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# Copyright (c) OpenMMLab. All rights reserved.
import numpy as np
import annotator.uniformer.mmcv as mmcv
try:
import torch
except ImportError:
torch = None
def tensor2imgs(tensor, mean=(0, 0, 0), std=(1, 1, 1), to_rgb=True):
"""Convert tensor to 3-channel images.
Args:
tensor (torch.Tensor): Tensor that contains multiple images, shape (
N, C, H, W).
mean (tuple[float], optional): Mean of images. Defaults to (0, 0, 0).
std (tuple[float], optional): Standard deviation of images.
Defaults to (1, 1, 1).
to_rgb (bool, optional): Whether the tensor was converted to RGB
format in the first place. If so, convert it back to BGR.
Defaults to True.
Returns:
list[np.ndarray]: A list that contains multiple images.
"""
if torch is None:
raise RuntimeError('pytorch is not installed')
assert torch.is_tensor(tensor) and tensor.ndim == 4
assert len(mean) == 3
assert len(std) == 3
num_imgs = tensor.size(0)
mean = np.array(mean, dtype=np.float32)
std = np.array(std, dtype=np.float32)
imgs = []
for img_id in range(num_imgs):
img = tensor[img_id, ...].cpu().numpy().transpose(1, 2, 0)
img = mmcv.imdenormalize(
img, mean, std, to_bgr=to_rgb).astype(np.uint8)
imgs.append(np.ascontiguousarray(img))
return imgs