<?php

$im = imagecreatetruecolor(400, 300);

$c_black = imageColorAllocate($im, 0,0,0);
$c_green = imageColorAllocate($im, 46,204,64);

imageellipse($im, 200, 150, 100, 100, $c_green);

imagePng($im, '/tmp/image.png');

• imagecreatetruecolor - creates true color lib:GD image object with specified width & height
• imageColorAllocate - creates color object to later use in image
• imageellipse - creates ellipse with specified coordinates, radius and border color
• 200, 150 - coordinates of center of circle
• 100, 100 - horizontal and vertical radius should be equal to get circle
• $c_green - fill color
• imagePng - saves image in PNG format to the given path

group: circle

<?php

$im = imagecreatetruecolor(400, 300);

$c_black = imageColorAllocate($im, 0,0,0);
$c_green = imageColorAllocate($im, 46,204,64);

imageellipse($im, 200, 150, 100, 100, $c_green);

imagePng($im, '/tmp/image.png');