How do I crop a percentage from the edges of an image?

I'm using a batch crop and straighten script to separate scanned photos, but there is always a little bit where the crop hasn't been performed perfectly. I'd like to find a way to crop 1-2% off all edges of my document/image. I'm not worried about loosing image integrity. Would be nice to have a script to add to my existing script. Essentially this step will make my edges crisp and eliminate any slivers of white space or bent corners.

Here is the script that I'm using to divide my scanned photos:

#target Photoshop 

app.bringToFront; 

var inFolder = Folder.selectDialog("Please select folder to process");  

if(inFolder != null){ 

var fileList = inFolder.getFiles(/\.(jpg|tif|psd|)$/i); 

var outfolder = new Folder(decodeURI(inFolder) + "/Edited"); 

if (outfolder.exists == false) outfolder.create(); 

for(var a = 0 ;a < fileList.length; a++){ 

  if(fileList instanceof File){ 

    var doc= open(fileList); 

    doc.flatten(); 

    var docname = fileList.name.slice(0,-4); 

    CropStraighten(); 

    doc.close(SaveOptions.DONOTSAVECHANGES);  

    var count = 1; 

    while(app.documents.length){ 

      var saveFile = new File(decodeURI(outfolder) + "/" + docname +"#"+ zeroPad(count,3) + ".jpg"); 

      SaveJPEG(saveFile, 12); 

      activeDocument.close(SaveOptions.DONOTSAVECHANGES) ;  

      count++; 

    } 

   } 

} 

}; 

function CropStraighten() { 

executeAction( stringIDToTypeID('CropPhotosAuto0001'), undefined, DialogModes.NO ); 

}; 

function SaveJPEG(saveFile, jpegQuality){ 

jpgSaveOptions = new JPEGSaveOptions(); 

jpgSaveOptions.embedColorProfile = true; 

jpgSaveOptions.formatOptions = FormatOptions.STANDARDBASELINE; 

jpgSaveOptions.matte = MatteType.NONE; 

jpgSaveOptions.quality = jpegQuality;  

activeDocument.saveAs(saveFile, jpgSaveOptions, true,Extension.LOWERCASE); 

} 

function zeroPad(n, s) {  

n = n.toString();  

while (n.length < s) n = '0' + n;  

return n;  

}; 

Message was edited by: Jeremy Klein