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| import cv2 | |
| import math | |
| import numpy as np | |
| import os | |
| import torch | |
| from torchvision.utils import make_grid | |
| def img2tensor(imgs, bgr2rgb=True, float32=True): | |
| """Numpy array to tensor. | |
| Args: | |
| imgs (list[ndarray] | ndarray): Input images. | |
| bgr2rgb (bool): Whether to change bgr to rgb. | |
| float32 (bool): Whether to change to float32. | |
| Returns: | |
| list[tensor] | tensor: Tensor images. If returned results only have | |
| one element, just return tensor. | |
| """ | |
| def _totensor(img, bgr2rgb, float32): | |
| if img.shape[2] == 3 and bgr2rgb: | |
| if img.dtype == 'float64': | |
| img = img.astype('float32') | |
| img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB) | |
| img = torch.from_numpy(img.transpose(2, 0, 1)) | |
| if float32: | |
| img = img.float() | |
| return img | |
| if isinstance(imgs, list): | |
| return [_totensor(img, bgr2rgb, float32) for img in imgs] | |
| else: | |
| return _totensor(imgs, bgr2rgb, float32) | |
| def tensor2img(tensor, rgb2bgr=True, out_type=np.uint8, min_max=(0, 1)): | |
| """Convert torch Tensors into image numpy arrays. | |
| After clamping to [min, max], values will be normalized to [0, 1]. | |
| Args: | |
| tensor (Tensor or list[Tensor]): Accept shapes: | |
| 1) 4D mini-batch Tensor of shape (B x 3/1 x H x W); | |
| 2) 3D Tensor of shape (3/1 x H x W); | |
| 3) 2D Tensor of shape (H x W). | |
| Tensor channel should be in RGB order. | |
| rgb2bgr (bool): Whether to change rgb to bgr. | |
| out_type (numpy type): output types. If ``np.uint8``, transform outputs | |
| to uint8 type with range [0, 255]; otherwise, float type with | |
| range [0, 1]. Default: ``np.uint8``. | |
| min_max (tuple[int]): min and max values for clamp. | |
| Returns: | |
| (Tensor or list): 3D ndarray of shape (H x W x C) OR 2D ndarray of | |
| shape (H x W). The channel order is BGR. | |
| """ | |
| if not (torch.is_tensor(tensor) or (isinstance(tensor, list) and all(torch.is_tensor(t) for t in tensor))): | |
| raise TypeError(f'tensor or list of tensors expected, got {type(tensor)}') | |
| if torch.is_tensor(tensor): | |
| tensor = [tensor] | |
| result = [] | |
| for _tensor in tensor: | |
| _tensor = _tensor.squeeze(0).float().detach().cpu().clamp_(*min_max) | |
| _tensor = (_tensor - min_max[0]) / (min_max[1] - min_max[0]) | |
| n_dim = _tensor.dim() | |
| if n_dim == 4: | |
| img_np = make_grid(_tensor, nrow=int(math.sqrt(_tensor.size(0))), normalize=False).numpy() | |
| img_np = img_np.transpose(1, 2, 0) | |
| if rgb2bgr: | |
| img_np = cv2.cvtColor(img_np, cv2.COLOR_RGB2BGR) | |
| elif n_dim == 3: | |
| img_np = _tensor.numpy() | |
| img_np = img_np.transpose(1, 2, 0) | |
| if img_np.shape[2] == 1: # gray image | |
| img_np = np.squeeze(img_np, axis=2) | |
| else: | |
| if rgb2bgr: | |
| img_np = cv2.cvtColor(img_np, cv2.COLOR_RGB2BGR) | |
| elif n_dim == 2: | |
| img_np = _tensor.numpy() | |
| else: | |
| raise TypeError(f'Only support 4D, 3D or 2D tensor. But received with dimension: {n_dim}') | |
| if out_type == np.uint8: | |
| # Unlike MATLAB, numpy.unit8() WILL NOT round by default. | |
| img_np = (img_np * 255.0).round() | |
| img_np = img_np.astype(out_type) | |
| result.append(img_np) | |
| if len(result) == 1: | |
| result = result[0] | |
| return result | |
| def tensor2img_fast(tensor, rgb2bgr=True, min_max=(0, 1)): | |
| """This implementation is slightly faster than tensor2img. | |
| It now only supports torch tensor with shape (1, c, h, w). | |
| Args: | |
| tensor (Tensor): Now only support torch tensor with (1, c, h, w). | |
| rgb2bgr (bool): Whether to change rgb to bgr. Default: True. | |
| min_max (tuple[int]): min and max values for clamp. | |
| """ | |
| output = tensor.squeeze(0).detach().clamp_(*min_max).permute(1, 2, 0) | |
| output = (output - min_max[0]) / (min_max[1] - min_max[0]) * 255 | |
| output = output.type(torch.uint8).cpu().numpy() | |
| if rgb2bgr: | |
| output = cv2.cvtColor(output, cv2.COLOR_RGB2BGR) | |
| return output | |
| def imfrombytes(content, flag='color', float32=False): | |
| """Read an image from bytes. | |
| Args: | |
| content (bytes): Image bytes got from files or other streams. | |
| flag (str): Flags specifying the color type of a loaded image, | |
| candidates are `color`, `grayscale` and `unchanged`. | |
| float32 (bool): Whether to change to float32., If True, will also norm | |
| to [0, 1]. Default: False. | |
| Returns: | |
| ndarray: Loaded image array. | |
| """ | |
| img_np = np.frombuffer(content, np.uint8) | |
| imread_flags = {'color': cv2.IMREAD_COLOR, 'grayscale': cv2.IMREAD_GRAYSCALE, 'unchanged': cv2.IMREAD_UNCHANGED} | |
| img = cv2.imdecode(img_np, imread_flags[flag]) | |
| if float32: | |
| img = img.astype(np.float32) / 255. | |
| return img | |
| def imwrite(img, file_path, params=None, auto_mkdir=True): | |
| """Write image to file. | |
| Args: | |
| img (ndarray): Image array to be written. | |
| file_path (str): Image file path. | |
| params (None or list): Same as opencv's :func:`imwrite` interface. | |
| auto_mkdir (bool): If the parent folder of `file_path` does not exist, | |
| whether to create it automatically. | |
| Returns: | |
| bool: Successful or not. | |
| """ | |
| if auto_mkdir: | |
| dir_name = os.path.abspath(os.path.dirname(file_path)) | |
| os.makedirs(dir_name, exist_ok=True) | |
| ok = cv2.imwrite(file_path, img, params) | |
| if not ok: | |
| raise IOError('Failed in writing images.') | |
| def crop_border(imgs, crop_border): | |
| """Crop borders of images. | |
| Args: | |
| imgs (list[ndarray] | ndarray): Images with shape (h, w, c). | |
| crop_border (int): Crop border for each end of height and weight. | |
| Returns: | |
| list[ndarray]: Cropped images. | |
| """ | |
| if crop_border == 0: | |
| return imgs | |
| else: | |
| if isinstance(imgs, list): | |
| return [v[crop_border:-crop_border, crop_border:-crop_border, ...] for v in imgs] | |
| else: | |
| return imgs[crop_border:-crop_border, crop_border:-crop_border, ...] | |