Nodejs Buffer处理图片

var fs = require('fs')
fs.readFile('logo.png',function (err, origin_buffer) {
    console.log(Buffer.isBuffer(origin_buffer))
    fs.writeFile('logo_bugger.png',origin_buffer,function (err) {
       if (err)
           console.log(err);
    })
    //var base64Image = new Buffer(origin_buffer).toString('base64')
    var base64Image = origin_buffer.toString('base64')
    console.log(base64Image);

    var decodedImage = new Buffer(base64Image,'base64');
    console.log(Buffer.compare(origin_buffer,decodedImage))

    fs.writeFile('logo_decoded.png',decodedImage,function (err) {
        if (err)
            console.log(err);
    })
})