       url: '/api/extract',
                    data: formData,
                    type: 'POST',
                    processData: false,
                    contentType: false,
                    dataType: 'json',
                    success: function(data) {
                        if (data.status === 'ok') {
                            $('#preview').attr('src', data.mark);
                            $('#notice')
                                .removeClass('uk-text-danger')
                            