# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. import numpy as np import paddle import paddle.nn as nn import paddle.nn.functional as F from ppdet.core.workspace import register from ppdet.modeling.bbox_utils import nonempty_bbox from .transformers import bbox_cxcywh_to_xyxy try: from collections.abc import Sequence except Exception: from collections import Sequence __all__ = [ 'BBoxPostProcess', 'MaskPostProcess', 'JDEBBoxPostProcess', 'CenterNetPostProcess', 'DETRBBoxPostProcess', 'SparsePostProcess' ] @register class BBoxPostProcess(object): __shared__ = ['num_classes', 'export_onnx', 'export_eb'] __inject__ = ['decode', 'nms'] def __init__(self, num_classes=80, decode=None, nms=None, export_onnx=False, export_eb=False): super(BBoxPostProcess, self).__init__() self.num_classes = num_classes self.decode = decode self.nms = nms self.export_onnx = export_onnx self.export_eb = export_eb def __call__(self, head_out, rois, im_shape, scale_factor): """ Decode the bbox and do NMS if needed. Args: head_out (tuple): bbox_pred and cls_prob of bbox_head output. rois (tuple): roi and rois_num of rpn_head output. im_shape (Tensor): The shape of the input image. scale_factor (Tensor): The scale factor of the input image. export_onnx (bool): whether export model to onnx Returns: bbox_pred (Tensor): The output prediction with shape [N, 6], including labels, scores and bboxes. The size of bboxes are corresponding to the input image, the bboxes may be used in other branch. bbox_num (Tensor): The number of prediction boxes of each batch with shape [1], and is N. """ if self.nms is not None: bboxes, score = self.decode(head_out, rois, im_shape, scale_factor) bbox_pred, bbox_num, _ = self.nms(bboxes, score, self.num_classes) else: bbox_pred, bbox_num = self.decode(head_out, rois, im_shape, scale_factor) if self.export_onnx: # add fake box after postprocess when exporting onnx fake_bboxes = paddle.to_tensor( np.array( [[0., 0.0, 0.0, 0.0, 1.0, 1.0]], dtype='float32')) bbox_pred = paddle.concat([bbox_pred, fake_bboxes]) bbox_num = bbox_num + 1 return bbox_pred, bbox_num def get_pred(self, bboxes, bbox_num, im_shape, scale_factor): """ Rescale, clip and filter the bbox from the output of NMS to get final prediction. Notes: Currently only support bs = 1. Args: bboxes (Tensor): The output bboxes with shape [N, 6] after decode and NMS, including labels, scores and bboxes. bbox_num (Tensor): The number of prediction boxes of each batch with shape [1], and is N. im_shape (Tensor): The shape of the input image. scale_factor (Tensor): The scale factor of the input image. Returns: pred_result (Tensor): The final prediction results with shape [N, 6] including labels, scores and bboxes. """ if self.export_eb: # enable rcnn models for edgeboard hw to skip the following postprocess. return bboxes, bboxes, bbox_num if not self.export_onnx: bboxes_list = [] bbox_num_list = [] id_start = 0 fake_bboxes = paddle.to_tensor( np.array( [[0., 0.0, 0.0, 0.0, 1.0, 1.0]], dtype='float32')) fake_bbox_num = paddle.to_tensor(np.array([1], dtype='int32')) # add fake bbox when output is empty for each batch for i in range(bbox_num.shape[0]): if bbox_num[i] == 0: bboxes_i = fake_bboxes bbox_num_i = fake_bbox_num else: bboxes_i = bboxes[id_start:id_start + bbox_num[i], :] bbox_num_i = bbox_num[i] id_start += bbox_num[i] bboxes_list.append(bboxes_i) bbox_num_list.append(bbox_num_i) bboxes = paddle.concat(bboxes_list) bbox_num = paddle.concat(bbox_num_list) origin_shape = paddle.floor(im_shape / scale_factor + 0.5) if not self.export_onnx: origin_shape_list = [] scale_factor_list = [] # scale_factor: scale_y, scale_x for i in range(bbox_num.shape[0]): expand_shape = paddle.expand(origin_shape[i:i + 1, :], [bbox_num[i], 2]) scale_y, scale_x = scale_factor[i][0], scale_factor[i][1] scale = paddle.concat([scale_x, scale_y, scale_x, scale_y]) expand_scale = paddle.expand(scale, [bbox_num[i], 4]) origin_shape_list.append(expand_shape) scale_factor_list.append(expand_scale) self.origin_shape_list = paddle.concat(origin_shape_list) scale_factor_list = paddle.concat(scale_factor_list) else: # simplify the computation for bs=1 when exporting onnx scale_y, scale_x = scale_factor[0][0], scale_factor[0][1] scale = paddle.concat( [scale_x, scale_y, scale_x, scale_y]).unsqueeze(0) self.origin_shape_list = paddle.expand(origin_shape, [bbox_num[0], 2]) scale_factor_list = paddle.expand(scale, [bbox_num[0], 4]) # bboxes: [N, 6], label, score, bbox pred_label = bboxes[:, 0:1] pred_score = bboxes[:, 1:2] pred_bbox = bboxes[:, 2:] # rescale bbox to original image scaled_bbox = pred_bbox / scale_factor_list origin_h = self.origin_shape_list[:, 0] origin_w = self.origin_shape_list[:, 1] zeros = paddle.zeros_like(origin_h) # clip bbox to [0, original_size] x1 = paddle.maximum(paddle.minimum(scaled_bbox[:, 0], origin_w), zeros) y1 = paddle.maximum(paddle.minimum(scaled_bbox[:, 1], origin_h), zeros) x2 = paddle.maximum(paddle.minimum(scaled_bbox[:, 2], origin_w), zeros) y2 = paddle.maximum(paddle.minimum(scaled_bbox[:, 3], origin_h), zeros) pred_bbox = paddle.stack([x1, y1, x2, y2], axis=-1) # filter empty bbox keep_mask = nonempty_bbox(pred_bbox, return_mask=True) keep_mask = paddle.unsqueeze(keep_mask, [1]) pred_label = paddle.where(keep_mask, pred_label, paddle.ones_like(pred_label) * -1) pred_result = paddle.concat([pred_label, pred_score, pred_bbox], axis=1) return bboxes, pred_result, bbox_num def get_origin_shape(self, ): return self.origin_shape_list @register class MaskPostProcess(object): __shared__ = ['export_onnx', 'assign_on_cpu'] """ refer to: https://github.com/facebookresearch/detectron2/layers/mask_ops.py Get Mask output according to the output from model """ def __init__(self, binary_thresh=0.5, export_onnx=False, assign_on_cpu=False): super(MaskPostProcess, self).__init__() self.binary_thresh = binary_thresh self.export_onnx = export_onnx self.assign_on_cpu = assign_on_cpu def paste_mask(self, masks, boxes, im_h, im_w): """ Paste the mask prediction to the original image. """ x0_int, y0_int = 0, 0 x1_int, y1_int = im_w, im_h x0, y0, x1, y1 = paddle.split(boxes, 4, axis=1) N = masks.shape[0] img_y = paddle.arange(y0_int, y1_int) + 0.5 img_x = paddle.arange(x0_int, x1_int) + 0.5 img_y = (img_y - y0) / (y1 - y0) * 2 - 1 img_x = (img_x - x0) / (x1 - x0) * 2 - 1 # img_x, img_y have shapes (N, w), (N, h) if self.assign_on_cpu: paddle.set_device('cpu') gx = img_x[:, None, :].expand( [N, paddle.shape(img_y)[1], paddle.shape(img_x)[1]]) gy = img_y[:, :, None].expand( [N, paddle.shape(img_y)[1], paddle.shape(img_x)[1]]) grid = paddle.stack([gx, gy], axis=3) img_masks = F.grid_sample(masks, grid, align_corners=False) return img_masks[:, 0] def __call__(self, mask_out, bboxes, bbox_num, origin_shape): """ Decode the mask_out and paste the mask to the origin image. Args: mask_out (Tensor): mask_head output with shape [N, 28, 28]. bbox_pred (Tensor): The output bboxes with shape [N, 6] after decode and NMS, including labels, scores and bboxes. bbox_num (Tensor): The number of prediction boxes of each batch with shape [1], and is N. origin_shape (Tensor): The origin shape of the input image, the tensor shape is [N, 2], and each row is [h, w]. Returns: pred_result (Tensor): The final prediction mask results with shape [N, h, w] in binary mask style. """ num_mask = mask_out.shape[0] origin_shape = paddle.cast(origin_shape, 'int32') device = paddle.device.get_device() if self.export_onnx: h, w = origin_shape[0][0], origin_shape[0][1] mask_onnx = self.paste_mask(mask_out[:, None, :, :], bboxes[:, 2:], h, w) mask_onnx = mask_onnx >= self.binary_thresh pred_result = paddle.cast(mask_onnx, 'int32') else: max_h = paddle.max(origin_shape[:, 0]) max_w = paddle.max(origin_shape[:, 1]) pred_result = paddle.zeros( [num_mask, max_h, max_w], dtype='int32') - 1 id_start = 0 for i in range(paddle.shape(bbox_num)[0]): bboxes_i = bboxes[id_start:id_start + bbox_num[i], :] mask_out_i = mask_out[id_start:id_start + bbox_num[i], :, :] im_h = origin_shape[i, 0] im_w = origin_shape[i, 1] bbox_num_i = bbox_num[id_start] pred_mask = self.paste_mask(mask_out_i[:, None, :, :], bboxes_i[:, 2:], im_h, im_w) pred_mask = paddle.cast(pred_mask >= self.binary_thresh, 'int32') pred_result[id_start:id_start + bbox_num[i], :im_h, : im_w] = pred_mask id_start += bbox_num[i] if self.assign_on_cpu: paddle.set_device(device) return pred_result @register class JDEBBoxPostProcess(nn.Layer): __shared__ = ['num_classes'] __inject__ = ['decode', 'nms'] def __init__(self, num_classes=1, decode=None, nms=None, return_idx=True): super(JDEBBoxPostProcess, self).__init__() self.num_classes = num_classes self.decode = decode self.nms = nms self.return_idx = return_idx self.fake_bbox_pred = paddle.to_tensor( np.array( [[-1, 0.0, 0.0, 0.0, 0.0, 0.0]], dtype='float32')) self.fake_bbox_num = paddle.to_tensor(np.array([1], dtype='int32')) self.fake_nms_keep_idx = paddle.to_tensor( np.array( [[0]], dtype='int32')) self.fake_yolo_boxes_out = paddle.to_tensor( np.array( [[[0.0, 0.0, 0.0, 0.0]]], dtype='float32')) self.fake_yolo_scores_out = paddle.to_tensor( np.array( [[[0.0]]], dtype='float32')) self.fake_boxes_idx = paddle.to_tensor(np.array([[0]], dtype='int64')) def forward(self, head_out, anchors): """ Decode the bbox and do NMS for JDE model. Args: head_out (list): Bbox_pred and cls_prob of bbox_head output. anchors (list): Anchors of JDE model. Returns: boxes_idx (Tensor): The index of kept bboxes after decode 'JDEBox'. bbox_pred (Tensor): The output is the prediction with shape [N, 6] including labels, scores and bboxes. bbox_num (Tensor): The number of prediction of each batch with shape [N]. nms_keep_idx (Tensor): The index of kept bboxes after NMS. """ boxes_idx, yolo_boxes_scores = self.decode(head_out, anchors) if len(boxes_idx) == 0: boxes_idx = self.fake_boxes_idx yolo_boxes_out = self.fake_yolo_boxes_out yolo_scores_out = self.fake_yolo_scores_out else: yolo_boxes = paddle.gather_nd(yolo_boxes_scores, boxes_idx) # TODO: only support bs=1 now yolo_boxes_out = paddle.reshape( yolo_boxes[:, :4], shape=[1, len(boxes_idx), 4]) yolo_scores_out = paddle.reshape( yolo_boxes[:, 4:5], shape=[1, 1, len(boxes_idx)]) boxes_idx = boxes_idx[:, 1:] if self.return_idx: bbox_pred, bbox_num, nms_keep_idx = self.nms( yolo_boxes_out, yolo_scores_out, self.num_classes) if bbox_pred.shape[0] == 0: bbox_pred = self.fake_bbox_pred bbox_num = self.fake_bbox_num nms_keep_idx = self.fake_nms_keep_idx return boxes_idx, bbox_pred, bbox_num, nms_keep_idx else: bbox_pred, bbox_num, _ = self.nms(yolo_boxes_out, yolo_scores_out, self.num_classes) if bbox_pred.shape[0] == 0: bbox_pred = self.fake_bbox_pred bbox_num = self.fake_bbox_num return _, bbox_pred, bbox_num, _ @register class CenterNetPostProcess(object): """ Postprocess the model outputs to get final prediction: 1. Do NMS for heatmap to get top `max_per_img` bboxes. 2. Decode bboxes using center offset and box size. 3. Rescale decoded bboxes reference to the origin image shape. Args: max_per_img(int): the maximum number of predicted objects in a image, 500 by default. down_ratio(int): the down ratio from images to heatmap, 4 by default. regress_ltrb (bool): whether to regress left/top/right/bottom or width/height for a box, true by default. """ __shared__ = ['down_ratio'] def __init__(self, max_per_img=500, down_ratio=4, regress_ltrb=True): super(CenterNetPostProcess, self).__init__() self.max_per_img = max_per_img self.down_ratio = down_ratio self.regress_ltrb = regress_ltrb # _simple_nms() _topk() are same as TTFBox in ppdet/modeling/layers.py def _simple_nms(self, heat, kernel=3): """ Use maxpool to filter the max score, get local peaks. """ pad = (kernel - 1) // 2 hmax = F.max_pool2d(heat, kernel, stride=1, padding=pad) keep = paddle.cast(hmax == heat, 'float32') return heat * keep def _topk(self, scores): """ Select top k scores and decode to get xy coordinates. """ k = self.max_per_img shape_fm = paddle.shape(scores) shape_fm.stop_gradient = True cat, height, width = shape_fm[1], shape_fm[2], shape_fm[3] # batch size is 1 scores_r = paddle.reshape(scores, [cat, -1]) topk_scores, topk_inds = paddle.topk(scores_r, k) topk_ys = topk_inds // width topk_xs = topk_inds % width topk_score_r = paddle.reshape(topk_scores, [-1]) topk_score, topk_ind = paddle.topk(topk_score_r, k) k_t = paddle.full(paddle.shape(topk_ind), k, dtype='int64') topk_clses = paddle.cast(paddle.floor_divide(topk_ind, k_t), 'float32') topk_inds = paddle.reshape(topk_inds, [-1]) topk_ys = paddle.reshape(topk_ys, [-1, 1]) topk_xs = paddle.reshape(topk_xs, [-1, 1]) topk_inds = paddle.gather(topk_inds, topk_ind) topk_ys = paddle.gather(topk_ys, topk_ind) topk_xs = paddle.gather(topk_xs, topk_ind) return topk_score, topk_inds, topk_clses, topk_ys, topk_xs def __call__(self, hm, wh, reg, im_shape, scale_factor): # 1.get clses and scores, note that hm had been done sigmoid heat = self._simple_nms(hm) scores, inds, topk_clses, ys, xs = self._topk(heat) clses = topk_clses.unsqueeze(1) scores = scores.unsqueeze(1) # 2.get bboxes, note only support batch_size=1 now reg_t = paddle.transpose(reg, [0, 2, 3, 1]) reg = paddle.reshape(reg_t, [-1, reg_t.shape[-1]]) reg = paddle.gather(reg, inds) xs = paddle.cast(xs, 'float32') ys = paddle.cast(ys, 'float32') xs = xs + reg[:, 0:1] ys = ys + reg[:, 1:2] wh_t = paddle.transpose(wh, [0, 2, 3, 1]) wh = paddle.reshape(wh_t, [-1, wh_t.shape[-1]]) wh = paddle.gather(wh, inds) if self.regress_ltrb: x1 = xs - wh[:, 0:1] y1 = ys - wh[:, 1:2] x2 = xs + wh[:, 2:3] y2 = ys + wh[:, 3:4] else: x1 = xs - wh[:, 0:1] / 2 y1 = ys - wh[:, 1:2] / 2 x2 = xs + wh[:, 0:1] / 2 y2 = ys + wh[:, 1:2] / 2 n, c, feat_h, feat_w = paddle.shape(hm) padw = (feat_w * self.down_ratio - im_shape[0, 1]) / 2 padh = (feat_h * self.down_ratio - im_shape[0, 0]) / 2 x1 = x1 * self.down_ratio y1 = y1 * self.down_ratio x2 = x2 * self.down_ratio y2 = y2 * self.down_ratio x1 = x1 - padw y1 = y1 - padh x2 = x2 - padw y2 = y2 - padh bboxes = paddle.concat([x1, y1, x2, y2], axis=1) scale_y = scale_factor[:, 0:1] scale_x = scale_factor[:, 1:2] scale_expand = paddle.concat( [scale_x, scale_y, scale_x, scale_y], axis=1) boxes_shape = bboxes.shape[:] scale_expand = paddle.expand(scale_expand, shape=boxes_shape) bboxes = paddle.divide(bboxes, scale_expand) results = paddle.concat([clses, scores, bboxes], axis=1) return results, paddle.shape(results)[0:1], inds, topk_clses, ys, xs @register class DETRBBoxPostProcess(object): __shared__ = ['num_classes', 'use_focal_loss'] __inject__ = [] def __init__(self, num_classes=80, num_top_queries=100, use_focal_loss=False): super(DETRBBoxPostProcess, self).__init__() self.num_classes = num_classes self.num_top_queries = num_top_queries self.use_focal_loss = use_focal_loss def __call__(self, head_out, im_shape, scale_factor): """ Decode the bbox. Args: head_out (tuple): bbox_pred, cls_logit and masks of bbox_head output. im_shape (Tensor): The shape of the input image. scale_factor (Tensor): The scale factor of the input image. Returns: bbox_pred (Tensor): The output prediction with shape [N, 6], including labels, scores and bboxes. The size of bboxes are corresponding to the input image, the bboxes may be used in other branch. bbox_num (Tensor): The number of prediction boxes of each batch with shape [bs], and is N. """ bboxes, logits, masks = head_out bbox_pred = bbox_cxcywh_to_xyxy(bboxes) origin_shape = paddle.floor(im_shape / scale_factor + 0.5) img_h, img_w = paddle.split(origin_shape, 2, axis=-1) origin_shape = paddle.concat( [img_w, img_h, img_w, img_h], axis=-1).reshape([-1, 1, 4]) bbox_pred *= origin_shape scores = F.sigmoid(logits) if self.use_focal_loss else F.softmax( logits)[:, :, :-1] if not self.use_focal_loss: scores, labels = scores.max(-1), scores.argmax(-1) if scores.shape[1] > self.num_top_queries: scores, index = paddle.topk( scores, self.num_top_queries, axis=-1) batch_ind = paddle.arange( end=scores.shape[0]).unsqueeze(-1).tile( [1, self.num_top_queries]) index = paddle.stack([batch_ind, index], axis=-1) labels = paddle.gather_nd(labels, index) bbox_pred = paddle.gather_nd(bbox_pred, index) else: scores, index = paddle.topk( scores.flatten(1), self.num_top_queries, axis=-1) labels = index % self.num_classes index = index // self.num_classes batch_ind = paddle.arange(end=scores.shape[0]).unsqueeze(-1).tile( [1, self.num_top_queries]) index = paddle.stack([batch_ind, index], axis=-1) bbox_pred = paddle.gather_nd(bbox_pred, index) bbox_pred = paddle.concat( [ labels.unsqueeze(-1).astype('float32'), scores.unsqueeze(-1), bbox_pred ], axis=-1) bbox_num = paddle.to_tensor( bbox_pred.shape[1], dtype='int32').tile([bbox_pred.shape[0]]) bbox_pred = bbox_pred.reshape([-1, 6]) return bbox_pred, bbox_num @register class SparsePostProcess(object): __shared__ = ['num_classes'] def __init__(self, num_proposals, num_classes=80): super(SparsePostProcess, self).__init__() self.num_classes = num_classes self.num_proposals = num_proposals def __call__(self, box_cls, box_pred, scale_factor_wh, img_whwh): """ Arguments: box_cls (Tensor): tensor of shape (batch_size, num_proposals, K). The tensor predicts the classification probability for each proposal. box_pred (Tensor): tensors of shape (batch_size, num_proposals, 4). The tensor predicts 4-vector (x,y,w,h) box regression values for every proposal scale_factor_wh (Tensor): tensors of shape [batch_size, 2] the scalor of per img img_whwh (Tensor): tensors of shape [batch_size, 4] Returns: bbox_pred (Tensor): tensors of shape [num_boxes, 6] Each row has 6 values: [label, confidence, xmin, ymin, xmax, ymax] bbox_num (Tensor): tensors of shape [batch_size] the number of RoIs in each image. """ assert len(box_cls) == len(scale_factor_wh) == len(img_whwh) img_wh = img_whwh[:, :2] scores = F.sigmoid(box_cls) labels = paddle.arange(0, self.num_classes). \ unsqueeze(0).tile([self.num_proposals, 1]).flatten(start_axis=0, stop_axis=1) classes_all = [] scores_all = [] boxes_all = [] for i, (scores_per_image, box_pred_per_image) in enumerate(zip(scores, box_pred)): scores_per_image, topk_indices = scores_per_image.flatten( 0, 1).topk( self.num_proposals, sorted=False) labels_per_image = paddle.gather(labels, topk_indices, axis=0) box_pred_per_image = box_pred_per_image.reshape([-1, 1, 4]).tile( [1, self.num_classes, 1]).reshape([-1, 4]) box_pred_per_image = paddle.gather( box_pred_per_image, topk_indices, axis=0) classes_all.append(labels_per_image) scores_all.append(scores_per_image) boxes_all.append(box_pred_per_image) bbox_num = paddle.zeros([len(scale_factor_wh)], dtype="int32") boxes_final = [] for i in range(len(scale_factor_wh)): classes = classes_all[i] boxes = boxes_all[i] scores = scores_all[i] boxes[:, 0::2] = paddle.clip( boxes[:, 0::2], min=0, max=img_wh[i][0]) / scale_factor_wh[i][0] boxes[:, 1::2] = paddle.clip( boxes[:, 1::2], min=0, max=img_wh[i][1]) / scale_factor_wh[i][1] boxes_w, boxes_h = (boxes[:, 2] - boxes[:, 0]).numpy(), ( boxes[:, 3] - boxes[:, 1]).numpy() keep = (boxes_w > 1.) & (boxes_h > 1.) if (keep.sum() == 0): bboxes = paddle.zeros([1, 6]).astype("float32") else: boxes = paddle.to_tensor(boxes.numpy()[keep]).astype("float32") classes = paddle.to_tensor(classes.numpy()[keep]).astype( "float32").unsqueeze(-1) scores = paddle.to_tensor(scores.numpy()[keep]).astype( "float32").unsqueeze(-1) bboxes = paddle.concat([classes, scores, boxes], axis=-1) boxes_final.append(bboxes) bbox_num[i] = bboxes.shape[0] bbox_pred = paddle.concat(boxes_final) return bbox_pred, bbox_num def multiclass_nms(bboxs, num_classes, match_threshold=0.6, match_metric='iou'): final_boxes = [] for c in range(num_classes): idxs = bboxs[:, 0] == c if np.count_nonzero(idxs) == 0: continue r = nms(bboxs[idxs, 1:], match_threshold, match_metric) final_boxes.append(np.concatenate([np.full((r.shape[0], 1), c), r], 1)) return final_boxes def nms(dets, match_threshold=0.6, match_metric='iou'): """ Apply NMS to avoid detecting too many overlapping bounding boxes. Args: dets: shape [N, 5], [score, x1, y1, x2, y2] match_metric: 'iou' or 'ios' match_threshold: overlap thresh for match metric. """ if dets.shape[0] == 0: return dets[[], :] scores = dets[:, 0] x1 = dets[:, 1] y1 = dets[:, 2] x2 = dets[:, 3] y2 = dets[:, 4] areas = (x2 - x1 + 1) * (y2 - y1 + 1) order = scores.argsort()[::-1] ndets = dets.shape[0] suppressed = np.zeros((ndets), dtype=np.int32) for _i in range(ndets): i = order[_i] if suppressed[i] == 1: continue ix1 = x1[i] iy1 = y1[i] ix2 = x2[i] iy2 = y2[i] iarea = areas[i] for _j in range(_i + 1, ndets): j = order[_j] if suppressed[j] == 1: continue xx1 = max(ix1, x1[j]) yy1 = max(iy1, y1[j]) xx2 = min(ix2, x2[j]) yy2 = min(iy2, y2[j]) w = max(0.0, xx2 - xx1 + 1) h = max(0.0, yy2 - yy1 + 1) inter = w * h if match_metric == 'iou': union = iarea + areas[j] - inter match_value = inter / union elif match_metric == 'ios': smaller = min(iarea, areas[j]) match_value = inter / smaller else: raise ValueError() if match_value >= match_threshold: suppressed[j] = 1 keep = np.where(suppressed == 0)[0] dets = dets[keep, :] return dets