What is Anti Aliasing? All You Need to Know



Category: Game Howtos

what is anti aliasing

Have you ever tried playing a PC game only to find out that your graphics card can't handle it? Rather than spectacular and crisp visual detail, you're met by blocky, pixelated textures and edges that remind you of 8-bit Super Mario Bros. If that's the case, you could do with a sweeping guide on what is anti-aliasing and how you can benefit from it.


What are "Jaggies"? What Causes Them?

These stair-like, pixelated edges are commonly known as "jaggies" in the world of PC games. Usually, they can be eliminated by increasing screen resolution, but it does not always work for everyone. For example, if you have an older graphics card or your card isn't particularly built for gaming, it would be almost impossible to achieve higher resolutions without slowing down your game drastically.

This is where anti-aliasing settings come in to help you improve graphic resolution without slowing your game drastically.

What is Anti Aliasing?

To understand anti-aliasing, it's important to start with aliasing. As you probably know, pixels are square or rectangular. When round shapes are displayed on-screen, you're more than likely to see the jagged edges, referred to as aliasing.

Therefore, as the name implies, anti-aliasing is a method of reducing aliasing as much as possible. Anti-aliasing is a graphic setting that helps you eliminate jaggies in your PC games. It allows your computer to smooth out pixels for sharper image quality.

Most PC games come with an in-game window where you can adjust graphic settings, including anti-aliasing. There are several anti-aliasing methods and techniques that can help you take care of the visual horror, each with its perks and downsides. In the following chapters, we'll look at different ways your PC can handle anti-aliasing.

But first...

How Does Anti Aliasing Work?

Anti-aliasing uses the rendering technique or post-processing filter to blend the colors at the pixel edges to create a smooth illusion. Unfortunately, it comes at the cost of performance, which often lowers FPS.

Different anti-aliasing methods have different impacts on performance. On lower-end AA titles, the game can get a bit blurry. On the other hand, anti-aliasing can lower framerate on higher-end, more demanding titles.

Now that we have a clear picture of what is anti-aliasing and how it works, let's look at the different anti-aliasing techniques:

Types of Anti Aliasing Methods

Most anti-aliasing methods can be grouped into two types:

  • Spatial anti-aliasing
  • Post-process anti-aliasing

1. Spatial Anti Aliasing

Spatial anti-aliasing works by filling the gaps that come with low-resolution images. The technique renders the image at a higher resolution and takes color samples of the excess pixels (pixels not present in the original image). Subsequently, the new high-resolution image is shrunk back to the original low resolution, with each pixel receiving a new color, averaged from the sampled pixels.

In other words, this method gives a low-resolution image the color accuracy of a high-res image. These new colors help pixels blend better, making jaggies less noticeable.

The spatial anti-aliasing method is made up of several different techniques:

a). Supersampling Anti Aliasing (SSAA)

Supersample anti-aliasing, also known as full-scene anti-aliasing (FSAA), was one of the first methods ever developed and is still one of the most effective. It's pretty efficient at processing photorealistic images because it gives them a softer look that makes them look more lifelike.

However, SSAA has its downsides. First, it affects images with multiple horizontal or vertical lines. Such lines are naturally sharp, so a softer look tends to reduce image quality.

Second, SSAA involves processing the whole image before smoothing out the jaggies, hence the name, "full-scene". However, since PC games are typically rendered in real-time, SSAA needs a massive amount of processing power to operate at speeds enough for gaming. As such, SSAA is no longer popular with PC gamers.

b). Multisample Anti Aliasing (MSAA)

When a graphics card renders an image on-screen, it usually differentiates between two distinct elements: a polygon (the general shape or outline of an object in the game) and a texture. A GPU first draws the polygon and then fills it with a texture.

Multi-sampling anti-aliasing only smooths out the edges of the polygon but not the textures. This fairly reduces the processing power needed, making MSAA a popular method among PC gamers. However, it's worth noting that as much as it works, you might still have to contend with pixelated textures.

c). CSAA and EQAA

World-leading GPU makers, NVIDIA and AMD, created a new form of anti-aliasing method: NVIDIA developed CSAA (coverage sampling anti-aliasing) while AMD came up with EQAA (enhanced quality anti-aliasing). Despite having different names, these two techniques work fairly similarly.

The GPU uses CSAA or EQAA to detect whether an image has a polygon. It then identifies the parts of the polygon likely to have jagged edges and then supersamples only the particular pixels with jaggies.

Their mode of operation makes both great tools since only select parts of the image are supersampled. That means it requires considerably less processing power. Plus, you won't need to soften the whole image.

2. Post-Process Anti Aliasing

When it comes to post-process anti-aliasing, each pixel is blurred a little after it's rendered. The GPU identifies the edges of a polygon by comparing color contrast between every two pixels - two identical pixels imply they belong to the same polygon. So, the pixels are blurred in relation to their contrast.

Blurring is pretty effective because it gets rid of the sharp contrast between oddly aligned pixels that cause jaggies. However, the downside is that post-process anti-aliasing can make images look to0 blurry. The blurriness is more visible in games with highly detailed textures as well as dynamic lighting features.

That said, post-process anti-aliasing is still a great tool because it's extremely fast and requires significantly less computing power than spatial anti-aliasing.

a). MLAA and FXAA

NVIDIA and AMD also created their own post-process anti-aliasing methods that work almost the same; MLAA (Morphological Anti-Aliasing) from AMD and FXAA (Fast Approximate Anti-Aliasing) from NVIDIA.

Both are easily the most popular methods at the moment, mainly because they sharpen graphics with remarkably little processing power. However, there's always a caveat, and in this case, graphics tend to look a tad blurrier. But for many gamers, the slight blur is worth trading off for crispier images.

b). Temporal Anti Aliasing (TXAA)

Temporal aliasing is a "film-style technique" that strives to maintain an incredibly smooth level of motion as the player moves through a virtual environment. It's a pretty complex method that employs both blurring and supersampling to create sharper graphics and more fluid motion.

TXAA delivers better images than MLAA or FXAA but requires significantly more computing power. Images might also appear a little soft due to blurring.

c). Enhanced Subpixel Morphological Anti Aliasing (SMAA)

Created by Jorge Jimenez, SMAA is the new kid on the block, turning jagged edges on their heads. It combines both post-process anti-aliasing and spatial anti-aliasing: Smooths out pixels with the same blurring method as MLAA and FXAA and then uses supersampling to sharpen the whole image.

That means using SMAA delivers the better, if not the same, image quality as MLAA or FXAA while requiring much less computing power.

What Anti Aliasing Method Works Best for You?

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The best anti-aliasing method varies from one person to another, but it mostly boils down to your graphics card budget and personal preference. Essentially it boils down to your games' graphics demands, your gaming hardware (GPU power) and the graphics features you prefer to be crisp and those you don't mind being blurring or pixelated.

Is Anti Aliasing Good for FPS?

No. Anti-aliasing comes with compromises, usually at the expense of processing power. The higher you climb up anti-aliasing tiers, the more performance drops. Therefore, you'll have to choose either snappy gameplay or crisp graphics.

But you can also consider getting a higher-resolution display, as long as your processor can handle it.

To Anti-Alias or Not to Anti-Alias?

Ultimately, this is the big question for most gamers and even graphic artists. While anti-aliasing will give you more enhanced visuals and gaming graphics, each method comes at a cost. On this account, it's all up to you to determine how much you're willing to trade-off.

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