下载文件后，文件已损坏

我目前正在制作从服务器下载文件的控制器。这一切都发生在索引操作中:

public function indexAction() {
    $schuurName = $this->_getParam('storageID');
    $fileName = $this->_getParam('fileName');
    $name = explode('.', $fileName)[0];
    $path = '..' . DIRECTORY_SEPARATOR . 'schuren' . DIRECTORY_SEPARATOR . $schuurName . DIRECTORY_SEPARATOR . $fileName;
    if (file_exists($path)) {
        $mimeType = mime_content_type($fileName);
        header('Content-Type: ' . $mimeType);
        header('Content-Length: ' . filesize($path));
        header('Content-Disposition: attachment; filename=' . $name . ';');
        $resource = fopen($path, 'r');
        while (!feof($resource)) {
            $chunk = fread($resource, 4096);
            echo $chunk;
        }
        $this->view->layout()->disableLayout();
        $this->_helper->viewRenderer->setNoRender(true);
    }
    else {
        echo 'file doesn''t exist';
    }
}

所以下载工作现在，我正在测试它与一个725字节的图像。问题是……图像已损坏，因此无法看到/编辑。我在代码中做错了什么?

谢谢!