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# Copyright (C) 2021-2024, Mindee.
# This program is licensed under the Apache License 2.0.
# See LICENSE or go to <https://opensource.org/licenses/Apache-2.0> for full license details.
from copy import deepcopy
from typing import Tuple
import numpy as np
import torch
from torchvision.transforms import functional as F
from doctr.utils.geometry import rotate_abs_geoms
from .base import create_shadow_mask, crop_boxes
__all__ = ["invert_colors", "rotate_sample", "crop_detection", "random_shadow"]
def invert_colors(img: torch.Tensor, min_val: float = 0.6) -> torch.Tensor:
"""Invert the colors of an image
Args:
----
img : torch.Tensor, the image to invert
min_val : minimum value of the random shift
Returns:
-------
the inverted image
"""
out = F.rgb_to_grayscale(img, num_output_channels=3)
# Random RGB shift
shift_shape = [img.shape[0], 3, 1, 1] if img.ndim == 4 else [3, 1, 1]
rgb_shift = min_val + (1 - min_val) * torch.rand(shift_shape)
# Inverse the color
if out.dtype == torch.uint8:
out = (out.to(dtype=rgb_shift.dtype) * rgb_shift).to(dtype=torch.uint8)
else:
out = out * rgb_shift.to(dtype=out.dtype)
# Inverse the color
out = 255 - out if out.dtype == torch.uint8 else 1 - out
return out
def rotate_sample(
img: torch.Tensor,
geoms: np.ndarray,
angle: float,
expand: bool = False,
) -> Tuple[torch.Tensor, np.ndarray]:
"""Rotate image around the center, interpolation=NEAREST, pad with 0 (black)
Args:
----
img: image to rotate
geoms: array of geometries of shape (N, 4) or (N, 4, 2)
angle: angle in degrees. +: counter-clockwise, -: clockwise
expand: whether the image should be padded before the rotation
Returns:
-------
A tuple of rotated img (tensor), rotated geometries of shape (N, 4, 2)
"""
rotated_img = F.rotate(img, angle=angle, fill=0, expand=expand) # Interpolation NEAREST by default
rotated_img = rotated_img[:3] # when expand=True, it expands to RGBA channels
# Get absolute coords
_geoms = deepcopy(geoms)
if _geoms.shape[1:] == (4,):
if np.max(_geoms) <= 1:
_geoms[:, [0, 2]] *= img.shape[-1]
_geoms[:, [1, 3]] *= img.shape[-2]
elif _geoms.shape[1:] == (4, 2):
if np.max(_geoms) <= 1:
_geoms[..., 0] *= img.shape[-1]
_geoms[..., 1] *= img.shape[-2]
else:
raise AssertionError("invalid format for arg `geoms`")
# Rotate the boxes: xmin, ymin, xmax, ymax or polygons --> (4, 2) polygon
rotated_geoms: np.ndarray = rotate_abs_geoms(
_geoms,
angle,
img.shape[1:], # type: ignore[arg-type]
expand,
).astype(np.float32)
# Always return relative boxes to avoid label confusions when resizing is performed aferwards
rotated_geoms[..., 0] = rotated_geoms[..., 0] / rotated_img.shape[2]
rotated_geoms[..., 1] = rotated_geoms[..., 1] / rotated_img.shape[1]
return rotated_img, np.clip(rotated_geoms, 0, 1)
def crop_detection(
img: torch.Tensor, boxes: np.ndarray, crop_box: Tuple[float, float, float, float]
) -> Tuple[torch.Tensor, np.ndarray]:
"""Crop and image and associated bboxes
Args:
----
img: image to crop
boxes: array of boxes to clip, absolute (int) or relative (float)
crop_box: box (xmin, ymin, xmax, ymax) to crop the image. Relative coords.
Returns:
-------
A tuple of cropped image, cropped boxes, where the image is not resized.
"""
if any(val < 0 or val > 1 for val in crop_box):
raise AssertionError("coordinates of arg `crop_box` should be relative")
h, w = img.shape[-2:]
xmin, ymin = int(round(crop_box[0] * (w - 1))), int(round(crop_box[1] * (h - 1)))
xmax, ymax = int(round(crop_box[2] * (w - 1))), int(round(crop_box[3] * (h - 1)))
cropped_img = F.crop(img, ymin, xmin, ymax - ymin, xmax - xmin)
# Crop the box
boxes = crop_boxes(boxes, crop_box if boxes.max() <= 1 else (xmin, ymin, xmax, ymax))
return cropped_img, boxes
def random_shadow(img: torch.Tensor, opacity_range: Tuple[float, float], **kwargs) -> torch.Tensor:
"""Crop and image and associated bboxes
Args:
----
img: image to modify
opacity_range: the minimum and maximum desired opacity of the shadow
**kwargs: additional arguments to pass to `create_shadow_mask`
Returns:
-------
shaded image
"""
shadow_mask = create_shadow_mask(img.shape[1:], **kwargs) # type: ignore[arg-type]
opacity = np.random.uniform(*opacity_range)
shadow_tensor = 1 - torch.from_numpy(shadow_mask[None, ...])
# Add some blur to make it believable
k = 7 + 2 * int(4 * np.random.rand(1))
sigma = np.random.uniform(0.5, 5.0)
shadow_tensor = F.gaussian_blur(shadow_tensor, k, sigma=[sigma, sigma])
return opacity * shadow_tensor * img + (1 - opacity) * img