PHP/Graphics Image/Circle

Drawing a Circle

<?php
     header ("Content-type: image/png");
   
     $im = ImageCreate (150, 150);
     $grey = ImageColorAllocate ($im, 230, 230, 230);
     $black = ImageColorAllocate ($im, 0, 0, 0);
   
     ImageString($im, 3, 5, 5, "Figure 18.5: Circle", $black);
     ImageArc($im, 75, 75, 50, 50, 0, 360, $black);
     ImagePng ($im);
     ImageDestroy ($im);
?>