What Is Antialiasing?

Curves and lines appear less jagged when you use antialiasing tools

Brain pixelated, artwork
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Aliasing in images can be described as stair-step lines or jagged edges (i.e. jaggies) that are often found in lower-resolution displays. The jaggies are obvious because the monitor or other output device isn't using a high enough resolution to show the smooth line.

Antialiasing, then, is a technology that attempts to resolve the aliasing found in the image.

You might find the option for anti-aliasing if you look through the settings of a video game. Some options might include 4x, 8x, and 16x, though 128x is possible with advanced hardware configurations. Antialiasing is often seen as anti-aliasing or AA and is sometimes called oversampling.

How Does Antialiasing Work?

We see smooth curves and lines in the real world. However, when computers render images for display on a monitor, those curves and lines break down into tiny square elements called pixels. This process results in lines and edges that often appear jagged.

Antialiasing reduces this problem by applying a particular technique to smooth out the edges for a better overall picture. This might work by slightly blurring the edges until they appear to lose that jagged quality. By sampling pixels around the edges, antialiasing adjusts the color of the surrounding pixels, blending away the jagged appearance.

Although the pixel blending removes the sharp edges, the antialiasing effect might make the pixels fuzzier.

Antialiasing Options

Different antialiasing techniques deliver a variety of results depending on hardware capabilities:

  • Supersample Antialiasing: The SSAA process takes high-resolution images and downsamples to the necessary size. This approach results in a much smoother edge, but supersampling requires more hardware resources from a graphics card, such as additional video memory. SSAA isn't used much anymore because of how much power it requires.
  • Multisample Antialiasing: The MSAA sampling process requires fewer resources by supersampling only parts of the image, particularly polygons. This process is not as resource intensive. However, MSAA doesn't perform well with alpha/transparent textures, and because it doesn't sample the entire scene, image quality may be reduced.
  • Adaptive Antialiasing: Adaptive Antialiasing is an extension of MSAA that works better with alpha/transparent textures but it doesn't take up the bandwidth and resources of a graphics card the way supersampling does.
  • Coverage Sampling Antialiasing: Developed by NVIDIA, CSAA produces results similar to higher quality MSAA with only a slight performance cost over standard MSAA.
  • Enhanced Quality Antialiasing: Developed by AMD for their Radeon graphics cards, EQAA is similar to CSAA and delivers higher quality antialiasing over MSAA with minor impact on performance and no increased video memory requirements.
  • Fast Approximate Antialiasing: FXAA is an improvement on MSAA that is much faster with less hardware performance cost. Plus, it smooths out the edges on the entire image. Images with FXAA antialiasing can, however, appear a bit more blurry, which isn't useful if you're looking for sharp graphics.
  • Temporal Antialiasing: TXAA is a newer antialiasing process that produces improved results over FXAA by incorporating several different smoothing techniques, but with a slightly higher performance cost. This method doesn't work on all graphics cards.

How to Adjust Antialiasing

Some games offer an option under the video settings to configure antialiasing. Others may only offer a couple options or may even not give you an option to change antialiasing at all.

You might also be able to customize antialiasing settings through your video card’s control panel. Some device drivers may provide you with other antialiasing options, as well.

You can usually choose to have antialiasing settings dictated by the application so that different settings may apply to different games — or you can turn antialiasing off completely.

Which Antialiasing Setting Is the Best?

This isn't an easy question to answer. Experiment with game and graphics card settings to see which options you prefer.

If you find performance is decreased substantially, such as with degraded frame rates or difficulty loading textures, reduce quality settings or try a less resource-intensive antialiasing.

Graphics cards are continuing to perform better and newer monitors have resolutions that eliminate most perceivable aliasing, so tweaking antialias settings is less important than it used to be.