Anti-alias

Anti-aliasing is a technique whereby the rough, jagged edges of curved and diagonal lines are smoothed. In a non-anti-aliased line the pixels in the image are either a part of the line, or they are not. If the line is black on a white background, the pixel must be either black, or white. When the line is anti-aliased, the graphic program tests the colors on both sides and calculates intermediate shades. The pixels on the edge of the graphic, (line in this case), are then colored with the resulting intermediate colors, simulating a straight, smooth edge.

This difference between a line that has been anti-aliased and one which has not is more readily apparent in an example that has not been enlarged for the purpose of displaying the intermediate shades. Note that in the example to the right the grey shades blend with the colors on each side, effectively removing the jagged edges.