified as pimonidazole, as described previously in [22]. Briefly, dark pixels were segmented from the blue channel of the RGB colour space. Saturation and colour were determined using the Hue-Saturation-Value colour space. The saturation channel was segmented. Red colour was determined using a fixed threshold (Hue =0° ± 10%). Light morphological processing (radius 6.2–24.8 µm) was performed during these steps to prevent fragmentation of the hypoxic regions due to noise and granular stains.
Related Knowledge Centers
- Absorption
- Cone Cell
- Reflectance
- Trichromacy
- Visual Perception
- Ultraviolet
- Brain
- Emission Spectrum
- Spectral Sensitivity
- Color Model