antialias

Antialiasing, often called antialias, is a set of techniques used in computer graphics to reduce aliasing—the jagged or stair-step appearance of curved or diagonal edges that occurs when a continuous image is sampled into a discrete grid of pixels.

Aliasing arises from finite sampling; high-frequency content and limited resolution create false patterns, shimmering in motion. The goal of antialiasing is to smooth these edges and produce more faithful representations of shapes and textures.

Common approaches include spatial antialiasing methods such as rendering at a higher resolution and downsampling, which averages values to smooth edges; multisampling that collects several samples per pixel to smooth coverage; and supersampling (SSAA), which samples the entire scene at higher resolution before downsampling. Post-processing techniques apply filters after rendering, such as FXAA for fast smoothing and SMAA for subpixel-aware edge detection. Temporal anti-aliasing uses information from multiple frames to reduce flicker and shimmering, particularly in motion.

Tradeoffs exist between image quality and computational cost. MSAA preserves sharp texture detail better than some post-processing methods but does not mitigate all aliasing artifacts; SSAA delivers strong results but is expensive. Post-processing approaches are faster but can blur fine textures or introduce artifacts in certain scenes, while temporal methods may cause ghosting if motion is rapid or scene changes are abrupt.

Applications span 2D and 3D graphics, fonts, and user interfaces. Antialiasing improves legibility and visual quality by producing smoother edges, helping lines and shapes appear more natural on raster displays.