Editing Raster graphics (section)

{{Short description|Image display as a 2D grid of pixels}}
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[[file:Rgb-raster-image.svg|right|thumb|upright=1|The [[Smiley|smiley face]] in the top left corner is a raster image. When enlarged, individual pixels appear as squares. Enlarging further, each pixel can be analyzed, with their colors constructed through combination of the values for red, green and blue.]]

In [[computer graphics]] and [[digital photography]], a '''raster graphic''', '''raster image''', or simply '''raster''' is a two-dimensional [[image]] or picture represented as a rectangular [[Matrix (mathematics)|matrix]] or grid of [[pixel]]s, viewable via a [[computer display]], [[paper]], or other display medium. A raster image is technically characterized by the width and height of the image in pixels and by the number of [[bits per pixel]].<ref>{{Cite web |title=Introduction to Computer Graphics, Section 1.1 -- Painting and Drawing |url=https://math.hws.edu/graphicsbook/c1/s1.html |access-date=2024-08-25 |website=math.hws.edu}}</ref> Raster images are stored in [[image file]]s with varying [[electronic publishing|dissemination]], [[raster graphics editor|production]], [[3D rendering|generation]], and [[raw image format|acquisition formats]].

The [[printing]] and [[prepress]] industries know raster graphics as '''contones''' (from "continuous [[tints and shades|tones]]"). In contrast, ''[[line art]]'' is usually implemented as [[vector graphics]] in digital systems.<ref>{{cite web|url=http://www.google.nl/patents/US6469805|title=Patent US6469805 – Post raster-image processing controls for digital color image printing|publisher=Google.nl|access-date=30 November 2014|archive-date=5 December 2014|archive-url=https://web.archive.org/web/20141205111425/http://www.google.nl/patents/US6469805|url-status=live}}</ref>

[[File:Matrix transpose.gif|thumb|[[transpose|Transposing]] an image to covert raster organization (a relatively costly operation for packed formats with less than a byte per pixel); [[function composition|composing]] an additional raster line [[reflection (mathematics)|reflection]] (almost free), either before or afterwards, amounts to a 90° image rotation in one direction or the other.]]
Many raster manipulations map directly onto the mathematical formalisms of [[linear algebra]], where mathematical objects of [[matrix (mathematics)|matrix]] structure are of central concern.