fileToDataURI

  if (!file) {
      return $q.reject(false);
  }

    return $q(function (resolve, reject) {
        var reader = new FileReader();

        reader.onloadend = function (response) {
            var src = response.target.result;
            var imgPromise = srcToDataURI(src);
            return resolve(src);
        };
        reader.readAsDataURL(file);
    });