What Exactly is Aliasing?

What Exactly is Aliasing?
By , Last updated on: 12/3/2014

I’m sure many of you have heard of Aliasing while looking through graphics cards, or even through things like digital photography, music editing, graphic design, etc. This article will mainly deal with the problem of Aliasing in the context of computer graphics and graphics design, and may answer some questions about digital photography. Even more specifically, it will deal with the problems of Aliasing in games. If you haven’t heard of Aliasing before, this may be an article you might want to read in order to familiarize yourself with Aliasing, just for background knowledge’s sake. Also, understanding Aliasing will help you understand more about computer graphics, and specifically ATI CrossFire’s new feature, SuperAA.

The main problem of Aliasing lies in the fact that as resolution increases more and more, such as in high definition movies/gaming, or more specifically high definition rendering, the computer screen cannot make the images look natural through pixels. More over, computer screens, or laptop screens, are limited by the size of their pixels. Think of it like dot-painting, where the dots are very small. If you look closely enough at the screen, you can still probably see the individual dots, whereas if you look closely at something in real life, it’s not made of little dots (rather they’re made up of atoms, which are very very small, and pixels will probably never be able to accomplish something of that size), hence the problem. In the past this wasn’t as big of a deal, because pixels could replicate lines and edges of objects fairly well through the limited graphics of simpler games. But, as the frames get more and more detailed, the lines and edges within these frames become finer and smaller.

To understand this a bit more, think about a straight line. You can draw a straight line by hand, and by this method you can actually get a straight line (use a ruler if you need to). But, a computer can’t physically draw a straight line, or rather a fluid one. It needs to make a straight line by filling in pixels, which, as you zoom in, look, not like a straight line, but rather like a staircase. If you don’t believe me, open up Microsoft Word, draw a diagonal line, and look very closely at it.

Now this isn’t a problem for graphics that don’t require a lot of detail, like many games and CGI we had in the past. But now, with graphic designers and gaming companies wanting everything to look as natural as possible, they put hundreds of man hours into doing all the finite details, from clothing all the way through plants on the ground. The edges of all of this details, whether it be clothing, plants, guns, aliens, etc, becomes very fine, just as it would be seen through the human eye. Because of these fine lines, you tend to see jagged edges, because computer screens cannot render the finite straight lines as well because of the pixel situation.

Now that you know exactly what Aliasing is, check out all of the graphics cards solutions to Aliasing (deemed, accordingly, Anti-Aliasing), and even more specifically, check out why ATI CrossFire’s SuperAA is a great solution to the Aliasing/Anti-Aliasing problem of computer graphics.


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