PHP imagecolorresolve() function

<?php
   $img = imagecreatefromgif('https://www.tutorialspoint.com/images/html.gif');
   $colors = array();
   $colors[] = imagecolorresolve($img, 120, 0, 190);
   $colors[] = imagecolorresolve($img, 110, 0, 140);
   $colors[] = imagecolorresolve($img, 120, 190, 0);
   print_r($colors);
   imagedestroy($img);
?>