Anti-aliasing refers to method of eliminating or often reducing the unwanted artifacts. In the context of rasterizing images, antialiasing refers to the reduction of the jagged borders between colors .Most software provides anti-aliasing as an option when placing text or objects in an image. When a line in a digital image runs at certain angle, then it will often appear with jagged edges. This effect is caused by the regular pixel grid in the image, and is called aliasing.
One of the most important techniques in making graphics and text easy to read so that it must be pleasing to the human eye on-screen is anti-aliasing. Anti-aliasing is a cheaty way of making objects appear as smooth as possible even tough they are rough with jagged edges.
Anti-aliasing, is the technique designed to reduce or eliminate the jaggy edged effect, by shading the pixels along the borders of graphical elements. It pretends that rendering takes place by averaging the image pixels that would be produced on any display device.
Jagged edges caused due to aliasing are produced because of the limitations in a computer screen, whether that be a CRT or TFT/LCD screen .Monitors are capable of producing nearly perfect straight lines either horizontally or vertically, but when it comes to diagonal lines of any angle ,the monitor produces a line with some jagged edges.
This is because the display screen is made up of pixels which are in a grid formation. When a diagonal line is drawn on a computer screen it has to cross several grid lines, these pixels create blocks of colour and the diagonal lines displace these blocks slightly causing jagged edges.
Anti-aliasing depends on screens that can display many colours.Screens managing 256 colours generally has good anti-aliasing effect at the expense of their range of colours. Anti-aliased edges produce a small blur around the edge of an image that gives it a smooth, blended look.Anti-aliasing increases file size. When the color around an anti-aliased edge is made transparent, the blurring effect along the edge remains intact and all of the varying shades are obvious fringed along the graphical objects.