What is anti-aliasing in graphics

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Anti-aliasing

One of the best-known graphics effects for games is "anti-aliasing", or in other words: anti-aliasing. No modern game can do without this filter, after all it ensures that unsightly pixel edges are smoothed out. In short, anti-aliasing compares neighboring pixels for differences in contrast and compensates for them.

Here Elite Dangerous without anti-aliasing (left), with less precise FXAA (middle) and with more precise MSAA (right).

However, there are major differences between the numerous anti-aliasing methods. The simplest variant, FXAA ("Fast Approximate Anti-Aliasing") hardly needs any computing time. It smooths all visible edges, but makes textures look washed out. The MSAA, which is widely used in practice, works better. Because the "Multi Sample Anti-Aliasing" analyzes the geometry of the 3D scene and only starts at the edges. However, MSAA is more computationally intensive and may not produce good results with certain perspectives. This is another reason why the method is optionally used multiple times (for example 4x MSAA or 8x MSAA).

There are also a number of other methods such as TXAA ("Temporal Approximate Anti-Aliasing"), SMAA, TSAA or MLAA. The computationally intensive SSAA ("Super Sampling Anti Aliasing") delivers the best result. More on this in the next paragraph.

Downsampling

The term "downsampling" refers to the downsampling of a game graphic before it appears on the monitor or television. The advantage: The optics appear sharper and cleaner. The disadvantage: The computational effort increases noticeably because more pixels have to be calculated.

With downsampling (right) you get higher quality without flickering, but also lower frame rates because of the higher computational effort.

Theoretically, downsampling works very simply: the graphics unit calculates each individual image of a game with increased resolution - for example with 3,840 by 2,160 pixels. The PC then scales the image down to the monitor resolution, such as 1,920 by 1,080 pixels. Sounds cumbersome, but it delivers a great end result. Because in this way you get a smoothed image that contains more image information than an image created in the same resolution. Objects and textures appear sharper and crisper.

SSAA ("Super Sampling Anti-Aliasing") is also used in this way. One of the best anti-aliasing methods. This "anti-aliasing" variant works more precisely and does not water down the image sharpness. When it comes to downsampling, you have to try it out, because your monitor has to play along with the increased resolution. Because of the much higher computing effort, older games in particular, such as The Elder Scrolls 5 - Skyrim, are better suited for the process. These have a less complex architecture and still deliver high frame rates when downsampling.

The reverse process is sometimes used on consoles: "upscaling". Games like Ryse - Son of Rome or Titanfall on the Xbox One do not generate a full resolution of 1080p. In this case, the console simply upscales the image to full HD resolution before sending it to the monitor.

Continue with: VSync, high dynamic range rendering