function gauss($x, $sigma, $mu)
{
	$x_mu = $x - $mu;
	$y = (1 /($sigma * sqrt(2*pi())))*exp ( - pow($x -$mu, 2) /(2*pow($sigma,2)));
	return $y;
}

function norm($ar,$k)
{
	if(is_array($ar))
	{
		$max = max($ar);
		foreach($ar as $key =>$val) $out[$key] = (int) floor($k *($val / $max));
		return $out;
	}	
}

$img = imagecreatetruecolor(256,256);
$res =15000;
$sigma = 50;
for($k =0; $k < 256; $k++)
{
	for($g =0; $g < 256; $g++)
	{
		$w = $g;
		if( $w < 90)
		{
			$ar['red'][$w] = 0 ;	
		
		}
		elseif($w >= 90 && $w < 180)
		{
			$ar['red'][$w] =  floor(100*$res*gauss($w, 30, 90));	
		}
		elseif($w >= 180)
		{
			$ar['red'][$w] = floor($res*gauss($w, 30, 255));
		}
		$ar['green'][$w] =  floor($res*gauss($w, 50, 126));
		$ar['blue'][$w] =  floor($res*gauss($w, 50, 190));
	}
	$ar['red'] = norm( $ar['red'], 255);
	$ar['green'] = norm( $ar['green'], 255);
	$ar['blue'] = norm( $ar['blue'], 255);
	
	foreach($ar['red'] as $key => $val )  
	{
		if($key <= 90)
		{
			$color = imagecolorallocate($img, 255, $ar['green'][$key], $ar['blue'][$key]);
		}
		else
		{
			$color = imagecolorallocate($img, $val, $ar['green'][$key] , $ar['blue'][$key]);	
		}
		imagesetpixel($img, $k, $key, $color);
	}	
}
header("Content-type: image/png");
imagepng($img);