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 favorite 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 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 byproduct 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 color behind when anti-aliasing is enabled? Anti-aliasing makes edges appear smoother and less pixilated by blending the color 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.