object_detection demo the argsort is wrong

[delongwu]

hi, the comparator in [nonMaxSuppression] function of pytorch/demo/objectdetection)/PrePostProcessor.java is asc order， not desc order. it is just oppositive than swift comparator. the right one in java is :

  // Do an argsort on the confidence scores, from high to low.
    Collections.sort(boxes,
            new Comparator<Result>() {
                @Override
                public int compare(Result o1, Result o2) {
                    return o2.score.compareTo(o1.score);
                }
            });

[FabrizioPe]

Hi, that seems to be the case! We were experiencing much lower confidence scores in the mobile app with respect to GPU. This fix apparently did the trick.