This invention relates to a method and an apparatus for generating multi-gradation data to represent characters according to light and shade information.
In a conventional computer system, fonts are used for representing characters. In a conventional computer system, each character in a given font is specified as a small rectangular bitmap, a ones and zeros representation of the rectangular array of pixels. For example, an alphabet is composed of eight pixels.times.eight pixels. A kanji character is composed of sixteen pixels.times.sixteen pixels. A raster display of the computer system stores the display primitives such as lines and characters in a refresh buffer in terms of their component pixels. The complete image on the raster display is formed from the raster, which is a set of horizontal raster lines, each a row of individual pixels. The raster is thus stored as a matrix of pixels representing the entire screen area. The entire image is scanned out by a video controller, allowing the constant refresh of the display. As known in the arts, there are two fundamental types of refresh: interlaced and noninterlaced. The former is used in broadcast television and in raster display designed to drive regular television. The refresh cycle is broken into two fields, each lasting 1/60 second; thus, a full refresh lasts 1/30 second. All odd-numbered scan lines are displayed in the first field, and all even-numbered ones are displayed in the second. The purpose of the interlaced scan is to place some new information in all areas of the screen at a 60-Hz rate, since a 30-Hz refresh rate tends to cause flicker. On the other hand, noninterlaced scan is used to scanout one raster line at a time from top to bottom. In other words, scanout starts in the upper left-hand corner of the display and simultaneously moves left to right and top to bottom to put a series of zig-zag lines on the screen.
Some television sets for home use include a device applying an interlaced scan technique. In this event, flicker appears on the screen. Accordingly, if small characters are displayed on the screen, flicker hinders clear recognition of the characters.
USPTO Backgrounds
USPTO Backgrounds