Classes/Utility/ImageUtility.php
public static function isTransparentPng($fileName)
    {
        $bytes = file_get_contents($fileName, false, null, 24, 2);    // read 24th and 25th bytes
        $byte24 = ord($bytes{0});
        $byte25 = ord($bytes{1});
        if ($byte24 === 16 || $byte25 === 6 || $byte25 === 4) {
            return true;
        } else {
            $content = file_get_contents($fileName);
            return strpos($content, 'tRNS') !== false;
        }
    }
public static function isTransparentPng($fileName)
    {
        $bytes = file_get_contents($fileName, false, null, 24, 2);    // read 24th and 25th bytes
        $byte24 = ord($bytes{0});
        $byte25 = ord($bytes{1});
        if ($byte24 === 16 || $byte25 === 6 || $byte25 === 4) {
            return true;
        } else {
            $content = file_get_contents($fileName);
            return strpos($content, 'tRNS') !== false;
        }
    }
public static function isTransparentPng ( $ fileName ) { $ bytes = file_get_contents ( $ fileName , false , null , 24 , 2 ) ; // read 24th and 25th bytes $ byte24 = ord ( $ bytes { 0 } ) ; $ byte25 = ord ( $ bytes { 1 } ) ; if ( $ byte24 === 16 || $ byte25 === 6 || $ byte25 === 4 ) { return true ; } else { $ content = file_get_contents ( $ fileName ) ; return strpos ( $ content , 'tRNS' ) !== false ; } }
Returns true if the given PNG file contains transparency information.

@param string $fileName
@return bool
Returns true if the given PNG file contains transparency information .