Definition

Noun: * The rectangular formation of parallel scanning lines that guide the electron beam on a television screen or a computer monitor: A fundamental structure in traditional display technology, consisting of a grid of horizontal lines that are illuminated in sequence to form a complete image.

Usage

The term "raster" is used primarily in technical contexts related to computer graphics, display hardware, and image processing. It refers to the underlying pattern or method used to construct an image on a cathode-ray tube (CRT) screen. It is the foundation for "raster graphics," where images are composed of a grid of pixels.

Examples

• The old television's raster was visible as faint horizontal lines when viewed up close.
• In a CRT monitor, the electron beam paints the image by following the fixed path of the raster.
• The image is stored in memory as a bitmap that directly corresponds to the raster of the display.

Advanced Usage

• Raster graphics: A type of digital image composed of a rectangular grid of pixels (picture elements). Each pixel contains color information. Photographs and complex digital paintings are typically stored as raster graphics (e.g., JPEG, PNG, BMP files), as opposed to vector graphics.
  • Example: Web images are almost always in raster graphics formats like JPEG or PNG.
• Raster scan: The process of displaying or capturing an image by sequentially sweeping across the raster lines, from top to bottom.
  • Example: Traditional television broadcasting uses a raster scan method to transmit pictures.
• Rasterization/Rasterisation: The process of converting vector-based geometric descriptions (like shapes and fonts) into a raster image (a pixel-based image) for display on a screen or printer.
  • Example: The 3D rendering engine performs rasterization to turn the scene model into the pixels you see on screen.

Variants and Related Words

• Rasterize (verb): To convert into a raster image.
  • Example: The software will rasterize the PDF before printing it.
• Raster Image Processor (RIP): Hardware or software that rasterizes vector data for printing.

Synonyms

• Scan pattern
• Grid (in the specific context of display technology)

Antonyms

• Vector: Refers to graphics defined by geometric formulas (points, lines, curves) rather than a fixed grid of pixels. The display method for vector graphics is not based on a predefined raster.

Noun

1. the rectangular formation of parallel scanning lines that guide the electron beam on a television screen or a computer monitor