Raster graphics

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Imagine the smiley face in the top left corner as an RGB bitmap image. When enlarged, it might look like the big smiley face to the right. Every square represents a pixel. Zooming in further, the individual pixels can be analyzed, with their colors constructed by adding the values for red, green and blue.





The word "raster" has its origins in the Latin rastrum (a rake), which is derived from radere (to scrape), and was originally used in the raster scan of cathode ray tubes (CRT), which paint the image line by line; it is used for a grid of pixels by generalization. See also rastrum, a device for drawing musical staff lines.



Raster-based image editors

Raster-based image editors, such as Photoshop, MS Paint, and GIMP, revolve around editing pixels, unlike vector-based image editors, such as CorelDRAW, Adobe Illustrator, or Inkscape, which revolve around editing lines and shapes (vectors). When an image is rendered in a raster-based image editor, the image is composed of millions of pixels. At its core, a raster image editor works by manipulating each individual pixel. Most pixel-based image editors work using the RGB color model, but some also allow the use of other color models such as the CMYK color model.

File formats


A bitmap or pixmap is pixel data storage structure employed by the majority of raster graphics file formats such as PNG.


OpenRaster is a file format being developed under the auspices of the Create Project to give free software graphics editors a common raster graphics interchange format, that maintains as much of the working information that the applications use.

See also



External links

  • Raster3D — a free, open source software package for generating high quality raster images