What is AA and AF and what do they do?



November 28th, 2007

Question:  When reading reviews of games and graphics cards I come across AA and AF and sometimes things like 4xAA.  What does this stuff mean?

Good question!

AA stands for Anti-aliasing (sometimes you might see FSAA which stands for Full Scene Anti-aliasing).  This is a technique that computers use to make curved or angular lines less jagged.  The science behind this is complex but the idea is simple - to make what you see on the screen seem more realistic.

When you read something like 4xAA, this refers to a particular level of anti-aliasing (for example, 2x, 4x, 6x ...).  The higher the number the more sampling pixels are used and the better the image, to a point at least.  For example 4xAA is usually enough when running a screen at 1280x1024, while you may only need 2xAA to get the same level of quality at 1600x1200, and your performance will better as well.  There is no hard and fast rule, experimentation is the name of the game.

AF stands for Anisotropic Filtering.  This is used to improve the quality of distant textures on screen (for example, the landscape of a game).  Again, 4xAF refers to a particular level of filtering (1x to 16x).  The higher the number, the better the image (but the more computer power you need).

Other terms you might see ar HDR which stands for High Definition Rendering which is used to add lighting effects, and bloom which is similar to HDR but not as complex.

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