Rename + resize photos with Gulp.js

gulpfile.js

var path = require('path');
var gulp = require('gulp');
var del = require('del');
var sort = require('gulp-sort');
var rename = require('gulp-rename');
var debug = require('gulp-debug');
var gm = require('gulp-gm');
var imagemin = require('gulp-imagemin');
var jpegtran = require('imagemin-jpegtran');

// constants
var ORIGINAL = './original/';
var RENAMED = './renamed/';
var RESIZED = './resized/';
var SCALE = 0.65;

function pad(num) {
  var s = "000" + num;
  return s.substr(s.length - 3);
}

function myRenameFunction() {
  var i, lastDir;
  return function (path) {
    // select the right number
    i = lastDir !== path.dirname ? 1 : i+1;
    lastDir = path.dirname;
    // rename
    path.basename = path.dirname + '-' + pad(i);
    path.extname = path.extname.toLowerCase();
    return path;
  };
}

gulp.task('clean-renamed', function() {
  return del(RENAMED);
});

gulp.task('clean-resized', function() {
  return del(RENAMED);
});

gulp.task('rename', ['clean-renamed'], function() {
  return gulp.src(path.join(ORIGINAL, '*', '*'))
  .pipe(sort({ asc: true }))
  .pipe(debug({title: 'renaming:'}))
  .pipe(rename(myRenameFunction()))
  .pipe(debug({title: 'in:'}))
  .pipe(gulp.dest(RENAMED));
});

gulp.task('resize', ['rename', 'clean-resized'], function() {
  return gulp.src(path.join(RENAMED, '*', '*'))
  .pipe(debug({title: 'rezizing:'}))
  .pipe(gm(function (gmfile, done) {
    gmfile.size(function (err, size) {
      done(null, gmfile.resize(
        size.width * SCALE,
        size.height * SCALE
      ));
    });
  }))
  .pipe(gm(function (gmfile) {
    return gmfile.autoOrient();
  }))
  .pipe(imagemin({
    progressive: true,
    use: [jpegtran()]
  }))
  .pipe(gm(function (gmfile) {
    return gmfile.label('Ciao');
  }))
  .pipe(gulp.dest(RESIZED));
});

gulp.task('default', ['resize']);

package.json

{
  "name": "rename-resize-photos",
  "version": "0.1.0",
  "description": "Resize + rename photos with Gulp.js",
  "author": "Davide Pedranz",
  "license": "MIT",
  "devDependencies": {
    "del": "^2.0.2",
    "gulp": "^3.9.0",
    "gulp-debug": "^2.1.2",
    "gulp-gm": "0.0.8",
    "gulp-imagemin": "^2.3.0",
    "gulp-rename": "^1.2.2",
    "gulp-sort": "^1.1.1"
  }
}

NB: install graphicsmagick and imagemagick
https://www.npmjs.com/package/gulp-gm