Php comparison image similarity code example

Php comparison image similarity code example

/** * Image similarity comparison * * @ Version $ Id: ImageHash. php 4429 2012-04-17 13: 20: 31Z jajax $ * @ Authorjax. hu * Www.osxue.com * // 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 ')); * */ Class ImageHash { /** Sampling rate: 1 ~ 10 * @ Access public * @ Staticvar int **/ Public static $ rate = 2; /** Allowed similarity values: 0 ~ 64 * @ Access public * @ Staticvar int **/ Public static $ similarity = 80; /** Enable the function corresponding to the image type * @ 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 ', ); /** Create an image from a file * @ Param string $ filePath file address path * @ Return resource: If the image is enabled successfully, the image resource ID is passed. If the image fails, the value is false. **/ Public static function createImage ($ filePath ){ If (! File_exists ($ filePath) {return false ;} /* Determine whether the file type can be enabled */ $ 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 image * @ Param resource $ src image resource ID * @ Return string the hash value of the image. If the image fails, the value is false. **/ Public static function hashImage ($ src ){ If (! $ Src) {return false ;} /* Reduce the image size */ $ Delta = 8 * self: $ rate; $ Img = imageCreateTrueColor ($ delta, $ delta ); ImageCopyResized ($ img, $ src, 0, 0, 0, $ delta, $ delta, imagesX ($ src), imagesY ($ src )); /* Calculate the gray-scale image value */ $ 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 ); /* Calculate the gray-scale average of all pixels */ $ Average = array_sum ($ grayArray)/count ($ grayArray ); /* Calculate the hash value */ $ HashStr = ''; Foreach ($ grayArray as $ gray ){ $ HashStr. = ($ gray >=$ average )? '1': '0 '; } Return $ hashStr; } /** Hash image file * @ Param string $ filePath file address path * @ Return string the hash value of the image. If the image fails, the value is false. **/ Public static function hashImageFile ($ filePath ){ $ Src = self: createImage ($ filePath ); $ HashStr = self: hashImage ($ src ); Imagedestroy ($ src ); Return $ hashStr; } /** Compare two hash values. is it similar? * @ Param string $ the hash value of the aHash a image. * @ Param string $ hash value of the bHash B image * @ Return bool: If the image is similar, true is passed; otherwise, false is used. **/ Public static function isHashSimilar ($ aHash, $ bHash ){ $ AL = strlen ($ aHash); $ bL = strlen ($ bHash ); If ($ aL! ==$ BL) {return false ;} /* Calculate the number of allowable gaps */ $ AllowGap = $ aL * (100-self: $ similarity)/100; /* Calculate the Hamming distance between two hash values */ $ Distance = 0; For ($ I = 0; $ I <$ aL; $ I ++ ){ If ($ aHash {$ I }! ==$ BHash {$ I}) {$ distance ++ ;} } Return ($ distance <= $ allowGap )? True: false; } /** Compare two image files. is it similar? * @ Param string $ path of the aHash a image * @ Param string $ bHash B Image path * @ Return bool: If the image is similar, true is passed; otherwise, false is used. **/ Public static function isImageFileSimilar ($ aPath, $ bPath ){ $ AHash = ImageHash: hashImageFile ($ aPath ); $ BHash = ImageHash: hashImageFile ($ bPath ); Return ImageHash: isHashSimilar ($ aHash, $ bHash ); } }