Anti-Aliasing Analysis, Part 1: Settings And Surprises

Some time has passed since we last delved into the state of anti-aliasing. In this article, we investigate the feature thoroughly from the basics to vendor-specific implementations and learn some shocking surprises about driver settings along the way.

What is anti-aliasing? The prefix “anti” can be defined as counteracting or neutralizing, and “aliasing” is a jagged, stair-step effect on curved or diagonal lines. Therefore, anti-aliasing means to counteract and neutralize jagged lines. When it comes to PC graphics technology, we usually refer to anti-aliasing as it pertains to 3D gaming—it’s a feature that our video cards offer to make graphics appear more attractive.

The concept sounds simple enough. But unfortunately, anti-aliasing isn’t turned on with a simple switch. Today’s video hardware offers a wide variety of options that can be used in 30 or more combinations, depending on the card you own. What does each setting change? What are the advantages and disadvantages of each option? Which ones should you enable or leave alone?

We’re going to do our best to clear up the confusion with this comprehensive anti-aliasing guide. Starting with a short recap of the basics, we move onto generic methods and then vendor-specific implementations. We show you where you can set the options, and give you examples of what those options look like as you play your favourite games. And we'll be following this informational article up in the next couple of weeks with part two, an in-depth numbers-based comparison that will demonstrate the level of anti-aliasing performance you can expect from a wide variety of graphics cards.

Anti-Aliasing Basics

Anti-aliasing has been around for some time and many of our readers already understand the concept. In an article like this, though, it’s important to start from the very beginning. Folks well acquainted with the fundamentals can think of this page as a brief refresher.

As always, with graphics, we must start with the pixel. Pixels are the little square dots that make up an image on a computer screen, the smallest addressable element. Aliasing is a by-product of using square dots to display an image. Consider a picture of a black diagonal line over a white background:

As you can see—especially when zoomed in—the nature of pixels creates a stair-stepping effect, which is called aliasing. Here’s what it looks like in a PC game:

See how the pixels on the edge of objects now blend in with the colour behind when anti-aliasing is enabled? Anti-aliasing makes edges appear smoother and less pixelated by blending the colour of the edge and the background.

Note that stair stepping appears more prominently at lower resolutions because there are fewer pixels with which to display the image.

Create a new thread in the UK Article comments forum about this subject
This thread is closed for comments
14 comments
Comment from the forums
    Your comment
  • mi1ez
    Is that picture on P1 from the Half-Life 2 demo thing?
  • Gonemad
    "making it less desirable in games that have a lot of small type, like MMOs"

    Bingo! That was garbling the text in one certain MMO I was playing. I mean, really garbling to the point it was unreadable, even at 19 x 12 resolutions.

    However, even after disabling AA on the driver and in-game, it was still active. Now you call that "inconclusive". Fortunately, I make a full backup copy of the game folder before tweaking settings, and it took me a full folder backup restoration to disable the option. The catch is, I am trying to recreate the conditions of the malfunction, without success.

    Good Job on the article.
  • tranzz
    Great article - a similar one about anisotropic filtering would be interesting too
  • Jay_83
    Yes tranzz, we hear you.
    Nvidia's naming scheme for AA modes made me lol. Bastards!
    Thanks for the article, cleared some stuff up for me.
  • cleeve
    Anonymous said:
    Is that picture on P1 from the Half-Life 2 demo thing?


    Yessir. Half Life Lost Coast.
  • cleeve
    Anonymous said:

    However, even after disabling AA on the driver and in-game, it was still active. Now you call that "inconclusive". Fortunately, I make a full backup copy of the game folder before tweaking settings, and it took me a full folder backup restoration to disable the option. The catch is, I am trying to recreate the conditions of the malfunction, without success.


    Ouch, that sounds like a royal pain in the arse. Thankfully I never experienced that issue yet.
  • mi1ez
    Anonymous said:
    Yessir. Half Life Lost Coast.

    Ah yes! That's the one!
  • Zingam
    We don't need AA at all. We just need 16000x10000 22" LCD panels :P
  • Zingam
    The choice of a water background for these screenshots is a bad one. You should have chosen static backgrounds for the screenshots. Nothing should change between aliased and anti-aliased modes in the picture.
  • silverblue
    mi1ezIs that picture on P1 from the Half-Life 2 demo thing?

    Exactly my thoughts as well. :)
  • Gonemad
    "We don't need AA at all. We just need 16000x10000 22" LCD panels"

    That is exactly what Supersampling does. But I distinctly remember some games that looked jagged in the good ol'days of 800x600 and looked better at 1024 x 768 with better FPS than enabling AA at 800x600. Or even going back to 640x480 and turn all the eye-candy (back then) on.

    I guess Supersampling is still valid when you hit the TOP resolution of whatever your setup is, but the graphics card( 3x SLI or 3xCF) is still not getting hit. Something like triple 30" monitors at full blast.
  • acer0169
    With my old machine, Crysis always looked better at 1080p than 1440x900 with 4x AA. Now though - new machine.. 1080p with 4x AA sexy :D
  • chechak
    Great job with this article i hope next one will mention anisotropic filtering !
  • AntiZig
    great article, for someone who studied anti-aliasing in school, it was a great read to see how the big boys do it in video games of today.

    would love to see similar article about anisotropic filtering and tessellation.