PHP实现搜索相似图片

感知哈希算法

count < =5 匹配最相似
count > 10 两张不同的图片
var_dump(ImageHash::run(‘./1.png', ‘./psb.jpg'));

<?php
class ImageHash {
 const FILE_NOT_FOUND = '-1';
 const FILE_EXTNAME_ILLEGAL = '-2';
 private function __construct() {}
 public static function run($src1, $src2) {
   static $self;
   if(!$self) $self = new static;
   if(!is_file($src1) || !is_file($src2)) exit(self::FILE_NOT_FOUND);
   $hash1 = $self->getHashValue($src1);
   $hash2 = $self->getHashValue($src2);
   if(strlen($hash1) !== strlen($hash2)) return false;
   $count = 0;
   $len = strlen($hash1);
   for($i = 0; $i < $len; $i++) if($hash1[$i] !== $hash2[$i]) $count++;
   return $count <= 10 ? true : false;
 }
 public function getImage($file) {
   $extname = pathinfo($file, PATHINFO_EXTENSION);
   if(!in_array($extname, ['jpg','jpeg','png','gif'])) exit(self::FILE_EXTNAME_ILLEGAL);
   $img = call_user_func('imagecreatefrom'. ( $extname == 'jpg' ? 'jpeg' : $extname ) , $file);
   return $img;
 }
 public function getHashValue($file) {
   $w = 8;
   $h = 8;
   $img = imagecreatetruecolor($w, $h);
   list($src_w, $src_h) = getimagesize($file);
   $src = $this->getImage($file);
   imagecopyresampled($img, $src, 0, 0, 0, 0, $w, $h, $src_w, $src_h);
   imagedestroy($src);
   $total = 0;
   $array = array();
   for( $y = 0; $y < $h; $y++) {
     for ($x = 0; $x < $w; $x++) {
       $gray = (imagecolorat($img, $x, $y) >> 8) & 0xFF;
       if(!isset($array[$y])) $array[$y] = array();
       $array[$y][$x] = $gray;
       $total += $gray;
     }
   }
   imagedestroy($img);
   $average = intval($total / ($w * $h * 2));
   $hash = '';
   for($y = 0; $y < $h; $y++) {
     for($x = 0; $x < $w; $x++) {
       $hash .= ($array[$y][$x] >= $average) ? '1' : '0';
     }
   }
   var_dump($hash);
   return $hash;
 }
}
var_dump(ImageHash::run('./1.png', './psb.jpg'));

方法二：

hash($f);
}
return $isString ? $result[0] : $result;
}
public function checkIsSimilarImg($imgHash, $otherImgHash){
if (file_exists($imgHash) && file_exists($otherImgHash)){
 $imgHash = $this->run($imgHash);
 $otherImgHash = $this->run($otherImgHash);
}
if (strlen($imgHash) !== strlen($otherImgHash)) return false;
$count = 0;
$len = strlen($imgHash);
for($i=0;$i<$len;$i++){
 if ($imgHash{$i} !== $otherImgHash{$i}){
 $count++;
 }
}
return $count <= (5 * $rate * $rate) ? true : false;
}
public function hash($file){
if (!file_exists($file)){
 return false;
}
$height = 8 * $this->rate;
$width = 8 * $this->rate;
$img = imagecreatetruecolor($width, $height);
list($w, $h) = getimagesize($file);
$source = $this->createImg($file);
imagecopyresampled($img, $source, 0, 0, 0, 0, $width, $height, $w, $h);
$value = $this->getHashValue($img);
imagedestroy($img);
return $value;
}
public function getHashValue($img){
$width = imagesx($img);
$height = imagesy($img);
$total = 0;
$array = array();
for ($y=0;$y<$height;$y++){
 for ($x=0;$x<$width;$x++){
 $gray = ( imagecolorat($img, $x, $y) >> 8 ) & 0xFF;
 if (!is_array($array[$y])){
  $array[$y] = array();
 }
 $array[$y][$x] = $gray;
 $total += $gray;
 }
}
$average = intval($total / (64 * $this->rate * $this->rate));
$result = '';
for ($y=0;$y<$height;$y++){
 for ($x=0;$x<$width;$x++){
 if ($array[$y][$x] >= $average){
  $result .= '1';
 }else{
  $result .= '0';
 }
 }
}
return $result;
}
public function createImg($file){
$ext = $this->getFileExt($file);
if ($ext === 'jpeg') $ext = 'jpg';
$img = null;
switch ($ext){
 case 'png' : $img = imagecreatefrompng($file);break;
 case 'jpg' : $img = imagecreatefromjpeg($file);break;
 case 'gif' : $img = imagecreatefromgif($file);
}
return $img;
}
public function getFileExt($file){
$infos = explode('.', $file);
$ext = strtolower($infos[count($infos) - 1]);
return $ext;
}
}

调用方式如下：

require_once "Imghash.class.php";
$instance = ImgHash::getInstance();
$result = $instance->checkIsSimilarImg('chenyin/IMG_3214.png', 'chenyin/IMG_3212.JPG');

如果$result值为true, 则表明2个图片相似，否则不相似。