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Atkinson Dithering
Atkinson dithering is a variant of Floyd-Steinberg dithering designed by Bill Atkinson at Apple Computer, and used in the original Macintosh computer. Implementation The algorithm achieves dithering using error diffusion, meaning it pushes (adds) the residual quantization error of a pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the smal ... onto its neighboring pixels, to be dealt with later. It spreads the debt out according to the distribution (shown as a map of the neighboring pixels): : \begin & & * & \frac & \frac \\ \ldots & \frac & \frac & \frac & \ldots \\ \ldots & & \frac & & \ldots \\ \end The pixel indicated with a star (*) indicates the pixel currently being scanned, and the blank pixels are the previously scanned pixels. The algorithm scans the image from lef ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bill Atkinson
Bill Atkinson (born March 17, 1951) is an American computer engineer and photographer. Atkinson worked at Apple Computer from 1978 to 1990. Atkinson was the principal designer and developer of the graphical user interface (GUI) of the Apple Lisa and, later, one of the first thirty members of the original Apple Macintosh development team, and was the creator of the MacPaint application. He also designed and implemented QuickDraw, the fundamental toolbox that the Lisa and Macintosh used for graphics. QuickDraw's performance was essential for the success of the Macintosh GUI. He also was one of the main designers of the Lisa and Macintosh user interfaces. Atkinson also conceived, designed and implemented HyperCard, an early and influential hypermedia system. HyperCard put the power of computer programming and database design into the hands of non programmers. In 1994, Atkinson received the EFF Pioneer Award for his contributions. Education He received his undergraduate degree ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apple Computer
Apple Inc. is an American multinational technology company headquartered in Cupertino, California, United States. Apple is the largest technology company by revenue (totaling in 2021) and, as of June 2022, is the world's biggest company by market capitalization, the fourth-largest personal computer vendor by unit sales and second-largest mobile phone manufacturer. It is one of the Big Five American information technology companies, alongside Alphabet, Amazon, Meta, and Microsoft. Apple was founded as Apple Computer Company on April 1, 1976, by Steve Wozniak, Steve Jobs and Ronald Wayne to develop and sell Wozniak's Apple I personal computer. It was incorporated by Jobs and Wozniak as Apple Computer, Inc. in 1977 and the company's next computer, the Apple II, became a best seller and one of the first mass-produced microcomputers. Apple went public in 1980 to instant financial success. The company developed computers featuring innovative graphical user interfaces, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macintosh Computer
The Mac (known as Macintosh until 1999) is a family of personal computers designed and marketed by Apple Inc. Macs are known for their ease of use and minimalist designs, and are popular among students, creative professionals, and software engineers. The current lineup includes the MacBook Air and MacBook Pro laptops, as well as the iMac, Mac Mini, Mac Studio and Mac Pro desktops. Macs run the macOS operating system. The first Mac was released in 1984, and was advertised with the highly-acclaimed "1984" ad. After a period of initial success, the Mac languished in the 1990s, until co-founder Steve Jobs returned to Apple in 1997. Jobs oversaw the release of many successful products, unveiled the modern Mac OS X, completed the 2005-06 Intel transition, and brought features from the iPhone back to the Mac. During Tim Cook's tenure as CEO, the Mac underwent a period of neglect, but was later reinvigorated with the introduction of popular high-end Macs and the ongoing Apple sil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Error Diffusion
Error diffusion is a type of halftoning in which the quantization residual is distributed to neighboring pixels that have not yet been processed. Its main use is to convert a multi-level image into a binary image, though it has other applications. Unlike many other halftoning methods, error diffusion is classified as an area operation, because what the algorithm does at one location influences what happens at other locations. This means buffering is required, and complicates parallel processing. Point operations, such as ordered dither, do not have these complications. Error diffusion has the tendency to enhance edges in an image. This can make text in images more readable than in other halftoning techniques. Early history Richard Howland Ranger received United States patent 1790723 for his invention, "Facsimile system." The patent, which issued in 1931, describes a system for transmitting images over telephone or telegraph lines, or by radio.Richard Howland Ranger, Facsimile ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantization Error
Quantization, in mathematics and digital signal processing, is the process of mapping input values from a large set (often a continuous set) to output values in a (countable) smaller set, often with a finite number of elements. Rounding and truncation are typical examples of quantization processes. Quantization is involved to some degree in nearly all digital signal processing, as the process of representing a signal in digital form ordinarily involves rounding. Quantization also forms the core of essentially all lossy compression algorithms. The difference between an input value and its quantized value (such as round-off error) is referred to as quantization error. A device or algorithmic function that performs quantization is called a quantizer. An analog-to-digital converter is an example of a quantizer. Example For example, rounding a real number x to the nearest integer value forms a very basic type of quantizer – a ''uniform'' one. A typical (''mid-tread'') uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the smallest element that can be manipulated through software. Each pixel is a sample of an original image; more samples typically provide more accurate representations of the original. The intensity of each pixel is variable. In color imaging systems, a color is typically represented by three or four component intensities such as red, green, and blue, or cyan, magenta, yellow, and black. In some contexts (such as descriptions of camera sensors), ''pixel'' refers to a single scalar element of a multi-component representation (called a ''photosite'' in the camera sensor context, although ''sensel'' is sometimes used), while in yet other contexts (like MRI) it may refer to a set of component intensities for a spatial position. Etymology The w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Image Processing
An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimensional picture, that resembles a subject. In the context of signal processing, an image is a distributed amplitude of color(s). In optics, the term “image” may refer specifically to a 2D image. An image does not have to use the entire visual system to be a visual representation. A popular example of this is of a greyscale image, which uses the visual system's sensitivity to brightness across all wavelengths, without taking into account different colors. A black and white visual representation of something is still an image, even though it does not make full use of the visual system's capabilities. Images are typically still, but in some cases can be moving or animated. Characteristics Images may be two or three-dimensional, such as a pho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
