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RGBA
RGBA stands for red green blue alpha. While it is sometimes described as a color space, it is actually a three-channel RGB color model supplemented with a fourth ''alpha channel''. Alpha indicates how opaque each pixel is and allows an image to be combined over others using alpha compositing, with transparent areas and anti-aliasing of the edges of opaque regions. The term does ''not'' define what RGB color space is being used. It also does not state whether or not the colors are premultiplied by the alpha value, and if they are it does not state what color space that premultiplication was done in. This means more information than just "RGBA" is needed to determine how to handle an image. In some contexts the abbreviation "RGBA" means a specific memory layout (called RGBA8888 below), with other terms such as "BGRA" used for alternatives. In other contexts "RGBA" means any layout. Representation In computer graphics, pixels encoding the RGBA color space information must ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RGBA Comp
RGBA stands for red green blue alpha. While it is sometimes described as a color space, it is actually a three-channel RGB color model supplemented with a fourth ''alpha channel''. Alpha indicates how opaque each pixel is and allows an image to be combined over others using alpha compositing, with transparent areas and anti-aliasing of the edges of opaque regions. The term does ''not'' define what RGB color space is being used. It also does not state whether or not the colors are premultiplied by the alpha value, and if they are it does not state what color space that premultiplication was done in. This means more information than just "RGBA" is needed to determine how to handle an image. In some contexts the abbreviation "RGBA" means a specific memory layout (called RGBA8888 below), with other terms such as "BGRA" used for alternatives. In other contexts "RGBA" means any layout. Representation In computer graphics, pixels encoding the RGBA color space information must be ... [...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 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portable Network Graphics
Portable Network Graphics (PNG, officially pronounced , colloquially pronounced ) is a raster-graphics file format that supports lossless data compression. PNG was developed as an improved, non-patented replacement for Graphics Interchange Format (GIF) — unofficially, the initials PNG stood for the recursive acronym "PNG's not GIF". PNG supports palette-based images (with palettes of 24-bit RGB or 32-bit RGBA colors), grayscale images (with or without an alpha channel for transparency), and full-color non-palette-based RGB or RGBA images. The PNG working group designed the format for transferring images on the Internet, not for professional-quality print graphics; therefore non-RGB color spaces such as CMYK are not supported. A PNG file contains a single image in an extensible structure of ''chunks'', encoding the basic pixels and other information such as textual comments and integrity checks documented in RFC 2083. PNG files use the file extension PNG or pn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Netpbm
Netpbm (formerly Pbmplus) is an open-source package of graphics programs and a programming library. It is used mainly in the Unix world, where one can find it included in all major open-source operating system distributions, but also works on Microsoft Windows, macOS, and other operating systems. File formats Several graphics formats are used and defined by the Netpbm project. The portable pixmap format (PPM), the portable graymap format (PGM) and the portable bitmap format (PBM) are image file formats designed to be easily exchanged between platforms. They are also sometimes referred to collectively as the portable anymap format (PNM), not to be confused with the related portable arbitrary map format (PAM). The "magic number" (Px) at the beginning of a file determines the type, not the file extension, although it is best practice to use the right extension if possible. The PBM format was invented by Jef Poskanzer in the 1980s as a format that allowed monochrome bitmaps to be t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Space
A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of colorwhether such representation entails an analog or a digital representation. A color space may be arbitrary, i.e. with physically realized colors assigned to a set of physical color swatches with corresponding assigned color names (including discrete numbers infor examplethe Pantone collection), or structured with mathematical rigor (as with the NCS System, Adobe RGB and sRGB). A "color space" is a useful conceptual tool for understanding the color capabilities of a particular device or digital file. When trying to reproduce color on another device, color spaces can show whether shadow/highlight detail and color saturation can be retained, and by how much either will be compromised. A " color model" is an abstract mathematical model describing the way colors can be represented as tuples of numbers (e.g. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RGB Color Model
The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue. The main purpose of the RGB color model is for the sensing, representation, and display of images in electronic systems, such as televisions and computers, though it has also been used in conventional photography. Before the electronic age, the RGB color model already had a solid theory behind it, based in human perception of colors. RGB is a ''device-dependent'' color model: different devices detect or reproduce a given RGB value differently, since the color elements (such as phosphors or dyes) and their response to the individual red, green, and blue levels vary from manufacturer to manufacturer, or even in the same device over time. Thus an RGB value does not define the same ''color'' acro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transparency (graphic)
Transparency in computer graphics is possible in a number of file formats. The term " transparency" is used in various ways by different people, but at its simplest there is "full transparency" i.e. something that is completely invisible. Only part of a graphic should be fully transparent, or there would be nothing to see. More complex is "partial transparency" or "translucency" where the effect is achieved that a graphic is partially transparent in the same way as colored glass. Since ultimately a printed page or computer or television screen can only be one color at a point, partial transparency is always simulated at some level by mixing colors. There are many different ways to mix colors, so in some cases transparency is ambiguous. In addition, transparency is often an "extra" for a graphics format, and some graphics programs will ignore the transparency. Raster file formats that support transparency include GIF, PNG, BMP, TIFF, TGA and JPEG 2000, through either a ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon Graphics
Silicon Graphics, Inc. (stylized as SiliconGraphics before 1999, later rebranded SGI, historically known as Silicon Graphics Computer Systems or SGCS) was an American high-performance computing manufacturer, producing computer hardware and software. Founded in Mountain View, California in November 1981 by Jim Clark, its initial market was 3D graphics computer workstations, but its products, strategies and market positions developed significantly over time. Early systems were based on the Geometry Engine that Clark and Marc Hannah had developed at Stanford University, and were derived from Clark's broader background in computer graphics. The Geometry Engine was the first very-large-scale integration (VLSI) implementation of a geometry pipeline, specialized hardware that accelerated the "inner-loop" geometric computations needed to display three-dimensional images. For much of its history, the company focused on 3D imaging and was a major supplier of both hardware and softwa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexadecimal
In mathematics and computing, the hexadecimal (also base-16 or simply hex) numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the decimal system representing numbers using 10 symbols, hexadecimal uses 16 distinct symbols, most often the symbols "0"–"9" to represent values 0 to 9, and "A"–"F" (or alternatively "a"–"f") to represent values from 10 to 15. Software developers and system designers widely use hexadecimal numbers because they provide a human-friendly representation of binary-coded values. Each hexadecimal digit represents four bits (binary digits), also known as a nibble (or nybble). For example, an 8-bit byte can have values ranging from 00000000 to 11111111 in binary form, which can be conveniently represented as 00 to FF in hexadecimal. In mathematics, a subscript is typically used to specify the base. For example, the decimal value would be expressed in hexadecimal as . In programming, a number o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Big-endian
In computing, endianness, also known as byte sex, is the order or sequence of bytes of a word of digital data in computer memory. Endianness is primarily expressed as big-endian (BE) or little-endian (LE). A big-endian system stores the most significant byte of a word at the smallest memory address and the least significant byte at the largest. A little-endian system, in contrast, stores the least-significant byte at the smallest address. Bi-endianness is a feature supported by numerous computer architectures that feature switchable endianness in data fetches and stores or for instruction fetches. Other orderings are generically called middle-endian or mixed-endian. Endianness may also be used to describe the order in which the bits are transmitted over a communication channel, e.g., big-endian in a communications channel transmits the most significant bits first. Bit-endianness is seldom used in other contexts. Etymology Danny Cohen introduced the terms ''big-endian'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
