Flutter 如何将相机拍摄的图像转换为带颤振的base64

我想将相机拍摄的图像转换为base64，但它似乎正在转换图像路径，而不是图像本身，请帮助我

File file;
final picker = ImagePicker();
void _choose() async {
  final pickedFile = await picker.getImage(source: ImageSource.camera);
  file = File(pickedFile.path);
  if (file != null) {
    setState(() {
      base64Encode(file.readAsBytesSync());
      print(base64Encode(Image.file(file));
    });
  }
}