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.