What is Anti-Aliasing?

Computer Graphics have become extremely complex and life-like. Achieving this requires a lot of intricate techniques, one of them is called Anti-Aliasing.

What Anti-Aliasing essentially is a technique that removes jagged details from a computer-generated image. Think of Aliasing as playing a game of Chinese-Whispers. As a sentence is passed down, it can become completely indistinguishable from the original sentence. Aliasing is the same thing but with computer graphics. The computer’s brain may create a realistic image, but it can look pixelated when rendered to us on a screen.

That was just a basic explanation of Anti-Aliasing, it is a way more diverse and far more interesting topic. Let us dive into its depths.

What is Anti-Aliasing in games? What is it in general?

Just a heads up, we will now be calling Anti-Aliasing AA. As mentioned above, Aliasing is an inevitable disruption in computer graphics. When it comes to video games, Anti Aliasing makes the video quality less blocky. Since Computer graphics are made of pointy polygons, they create blocky artifacts in gaming. AA smoothes all of that.

To truly understand AA, we need to know what it is trying to correct for. What even is Aliasing. It would be extremely difficult to explain it through text alone. So let us look at a series of images to comprehend it.

What is Aliasing?

The image below looks like a gear cog. But something about it feels wrong. The edges of it look all jagged. A gear cog in real life is smooth and even. Now we will zoom into the teeth of the cog to see these jagged lines up close.

Looking at the zoomed-in image, it is visible at the edges that there are little stair-case-like features, as shown by the black arrow. This is aliasing.

As you can see, it is an unpleasant effect. It can ruin beautifully created computer images into a jagged mess. System engineers know about it, so Anti-Aliasing was created to combat it. The difference can be quite significant.

What does Anti-Aliasing do?

Now let us look at the very same. This time it has gone through Anti Aliasing procedures. The difference is quite stark.

It is visible that the edges are smooth and closer to what would be seen by your eyes.

A close-up of the teeth of the gear shows the stark changes caused when AA is applied to an image. Gone are the stair-case features. The image looks more presentable. AA essentially smooths out all the jagged distortions in a computer image.

Anti Aliasing Philosophies

There are two primary philosophies for AA:

Spatial Anti Aliasing techniques work by manipulating the resolution of your display. It works by converting a low-resolution jaggedy image into a smaller higher resolution one. Then compares this image’s data to correct for any aliasing in the original image. It is divided into two subcategories.

FXAA or Fast Approximate Anti-Aliasing uses the same techniques as stated above but, it performs this for the entire image.
MSAA or Multi-Sample Anti Aliasing is only focused on edges of the features in Computer-Generated Graphics

2. Post Processing Anti Aliasing compares two pixels and if there is not a lot of difference in their color values, it will blur both these pixels. It is akin to an artist smudging two nearby colors to create a smoothed blur effect. It is also divided into two subcategories

Temporal Anti Aliasing or TAA combines the capabilities of both FSAA and the blurring effect under Post Processing AA.
Enhanced Subpixel Morphological Anti Aliasing or SMAA uses a mix of all the techniques stated above. That means its effects are applied to the whole image.

Each methodology has its pros and cons. They are utilized in their specific domains. By comparing these different AA techniques, we can learn when they should be used.

SMAA vs FXAA

SMAA	FXAA
Is not very compute-intensive due to its ability to use a lot of tools.	Very compute-intensive since it renders a scene several times, before outputting the final result.
Recommended to be used on lower-end computers. Such as Laptops with only Integrated Graphics Processors.	Computers with lower-end dedicated Graphics processors use this technique. Any GPU with 4GB of Video Memory can handle this.
Can be used in dynamic scenes such as video games, without being too tasking on a system.	Used for rendering high-quality Computer Generated still images. Not very efficient for video games.

MSSA vs FXAA

MSAA	FXAA
Moderately Computer-intensive. Efficiency depends on the developer’s implementation.	On equal systems renders images much faster than MSAA. Although uses up more Computing resources.
Can allow moderately priced systems to achieve excellent graphics rendering performance without affecting frame rates in dynamic situations.	Can also allow moderately priced systems to achieve great graphics rendering. But effects frame rates in dynamic situations, such as games.
Use a lot in older games but is quickly being outdated by other more powerful AA techniques.	Not used as often because of the smearing effect caused when the field of view in an image changes. It essentially makes video games quite blurry.

At the end of every comparison, it is expected that there will be a clear winner. The answer here is: it is complicated.

Best Anti Aliasing Technique

Now before that, if a question ever comes up between should, Anti Aliasing be On or Off, the answer to that is simple. Always keep it on; with modern-day GPUs and optimization by game developers, AA results in superior image quality without sacrificing too much performance.

Now to the best AA, well it depends on your use case and Computer. If you have a very High-end system, then TAA is the way to go; it results in unrivaled image quality. Likewise, if you have a lower-end Computer SMAA can allow adequate video quality in games simultaneously, allowing the user to have a decent frame rate.

Understanding your use case is the key to applying the correct AA to Computer Graphics.