<?php

	function Lum($colour) {
		return ($colour['r'] * 0.3) + ($colour['g'] * 0.59) + ($colour['b'] * 0.11);
	}

	function ClipColour($colour) {
	    $result 	= $colour;
	    $luminance 	= Lum($colour);

	    $cMin = min($colour['r'], $colour['g'], $colour['b']);
	    $cMax = max($colour['r'], $colour['g'], $colour['b']);

	    if ($cMin < 0.0) {
	        $result['r'] = $luminance + ((($colour['r'] - $luminance) * $luminance) / ($luminance - $cMin));
	        $result['g'] = $luminance + ((($colour['g'] - $luminance) * $luminance) / ($luminance - $cMin));
	        $result['b'] = $luminance + ((($colour['b'] - $luminance) * $luminance) / ($luminance - $cMin));
	    } 

	    if ($cMax > 255) {
	        $result['r'] = $luminance + ((($colour['r'] - $luminance) * (255 - $luminance)) / ($cMax - $luminance));
	        $result['g'] = $luminance + ((($colour['g'] - $luminance) * (255 - $luminance)) / ($cMax - $luminance));
	        $result['b'] = $luminance + ((($colour['b'] - $luminance) * (255 - $luminance)) / ($cMax - $luminance));
	    }

	    return $result;
	}

	function SetLum($colour, $luminance) {

	    $result = array();

	    $diff =   $luminance - Lum($colour);

	    $result['r'] = $colour['r'] + $diff;
	    $result['g'] = $colour['g'] + $diff;
	    $result['b'] = $colour['b'] + $diff;

	    return ClipColour($result);

	} 

	function normalizeColor( $color ) {
		$color['r'] = $color['r'] / 255;
		$color['g'] = $color['g'] / 255;
		$color['b'] = $color['b'] / 255;

		return $color;
	}
	
	function denormalizeColor( $color ) {
		$color['r'] = round($color['r'] * 255);
		$color['g'] = round($color['g'] * 255);
		$color['b'] = round($color['b'] * 255);

		return $color;
	}

	$overlay_color = array('r'=>180,'g'=>22,'b'=>1, 'a' => 0.35);

	$img = new Imagick();

	if( !isset($_GET['case']) ) {
		$_GET['case'] = '';
	}
	
	//unmodified version
	$original 	= new Imagick('girl.jpg');
			
	//photoshop image to compare
	$ps = new Imagick('original.jpg');

	$img->addImage($original);
	$it = $original->getPixelIterator();

	foreach( $it as $row => $pixels ) {
	    foreach ( $pixels as $column => $pixel ) {
            $rgbIni = $pixel->getColor();
		
			$rgb = SetLum($overlay_color, Lum($rgbIni));
			 $overlay_color 	= normalizeColor($overlay_color);
				$rgb 		= normalizeColor($rgb);

				$rgbIni 		= normalizeColor($rgbIni);

			$rgb['r'] = ((1 - $overlay_color['a']) * $rgbIni['r']) + ($overlay_color['a'] * $rgb['r']);
			$rgb['g'] = ((1 - $overlay_color['a']) * $rgbIni['g']) + ($overlay_color['a'] * $rgb['g']);
			$rgb['b'] = ((1 - $overlay_color['a']) * $rgbIni['b']) + ($overlay_color['a'] * $rgb['b']);

			$test 			= denormalizeColor($test);
            $rgb 			= denormalizeColor($rgb);
            $overlay_color 	= denormalizeColor($overlay_color);

			$pixel->setColor('rgb('.round($rgb['r']).','. round($rgb['g']).','.round($rgb['b']).')');

	    }

	    $it->syncIterator();
	}

	//add modified version
	$img->addImage($original);
	$img->addImage($ps);

	$img->resetIterator();
	$combined = $img->appendImages(true); //stack images

	header('content-type: image/jpeg');

	$combined->setImageFormat("jpeg");

	echo $combined;

?>