change font color if background is dark or light in php

1get_brightness($hex) { 
2  // returns brightness value from 0 to 255 
3  // strip off any leading # 
4  $hex = str_replace('#', '', $hex); 
5  $c_r = hexdec(substr($hex, 0, 2)); 
6  $c_g = hexdec(substr($hex, 2, 2)); 
7  $c_b = hexdec(substr($hex, 4, 2)); 
8  
9  return (($c_r * 299) + ($c_g * 587) + ($c_b * 114)) / 1000;
10}
11
12$color = "#******"; 
13if ($get_brightness($color) > 130) { // will have to experiment with this number 
14  echo '<font style="color:black;">Black</font>'; 
15} else {  
16  echo '<font style="color:white;">White</font>'; 
17}