When the Amiga computer came out many years ago there was a company called Psygnosis which led the way to better images in games on computers… but nobody was quite sure why they were so good. Their images were not so jagged as the other Amiga games, they looked smooth, even though the resolution of the Amiga was not very good. Psygnosis had discovered Anti-Alias!
Anti-aliasing is the smoothing of jagged edges in digital images by averaging the colours of the pixels at a boundary.
I worked for a company called Arc Developments who taught me to add intermediate colours to my images.
If you take a look at the the text “Charlie Don’t Surf” you will see that I added a dark green layer which mixes with the helmet colour, and that is Anti-Alias which hides jagged edges in images.
So if you want to hide your jagged edges that is one way to do it, or to use transparency near the edges which automatically creates an intermediate colour.