Abstract: A two-dimensional image coordinate system is divided into areas each composed of N pixels in a first direction and M pixels in a second direction perpendicular to the first direction. Variations of rendering data for pixels are calculated with respect to the first and second directions and are used for interpolating values of the rendering data for each pixel from predetermined apex data of a predetermined graphic. An initial value of the rendering data on the side of the predetermined graphic is calculated using the value of a predetermined apex and the variation of the rendering data with respect to the first direction. First N×M rendering data is calculated using the initial value and the variations of the rendering data. Other N×M rendering data is calculated based on the variations of the rendering data with respect to the first direction and the second direction.

Abstract: There is provided a rendering system for processing pixels corresponding to a predetermined graphic in parallel by dividing a two-dimensional image coordinate system into areas each composed of a plurality of pixels of N pixels in a first direction and M pixels in a second direction perpendicular to the first direction, i.e. N×M pixels in total, and by allocating N×M computing sections respectively to the N×M pixels contained in that area.

Abstract: In the data compression method and apparatus, difference value data each consisting of m bits that include an absolute value represented by m-1 bits and a 1-bit sign bit representing a sign are received, each of the difference value data having been obtained by calculating a difference between data to be coded and data immediately preceding it. N of the received difference value data are rearranged on a bit-by-bit basis, to generate a bit sequence in which bits at the same place of the n difference value data appear consecutively in predetermined order. A coded bit sequence is generated by compressing the generated bit sequence by a predetermined compression method. In the data expansion apparatus and method, a bit sequence of consecutive bits is generated by expanding a coded bit sequence by a decoding method corresponding to a predetermined compression method.

Abstract: It is determined, for each polygon, whether to perform an operation of calculating coordinate data of apices of the polygon, offset values of a display position of the polygon, and color data of the apices of the polygon on a coordinate system corresponding to a given display area based on coordinate data and color data of the apices of the polygon in a three-dimensional space, or an operation of calculating only the offset values of the display position of the polygon, and the determined operation is performed. Coordinate data of the apices of the polygon in the display area that are obtained by adding together the calculated offset values of the display position of the polygon and one of the calculated coordinate data of the apices of the polygon and the coordinate values of the apices of the polygon supplied from a memory are output, and one of the calculated color data of the apices of the polygon and the color data of the apices of the polygon supplied from the memory are also output.

Abstract: A method and apparatus for shading images by approximating a three-dimensional curved surface for computer graphics. Shading of a two-dimensional surface is provided by varying pixel brightness values to indicate a depth dimension of the two-dimensional surface. A plurality of polygons are employed, with each polygon being used to approximate a portion of the curved surface. A coordinate grid is provided extending in horizontal and vertical directions. The polygons are plotted on this coordinate grid. Coordinate grid points of the coordinate grid each represent respective pixels whose brightness is to be varied for the graphics. Scanning occurs across scan lines in a horizontal direction across the grid from grid point to grid point. Vertices of the polygons are provided on the coordinate grid, which vertices may not necessarily lie directly on a grid point. Brightness values at each vertex of the polygon are provided.

Abstract: A bit map display system has a frame buffer memory for storing image data in pixel blocks each composed of a plurality of dots or pixels. To transfer image data from a source address region to a destination address region, block addresses are generated from relative addresses of starting and ending pixel points in the source address region and relative addresses of starting and ending pixel points in the destination address region, and supplied to the frame buffer memory. A decision circuit generates a pre-reading signal and a non-reading signal from the relative addresses depending on the direction in which the image data are to be transferred. The pre-reading and non-reading signals are set according to certain predetermined conditions. The image data are transferred from the source address region to the destination address region in the frame buffer memory in various ways depending on whether the pre-reading and non-reading signals are set or not.

Abstract: A method of filling a polygonal region enables a polygon of any shape to be filled with pixels with a simple algorithm. A display memory area and a working area each having a plurality of addresses correponding to all the pixels on a display screen are provided. A minimum rectangular area including the polygon is determined in accordance with all the polygon vertices, and the minimum rectangular area within the working area is cleared. A straight line (or an edge) connecting each pair of adjoining vertices of the polygon is described to the display memory area with predetermined values. The edges are also described to the working area but in accordance with three rules. Under Rule 1, when a constituent dot of the edge is described to the corresponding address, the data in the address is inverted. Under Rule 2, a start constituent dot of each edge is described only when the edge to be described has an inclination different in polarity from the precedingly described edge.