Anti-aliasing in Photoshop CS

Aliasing is caused by inadequate sampling frequency. The term is most commonly applied to spatial aliasing, which manifests as visible pixelation ( a blocky or jagged effect ) especially with near horizontal or near vertical lines of high contrast, thus mostly noticeable using large fonts.

Anti-aliasing is the process of blurring sharp edges in pictures to get rid of the jagged edges on lines. After an image is rendered, some applications automatically anti-alias images. The program looks for edges in an image, and then blurs adjacent pixels to produce a smoother edge.

In order to anti-alias an image when rendering, the computer has to take samples smaller than a pixel in order to figure out exactly where to blur and where not to. This process is called 'raytracing'.

In the below example, you can see an image without anti-aliasing and with anti-aliasing and enlargements of these two pictures.

Verdana 60 pixels aliased	Verdana 60 pixels 300% magnification, aliased
Verdana 60 pixels anti-aliased	Verdana 60 pixels, zoomed 300%, anti-aliased. Notice how the anti-aliasing process appears to have smudged the edges.
Anti-aliased circle	Aliased circle ( note the jagged edges )

In Photoshop 6, make sure for fonts over 12 points in size ( as a rule of thumb ) are set to be anti-aliased. When you click on the type tool, you will see the anti-aliasing options next to the font size and type. I set mine to smooth.

When using line related tools or the circle marquee, the anti-alias check box is also on the menu bar up top.

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