What is a Raster?
Rasters are the sections of cathode ray tubes and liquid crystal display monitors that make it possible to create images for display. Essentially, a raster functions by creating a series of horizontal lines that run across the viewing area. An electron beam scans the lines using a dual scanning pattern that runs the beams left to right and up and down over the horizontal lines. This continuous action results in the ability to view a complete image. While the basic function of a raster is the same with just about any type of cathode ray tube or CRT display, there are some differences in the process used by different devices. Televisions that may use of the CRT model often will not have quite as sharp an image display as a computer monitor using the same basic approach. The reason for this is that the setup of the CRT on a television set is normally referred to as an interlaced raster pattern, while the computer monitor is likely to use a raster scanning approach that is considered to be
Rasters are monochrome pictures in a form that computers can display and manipulate. They are a pattern of many rows of black and white dots called “pixels.” The computer stores each pixel and its location as a pattern of bits, so rasters are sometimes called “bit map images.” There are no gray pixels in a raster, but shades of gray are created by intermingling the black and white pixels in different proportions. You can make rasters scanner program–>, or use a supplied raster, as explained below. Also, see Image: A Continuous Tone Digital Picture Inset for working with color images. For historical reasons, rasters on Andrew are stored in several different formats. You can use raster to edit files in all of the following formats: RasterFile format, the format in which screen snapshots are currently stored (also called “OldRaster”) BE2/ATK Raster Version 1 BE2/ATK Raster Version 2, the current format raster automatically converts rasters in all formats into the most current ATK raster
