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Retinex
Color constancy is an example of subjective constancy and a feature of the human color perception system which ensures that the perceived color of objects remains relatively constant under varying illumination conditions. A green apple for instance looks green to us at midday, when the main illumination is white sunlight, and also at sunset, when the main illumination is red. This helps us identify objects. History Ibn al-Haytham gave an early explanation of color constancy by observing that the light reflected from an object is modified by the object's color. He explained that the quality of the light and the color of the object are mixed, and the visual system separates light and color. He writes:Again the light does not travel from the colored object to the eye unaccompanied by the color, nor does the form of the color pass from the colored object to the eye unaccompanied by the light. Neither the form of the light nor that of the color existing in the colored object ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Perception
Color vision, a feature of visual perception, is an ability to perceive differences between light composed of different frequencies independently of light intensity. Color perception is a part of the larger visual system and is mediated by a complex process between neurons that begins with differential stimulation of different types of photoreceptors by light entering the eye. Those photoreceptors then emit outputs that are propagated through many layers of neurons ultimately leading to higher cognitive functions in the brain. Color vision is found in many animals and is mediated by similar underlying mechanisms with common types of biological molecules and a complex history of the evolution of color vision within different animal taxa. In primates, color vision may have evolved under selective pressure for a variety of visual tasks including the foraging for nutritious young leaves, ripe fruit, and flowers, as well as detecting predator camouflage and emotional states in other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hot Air Balloon - Color Constancy
Hot commonly refers refer to: *Heat, a hot temperature *Pungency, in food, a spicy or hot quality Hot or HOT may also refer to: Places *Hot district, a district of Chiang Mai province, Thailand ** Hot subdistrict, a sub-district of Hot District, Thailand ** Tha Kham, Chiang Mai, also known as Hot, a town in Hot District, Chiang Mai province, Thailand * Hot, Albania, a village in the Malësi e Madhe municipality, Shkodër County, Albania Music * H.O.T. pronounced "H. O. T.", (High-Five of Teenagers), a South Korean boy band * Hawaii Opera Theatre, an opera company in Honolulu, Hawaii * Hot (American vocal group), best known for 1977 hit "Angel in Your Arms" 1976–1980 Albums * ''Hot'' (James Brown album) or the title song (see below), 1976 * ''Hot'' (Freda Payne album), 1979 * ''Hot'' (Paul Bley album), 1985 * ''Hot'' (Half Japanese album), 1995 * ''Hot'' (Squirrel Nut Zippers album), 1996 * ''Hot'' (Mel B album), 2000 * ''Hot'' (Taeyang EP), or the title song, 2008 * ''Hot'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Receptive Field
The receptive field, or sensory space, is a delimited medium where some physiological stimuli can evoke a sensory neuronal response in specific organisms. Complexity of the receptive field ranges from the unidimensional chemical structure of odorants to the multidimensional spacetime of human visual field, through the bidimensional skin surface, being a receptive field for touch perception. Receptive fields can positively or negatively alter the membrane potential with or without affecting the rate of action potentials. A sensory space can be dependent of an animal's location. For a particular sound wave traveling in an appropriate transmission medium, by means of sound localization, an auditory space would amount to a reference system that continuously shifts as the animal moves (taking into consideration the space inside the ears as well). Conversely, receptive fields can be largely independent of the animal's location, as in the case of place cells. A sensory space can also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Cortex
The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and then reaches the visual cortex. The area of the visual cortex that receives the sensory input from the lateral geniculate nucleus is the primary visual cortex, also known as visual area 1 ( V1), Brodmann area 17, or the striate cortex. The extrastriate areas consist of visual areas 2, 3, 4, and 5 (also known as V2, V3, V4, and V5, or Brodmann area 18 and all Brodmann area 19). Both hemispheres of the brain include a visual cortex; the visual cortex in the left hemisphere receives signals from the right visual field, and the visual cortex in the right hemisphere receives signals from the left visual field. Introduction The primary visual cortex (V1) is located in and around the calcarine fissure in the occipital lobe. Each h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichoptic Presentation
Dichoptic () is viewing a separate and independent field by each eye. In dichoptic presentation, stimulus A is presented to the left eye and a different stimulus B is presented to the right eye. Dichoptic moving images and games Dichoptic perceptual training has been tested in order to stimulate the simultaneous use of both eyes. In recent years, efforts have been made to develop methods of perceptual learning in vision therapy for treating interocular suppression and improving binocular vision in patients with anisometropic or strabismic amblyopia. In these methods, data has been presented within a virtual reality environment, and has also been presented using a computer screen or handheld device together with matched active or passive filter glasses for the user, which present a different image to each eye. In order to balance the input of visual information from each eye to the brain, the data is presented in such a manner that the user needs to use both eyes to see the comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Geniculate Nucleus
In neuroanatomy, the lateral geniculate nucleus (LGN; also called the lateral geniculate body or lateral geniculate complex) is a structure in the thalamus and a key component of the mammalian visual pathway. It is a small, ovoid, Anatomical terms of location#Dorsal_and_ventral, ventral projection of the thalamus where the thalamus connects with the optic nerve. There are two LGNs, one on the left and another on the right side of the thalamus. In humans, both LGNs have six layers of neurons (grey matter) alternating with optic fibers (white matter). The LGN receives information directly from the ascending retinal ganglion cells via the optic tract and from the reticular activating system. Neurons of the LGN send their axons through the optic radiation, a direct pathway to the primary visual cortex. In addition, the LGN receives many strong feedback connections from the primary visual cortex. In humans as well as other mammals, the two strongest pathways linking the eye to the bra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parvocellular Cell
In neuroscience, parvocellular cells, also called P-cells, are neurons located within the parvocellular layers of the lateral geniculate nucleus (LGN) of the thalamus. Their name comes , due to the small size of the cell compared to the larger magnocellular cells. Phylogenetically, parvocellular neurons are more modern than magnocellular ones. Function The parvocellular neurons of the visual system receive their input from midget cells, a type of retinal ganglion cell, whose axons comprise the optic tract. These synapses occur in one of the four dorsal parvocellular layers of the lateral geniculate nucleus. The information from each eye is kept separate at this point, and continues to be segregated until processing in the visual cortex. The electrically-encoded visual information leaves the parvocellular cells via relay cells in the optic radiations, traveling to the primary visual cortex layer 4C-β. The parvocellular neurons are sensitive to colour, and are more ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatic Adaptation
Chromatic adaptation is the human visual system’s ability to adjust to changes in illumination in order to preserve the appearance of object colors. It is responsible for the stable appearance of object colors despite the wide variation of light which might be reflected from an object and observed by our eyes. A chromatic adaptation transform (CAT) function emulates this important aspect of color perception in color appearance models. An object may be viewed under various conditions. For example, it may be illuminated by sunlight, the light of a fire, or a harsh electric light. In all of these situations, human vision perceives that the object has the same color: a red apple always appears red, whether viewed during the day or at night (if the red apple is illuminated as rods in our eyes do not see red). On the other hand, a camera with no adjustment for light may register the apple as having varying color. This feature of the visual system is called chromatic adaptation, or color ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retina
The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception. The retina serves a function which is in many ways analogous to that of the photographic film, film or image sensor in a camera. The neural retina consists of several layers of neurons interconnected by Chemical synapse, synapses and is supported by an outer layer of pigmented epithelial cells. The primary light-sensing cells in the retina are the photoreceptor cells, which are of two types: rod cell, rods and cone cell, cones. Rods function mainly in dim light and provide monochromatic vision. Cones function in well-lit conditions and are responsible fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflectance
The reflectance of the surface of a material is its effectiveness in reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the response of the electronic structure of the material to the electromagnetic field of light, and is in general a function of the frequency, or wavelength, of the light, its polarization, and the angle of incidence. The dependence of reflectance on the wavelength is called a ''reflectance spectrum'' or ''spectral reflectance curve''. Mathematical definitions Hemispherical reflectance The ''hemispherical reflectance'' of a surface, denoted , is defined as R = \frac, where is the radiant flux ''reflected'' by that surface and is the radiant flux ''received'' by that surface. Spectral hemispherical reflectance The ''spectral hemispherical reflectance in frequency'' and ''spectral hemispherical reflectance in wavelength'' of a surface, denoted and respectively, are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SPIE
SPIE (formerly the Society of Photographic Instrumentation Engineers, later the Society of Photo-Optical Instrumentation Engineers) is an international not-for-profit professional society for optics and photonics technology, founded in 1955. It organizes technical conferences, trade exhibitions, and continuing education programs for researchers and developers in the light-based fields of physics, including: optics, photonics, and imaging engineering. The society publishes peer-reviewed scientific journals, conference proceedings, monographs, tutorial texts, field guides, and reference volumes in print and online. SPIE is especially well-known for Photonics West, one of the laser and photonics industry's largest combined conferences and tradeshows which is held annually in San Francisco. SPIE also participates as partners in leading educational initiatives, and in 2020, for example, provided more than $5.8 million in support of optics education and outreach programs around the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
