我无法在Dart中将调整大小的图像对象转换为Base64字符串

import 'dart:io';
import 'dart:ui';

File imageFile = File('path_to_resized_image.jpg');
List<int> imageBytes = await imageFile.readAsBytes();

Image image = Image.memory(Uint8List.fromList(imageBytes));

PictureRecorder recorder = PictureRecorder();
Canvas canvas = Canvas(recorder);
canvas.drawImage(image, Offset.zero, Paint());
Picture picture = recorder.endRecording();

Image imageWithAlpha = picture.toImage(image.width, image.height);
ByteData byteData = await imageWithAlpha.toByteData(format: ImageByteFormat.png);
List<int> pngBytes = byteData.buffer.asUint8List();

import 'dart:convert';

String base64Image = base64Encode(pngBytes);