mmselfsup.datasets.transforms.pytorch_transform 源代码
# Copyright (c) OpenMMLab. All rights reserved.
import math
from typing import Tuple
import torch
import torchvision.transforms.functional as F
from PIL import Image
from torchvision import transforms
from mmselfsup.registry import TRANSFORMS
[文档]@TRANSFORMS.register_module()
class MAERandomResizedCrop(transforms.RandomResizedCrop):
"""RandomResizedCrop for matching TF/TPU implementation: no for-loop is
used.
This may lead to results different with torchvision's version.
Following BYOL's TF code:
https://github.com/deepmind/deepmind-research/blob/master/byol/utils/dataset.py#L206 # noqa: E501
"""
[文档] @staticmethod
def get_params(img: Image.Image, scale: tuple, ratio: tuple) -> Tuple:
width, height = img.size
area = height * width
target_area = area * torch.empty(1).uniform_(scale[0], scale[1]).item()
log_ratio = torch.log(torch.tensor(ratio))
aspect_ratio = torch.exp(
torch.empty(1).uniform_(log_ratio[0], log_ratio[1])).item()
w = int(round(math.sqrt(target_area * aspect_ratio)))
h = int(round(math.sqrt(target_area / aspect_ratio)))
w = min(w, width)
h = min(h, height)
i = torch.randint(0, height - h + 1, size=(1, )).item()
j = torch.randint(0, width - w + 1, size=(1, )).item()
return i, j, h, w
[文档] def forward(self, results: dict) -> dict:
"""The forward function of MAERandomResizedCrop.
Args:
results (dict): The results dict contains the image and all these
information related to the image.
Returns:
dict: The results dict contains the cropped image and all these
information related to the image.
"""
img = results['img']
i, j, h, w = self.get_params(img, self.scale, self.ratio)
img = F.resized_crop(img, i, j, h, w, self.size, self.interpolation)
results['img'] = img
return results