isImage(obj) {
    if (!obj) return false;
    if (obj.__isImage) return true;

    const tagName = `${obj.tagName}`.toUpperCase();
    const nodeName = `${obj.nodeName}`.toUpperCase();
    if (nodeName === "IMG" || tagName === "IMG") {
      obj.__isImage = true;
      return true;
    }

    return false;
  }
Determine whether it is a picture object

@return {boolean} is or no