Mipmap

In computer graphics, mipmaps (also MIP maps) or pyramids[1][2][3] are pre-calculated, optimized sequences of images, each of which is a progressively lower resolution representation of the previous.

Mipmaps are widely used in 3D computer games, flight simulators, other 3D imaging systems for texture filtering, and 2D and 3D GIS software.

They also improve image quality by reducing aliasing and Moiré patterns that occur at large viewing distances,[5] at the cost of 33% more memory per texture.

[4] From the abstract: "This paper advances a 'pyramidal parametric' prefiltering and sampling geometry which minimizes aliasing effects and assures continuity within and between target images."

The first patent issued on Mipmap and texture generation was in 1983 by Johnson Yan, Nicholas Szabo, and Lish-Yann Chen of Link Flight Simulation (Singer).

If using a limited number of texture samples per display pixel (as is the case with bilinear filtering) then artifacts are reduced since the mipmap images are effectively already anti-aliased.

However anisotropic filtering attempts to resolve this trade-off by sampling a non isotropic texture footprint for each pixel rather than merely adjusting the MIP LOD.

However, they again hurt cache coherence, and need wider types to store the partial sums, which are larger than the base texture's word size.