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'));
rush:PHP;">
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,$w,$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 $hash;
}
}
var_dump(ImageHash::run('./1.png','./psb.jpg'));
方法二：
run($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,$width,$height,$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,$y) >> 8 ) & 0xFF;
if (!is_array($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');
$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。
