Question

I have an application that uses imagefilledellipse method (http://php.net/manual/en/function.imagefilledellipse.php) to draw plot points (circles) on an image. For the sake of accuracy, these are supposed to be relatively small. However, as soon as I drop the radius below 6px, they become diamonds. Is this because it is simply impossible (pixel wise) to draw a circle that small? Are there any workarounds that will make the plot points look more circular?

Answer 1

It was poor anti-alising. As deceze mentioned, the a commenter on the manual provides a solution in the comments.