Meteor collection for images using CollectionFS

images.js

var createThumb = function(fileObj, readStream, writeStream) {
  // Transform the image into a 10x10px thumbnail
  gm(readStream, fileObj.name()).resize('10', '10').stream().pipe(writeStream);
};
var createWeb = function(fileObj, readStream, writeStream) {
  // Transform the image into a 10x10px thumbnail
  gm(readStream, fileObj.name()).resize('320', '180').stream().pipe(writeStream);
};
var convertToPng = function(fileObj) {
  return {
    extension: 'png',
    type: 'image/png'
  }
};

this.Images = new FS.Collection("images", {
  stores: [
    new FS.Store.FileSystem("full", {
      beforeWrite: convertToPng
    }),
    new FS.Store.FileSystem("web", {
      beforeWrite: convertToPng,
      transformWrite: createWeb
    }),
    new FS.Store.FileSystem("thumb", {
      beforeWrite: convertToPng,
      transformWrite: createThumb
    })
  ],
  filter: {
    allow: {
      contentTypes: ['image/*']
    }
  }
});

this.Images.userCanInsert = function(userId, doc) {
  return Users.isInRoles(userId, ["user"]);
}

this.Images.userCanUpdate = function(userId, doc) {
  return userId && Users.isInRoles(userId, ["user"]);
}

this.Images.userCanRemove = function(userId, doc) {
  return userId && Users.isInRoles(userId, ["admin"]);
}

this.Images.userCanDownload = function(userId, doc) {
  return Users.isInRoles(userId, ["user"]);
}