Someone

function gradient($start, $end, $steps = 256) {
	$s = hexdec($start) & 0xFFFFFF;	
	$e = hexdec($end) & 0xFFFFFF;
	$sr = ($s >> 16) & 0xFF;
	$sg = ($s >> 8) & 0xFF;
	$sb = $s & 0xFF;
	$er = ($e >> 16) & 0xFF;
	$eg = ($e >> 8) & 0xFF;
	$eb = $e & 0xFF;
	$dr = ($sr - $er) / $steps;
	$dg = ($sg - $eg) / $steps;
	$db = ($sb - $eb) / $steps;
	$ret = array();
	for($i = 0; $i < $steps; $i++) {
		$ret[] = sprintf('%02x%02x%02x', $sr - ($dr * $i), $sg - ($dg * $i), $sb - ($db * $i));
	}
	return $ret;
}