def evaluateImg(self, imgId, catId, aRng, maxDet):
        '''
        perform evaluation for single category and image
        :return: dict (single image results)
        '''
        p = self.params
        if p.useCats:
            gt = self._gts[imgId, catId]
            dt = self._dts[imgId, catId]
        else:
            gt = [_ for cId in p.catIds for _ in self._gts[imgId, cId]]
            dt = [_ for cId in p.catIds for _ in self._dts[imgId, cId]]
        if len(gt) == 0 and len(dt) == 0:
            return None

        for g in gt:
            if g['ignore'] or (g['area'] < aRng[0] or g['area'] > aRng[1]):
                g['_ignore'] = 1
            else:
                g['_ignore'] = 0

        # sort dt highest score first, sort gt ignore last
        gtind = np.argsort([g['_ignore'] for g in gt], kind='mergesort')
        gt = [gt[i] for i in gtind]
        dtind = np.argsort([-d['score'] for d in dt], kind='mergesort')
        dt = [dt[i] for i in dtind[0:maxDet]]
        iscrowd = [int(o['iscrowd']) for o in gt]
        # load computed ious
        ious = self.ious[imgId, catId][:, gtind] if len(self.ious[
            imgId, catId]) > 0 else self.ious[imgId, catId]

        T = len(p.iouThrs)
        G = len(gt)
        D = len(dt)
        gtm = np.zeros((T, G))
        dtm = np.zeros((T, D))
        gtIg = np.array([g['_ignore'] for g in gt])
        dtIg = np.zeros((T, D))
        if not len(ious) == 0:
            for tind, t in enumerate(p.iouThrs):
                for dind, d in enumerate(dt):
                    # information about best match so far (m=-1 -> unmatched)
                    iou = min([t, 1 - 1e-10])
                    m = -1
                    for gind, g in enumerate(gt):
                        # if this gt already matched, and not a crowd, continue
                        if gtm[tind, gind] > 0 and not iscrowd[gind]:
                            continue
                        # if dt matched to reg gt, and on ignore gt, stop
                        if m > -1 and gtIg[m] == 0 and gtIg[gind] == 1:
                            break
                        # continue to next gt unless better match made
                        if ious[dind, gind] < iou:
                            continue
                        # if match successful and best so far, store appropriately
                        iou = ious[dind, gind]
                        m = gind
                    # if match made store id of match for both dt and gt
                    if m == -1:
                        continue
                    dtIg[tind, dind] = gtIg[m]
                    dtm[tind, dind] = gt[m]['id']
                    gtm[tind, m] = d['id']
        # set unmatched detections outside of area range to ignore
        a = np.array(
            [d['area'] < aRng[0] or d['area'] > aRng[1] for d in dt]).reshape(
                (1, len(dt)))
        dtIg = np.logical_or(dtIg, np.logical_and(dtm == 0, np.repeat(a, T, 0)))
        # store results for given image and category
        return {
            'image_id': imgId,
            'category_id': catId,
            'aRng': aRng,
            'maxDet': maxDet,
            'dtIds': [d['id'] for d in dt],
            'gtIds': [g['id'] for g in gt],
            'dtMatches': dtm,
            'gtMatches': gtm,
            'dtScores': [d['score'] for d in dt],
            'gtIgnore': gtIg,
            'dtIgnore': dtIg,
        }

        perform evaluation for single category and image
        :return: dict (single image results)
        
EISeg/eiseg/util/coco/cocoeval.py