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# copyright (c) 2020 PaddlePaddle Authors. All Rights Reserve. | |
# | |
# 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 refer from: | |
https://github.com/WenmuZhou/DBNet.pytorch/blob/master/data_loader/modules/make_shrink_map.py | |
""" | |
from __future__ import absolute_import | |
from __future__ import division | |
from __future__ import print_function | |
from __future__ import unicode_literals | |
import numpy as np | |
import cv2 | |
from shapely.geometry import Polygon | |
import pyclipper | |
__all__ = ['MakeShrinkMap'] | |
class MakeShrinkMap(object): | |
r''' | |
Making binary mask from detection data with ICDAR format. | |
Typically following the process of class `MakeICDARData`. | |
''' | |
def __init__(self, min_text_size=8, shrink_ratio=0.4, **kwargs): | |
self.min_text_size = min_text_size | |
self.shrink_ratio = shrink_ratio | |
if 'total_epoch' in kwargs and 'epoch' in kwargs and kwargs[ | |
'epoch'] != "None": | |
self.shrink_ratio = self.shrink_ratio + 0.2 * kwargs[ | |
'epoch'] / float(kwargs['total_epoch']) | |
def __call__(self, data): | |
image = data['image'] | |
text_polys = data['polys'] | |
ignore_tags = data['ignore_tags'] | |
h, w = image.shape[:2] | |
text_polys, ignore_tags = self.validate_polygons(text_polys, | |
ignore_tags, h, w) | |
gt = np.zeros((h, w), dtype=np.float32) | |
mask = np.ones((h, w), dtype=np.float32) | |
for i in range(len(text_polys)): | |
polygon = text_polys[i] | |
height = max(polygon[:, 1]) - min(polygon[:, 1]) | |
width = max(polygon[:, 0]) - min(polygon[:, 0]) | |
if ignore_tags[i] or min(height, width) < self.min_text_size: | |
cv2.fillPoly(mask, | |
polygon.astype(np.int32)[np.newaxis, :, :], 0) | |
ignore_tags[i] = True | |
else: | |
polygon_shape = Polygon(polygon) | |
subject = [tuple(l) for l in polygon] | |
padding = pyclipper.PyclipperOffset() | |
padding.AddPath(subject, pyclipper.JT_ROUND, | |
pyclipper.ET_CLOSEDPOLYGON) | |
shrinked = [] | |
# Increase the shrink ratio every time we get multiple polygon returned back | |
possible_ratios = np.arange(self.shrink_ratio, 1, | |
self.shrink_ratio) | |
np.append(possible_ratios, 1) | |
# print(possible_ratios) | |
for ratio in possible_ratios: | |
# print(f"Change shrink ratio to {ratio}") | |
distance = polygon_shape.area * ( | |
1 - np.power(ratio, 2)) / polygon_shape.length | |
shrinked = padding.Execute(-distance) | |
if len(shrinked) == 1: | |
break | |
if shrinked == []: | |
cv2.fillPoly(mask, | |
polygon.astype(np.int32)[np.newaxis, :, :], 0) | |
ignore_tags[i] = True | |
continue | |
for each_shirnk in shrinked: | |
shirnk = np.array(each_shirnk).reshape(-1, 2) | |
cv2.fillPoly(gt, [shirnk.astype(np.int32)], 1) | |
data['shrink_map'] = gt | |
data['shrink_mask'] = mask | |
return data | |
def validate_polygons(self, polygons, ignore_tags, h, w): | |
''' | |
polygons (numpy.array, required): of shape (num_instances, num_points, 2) | |
''' | |
if len(polygons) == 0: | |
return polygons, ignore_tags | |
assert len(polygons) == len(ignore_tags) | |
for polygon in polygons: | |
polygon[:, 0] = np.clip(polygon[:, 0], 0, w - 1) | |
polygon[:, 1] = np.clip(polygon[:, 1], 0, h - 1) | |
for i in range(len(polygons)): | |
area = self.polygon_area(polygons[i]) | |
if abs(area) < 1: | |
ignore_tags[i] = True | |
if area > 0: | |
polygons[i] = polygons[i][::-1, :] | |
return polygons, ignore_tags | |
def polygon_area(self, polygon): | |
""" | |
compute polygon area | |
""" | |
area = 0 | |
q = polygon[-1] | |
for p in polygon: | |
area += p[0] * q[1] - p[1] * q[0] | |
q = p | |
return area / 2.0 | |