php图像上传与间隔文件名

I'm having problem with image upload, i'm using parse as backend and everything is working, but i realize if filename is with space like "this is img.jpg" the uploader is not working, this is actual code

if (isset($_FILES['image']['name'])) {
    if (strlen($_FILES['image']['name'])>3) {
      $image = ParseFile::createFromData( file_get_contents( $_FILES['image']['tmp_name'] ), $_FILES['image']['name']  );
      $content->set("image", $image);
      @unlink($_FILES['image']['tmp_name']);
    }
  }

i tried to use str_replace but still is not working, i get blank page, i think im doin something wrong

  if (isset($_FILES['image']['name'])) {
    if (strlen($_FILES['image']['name'])>3) {
      $image = ParseFile::createFromData( file_get_contents( $_FILES['image']['tmp_name'] ), $_FILES['image']['name']  );
      $img = str_replace(' ', '_', $image);
      $content->set("image", $img);
      @unlink($_FILES['image']['tmp_name']);
    }
  }