what exactly is anti aliasing? I usually dont mess around with graphic settings in games, but recently I’ve gotten curious.
In: Technology
Firstly, aliasing in computer graphics refers to the jagged edges caused by the pixelated nature of monitors. [This](https://web.cs.wpi.edu/~matt/courses/cs563/talks/antialiasing/34_93.gif) causes noticeable artifacts when dealing with 3D objects which appear to be sharper where their real-life counterparts are smooth.
AA is a broad term which described a set of techniques which are used to counteract this effect, generally having a sort of blurring or smoothing effect on the colors of pixels to hide the transitions between them.
A common approach is multi-sampling (MSAA) which, to oversimply things involves rendering each pixel multiple times with slight offsets and then using and then averaging the results. The idea is that by sampling the area in 3D space the pixel covers at multiple locations, the better it will represent it.
Another common approach is FXAA which is basically a selective blur applied to areas that are near edges in geometry.
It smooths out rough/jagged looking graphics for a more realistic feel, it’s usually toggleable since it can often have an effect on FPS/game performance.
your computer’s monitor is made up of a bunch of pixels, which are tiny squares that are each one color. this is great for drawing perfectly horizontal or vertical lines, but of course a diagonal line or a curve doesn’t perfectly fit into square pixels, so in order for these to not come out with jagged edges, we shade the edges, aka antialiasing.
[click here for an example of before and after](https://ageeky.com/wp-content/uploads/2015/08/aaexampleIMG_id1386238400_343178-300×197.jpg)
The term ‘aliasing’ refers to how integer multiples of frequencies can be confused for one another under certain sampling assumptions.
For example, imagine a clock at one. I ask you to close your eyes and then I rotate the clock fully around back to one before I ask you to open your eyes. From your perception, how many rotations occurred in the time your eyes were closed?
From the information you have, it could be 0, 1, 2, … , etc. Any integer number of rotations would match the information you have – that the clock returned to its original position in the time your eyes were closed.
These are ‘aliases’ of one another – they all refer to same information you possess just like all aliases for a single person refer to that single person.
The above is what is known as ‘temporal aliasing’. When you’re talking about your computer graphics you get a similar phenomenon known as ‘spatial aliasing’.
Your monitor (and video signal) have a certain resolution. However, the image they’re trying to display is philosophically analog – you’re trying draw circles, diagonal lines and other elements that do not exactly match up against the pixel sampling of your monitor.
For large-scale images, this isn’t a big deal. But as you get into smaller elements of those images, you end up with the pixels being ‘too thick’ to accurately represent what you want to see. In essence, you’re attempting to reproduce high frequency signals on a low frequency device and you’re inaccurately ‘aliasing’ them to those lower frequencies.
In temporal aliasing, you normally solve the problem by filtering out the high frequencies. In spatial aliasing, those high frequencies are actually what you’re interesting in, so you normally solve the problem by blending nearby frequencies.
TL;DR: Anti-aliasing in graphics smooths other otherwise blocky or jagged portions of the graphics.
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