Give rgb color and percent and function will return you same color but brighter according to percent. From 0% to 100%. Example: <?php echo rgb_gen('64,128,0', '50%'); ?>

rgb_den

<?php
function rgb_gen($rgb, $percent) {
    $cleaned_percent = preg_replace("/\..*|%/", "", $percent);
    $rgb_increment = 100 - $cleaned_percent;
    $rgb_arr = explode(',', $rgb);
    $rgb_arr[0] + $rgb_increment <= 255 ? $rgb_arr[0]+=$rgb_increment : $rgb_arr[0] = 255;
    $rgb_arr[1] + $rgb_increment <= 255 ? $rgb_arr[1]+=$rgb_increment : $rgb_arr[1] = 255;
    $rgb_arr[2] + $rgb_increment <= 255 ? $rgb_arr[2]+=$rgb_increment : $rgb_arr[2] = 255;
    $new_rgb = implode(',', $rgb_arr);
    return $new_rgb;
}
?>