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| from __future__ import absolute_import, division, print_function, unicode_literals | |
| import cv2 | |
| import numpy as np | |
| import pyclipper | |
| from shapely.geometry import Polygon | |
| __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 | |
| 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 | |