Most modern color raster formats represent color using 24 bits (over 16 million distinct colors), with 8 bits (values 0–255) for each color channel (red, green, and blue).
Difference between a vector graphic and a raster graphic full#
Common pixel formats are binary, gray-scale, palettized, and full-color, where color depth determines the fidelity of the colors represented, and color space determines the range of color coverage (which is often less than the full range of human color vision). Each raster grid has a specified pixel format, the data type for each number. For most images, this value is a visible color, but other measurements are possible, even numeric codes for qualitative categories. Raster or gridded data may be the result of a gridding procedure.Ī single numeric value is then stored for each pixel. The size of each square pixel, known as the resolution or support, is constant across the grid. In digital photography, the plane is the visual field as projected onto the image sensor in computer art, the plane is a virtual canvas in geographic information systems, the plane is a projection of the Earth's surface. The fundamental strategy underlying the raster data model is the tessellation of a plane, into a two-dimensional array of squares, each called a cell or pixel (from "picture element"). The word rastrum is now used to refer to a device for drawing musical staff lines.ĭata model A simple raster graphic By association, it can also refer to a rectangular grid of pixels. It originates from the raster scan of cathode ray tube (CRT) video monitors, which paint the image line by line by magnetically or electrostatically steering a focused electron beam. The word "raster" has its origins in the Latin rastrum (a rake), which is derived from radere (to scrape).
Many raster manipulations map directly onto the mathematical formalisms of linear algebra, where mathematical objects of matrix structure are of central concern. Transposing an image to covert raster organization (a relatively costly operation for packed formats with less than a byte per pixel) composing an additional raster line reflection (almost free), either before or afterwards, amounts to a 90° image rotation in one direction or the other. In contrast, line art is usually implemented as vector graphics in digital systems. The printing and prepress industries know raster graphics as contones (from continuous tones). Raster images are stored in image files with varying dissemination, production, generation, and acquisition formats. A raster is technically characterized by the width and height of the image in pixels and by the number of bits per pixel. In computer graphics and digital photography, a raster graphics represents a two-dimensional picture as a rectangular matrix or grid of square pixels, viewable via a computer display, paper, or other display medium.
Enlarging further, each pixel can be analyzed, with their colors constructed through combination of the values for red, green and blue. When enlarged, individual pixels appear as squares. The smiley face in the top left corner is a raster image. JSTOR ( November 2016) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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