# Copyright 2021 biubug6 . 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.
# This code is modified by Zilliz.
#adapted from https://github.com/biubug6/Pytorch_Retinaface
from itertools import product
from typing import Dict, List
from math import ceil
import torch
[docs]class PriorBox(object):
"""
PriorBox
Anchor boxes utility for decoding the prior box.
Args:
cfg (`Dict`):
retinaface configs.
image_size (`Linst[int]`):
input image size.
"""
[docs] def __init__(self, cfg: Dict, image_size: List[int]=None):
super().__init__()
self.min_sizes = cfg['min_sizes']
self.steps = cfg['steps']
self.clip = cfg['clip']
self.image_size = image_size
self.feature_maps = [[ceil(self.image_size[0]/step), ceil(self.image_size[1]/step)] for step in self.steps]
def forward(self):
anchors = []
for k, f in enumerate(self.feature_maps):
min_sizes = self.min_sizes[k]
for i, j in product(range(f[0]), range(f[1])):
for min_size in min_sizes:
s_kx = min_size / self.image_size[1]
s_ky = min_size / self.image_size[0]
dense_cx = [x * self.steps[k] / self.image_size[1] for x in [j + 0.5]]
dense_cy = [y * self.steps[k] / self.image_size[0] for y in [i + 0.5]]
for cy, cx in product(dense_cy, dense_cx):
anchors += [cx, cy, s_kx, s_ky]
# back to torch land
output = torch.Tensor(anchors).view(-1, 4)
if self.clip:
output.clamp_(max=1, min=0)
return output
