var inputFolder = Folder.selectDialog("Select a folder to tag");
if (inputFolder != null) {
  var fileList = inputFolder.getFiles()
  var jpegOptions = new JPEGSaveOptions()
  jpegOptions.quality = 12;
  for (var i = 0; i < fileList.length; i++) {
      var docRef = open(fileList[i])
      docRef.info.title = docRef.info.caption
      docRef.bitsPerChannel = BitsPerChannelType.EIGHT
      docRef.saveAs(fileList[i], jpegOptions)
      docRef.close()
  }
  alert("OK");
}

        var chkAddKeywords = grpGlob_Right.add( "checkbox", undefined,"Add keywords");
        wrapper.chkAddBox.push(chkAddKeywords);
        chkAddKeywords.alignment = ["right", "top"];
        chkAddKeywords.enabled = true;
        chkAddKeywords.value= false;

        var chkDescriptionToTitle = grpGlob_Right.add( "checkbox", undefined,"Description to title");
        wrapper.chkAddBox.push(chkDescriptionToTitle);
        chkDescriptionToTitle.alignment = ["right", "top"];
        chkDescriptionToTitle.enabled = true;
        chkDescriptionToTitle.value= false;

    function syncMetadata( masterThumb, listThumbs, params  ){
...
...
        {
                saveMetadata(listThumbs[k], master_title, master_descr, master_keywords, { sort:params.sort, append:params.append} );
        }
    }

        for ( var k  =0 ; k < listThumbs.length; k++)
        {

                saveMetadata(listThumbs[k], master_title, master_descr, master_keywords, { sort:params.sort, append:params.append} );

         if(wrapper.chkAddBox[1].value)
         {
            md = listThumbs[k].synchronousMetadata;
            md.namespace =  "http://purl.org/dc/elements/1.1/";
            master_title = md.description[0];
            master_descr = md.description[0];
            master_keywords = md.subject;
         }