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Tone Mapping
Tone mapping is a technique used in image processing and computer graphics to map one set of colors to another to approximate the appearance of high-dynamic-range (HDR) images in a medium that has a more limited dynamic range. Print-outs, CRT or LCD monitors, and projectors all have a limited dynamic range that is inadequate to reproduce the full range of light intensities present in natural scenes. Tone mapping addresses the problem of strong contrast reduction from the scene radiance to the displayable range while preserving the image details and color appearance important to appreciate the original scene content. Inverse tone mapping is the inverse technique that allows to expand the luminance range, mapping a low dynamic range image into a higher dynamic range image. It is notably used to upscale SDR videos to HDR videos. Background The introduction of film-based photography created issues since capturing the wide dynamic range of lighting from the real world on a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contrast (vision)
Contrast is the difference in luminance or color that makes an object (or its representation in an image or display) visible against a background of different luminance or color. The human visual system is more sensitive to contrast than to absolute luminance; thus, we can perceive the world similarly despite significant changes in illumination throughout the day or across different locations. The maximum contrast of an image is termed the contrast ratio or dynamic range. In images where the contrast ratio approaches the maximum possible for the medium, there is a ''conservation of contrast''. In such cases, increasing contrast in certain parts of the image will necessarily result in a decrease in contrast elsewhere. Brightening an image increases contrast in darker areas but decreases it in brighter areas; conversely, darkening the image will have the opposite effect. Bleach bypass reduces contrast in the darkest and brightest parts of an image while enhancing luminance contr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Old Saint Pauls 1
Old or OLD may refer to: Places *Old, Baranya, Hungary *Old, Northamptonshire, England *Old Street station, a railway and tube station in London (station code OLD) *OLD, IATA code for Old Town Municipal Airport and Seaplane Base, Old Town, Maine, United States People *Old (surname) Music *OLD (band), a grindcore/industrial metal group * ''Old'' (Danny Brown album), a 2013 album by Danny Brown * ''Old'' (Starflyer 59 album), a 2003 album by Starflyer 59 * "Old" (song), a 1995 song by Machine Head *"Old", a 1982 song by Dexys Midnight Runners from ''Too-Rye-Ay'' Other uses * ''Old'' (film), a 2021 American thriller film *''Oxford Latin Dictionary'' *Online dating *Over-Locknut Distance (or Dimension), a measurement of a bicycle wheel and frame See also *Old age *List of people known as the Old *''Old LP'', a 2019 album by That Dog * * *Olde, a list of people with the surname *Olds (other) Olds may refer to: People * The olds, a jocular and irreverent online nick ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exposure Compensation
Exposure compensation is a technique for adjusting the exposure indicated by a photographic exposure meter, in consideration of factors that may cause the indicated exposure to result in a less-than-optimal image. Factors considered may include unusual lighting distribution, variations within a camera system, filters, non-standard processing, or intended underexposure or overexposure. Cinematographers may also apply exposure compensation for changes in shutter angle or film speed (as exposure index), among other factors. Many digital cameras have a display setting and possibly a physical dial whereby the photographer can set the camera to either over or under expose the subject by up to three f-stops (f-numbers) in 1/3 stop intervals. Each number on the scale (1,2,3) represents one f-stop, decreasing the exposure by one f-stop will halve the amount of light reaching the sensor. The dots in between the numbers represent 1/3 of an f-stop. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ansel Adams
Ansel Easton Adams (February 20, 1902 – April 22, 1984) was an American landscape photographer and environmentalist known for his Monochrome photography, black-and-white images of the American West. He helped found Group f/64, an association of photographers advocating "pure" photography which favored Deep focus, sharp focus and the use of the full Dynamic range#Photography, tonal range of a photograph. He and Fred R. Archer, Fred Archer developed a system of image-making called the Zone System, a method of achieving a desired final print through a technical understanding of how the tonal range of an image is the result of choices made in Exposure (photography), exposure, Negative (photography), negative development, and Photographic printing, printing. Adams was a life-long advocate for Nature conservation, environmental conservation, and his photographic practice was deeply entwined with this advocacy. At age 14, he was given his first camera during his first visit to Yosemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Appearance Model
A color appearance model (CAM) is a mathematical model that seeks to describe the perceptual aspects of human color vision, i.e. viewing conditions under which the appearance of a color does not tally with the corresponding physical measurement of the stimulus source. (In contrast, a color model defines a coordinate space to describe colors, such as the RGB and CMYK color models.) A uniform color space (UCS) is a color model that seeks to make the color-making attributes perceptually uniform, i.e. identical spatial distance between two colors equals identical amount of perceived color difference. A CAM under a fixed viewing condition results in a UCS; a UCS with a modeling of variable viewing conditions results in a CAM. A UCS without such modelling can still be used as a rudimentary CAM. Background Color appearance Color originates in the mind of the observer; “objectively”, there is only the spectral power distribution of the light that meets the eye. In this sense ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Local Contrast Enhancement
Local may refer to: Geography and transportation * Local (train), a train serving local traffic demand * Local, Missouri, a community in the United States Arts, entertainment, and media * ''Local'' (comics), a limited series comic book by Brian Wood and Ryan Kelly * ''Local'' (novel), a 2001 novel by Jaideep Varma * ''The Local'' (film), a 2008 action-drama film * ''The Local'', English-language news websites in several European countries Computing * .local, a network address component Mathematics * Local property, a property which occurs on ''sufficiently small'' or ''arbitrarily small'' neighborhoods of points * Local ring, type of ring in commutative algebra Other uses * Pub, a drinking establishment, known as a "local" to its regulars See also * * * Local group (other) * Locale (other) * Localism (other) * Locality (other) * Localization (other) * Locus (other) * Lokal (other) Lokal may refer to: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unsharp Masking
Unsharp masking (USM) is an image sharpening technique, first implemented in darkroom photography, but now commonly used in digital image processing software. Its name derives from the fact that the technique uses a blurred, or "unsharp", negative image to create a mask of the original image. The unsharp mask is then combined with the original positive image, creating an image that is less blurry than the original. The resulting image, although clearer, may be a less accurate representation of the image's subject. In the context of signal processing, an unsharp mask is generally a linear or nonlinear filter that amplifies the high-frequency components of a signal. Photographic darkroom unsharp masking For the photographic darkroom process, a large-format glass plate negative is contact-copied onto a low-contrast film or plate to create a positive image. However, the positive copy is made with the copy material in contact with the back of the original, rather than emulsio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Checker Shadow Illusion
The checker shadow illusion is an optical illusion published by Edward H. Adelson, professor of vision science at Massachusetts Institute of Technology, MIT, in 1995. Description The image depicts a checkerboard with light and dark squares, partly shadowed by another object. The optical illusion is that the area labeled A appears to be a darker color than the area labeled B. However, within the context of the two-dimensional image, they are of identical brightness, i.e., they would be printed with identical mixtures of ink, or displayed on a screen with pixels of identical color. Related illusions While being one of the most well-known Contrast_effect, contrast illusions, there are similar effects which cause two regions of identical color to appear differently depending on context: * The Cornsweet illusion creates a boundary between two identically-shaded regions with a discontinuous gradient, resulting in the opposing sides appearing to be different. * The Chubb illusion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anchoring Theory Of Lightness Perception
An anchor is a device, normally made of metal, used to secure a vessel to the bed of a body of water to prevent the craft from drifting due to wind or current. The word derives from Latin ', which itself comes from the Greek (). Anchors can either be temporary or permanent. Permanent anchors are used in the creation of a mooring, and are rarely moved; a specialist service is normally needed to move or maintain them. Vessels carry one or more temporary anchors, which may be of different designs and weights. A sea anchor is a drag device, not in contact with the seabed, used to minimize drift of a vessel relative to the water. A drogue is a drag device used to slow or help steer a vessel running before a storm in a following or overtaking sea, or when crossing a bar in a breaking sea. Anchoring Anchors achieve holding power either by "hooking" into the seabed, or weight, or a combination of the two. The weight of the anchor chain can be more than that of the anch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gradient Domain High Dynamic Range Compression
Gradient domain image processing, also called Poisson image editing, is a type of digital image processing that operates directly on the differences between neighboring pixels, rather than on the pixel values. Mathematically, an image gradient represents the derivative of an image, so the goal of gradient domain processing is to construct a new image by integrating the gradient, which requires solving Poisson's equation. Overview Processing images in the gradient domain is a two-step process. The first step is to choose an image gradient. This is often extracted from one or more images and then modified, but it can also be obtained through other means. For example, some researchers have explored the advantages of users painting directly in the gradient domain, while others have proposed sampling a gradient directly from a camera sensor. The second step is to solve Poisson's equation to find a new image that can produce the gradient from the first step. An exact solution often doe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
