Abstract: The present invention is directed to a real-time controllable reflection mapping function which covers all stereoscopic directions of space. More specifically, the surface of a mirrored object is segmented into a plurality of polygonal elements (for example, triangles). Then, a polyhedron, which includes a predetermined point (for example, the center of the mirrored object) in a three-dimensional space (for example, a cube) in the interior thereof, is generated and a rendering process is performed for each surface of the polyhedron with the predetermined point as a view point. The rendered image is stored. Thereafter, a reflection vector is calculated between each vertex of the polygonal elements and a view point used when the entire three-dimensional space is rendered. Next, the surface of the polyhedron, in which an intersecting point between the reflection vector with the predetermined point as a start point and the polyhedron exists, is obtained.

Abstract: In order to render a three-dimensional space which has a spotlight source with a cone angle .theta. at high speed and with better quality, an object's surface in the three-dimensional space is first meshed into a plurality of elements. Then, a radiosity from the spotlight source is calculated for each element which is included inside of the cone angle .theta. when viewed from the spotlight source. Thereafter, an intensity-value at each vertex of each element is calculated from the radiosity calculated for each element. Next, Gouraud shading is performed by using the intensity-value at each vertex of each element, and the result is displayed on a display.

Abstract: A high-speed method and an apparatus for color image quantization utilizing an adaptive sampling technique in which the processing time is substantially determined by the number of simultaneously displayed colors to be selected, but is not affected by the number of colors or the color distribution in the original image. Factors contributing to improve the speed of color image quantization are that all calculations necessary for selecting the representative colors can be performed in an integer operation, and there is no need of distance calculation for mapping to neighboring representative colors. All that is required as data are a histogram, a divided color-space management list, and a division priority management list, so that required storage capacity may be small. Accordingly the invention can be implemented on a personal computer.