Line scan-conversion method

The invention relates generally to information processing systems, and more specifically to an improved method for scan-converting a line for use with a graphical output in an information processing system. An integer arithmetic graphic line scan-conversion procedure sub-divides a pixel grid into a 1/N sub-pixel grid, where N is a positive integer selected to provide a desired precision. A line segment is defined by a pair of vertices relative to the sub-pixel grid. The vertices are ordered such that the line segment is in one of the first and the second quadrants, depending upon the slope of the line segment. An integer estimate is made of the slope of the line segment relative to the sub-pixel grid. The scan progresses along a major axis at pixel intervals, while best-fit integer projections of the line segment are made along an orthogonal axis relative to the sub-pixel grid. A resulting array of integer line-scan points relative to the sub-pixel grid are used to adjust color and brightness attributes of display pixels, and the resulting adjusted pixels are output to a display device to create an image of the scanned line segment. In a preferred embodiment, N is a positive power of 2. In other embodiments, the method is used for general linear interpolation in any graphic subsystem, such as in the processes of drawing polygons, shading and morphing.