source/PaddleOCR/ppocr/data/imaug/text_image_aug/augment.py

# 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/RubanSeven/Text-Image-Augmentation-python/blob/master/augment.py
"""

import numpy as np
from .warp_mls import WarpMLS


def tia_distort(src, segment=4):
    img_h, img_w = src.shape[:2]

    cut = img_w // segment
    thresh = cut // 3

    src_pts = list()
    dst_pts = list()

    src_pts.append([0, 0])
    src_pts.append([img_w, 0])
    src_pts.append([img_w, img_h])
    src_pts.append([0, img_h])

    dst_pts.append([np.random.randint(thresh), np.random.randint(thresh)])
    dst_pts.append([img_w - np.random.randint(thresh), np.random.randint(thresh)])
    dst_pts.append(
        [img_w - np.random.randint(thresh), img_h - np.random.randint(thresh)]
    )
    dst_pts.append([np.random.randint(thresh), img_h - np.random.randint(thresh)])

    half_thresh = thresh * 0.5

    for cut_idx in np.arange(1, segment, 1):
        src_pts.append([cut * cut_idx, 0])
        src_pts.append([cut * cut_idx, img_h])
        dst_pts.append(
            [
                cut * cut_idx + np.random.randint(thresh) - half_thresh,
                np.random.randint(thresh) - half_thresh,
            ]
        )
        dst_pts.append(
            [
                cut * cut_idx + np.random.randint(thresh) - half_thresh,
                img_h + np.random.randint(thresh) - half_thresh,
            ]
        )

    trans = WarpMLS(src, src_pts, dst_pts, img_w, img_h)
    dst = trans.generate()

    return dst


def tia_stretch(src, segment=4):
    img_h, img_w = src.shape[:2]

    cut = img_w // segment
    thresh = cut * 4 // 5

    src_pts = list()
    dst_pts = list()

    src_pts.append([0, 0])
    src_pts.append([img_w, 0])
    src_pts.append([img_w, img_h])
    src_pts.append([0, img_h])

    dst_pts.append([0, 0])
    dst_pts.append([img_w, 0])
    dst_pts.append([img_w, img_h])
    dst_pts.append([0, img_h])

    half_thresh = thresh * 0.5

    for cut_idx in np.arange(1, segment, 1):
        move = np.random.randint(thresh) - half_thresh
        src_pts.append([cut * cut_idx, 0])
        src_pts.append([cut * cut_idx, img_h])
        dst_pts.append([cut * cut_idx + move, 0])
        dst_pts.append([cut * cut_idx + move, img_h])

    trans = WarpMLS(src, src_pts, dst_pts, img_w, img_h)
    dst = trans.generate()

    return dst


def tia_perspective(src):
    img_h, img_w = src.shape[:2]

    thresh = img_h // 2

    src_pts = list()
    dst_pts = list()

    src_pts.append([0, 0])
    src_pts.append([img_w, 0])
    src_pts.append([img_w, img_h])
    src_pts.append([0, img_h])

    dst_pts.append([0, np.random.randint(thresh)])
    dst_pts.append([img_w, np.random.randint(thresh)])
    dst_pts.append([img_w, img_h - np.random.randint(thresh)])
    dst_pts.append([0, img_h - np.random.randint(thresh)])

    trans = WarpMLS(src, src_pts, dst_pts, img_w, img_h)
    dst = trans.generate()

    return dst