ShowHistoContrastDlg example for Delphi

procedure TForm1.ShowHistoContrastDlg1Click(Sender: TObject); 
var
   nRet: L_INT; 
begin
   LEADDlgColor1.DlgFlags:= DLG_HISTOCONTRAST_SHOW_PREVIEW Or
                             DLG_HISTOCONTRAST_SHOW_TOOL_ZOOMLEVEL; 
   LEADDlgColor1.LEADImage:= LEADImage1; 
   LEADDlgColor1.LEADDlgService:= LEADDlgService1; 
   nRet:= LEADDlgColor1.ShowHistoContrastDlg ( Self ); 
   if ( nRet = SUCCESS_DLG_OK ) then
   begin
      LEADImage1.HistoContrast ( LEADDlgColor1.Change ); 
   end; 
end;