copy_paste.py

# copyright (c) 2021 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.
import copy
import cv2
import random
import numpy as np
from PIL import Image
from shapely.geometry import Polygon

from ppocr.data.imaug.iaa_augment import IaaAugment
from ppocr.data.imaug.random_crop_data import is_poly_outside_rect
from tools.infer.utility import get_rotate_crop_image


class CopyPaste(object):
    def __init__(self, objects_paste_ratio=0.2, limit_paste=True, **kwargs):
        self.ext_data_num = 1
        self.objects_paste_ratio = objects_paste_ratio
        self.limit_paste = limit_paste
        augmenter_args = [{'type': 'Resize', 'args': {'size': [0.5, 3]}}]
        self.aug = IaaAugment(augmenter_args)

    def __call__(self, data):
        point_num = data['polys'].shape[1]
        src_img = data['image']
        src_polys = data['polys'].tolist()
        src_ignores = data['ignore_tags'].tolist()
        ext_data = data['ext_data'][0]
        ext_image = ext_data['image']
        ext_polys = ext_data['polys']
        ext_ignores = ext_data['ignore_tags']

        indexs = [i for i in range(len(ext_ignores)) if not ext_ignores[i]]
        select_num = max(
            1, min(int(self.objects_paste_ratio * len(ext_polys)), 30))

        random.shuffle(indexs)
        select_idxs = indexs[:select_num]
        select_polys = ext_polys[select_idxs]
        select_ignores = ext_ignores[select_idxs]

        src_img = cv2.cvtColor(src_img, cv2.COLOR_BGR2RGB)
        ext_image = cv2.cvtColor(ext_image, cv2.COLOR_BGR2RGB)
        src_img = Image.fromarray(src_img).convert('RGBA')
        for poly, tag in zip(select_polys, select_ignores):
            box_img = get_rotate_crop_image(ext_image, poly)

            src_img, box = self.paste_img(src_img, box_img, src_polys)
            if box is not None:
                box = box.tolist() 
                for _ in range(len(box), point_num):
                    box.append(box[-1])
                src_polys.append(box)
                src_ignores.append(tag)
        src_img = cv2.cvtColor(np.array(src_img), cv2.COLOR_RGB2BGR)
        h, w = src_img.shape[:2]
        src_polys = np.array(src_polys)
        src_polys[:, :, 0] = np.clip(src_polys[:, :, 0], 0, w)
        src_polys[:, :, 1] = np.clip(src_polys[:, :, 1], 0, h)
        data['image'] = src_img
        data['polys'] = src_polys
        data['ignore_tags'] = np.array(src_ignores)
        return data

    def paste_img(self, src_img, box_img, src_polys):
        box_img_pil = Image.fromarray(box_img).convert('RGBA')
        src_w, src_h = src_img.size
        box_w, box_h = box_img_pil.size

        angle = np.random.randint(0, 360)
        box = np.array([[[0, 0], [box_w, 0], [box_w, box_h], [0, box_h]]])
        box = rotate_bbox(box_img, box, angle)[0]
        box_img_pil = box_img_pil.rotate(angle, expand=1)
        box_w, box_h = box_img_pil.width, box_img_pil.height
        if src_w - box_w < 0 or src_h - box_h < 0:
            return src_img, None

        paste_x, paste_y = self.select_coord(src_polys, box, src_w - box_w,
                                             src_h - box_h)
        if paste_x is None:
            return src_img, None
        box[:, 0] += paste_x
        box[:, 1] += paste_y
        r, g, b, A = box_img_pil.split()
        src_img.paste(box_img_pil, (paste_x, paste_y), mask=A)

        return src_img, box

    def select_coord(self, src_polys, box, endx, endy):
        if self.limit_paste:
            xmin, ymin, xmax, ymax = box[:, 0].min(), box[:, 1].min(
            ), box[:, 0].max(), box[:, 1].max()
            for _ in range(50):
                paste_x = random.randint(0, endx)
                paste_y = random.randint(0, endy)
                xmin1 = xmin + paste_x
                xmax1 = xmax + paste_x
                ymin1 = ymin + paste_y
                ymax1 = ymax + paste_y

                num_poly_in_rect = 0
                for poly in src_polys:
                    if not is_poly_outside_rect(poly, xmin1, ymin1,
                                                xmax1 - xmin1, ymax1 - ymin1):
                        num_poly_in_rect += 1
                        break
                if num_poly_in_rect == 0:
                    return paste_x, paste_y
            return None, None
        else:
            paste_x = random.randint(0, endx)
            paste_y = random.randint(0, endy)
            return paste_x, paste_y


def get_union(pD, pG):
    return Polygon(pD).union(Polygon(pG)).area


def get_intersection_over_union(pD, pG):
    return get_intersection(pD, pG) / get_union(pD, pG)


def get_intersection(pD, pG):
    return Polygon(pD).intersection(Polygon(pG)).area


def rotate_bbox(img, text_polys, angle, scale=1):
    """
    from https://github.com/WenmuZhou/DBNet.pytorch/blob/master/data_loader/modules/augment.py
    Args:
        img: np.ndarray
        text_polys: np.ndarray N*4*2
        angle: int
        scale: int

    Returns:

    """
    w = img.shape[1]
    h = img.shape[0]

    rangle = np.deg2rad(angle)
    nw = (abs(np.sin(rangle) * h) + abs(np.cos(rangle) * w))
    nh = (abs(np.cos(rangle) * h) + abs(np.sin(rangle) * w))
    rot_mat = cv2.getRotationMatrix2D((nw * 0.5, nh * 0.5), angle, scale)
    rot_move = np.dot(rot_mat, np.array([(nw - w) * 0.5, (nh - h) * 0.5, 0]))
    rot_mat[0, 2] += rot_move[0]
    rot_mat[1, 2] += rot_move[1]

    # ---------------------- rotate box ----------------------
    rot_text_polys = list()
    for bbox in text_polys:
        point1 = np.dot(rot_mat, np.array([bbox[0, 0], bbox[0, 1], 1]))
        point2 = np.dot(rot_mat, np.array([bbox[1, 0], bbox[1, 1], 1]))
        point3 = np.dot(rot_mat, np.array([bbox[2, 0], bbox[2, 1], 1]))
        point4 = np.dot(rot_mat, np.array([bbox[3, 0], bbox[3, 1], 1]))
        rot_text_polys.append([point1, point2, point3, point4])
    return np.array(rot_text_polys, dtype=np.float32)