如何处理base64编码字符串中的二进制内容？

我有一个base64字符串，其中包含二进制图像数据：

{

    body: 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',
    isBase64Encoded: true
};

当字符串被base64解码时，其内容如下所示。 内容参数包含图像信息。

{ test: 'asdddd',
  file:
   { type: 'file',
     filename: 'Untitled.png',
     contentType: 'image/png',
     content:
      '�PNG\r\n\u001a\n\u0000\u

我正在尝试保存该图像。我应该怎么做才能将此保存为常规png图像？每次尝试打开它时，系统都会提示我无法打开文件。

var fs = require('fs');
fs.writeFileSync('image.png',  parsed.file.content);
// returns blank

内容似乎在utf-8中，尝试从那里创建一个缓冲区，然后保存该缓冲区。像这样的东西：

const imageBuffer = Buffer.from(parsed.file.content, 'utf8')
fs.createWriteStream('image.png').write(imageBuffer);

希望有帮助！