data.getCategoryGroup());
data.getCategoryGroup(), datasets);
    List retrieveImagesDiffInUserDatasetsNotInCategoryGroup(CategoryData data)    {        List imagesDiff = new ArrayList();        try {            imagesDiff = retrieveImagesInUserDatasetsNotInCategoryGroup(                        data.getCategoryGroup());               List images = data.getImages();            ImageSummary isg;            Iterator i;            for (int j = 0; j < imagesDiff.size(); j++) {                isg = (ImageSummary) imagesDiff.get(j);                i = images.iterator();                while (i.hasNext()) {                    if (((ImageSummary) i.next()).getID() == isg.getID())                          imagesDiff.remove(isg);                 }            }        } catch(DSAccessException dsae) {            String s = "Can't retrieve user's images.";            getRegistry().getLogger().error(this, s+" Error: "+dsae);            getRegistry().getUserNotifier().notifyError("Data Retrieval " +                    "Failure", s, dsae);           }         return imagesDiff;    }