Give this a shot:
var aDoc = app.activeDocument;
var docPages = aDoc.pages;
for(p=0;p<docPages.length;p++){
var myPageItems = docPages[p].allPageItems
var myPageName = docPages[p].name;
for(i=0;i<myPageItems.length;i++){
//set selection as variable
var thisItem = myPageItems[i];
if(thisItem instanceof Rectangle || thisItem instanceof Polygon || thisItem instanceof Oval){
//get image within the frame
var myLinkedItem = thisItem.pageItems[0];
//get name of the linked image
var myLinkName = myLinkedItem.itemLink.name;
//strip extension from linked image name
var myLinkName = myLinkName.split(“.”)[0];
app.jpegExportPreferences.jpegQuality = JPEGOptionsQuality.maximum; // low medium high maximum
app.jpegExportPreferences.exportResolution = 300;
app.jpegExportPreferences.jpegExportRange = ExportRangeOrAllPages.exportRange;
app.jpegExportPreferences.pageString = myPageName;
//Set Name of exported pdf to match the name of the linked image
var myFile = File(“/Users/admin/Desktop/” + myLinkName + “.jpg”);
//export the pdf
aDoc.exportFile(ExportFormat.JPG, myFile, false);
}
}
}