Modifying Fill Edges
Once you have filled an object, you can control how the edges of the object display that fill.
To change the edges of a fill:
Choose one of the vector drawing tools or select a vector object. The Property Inspector displays the Fill options.
Hard leaves the edge of the object as single-colored pixels.
Anti-Alias softens the edge of the object by changing the color of the pixels so they blend into the background or other objects.
The feather amount is in pixels and is applied equally to both sides of the edge.
Anti-Aliasing Adds Colors
Anti-aliasing smooths out the harsh edges of objects. Remember, though, that when you apply anti-aliasing you also add colors to the object.
Those extra colors can add to the size of your file. You can reduce the number of colors by selectively changing the anti-alias setting to a hard edge when objects have similar colors.
For instance, a yellow object with a hard edge is very noticeable over a blue background and needs anti-aliasing to avoid looking jagged. But a light yellow object over a gold background may not need anti-aliasing.