Multisample anti-aliasing (MSAA) is a type of anti-aliasing, a technique used in computer graphics to improve image quality.
The term generally refers to a hardware optimization of supersampling. Initial implementations of full-scene anti-aliasing (FSAA) worked by simply rendering a scene at a higher resolution, and then downconverting to a lower-resolution output. With "multisampling", support for sampling and computing multiple samples within a pixel is added directly in the graphics pipeline hardware, providing much better performance. This method can also employ nonuniform sample patterns for improved visual quality.
While hardware can be designed to perform MSAA at full speed for basic cases, MSAA does still consume more memory bandwidth than rendering without anti-aliasing. Programmable shaders are also run for each sample. Furthermore, MSAA performance does not scale well some newer rendering techniques, such as the use of multiple render targets for "deferred" rendering effects.
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