Who’s Anty? No, Anti-alias is not some distant relative that you never knew. Anti-alias is a process in which bits of intermediate colour and shade are added to an image. This fools the eye into seeing edges as smoother than they really are. This process reduces the jagies from curved and diagonal lines giving your images a smoother softer appearance. Anti-aliasing can work against you, particularly when assigning a transparent background to an image, it tends to produce a hallow effect around the outer edge of the image

With or without anti-aliasing, which one is better? It’s a matter of opinion I guess. In this case I tend to like the image with anti-aliasing, although I can understand the argument that anti-aliasing makes the image blurry and obscures some of the fine detail (compare the two sailors on the boat the image on the right is clearer in the fine details). Images with anti-aliasing applied to them require more colours as a result file size tends to be larger in this case the image on the left is over 4,400 bytes larger.

Another issues worth mentioning is that applying transparent colours to images without anti-aliasing is far more strait foreword since there are no intermediate colours to worry about.