PHP实现搜索相似图片

2024-05-04 23:39:04

字体：大中小

来源：转载

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感知哈希的优点是简单快速，不受图片大小缩放的影响，缺点是图片的内容不能变更。实际应用中，往往采用更强大的pHash算法和SIFT算法，它们能够识别图片的变形。只要变形程度不超过25%，它们就能匹配原图。

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');