Add logoimage and title for excel eport file

In my project, we need to export logoimage and table title into excel.
I change some code in DefaultExcelExporter and ExcelBuilder.
Using:

    InputStream is = new FileInputStream(imagepath)
    byte[] image = IOUtils.toByteArray(is)
    def excelReport = []
    excelReport << [
      image: image,
      width: 10,
      height: 2000,
      mergeColumn: 0,
      mergeRow: 0,
      mergeToColumn: fields.size() ? fields.size() - 1 : 0,
      mergeToRow: 0,
      beginColumn: 0,
      beginRow: 0,
      crossColumn: 6,
      crossRow: 1,
      title: "your table title",
      titleformat: [
        fontfamily: 'arial',
        bold: true,
        size: 20,
        alignment: 'CENTRE'
      ]
    ]
    exportService.export( 'excel', response.outputStream, excelReport, fields, labels, formatters, parameters )

if excelReport do not has 'image',the export excel file is as before.