index.js

var express = require('express')
var fs = require('fs')
var gm = require('gm').subClass({imageMagick: true})
var app = express()

app.get('/head/:username/:size?', function (req, res) {
  console.info('Display head skin for ' + req.params.username)

  var filename = '/var/www/skins/' + req.params.username + '.png'
  var size = (req.params.size && req.params.size < 900) ? req.params.size : 64

  fs.stat(filename, function (err, stat) {
    if (err)
      var file = steve
    else
      var file = gm(filename)

    res.set('Content-Type', 'image/png')
    file
      .crop(8, 8, 8, 8)
      .scale(size, size)
      .stream(function (err, stdout, stderr) {
        if (err) return res.status(500).end()
        stdout.pipe(res)
      })
  })
})

var steve = gm(new Buffer('\\' +
'iVBORw0KGgoAAAANSUhEUgAAAEAAAAAgCAMAAACVQ462AAAABGdBTUEAALGPC/xhBQAAAwBQTFRF' +
'AAAAHxALIxcJJBgIJBgKJhgLJhoKJxsLJhoMKBsKKBsLKBoNKBwLKRwMKh0NKx4NKx4OLR0OLB4O' +
'Lx8PLB4RLyANLSAQLyIRMiMQMyQRNCUSOigUPyoVKCgoPz8/JiFbMChyAFtbAGBgAGhoAH9/Qh0K' +
'QSEMRSIOQioSUigmUTElYkMvbUMqb0UsakAwdUcvdEgvek4za2trOjGJUj2JRjqlVknMAJmZAJ6e' +
'AKioAK+vAMzMikw9gFM0hFIxhlM0gVM5g1U7h1U7h1g6ilk7iFo5j14+kF5Dll9All9BmmNEnGNF' +
'nGNGmmRKnGdIn2hJnGlMnWpPlm9bnHJcompHrHZaqn1ms3titXtnrYBttIRttolsvohst4Jyu4ly' +
'vYtyvY5yvY50xpaA////AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' +
'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' +
'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' +
'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' +
'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' +
'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' +
'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' +
'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' +
'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAPSUN6AAAAQB0Uk5T////////////////////////' +
'////////////////////////////////////////////////////////////////////////////' +
'////////////////////////////////////////////////////////////////////////////' +
'////////////////////////////////////////////////////////////////////////////' +
'////////////////////////////////////////////////////////////////////////////' +
'////////////AFP3ByUAAAAYdEVYdFNvZnR3YXJlAFBhaW50Lk5FVCB2My4zNqnn4iUAAAKjSURB' +
'VEhLpZSLVtNAEIYLpSlLSUITLCBaGhNBQRM01M2mSCoXNUURIkZFxQvv/wz6724Wij2HCM7J6UyS' +
'/b+dmZ208rsww6jiqo4FhannZb5yDqjaNgDVwE/8JAmCMqF6fwGwbU0CKjD/+oAq9jcM27gxAFpN' +
'QxU3Bwi9Ajy8fgmGZuvaGAcIuwFA12CGce1jJESr6/Ot1i3Tnq5qptFqzet1jRA1F2XHWQFAs3Rz' +
'wTTNhQd3rOkFU7c0DijmohRg1TR9ZmpCN7/8+PX954fb+sTUjK7VLKOYi1IAaTQtUrfm8pP88/vT' +
'w8M5q06sZoOouSgHEDI5vrO/eHK28el04yxf3N8ZnyQooZiLfwA0arNb6d6bj998/+vx8710a7bW' +
'4E2Uc1EKsEhz7WiQBK9eL29urrzsB8ngaK1JLDUXpYAkGSQH6e7640fL91dWXjxZ33138PZggA+S' +
'z0WQlAL4gmewuzC1uCenqXevMPWc9XrMX/VXh6Hicx4ByHEeAfRg/wtgSMAvz+CKEkYAnc5SpwuD' +
'4z70PM+hUf+4348ixF7EGItjxmQcCx/Dzv/SOkuXAF3PdT3GIujjGLELNYwxhF7M4oi//wsgdlYZ' +
'dMXCmEUUSsSu0OOBACMoBTiu62BdRPEjYxozXFyIpK7IAE0IYa7jOBRqGlOK0BFq3Kdpup3DthFw' +
'P9QDlBCGKEECoHEBEDLAXHAQMQnI8jwFYRQw3AMOQAJoOADoAVcDAh0HZAKQZUMZdC43kdeqAPwU' +
'BEsC+M4cIEq5KEEBCl90mR8CVR3nxwCdBBS9OAe020UGnXb7KcxzPY9SXoEEIBZtgE7UDgBKyLMh' +
'gBS2YdzjMJb4XHRDAPiQhSGjNOxKQIZTgC8BiMECgarxprjjO0OXiV4MAf4A/x0nbcyiS5EAAAAA' +
'SUVORK5CYII=', 'base64'))

app.listen(3000, function () {
  console.info('App listening on port 3000!')
})