Abstract: A scan-conversion processor converts a graphic primitive defined by its outline to pixel data by storing edge data blocks containing the y-coordinates of the vertices of each edge, the x-coordinate of the lower vertex, and x-coordinate increment data. The edge blocks are linked in ascending order of teir minimum y-coordinate values into edge chains representing consecutive series of upward- or downward-inclined edges. Information indicating the edge inclination can also be stored in each edge data block, to support use of the non-zero-winding algorithm to discriminate between the interior and exterior of the graphic primitive. since it requires relatively little memory space, the scan-conversion processor, including its memory, can be implemented as a single integrated circuit on a semiconductor chip.

Abstract: A machine-implemented circle-generation method calculates a sequence of coordinates (x.sub.n, y.sub.n) of points approximating a circle or circular arc according to the iterative formula: ##EQU1## or an approximation thereto. This formula is suitable for high-speed computation and approximates a true circle extremely closely. When rounded off to integer coordinates, the starting and ending points of a full circle coincide.

Abstract: A rectangular source image formed by pixels in a two-axis coordinate system is transformed to a destination image by mapping vertices of the source image onto vertices of the destination image, then mapping edges of the destination image onto edges of the source image, mapping scan lines in the destination image onto the source image, and assigning to pixels on these scan lines the values of corresponding pixels in the source image. DDA algorithms are employed for the edge mapping and scan line mapping steps. This method enables arbitrary affine transformations, including combinations of a rotation with an enlargement or reduction, to be executed without introducing image defects.

Abstract: A clipping processor clips a two-dimensional subject figure against a clip region by first scan-converting the clip region and storing it as endpoint data of clip segments, then scan-converting the subject figure, clipping the subject segments a scan line at a time against each of the clip segments on that scan line, and converting the clipped segments to pixel data. The clipping process is thus efficiently combined with the standard processes of scan conversion and pixel generation, producing clipped data that are ready for raster output. The clipping process is moreover performable by simple, rapid DDA algorithms, even when the clip region is bounded by high-order curves such as Bezier curves and spline curves, and can easily be implemented in high-speed, dedicated hardware.