Abstract: A graphic video display system including at least one graphic layer having sizable, positionable windows and programmable priority values the sprites having fixed priority values. Portions of graphic layer windows and sprites which overlap with a current horizontal scan line of a video display are written to a line buffer. Overlapping objects are resolved by writing portions of objects overlapping the current horizontal scan line to the line buffer in order of the priority values of the objects.

Abstract: A scanning apparatus for uniquely identifying an actuated key on a keyboard and an actuated location in a drawing tablet. The scanning apparatus includes independently actuatable switches associated with the keyboard. The scanning apparatus also includes vertical and horizontal conducting traces juxtaposed one to another and electrically connected to a horizontal and vertical resistive bar, respectively, associated with the drawing tablet. The switches and traces are energized under control of the apparatus such that portions of each can be actuated by a user resulting in the generation of unique analog signals indicative of the particular key and particular location upon the drawing tablet actuated by the user. These unique analog signals are converted to digital signals for further processing.

Abstract: A method for encoding and decoding still video frames, and a sequence of frames of digitized motion picture video data, using inter-frame analysis. Sequences of frames are encoded by first subdividing each frame within a set of adjacent frames into a plurality of blocks, each corresponding to at least one other block within at least one adjacent frame, so as to create a group of corresponding of blocks. A luminance component of each pixel within each group of corresponding blocks is averaged to generate a mean luminance value for each group of corresponding blocks. An upper color value for each group of corresponding blocks is determined, as well as a lower color value. A one-bit value is assigned to each pixel within each block. The one-bit value is set to a first binary level when the luminance component of an associated pixel value is greater in magnitude than the corresponding mean luminance value.