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Alpha Compositing
In computer graphics, alpha compositing or alpha blending is the process of combining one image with a background to create the appearance of partial or full transparency. It is often useful to render picture elements (pixels) in separate passes or layers and then combine the resulting 2D images into a single, final image called the composite. Compositing is used extensively in film when combining computer-rendered image elements with live footage. Alpha blending is also used in 2D computer graphics to put rasterized foreground elements over a background. In order to combine the picture elements of the images correctly, it is necessary to keep an associated '' matte'' for each element in addition to its color. This matte layer contains the coverage information—the shape of the geometry being drawn—making it possible to distinguish between parts of the image where something was drawn and parts that are empty. Although the most basic operation of combining two images is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hue Alpha Falloff
In color theory, hue is one of the properties (called Color appearance model#Color appearance parameters, color appearance parameters) of a color, defined in the CIECAM02 model as "the degree to which a Stimulus (physiology)#vision, stimulus can be described as similar to or different from stimuli that are described as red, Orange (colour), orange, yellow, green, blue, violet (color), violet," within certain theories of color vision. Hue can typically be represented quantitatively by a single number, often corresponding to an angular position around a central or neutral point or axis on a color space coordinate diagram (such as a chromaticity diagram) or color wheel, or by its dominant wavelength or by that of its complementary color. The other color appearance parameters are colorfulness, Saturation (color theory), saturation (also known as intensity or chroma), lightness, and brightness. Usually, colors with the same hue are distinguished with adjectives referring to their l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Porter (Pixar)
Thomas K. Porter is the senior vice president of production strategy at Pixar and one of the studio's founding employees. Professional life After receiving a master's degree in computer science at Stanford University in 1975, Porter worked at the National Institutes of Health on computer visualization of molecular models and wrote software at Ampex for the world's first commercial digital paint program, AVA. Porter joined Lucasfilm's Computer Research and Development Division in early 1981. He and Tom Duff, another Lucasfilm employee, developed a new approach to compositing images; their 1984 paper, "Compositing Digital Images", is " e seminal work on an algebra for image compositing", according to Keith Packard. " Porter-Duff compositing" is now a key technique in computer graphics. Porter is listed as one of Pixar's 40 founding employees at the time of its spin-out as a corporation with funding from Steve Jobs in 1986. Porter expanded on Robert L. Cook’s research into Mon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuple
In mathematics, a tuple is a finite sequence or ''ordered list'' of numbers or, more generally, mathematical objects, which are called the ''elements'' of the tuple. An -tuple is a tuple of elements, where is a non-negative integer. There is only one 0-tuple, called the ''empty tuple''. A 1-tuple and a 2-tuple are commonly called a singleton and an ordered pair, respectively. The term ''"infinite tuple"'' is occasionally used for ''"infinite sequences"''. Tuples are usually written by listing the elements within parentheses "" and separated by commas; for example, denotes a 5-tuple. Other types of brackets are sometimes used, although they may have a different meaning. An -tuple can be formally defined as the image of a function that has the set of the first natural numbers as its domain. Tuples may be also defined from ordered pairs by a recurrence starting from an ordered pair; indeed, an -tuple can be identified with the ordered pair of its first elements and its t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. The process of reducing the size of a data file is often referred to as data compression. In the context of data transmission, it is called source coding: encoding is done at the source of the data before it is stored or transmitted. Source coding should not be confused with channel coding, for error detection and correction or line coding, the means for mapping data onto a sig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blend Modes
Blend modes (alternatively blending modes or mixing modes) in digital image editing and computer graphics are used to determine how two Layers (digital image editing), layers are blended with each other. The default blend mode in most applications is simply to obscure the lower layer by covering it with whatever is present in the top layer (see alpha compositing); because each pixel has numerical values, there also are many other ways to blend two layers. Most Graphics software, graphics editing programs, such as Adobe Photoshop and GIMP, allow users to modify the basic blend modes, for example by applying different levels of opacity to the top "layer". The top "layer" is not necessarily a layer in the application; it may be applied with a painting or editing tool. The top "layer" also is called the "blend layer" and the "active layer". In the formulas shown on this page, values go from 0.0 (black) to 1.0 (white). ''Normal'' blend mode This is the standard blend mode which uses th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filter (signal Processing)
In signal processing, a filter is a device or process that removes some unwanted components or features from a Signal (electronics), signal. Filtering is a class of signal processing, the defining feature of filters being the complete or partial suppression of some aspect of the signal. Most often, this means removing some frequency, frequencies or frequency bands. However, filters do not exclusively act in the frequency domain; especially in the field of image processing many other targets for filtering exist. Correlations can be removed for certain frequency components and not for others without having to act in the frequency domain. Filters are widely used in electronics and telecommunication, in radio, television, audio recording, radar, control systems, music synthesis, image processing, computer graphics, and structural dynamics. There are many different bases of classifying filters and these overlap in many different ways; there is no simple hierarchical classification. Fil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interpolation
In the mathematics, mathematical field of numerical analysis, interpolation is a type of estimation, a method of constructing (finding) new data points based on the range of a discrete set of known data points. In engineering and science, one often has a number of data points, obtained by sampling (statistics), sampling or experimentation, which represent the values of a function for a limited number of values of the Dependent and independent variables, independent variable. It is often required to interpolate; that is, estimate the value of that function for an intermediate value of the independent variable. A closely related problem is the function approximation, approximation of a complicated function by a simple function. Suppose the formula for some given function is known, but too complicated to evaluate efficiently. A few data points from the original function can be interpolated to produce a simpler function which is still fairly close to the original. The resulting gai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clipping Path
A clipping path (or "deep etch") is a closed vector path, or shape, used to cut out a 2D image in image editing software. Anything inside the path will be included after the clipping path is applied; anything outside the path will be omitted from the output. Applying the clipping path results in a hard (aliased) or soft (anti-aliased) edge, depending on the image editor's capabilities By convention, the inside of the path is defined by its direction. Reversing the direction of a path reverses what is considered inside or outside. An ''inclusive path'' is one where what is visually "inside" the path corresponds to what will be preserved; an ''exclusive path'', of opposite direction, contains what is visually "outside" the path. By convention, a clockwise path that is non-self-intersecting is considered inclusive. A compound path results from the combination of multiple paths (inclusive and exclusive) and the Boolean operations that ultimately determine what the combined path c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Painter's Algorithm
The painter's algorithm (also depth-sort algorithm and priority fill) is an algorithm for Hidden-surface determination#Visible surface determination, visible surface determination in 3D computer graphics that works on a polygon, polygon-by-polygon basis rather than a pixel, pixel-by-pixel, row by row, or area by area basis of other hidden surface removal, Hidden-Surface Removal algorithms. The painter's algorithm creates images by sorting the polygons within the image by their depth and placing each polygon in order from the farthest to the closest object. The painter's algorithm was initially proposed as a basic method to address the Hidden-surface determination problem by Martin Newell (computer scientist), Martin Newell, Dick Newell, Richard Newell, and Tom Sancha in 1972, while all three were working at CADCentre. The name "painter's algorithm" refers to the technique employed by many painters where they begin by painting distant parts of a scene before parts that are nearer, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Compositing
In computer graphics, alpha compositing or alpha blending is the process of combining one image with a background to create the appearance of partial or full transparency. It is often useful to render picture elements (pixels) in separate passes or layers and then combine the resulting 2D images into a single, final image called the composite. Compositing is used extensively in film when combining computer-rendered image elements with live footage. Alpha blending is also used in 2D computer graphics to put rasterized foreground elements over a background. In order to combine the picture elements of the images correctly, it is necessary to keep an associated '' matte'' for each element in addition to its color. This matte layer contains the coverage information—the shape of the geometry being drawn—making it possible to distinguish between parts of the image where something was drawn and parts that are empty. Although the most basic operation of combining two images is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matte (filmmaking)
Mattes are used in photography and special effects filmmaking to combine two or more image elements into a single, final image. Usually, mattes are used to combine a foreground image (e.g. actors on a set) with a background image (e.g. a scenic vista or a starfield with planets). In this case, the matte is the background painting. In film and stage, mattes can be physically huge sections of painted canvas, portraying large scenic expanses of landscapes. In film, the principle of a matte requires masking certain areas of the film emulsion to selectively control which areas are exposed. However, many complex special-effects scenes have included dozens of discrete image elements, requiring very complex use of mattes and layering mattes on top of one another. For an example of a simple matte, the director may wish to depict a group of actors in front of a store, with a massive city and sky visible above the store's roof. There would be two images—the actors on the set, and the imag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transparency And Translucency
In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions are much larger than the wavelengths of the photons in question), the photons can be said to follow Snell's law. Translucency (also called translucence or translucidity) is the physical property of allowing light to pass through the material (with or without scattering of light). It allows light to pass through but the light does not necessarily follow Snell's law on the macroscopic scale; the photons may be scattered at either of the two interfaces, or internally, where there is a change in the index of refraction. In other words, a translucent material is made up of components with different indices of refraction. A transparent material is made up of components with a uniform index of refraction. Transparent materials appear clear, with t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
