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Raster image : ウィキペディア英語版 | Raster graphics
In computer graphics, a raster graphics image is a dot matrix data structure representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, paper, or other display medium. Raster images are stored in image files with varying formats.〔(【引用サイトリンク】title=Raster Graphics - Scratch Wiki )〕 A bitmap, a single-bit raster,〔James D. Foley (1995). Computer Graphics: Principles and Practice. Addison-Wesley Professional. p. 13. ISBN 0-201-84840-6. "The term bitmap, strictly speaking, applies only to 1-bit-per-pixel bilevel systems; for multiple-bit-per-pixel systems, we use the more general term pixmap (short for pixel map)."〕 corresponds bit-for-bit with an image displayed on a screen, generally in the same format used for storage in the display's video memory, or maybe as a device-independent bitmap. A raster is technically characterized by the width and height of the image in pixels and by the number of bits per pixel (a color depth, which determines the number of colors it can represent).〔(【引用サイトリンク】title=Bitmap Class )〕 The printing and prepress industries know raster graphics as contones (from "continuous tones"). The opposite to contones is "line work", usually implemented as vector graphics in digital systems.〔(【引用サイトリンク】title=Patent US6469805 - Post raster-image processing controls for digital color image printing )〕 ==Etymology== The word "raster" has its origins in the Latin ''rastrum'' (a rake), which is derived from ''radere'' (to scrape). It originates from the raster scan of cathode ray tube (CRT) video monitors, which paint the image line by line by magnetically steering a focused electron beam. By association, it came also to refer to a rectangular grid of pixels. The word rastrum is now used to refer to a device for drawing musical staff lines.
抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Raster graphics」の詳細全文を読む
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