comparison of images test multiple methods.

<?php

set_time_limit(0);
error_reporting(E_ALL);

date_default_timezone_set("Europe/Amsterdam");

/*
$image1 = new imagick("image1.png");
$image2 = new imagick("image2.png");

$result = $image1->compareImages($image2, Imagick::METRIC_MEANSQUAREERROR);
$result[0]->setImageFormat("png");

header("Content-Type: image/png");
echo $result[0];

exit;
*/
$enter = "\r\n";

class compareImages
{
    private function mimeType($i) {
        /*returns array with mime type and if its jpg or png. Returns false if it isn't jpg or png*/
        $mime = getimagesize($i);
        $return = array($mime[0],$mime[1]);

        switch ($mime['mime']) {
            case 'image/jpeg':
                $return[] = 'jpg';
                return $return;
            case 'image/png':
                $return[] = 'png';
                return $return;
            default:
                return false;
        }
    }

    private function createImage($i) {
        /*retuns image resource or false if its not jpg or png*/
        $mime = $this->mimeType($i);

        if($mime[2] == 'jpg') {
            return imagecreatefromjpeg ($i);
        }
        else if ($mime[2] == 'png')  {
            return imagecreatefrompng ($i);
        }
        else {
            return false;
        }
    }

    private function resizeImage($i,$source) {
        /*resizes the image to a 8x8 squere and returns as image resource*/
        $mime = $this->mimeType($source);

        $t = imagecreatetruecolor(8, 8);

        $source = $this->createImage($source);

        imagecopyresized($t, $source, 0, 0, 0, 0, 8, 8, $mime[0], $mime[1]);

        return $t;
    }

    private function colorMeanValue($i) {
        /*returns the mean value of the colors and the list of all pixel's colors*/
        $colorList = array();
        $colorSum = 0;
        for($a = 0;$a<8;$a++) {
            for($b = 0;$b<8;$b++) {
                $rgb = imagecolorat($i, $a, $b);
                $colorList[] = $rgb & 0xFF;
                $colorSum += $rgb & 0xFF;
            }
        }

        return array($colorSum/64,$colorList);
    }

    private function bits($colorMean) {
        /*returns an array with 1 and zeros. If a color is bigger than the mean value of colors it is 1*/
        $bits = array();

        foreach($colorMean[1] as $color){$bits[]= ($color>=$colorMean[0])?1:0;}

        return $bits;
    }

    public function compare($a,$b) {
        /*main function. returns the hammering distance of two images' bit value*/
        $i1 = $this->createImage($a);
        $i2 = $this->createImage($b);

        if(!$i1 || !$i2){return false;}

        $i1 = $this->resizeImage($i1,$a);
        $i2 = $this->resizeImage($i2,$b);

        imagefilter($i1, IMG_FILTER_GRAYSCALE);
        imagefilter($i2, IMG_FILTER_GRAYSCALE);

        $colorMean1 = $this->colorMeanValue($i1);
        $colorMean2 = $this->colorMeanValue($i2);

        $bits1 = $this->bits($colorMean1);
        $bits2 = $this->bits($colorMean2);

        $hammeringDistance = 0;

        for($a = 0;$a<64;$a++) {

            if($bits1[$a] != $bits2[$a]) {
                $hammeringDistance++;
            }
        }

        return $hammeringDistance;
    }
}

class imagediff {
    private $image1, $image2;
    private $rectX, $rectY;
    private $diference = array();
    private $different_pixels = array();
    private $image1src;
    private $image2src;
    private $rectZone;

    function __construct($img1, $img2, $rectX = 50, $rectY = 50) {
        $this->image1['path'] = realpath($img1);
        $this->image2['path'] = realpath($img2);
        $this->image1src = $img1;
        $this->image2src = $img2;
        $this->rectX = $rectX;
        $this->rectY = $rectY;

        if ($this->image1['path'] === false || $this->image2['path'] === false) {
            throw new Exception('Image "' . htmlspecialchars($this->image1 ? $img2 : $img1) . '" not found!<br />');
        }
        else {
            $this->image1['type'] = $this->imagetyte($this->image1['path']);
            $this->image2['type'] = $this->imagetyte($this->image2['path']);
        }
    }

    private function imagetyte($imgname) {
        $file_info = pathinfo($imgname);
        if (!empty($file_info['extension'])) {
            $filetype = strtolower($file_info['extension']);
            $filetype = $filetype == 'jpg' ? 'jpeg' : $filetype;
            $func = 'imagecreatefrom' . $filetype;
            if (function_exists($func)) {
                return $filetype;
            } else {
                throw new Exception('File type "' . htmlspecialchars($filetype) . '" not supported!<br />');
            }
        }
        else {
            throw new Exception('File type not supported! <br />');
        }
    }
    public function createDiffImage($i1, $i2) {
        /* http://www.phpied.com/image-diff/ */

        $this->rectZone[0] = $this->rectX;
        $this->rectZone[1] = $this->rectY;

        list($src_W, $src_H) = getimagesize($i1);
        $ratio_src = $src_W / $src_H;

        ($this->rectZone[0] / $this->rectZone[1] > $ratio_src) ? $this->rectZone[0] = $this->rectZone[1] * $ratio_src : $this->rectZone[1] = $this->rectZone[0] / $ratio_src;

        $i1 = @imagecreatefromjpeg($i1);
        $i2 = @imagecreatefromjpeg($i2);

        $zone1 = imagecreate($this->rectZone[0], $this->rectZone[1]);
        imagecopyresampled($zone1, $i1, 0, 0, 0, 0, $this->rectZone[0], $this->rectZone[1], $src_W, $src_H);
        $zone2 = imagecreate($this->rectZone[0], $this->rectZone[1]);
        imagecopyresampled($zone2, $i2, 0, 0, 0, 0, $this->rectZone[0], $this->rectZone[1], $src_W, $src_H);

        imagefilter($zone1, IMG_FILTER_GRAYSCALE);
        imagefilter($zone2, IMG_FILTER_GRAYSCALE);
        /*
        $gaussian = array(array(1.0, 2.0, 1.0), array(2.0, 4.0, 2.0), array(1.0, 2.0, 1.0));
        imageconvolution($zone1, $gaussian, 16, 0);
        imageconvolution($zone2, $gaussian, 16, 0);
        imagefilter($zone1,IMG_FILTER_PIXELATE,round($this->rectZone[0]/5,0));
        imagefilter($zone2,IMG_FILTER_PIXELATE,round($this->rectZone[0]/5,0));
        */

        $sx1 = imagesx($zone1);
        $sy1 = imagesy($zone1);
        $diffi = imagecreatetruecolor($sx1, $sy1);
        $red = imagecolorallocate($diffi, 255, 0, 0);
        imagefill($diffi, 0, 0, imagecolorallocate($diffi, 0, 0, 0));
        $different_pixels = 0;

        $sumtotal = 0;

        for ($x = 0; $x < $sx1; $x++) {
            for ($y = 0; $y < $sy1; $y++) {

                $rgb1 = imagecolorat($zone1, $x, $y);
                $pix1 = imagecolorsforindex($zone1, $rgb1);

                $rgb2 = imagecolorat($zone2, $x, $y);
                $pix2 = imagecolorsforindex($zone2, $rgb2);

                $mediapixels = pow($pix1['red']   - $pix2['red'], 2) +
                               pow($pix1['green'] - $pix2['green'], 2) +
                               pow($pix1['blue']  - $pix2['blue'], 2);
                $sumtotal = $sumtotal + $mediapixels;
                if ($mediapixels > 1500) {
                    $different_pixels++;
                    imagesetpixel($diffi, $x, $y, $red);
                }
            }
        }

        $total = $sx1 * $sy1;
        $percent = number_format(100 * $different_pixels / $total, 2);

        array_push($this->different_pixels, $different_pixels, $percent, ($this->rectZone[0] * $this->rectZone[1]));
        return $this->different_pixels;
    }

    private function imagehex($image) {
        error_reporting(0);
        ini_set("gd.jpeg_ignore_warning", true);

        $this->rectZone[0] = $this->rectX;
        $this->rectZone[1] = $this->rectY;
        $size = getimagesize($image['path']);
        $func = 'imagecreatefrom' . $image['type'];
        $imageres = $func($image['path']);
        $zone = imagecreate($this->rectZone[0], $this->rectZone[1]);
        imagecopyresized($zone, $imageres, 0, 0, 0, 0, $this->rectZone[0], $this->rectZone[1], $size[0], $size[1]);
        $colormap = array();
        $average = 0;
        $result = array();

        for ($x = 0; $x < $this->rectZone[0]; $x++) {
            for ($y = 0; $y < $this->rectZone[1]; $y++) {
                $color = imagecolorat($zone, $x, $y);
                $color = imagecolorsforindex($zone, $color);
                $colormap[$x][$y] = 0.212671 * $color['red'] +
                                    0.715160 * $color['green'] +
                                    0.072169 * $color['blue'];
                $average += $colormap[$x][$y];
            }
        }

        $average /= ($this->rectZone[0] * $this->rectZone[1]);
        for ($x = 0; $x < $this->rectZone[0]; $x++) {
            for ($y = 0; $y < $this->rectZone[1]; $y++) {
                $result[] = ($x < 10 ? $x : chr($x + 97)) . ($y < 10 ? $y : chr($y + 97)) . round(2 * $colormap[$x][$y] / $average);
            }
        }

        return $result;
    }

    public function diff() {
        $hex1 = $this->imagehex($this->image1);
        $hex2 = $this->imagehex($this->image2);
        $result = (count($hex1) + count($hex2)) - count(array_diff($hex2, $hex1)) - ($this->rectZone[0] * $this->rectZone[1]);
        return $result / ((count($hex1) + count($hex2)) / 2);
    }
}

class imagediffOld
{
    private $image1;
    private $image2;

    function  __construct($img1, $img2) {
        $this->image1['path'] = realpath($img1);
        $this->image2['path'] = realpath($img2);
        if($this->image1['path'] === false || $this->image2['path'] === false) {
            throw new Exception('Image "'.htmlspecialchars( $this->image1 ? $img2 : $img1 ).'" not found!');
        }
        else {
            $this->image1['type'] = $this->imagetyte($this->image1['path']);
            $this->image2['type'] = $this->imagetyte($this->image2['path']);
        }
    }

    private function imagetyte($imgname) {
        $file_info = pathinfo($imgname);
        if(!empty ($file_info['extension'])) {
            $filetype = strtolower($file_info['extension']);
            $filetype = $filetype == 'jpg' ? 'jpeg' : $filetype;
            $func = 'imagecreatefrom' . $filetype;
            if(function_exists($func)) {
                return $filetype;
            }
            else {
                throw new Exception('File type "'.htmlspecialchars( $filetype ).'" not supported!');
            }
        }
        else {
            throw new Exception('File type not supported!');
        }
    }

    private function imagehex($image) {
        $size = getimagesize($image['path']);
        $func = 'imagecreatefrom'.$image['type'];
        $imageres = $func($image['path']);
        $zone = imagecreate(20, 20);
        imagecopyresized($zone, $imageres, 0, 0, 0, 0, 20, 20, $size[0], $size[1]);
        $colormap = array();
        $average = 0;
        $result = array();
        for($x=0; $x<20; $x++) {
            for($y=0; $y<20; $y++) {
                $color = imagecolorat($zone, $x, $y);

                $color = imagecolorsforindex($zone, $color);

                $colormap[$x][$y]= 0.212671 * $color['red'] + 0.715160 * $color['green'] + 0.072169 * $color['blue'];
                $average += $colormap[$x][$y];
            }
        }
        $average /= 400;
        for($x=0; $x<20; $x++) {
            for($y=0; $y<20; $y++) {
                $result[]=($x<10?$x:chr($x+97)) . ($y<10?$y:chr($y+97)) . round(2*$colormap[$x][$y]/$average);
            }
        }
        return $result;
    }

    public function diff() {
        $hex1 = $this->imagehex($this->image1) ;
        $hex2 = $this->imagehex($this->image2);
        $result=(count($hex1) + count($hex2)) - count(array_diff($hex2,$hex1))-400;
        return $result / ( ( count($hex1) + count($hex2) ) / 2 );
    }
}

$photos = glob("d:/photos/snapshots/20140301/*.jpg");
usort($photos, function($a, $b) {
    return strcmp($b, $a);
});
$current = array_shift($photos);
$cnt = 0;
echo '<table>';
function microtime_float() {
    list($usec, $sec) = explode(" ", microtime());
    return ((float)$usec + (float)$sec);
}

$best = array();
$missed = array();
foreach ($photos AS $next) {
    $start = microtime_float();
    $diff = new imagediff($current, $next, 64, 64, true);
    $tmp = $diff->diff() * 100;
    $endTime = microtime_float() - $start;
    $cnt++;
    $array = array();
    $best_cur = 999;
    $best_cur_id = 999;

    if ($tmp < 80) {
        $comp = new compareImages();

        echo '<tr><td>' . $enter;
        echo '<img src="file:///' . str_replace("\\", "/", $current) . '" width="256" height="256"></td><td><img src="file:///' . str_replace("\\", "/", $next) . '" width="256" height="256"></td><td>' . $enter;
        echo 'Time: ' . date("H:i:s") . '<br />';
        echo 'Item: ' . $cnt . $enter . '<br />';

        $tmp = number_format($tmp, 2);
        $array[] = array($tmp, $endTime);

        $start = microtime_float();
        $tmp = $comp->compare($current, $next);
        $endTime = number_format(microtime_float() - $start,2);
        $array[] = array($tmp, $endTime);

        $start = microtime_float();
        $diffy = new imagediffOld($current, $next);
        $tmp = ($diffy->diff() * 100);
        $endTime = number_format(microtime_float() - $start,2);
        $array[] = array($tmp, $endTime);

        $start = microtime_float();
        $tmp = number_format(exec('"c:\Program Files\ImageMagick-6.8.8-Q16\compare.exe" -metric PSNR ' . $current . ' ' . $next . ' NULL: 2>&1'),2);
        $endTime = number_format(microtime_float() - $start,2);
        $array[] = array($tmp, $endTime);

        $start = microtime_float();
        $tmp = number_format(exec('"c:\Program Files\ImageMagick-6.8.8-Q16\compare.exe" -metric NCC ' . $current . ' ' . $next . ' NULL: 2>&1'),2);
        $endTime = number_format(microtime_float() - $start,2);
        $array[] = array($tmp, $endTime);

        foreach ($array AS $k=>$v) {
            if ($best_cur > $v[1]) { $best_cur = $v[1]; $best_cur_id = $k; }
            echo $k . ': ' . $v[0] . ' (' . number_format($v[1], 2) . ')<br />';
        }
        $best[$best_cur_id]++;
//        echo $current . ';' . '</td><td>';
//        echo $next . ';' . $enter;
        echo '</td></tr>';
    }
    else {
        $missed[] = $next;
    }
    $current = $next;
    flush();
}

print_r($best);
print_r($missed);