window.addEventListener('DOMContentLoaded', function () {
            var image = document.querySelector('#image');
            var cropper = new Cropper(image, {
                ready: function () {
                    this.cropper.setCropBoxData({
      "left":750,
      "top":190,
      "width":500,
      "height":50
    });
  },
});

"width":100,
"height":50

"width": $VALOR,
"height":$VALOR2