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php计算两张图片的相似度(汉明距离)

关键词: php 图片相似度汉明距离

php计算两张图片的相似度(汉明距离)

```
<?php
class dryImageSimilar{
    public static $pixel=8;
    private static $createFunction=array('gif'=>'imageCreateFromGIF','jpg'=>'imageCreateFromJPEG','png'=>'imageCreateFromPNG');
    public static function getSimilar($path1,$path2){
        return dryImageSimilar::getSimilarData(dryImageSimilar::getImageHash($path1),dryImageSimilar::getImageHash($path2));
    }
    public static function getImageHash($file){
        $src=self::createImage($file);
        $widthHeight=self::$pixel;
        $img=imageCreateTrueColor($widthHeight,$widthHeight);
        imageCopyResized($img,$src,0,0,0,0,$widthHeight,$widthHeight,imagesX($src),imagesY($src));
        $grayArray=array();
        for($y=0;$y<$widthHeight;$y++){
            for($x=0;$x<$widthHeight;$x++){
                $rgb=imagecolorat($img,$x,$y);
                $redGreenBlue=imagecolorsforindex($img,$rgb);
                $gray=intval(($redGreenBlue['red']+$redGreenBlue['green']+$redGreenBlue['blue'])/3)&0xFF;
                $grayArray[]=$gray;
            }
        }
        imagedestroy($img);
        $average=array_sum($grayArray)/count($grayArray);
        $hash='';
        foreach($grayArray as $gray){
            $hash.=($gray>=$average)?'1':'0';
        }
        imagedestroy($src);
        return $hash;
    }
    public static function createImage($file){
        if(!file_exists($file)){
            exit("file '{$filePath}' not exists");
        }
        $extension=strtolower(pathinfo($file)['extension']);
        if(!array_key_exists($extension,self::$createFunction)){
            exit("file extension '{$extension}' not support,only support gif|jpg|png");
        }
        $function=self::$createFunction[$extension];
        return $function($file);
    }
    public static function getSimilarData($hash1,$hash2){
        $length=strlen($hash1);
        $similar=0;
        for($i=0;$i<$length;$i++){
            if($hash1{$i}==$hash2{$i}){
                $similar++;
            }
        }
        return array('similar'=>$similar/(self::$pixel*self::$pixel),'hash1'=>$hash1,'hash2'=>$hash2);
    }
}

$data=dryImageSimilar::getSimilar('test/a.png','test/b.png');
echo '<pre>';
print_r($data);
?>
```
运行结果如下
```
Array
(
    [similar] => 0.75
    [hash1] => 1000001111111011111111111111111110110111111111111111111111111111
    [hash2] => 0011000101111101011111010101110111111111111011111110111111111111
)
```

admin
2016-12-31 22:35:45
php

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php计算两张图片的相似度(汉明距离)