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import cv2
import random
import torch
def mod_crop(img, scale):
"""Mod crop images, used during testing.
Args:
img (ndarray): Input image.
scale (int): Scale factor.
Returns:
ndarray: Result image.
"""
img = img.copy()
if img.ndim in (2, 3):
h, w = img.shape[0], img.shape[1]
h_remainder, w_remainder = h % scale, w % scale
img = img[:h - h_remainder, :w - w_remainder, ...]
else:
raise ValueError(f'Wrong img ndim: {img.ndim}.')
return img
def paired_random_crop(img_gts, img_lqs, gt_patch_size, scale, gt_path=None):
"""Paired random crop. Support Numpy array and Tensor inputs.
It crops lists of lq and gt images with corresponding locations.
Args:
img_gts (list[ndarray] | ndarray | list[Tensor] | Tensor): GT images. Note that all images
should have the same shape. If the input is an ndarray, it will
be transformed to a list containing itself.
img_lqs (list[ndarray] | ndarray): LQ images. Note that all images
should have the same shape. If the input is an ndarray, it will
be transformed to a list containing itself.
gt_patch_size (int): GT patch size.
scale (int): Scale factor.
gt_path (str): Path to ground-truth. Default: None.
Returns:
list[ndarray] | ndarray: GT images and LQ images. If returned results
only have one element, just return ndarray.
"""
if not isinstance(img_gts, list):
img_gts = [img_gts]
if not isinstance(img_lqs, list):
img_lqs = [img_lqs]
# determine input type: Numpy array or Tensor
input_type = 'Tensor' if torch.is_tensor(img_gts[0]) else 'Numpy'
if input_type == 'Tensor':
h_lq, w_lq = img_lqs[0].size()[-2:]
h_gt, w_gt = img_gts[0].size()[-2:]
else:
h_lq, w_lq = img_lqs[0].shape[0:2]
h_gt, w_gt = img_gts[0].shape[0:2]
lq_patch_size = gt_patch_size // scale
if h_gt != h_lq * scale or w_gt != w_lq * scale:
raise ValueError(f'Scale mismatches. GT ({h_gt}, {w_gt}) is not {scale}x ',
f'multiplication of LQ ({h_lq}, {w_lq}).')
if h_lq < lq_patch_size or w_lq < lq_patch_size:
raise ValueError(f'LQ ({h_lq}, {w_lq}) is smaller than patch size '
f'({lq_patch_size}, {lq_patch_size}). '
f'Please remove {gt_path}.')
# randomly choose top and left coordinates for lq patch
top = random.randint(0, h_lq - lq_patch_size)
left = random.randint(0, w_lq - lq_patch_size)
# crop lq patch
if input_type == 'Tensor':
img_lqs = [v[:, :, top:top + lq_patch_size, left:left + lq_patch_size] for v in img_lqs]
else:
img_lqs = [v[top:top + lq_patch_size, left:left + lq_patch_size, ...] for v in img_lqs]
# crop corresponding gt patch
top_gt, left_gt = int(top * scale), int(left * scale)
if input_type == 'Tensor':
img_gts = [v[:, :, top_gt:top_gt + gt_patch_size, left_gt:left_gt + gt_patch_size] for v in img_gts]
else:
img_gts = [v[top_gt:top_gt + gt_patch_size, left_gt:left_gt + gt_patch_size, ...] for v in img_gts]
if len(img_gts) == 1:
img_gts = img_gts[0]
if len(img_lqs) == 1:
img_lqs = img_lqs[0]
return img_gts, img_lqs
def augment(imgs, hflip=True, rotation=True, flows=None, return_status=False):
"""Augment: horizontal flips OR rotate (0, 90, 180, 270 degrees).
We use vertical flip and transpose for rotation implementation.
All the images in the list use the same augmentation.
Args:
imgs (list[ndarray] | ndarray): Images to be augmented. If the input
is an ndarray, it will be transformed to a list.
hflip (bool): Horizontal flip. Default: True.
rotation (bool): Ratotation. Default: True.
flows (list[ndarray]: Flows to be augmented. If the input is an
ndarray, it will be transformed to a list.
Dimension is (h, w, 2). Default: None.
return_status (bool): Return the status of flip and rotation.
Default: False.
Returns:
list[ndarray] | ndarray: Augmented images and flows. If returned
results only have one element, just return ndarray.
"""
hflip = hflip and random.random() < 0.5
vflip = rotation and random.random() < 0.5
rot90 = rotation and random.random() < 0.5
def _augment(img):
if hflip: # horizontal
cv2.flip(img, 1, img)
if vflip: # vertical
cv2.flip(img, 0, img)
if rot90:
img = img.transpose(1, 0, 2)
return img
def _augment_flow(flow):
if hflip: # horizontal
cv2.flip(flow, 1, flow)
flow[:, :, 0] *= -1
if vflip: # vertical
cv2.flip(flow, 0, flow)
flow[:, :, 1] *= -1
if rot90:
flow = flow.transpose(1, 0, 2)
flow = flow[:, :, [1, 0]]
return flow
if not isinstance(imgs, list):
imgs = [imgs]
imgs = [_augment(img) for img in imgs]
if len(imgs) == 1:
imgs = imgs[0]
if flows is not None:
if not isinstance(flows, list):
flows = [flows]
flows = [_augment_flow(flow) for flow in flows]
if len(flows) == 1:
flows = flows[0]
return imgs, flows
else:
if return_status:
return imgs, (hflip, vflip, rot90)
else:
return imgs
def img_rotate(img, angle, center=None, scale=1.0):
"""Rotate image.
Args:
img (ndarray): Image to be rotated.
angle (float): Rotation angle in degrees. Positive values mean
counter-clockwise rotation.
center (tuple[int]): Rotation center. If the center is None,
initialize it as the center of the image. Default: None.
scale (float): Isotropic scale factor. Default: 1.0.
"""
(h, w) = img.shape[:2]
if center is None:
center = (w // 2, h // 2)
matrix = cv2.getRotationMatrix2D(center, angle, scale)
rotated_img = cv2.warpAffine(img, matrix, (w, h))
return rotated_img
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