text-color-check.php

<?php
/**
 * Takes an input background color and tells you if you should use a white or black for the text color
 */

$input_color = '49DCBB';
$red         = base_convert(substr($input_color, 0, 2), 16, 10);
$green       = base_convert(substr($input_color, 2, 2), 16, 10);
$blue        = base_convert(substr($input_color, 4, 2), 16, 10);

$text_color = 'FFFFFF'; // use white text
if (((($red * 299) + ($green * 587) + ($blue * 114)) / 1000) > 127) {
	$text_color = '000000'; // use black text
}

echo $text_color;