Window dependent pixel datatypes in a computer video graphics system

摘要

This invention allows each of a plurality of windows to use its own distinct datatype and format while more than one window is being displayed on a monitor screen of a computer video graphics system. Different windows can use full color or pseudocolor frame buffer organizations, can use overlay planes or not, and can have other differences in the interpretation of the pixel values without affecting each other. Window dependent pixel datatypes are provided by means of a lookup table that is contained in logic between the frame buffer and the colormap/DAC that drives the monitor. This lookup table contains descriptors for pixel datatypes. It is indexed by a window number that is specified for each pixel. The pixel datatype descriptor accessed at each pixel is then used to control logic that processes that pixel value to create an index for the colormap. This allows each window to specify its own pixel datatype and format, that is used to interpret the pixels contained in the window.