Method and system for filtering texture map data for improved image quality in a graphics computer system

Abstract

A method and system for filtering texture map data for improved image quality in a graphics computer system. The present invention is directed to a method and system for performing texture map filtering for reducing “flickering” and “sparkling” when rendering a relatively small graphics primitives using a texel map of relatively larger area and low color frequency. A footprint area is defined as the area of texel map space that is mapped into one pixel coordinate of display space. One embodiment of the present invention is particularly useful in texture mapping where the footprint area is larger than one. In this instance, during rendering, the change in texel map coordinates (e.g., du, dv) is large for a unit change in screen coordinates (e.g., dx, dy). When obtaining a texel at location (u, v), the present invention performs a color filtering of texels located at distances du and dv away from the texel at location (u, v). If texel wrap is not allowed, edge pinning is used to obtain the required texels for color filtering. The texels which are rendered in adjacent pixels on the display screen become more colored filtered with respect to each other rather than filtering nearest neighbor texels which often leads to flickering and sparkling in texture mapping cases of large footprint areas. The present invention reduces flickering and sparkling without requiring multiple texture maps (and therefore additional memory), as required using mipmapping.