PHP致命错误：未找到类'Imagick'

Question

I am trying to create JPEG image from TIFF binary data. I call a SOAP service and get a TIFF binary array as follows:

$val = array(
                "arg0" => XXX,
                "arg1" => XXX,
        );

        $headerbody  = array(
                'Username'=>XXX,
                'Password'=>XXX,
        );
$wsdl =  'wsdl services url';   
    $client = new SoapClient($wsdl);
            $soap_var_header = new SoapVar($headerbody, SOAP_ENC_OBJECT);
            $header = new SoapHeader("http://webservices.averittexpress.com/authn",'authnHeader', $soap_var_header);
            $client->__setSoapHeaders($header);
            $value = $client->getDocument($val);

        try {           
        $im = new Imagick();
        $im->readImageBlob($value->return);
        $im->setFormat('JPEG');
        file_put_contents('Test.jpeg', $im->getImageBlob());
        } catch (Exception $e) {
            return $e->getMessage();
        }

The problem is that the code fails with error:

Fatal error: Class 'Imagick' not found

I have enabled php_imagick.dll in php.ini:

; Imagick Extension
[Imagick]
extension = "php_imagick.dll"

php_imagick library is displayed as PHP extension.

Thanks in advance.