《PHP教程：PHP實現(xiàn)的簡易版圖片相似度比較》要點：
本文介紹了PHP教程：PHP實現(xiàn)的簡易版圖片相似度比較，希望對您有用。如果有疑問，可以聯(lián)系我們。
由于相似圖片搜索的php實現(xiàn)的 API 不怎么符合我的用途,所以我重新定義 API 的架構(gòu),改寫成比擬簡單的函數(shù)方式,雖然還是用對象的方式包裝.
PHP實戰(zhàn)
代碼如下:
<?php???
/**??
* 圖片相似度比擬??
*??
* @version???? $Id: ImageHash.php 4429 2012-04-17 13:20:31Z jax $??
* @author????? jax.hu??
*??
* <code>??
*? //Sample_1??
*? $aHash = ImageHash::hashImageFile('wsz.11.jpg');??
*? $bHash = ImageHash::hashImageFile('wsz.12.jpg');??
*? var_dump(ImageHash::isHashSimilar($aHash, $bHash));??
*??
*? //Sample_2??
*? var_dump(ImageHash::isImageFileSimilar('wsz.11.jpg', 'wsz.12.jpg'));??
* </code>??
*/???
???
class ImageHash {???
???
?? /**取樣倍率 1~10??
??? * @access public??
??? * @staticvar int??
??? * */???
?? public static $rate = 2;???
???
?? /**相似度允許值 0~64??
??? * @access public??
??? * @staticvar int??
??? * */???
?? public static $similarity = 80;???
???
?? /**圖片類型對應(yīng)的開啟函數(shù)??
??? * @access private??
??? * @staticvar string??
??? * */???
?? private static $_createFunc = array(???
?????? IMAGETYPE_GIF?? =>'imageCreateFromGIF',???
?????? IMAGETYPE_JPEG? =>'imageCreateFromJPEG',???
?????? IMAGETYPE_PNG?? =>'imageCreateFromPNG',???
?????? IMAGETYPE_BMP?? =>'imageCreateFromBMP',???
?????? IMAGETYPE_WBMP? =>'imageCreateFromWBMP',???
?????? IMAGETYPE_XBM?? =>'imageCreateFromXBM',???
?? );???
???
???
?? /**從文件建立圖片??
??? * @param string $filePath 文件地址路徑??
??? * @return resource 當成功開啟圖片則傳遞圖片 resource ID,失敗則是 false??
??? * */???
?? public static function createImage($filePath){???
?????? if(!file_exists($filePath)){ return false; }???
???
?????? /*判斷文件類型是否可以開啟*/???
?????? $type = exif_imagetype($filePath);???
?????? if(!array_key_exists($type,self::$_createFunc)){ return false; }???
???
?????? $func = self::$_createFunc[$type];???
?????? if(!function_exists($func)){ return false; }???
???
?????? return $func($filePath);???
?? }???
???
???
?? /**hash 圖片??
??? * @param resource $src 圖片 resource ID??
??? * @return string 圖片 hash 值,失敗則是 false??
??? * */???
?? public static function hashImage($src){???
?????? if(!$src){ return false; }???
???
?????? /*縮小圖片尺寸*/???
?????? $delta = 8 * self::$rate;???
?????? $img = imageCreateTrueColor($delta,$delta);???
?????? imageCopyResized($img,$src, 0,0,0,0, $delta,$delta,imagesX($src),imagesY($src));???
???
?????? /*計算圖片灰階值*/???
?????? $grayArray = array();???
?????? for ($y=0; $y<$delta; $y++){???
?????????? for ($x=0; $x<$delta; $x++){???
?????????????? $rgb = imagecolorat($img,$x,$y);???
?????????????? $col = imagecolorsforindex($img, $rgb);???
?????????????? $gray = intval(($col['red']+$col['green']+$col['blue'])/3)& 0xFF;???
???
?????????????? $grayArray[] = $gray;???
?????????? }???
?????? }???
?????? imagedestroy($img);???
???
?????? /*計算所有像素的灰階平均值*/???
?????? $average = array_sum($grayArray)/count($grayArray);???
???
?????? /*計算 hash 值*/???
?????? $hashStr = '';???
?????? foreach ($grayArray as $gray){???
?????????? $hashStr .= ($gray>=$average) ? '1' : '0';???
?????? }???
???
?????? return $hashStr;???
?? }???
???
???
?? /**hash 圖片文件??
??? * @param string $filePath 文件地址路徑??
??? * @return string 圖片 hash 值,失敗則是 false??
??? * */???
?? public static function hashImageFile($filePath){???
?????? $src = self::createImage($filePath);???
?????? $hashStr = self::hashImage($src);???
?????? imagedestroy($src);???
???
?????? return $hashStr;???
?? }???
???
???
?? /**比擬兩個 hash 值,是不是相似??
??? * @param string $aHash A圖片的 hash 值??
??? * @param string $bHash B圖片的 hash 值??
??? * @return bool 當圖片相似則傳遞 true,否則是 false??
??? * */???
?? public static function isHashSimilar($aHash, $bHash){???
?????? $aL = strlen($aHash); $bL = strlen($bHash);???
?????? if ($aL !== $bL){ return false; }???
???
?????? /*計算容許落差的數(shù)量*/???
?????? $allowGap = $aL*(100-self::$similarity)/100;???
???
?????? /*計算兩個 hash 值的漢明距離*/???
?????? $distance = 0;???
?????? for($i=0; $i<$aL; $i++){???
?????????? if ($aHash{$i} !== $bHash{$i}){ $distance++; }???
?????? }???
???
?????? return ($distance<=$allowGap) ? true : false;???
?? }???
???
???
?? /**比擬兩個圖片文件,是不是相似??
??? * @param string $aHash A圖片的路徑??
??? * @param string $bHash B圖片的路徑??
??? * @return bool 當圖片相似則傳遞 true,否則是 false??
??? * */???
?? public static function isImageFileSimilar($aPath, $bPath){???
?????? $aHash = ImageHash::hashImageFile($aPath);???
?????? $bHash = ImageHash::hashImageFile($bPath);???
?????? return ImageHash::isHashSimilar($aHash, $bHash);???
?? }???
???
}?
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