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。