ResNet¶
- class mmpretrain.models.backbones.ResNet(depth, in_channels=3, stem_channels=64, base_channels=64, expansion=None, num_stages=4, strides=(1, 2, 2, 2), dilations=(1, 1, 1, 1), out_indices=(3,), style='pytorch', deep_stem=False, avg_down=False, frozen_stages=-1, conv_cfg=None, norm_cfg={'requires_grad': True, 'type': 'BN'}, norm_eval=False, with_cp=False, zero_init_residual=True, init_cfg=[{'type': 'Kaiming', 'layer': ['Conv2d']}, {'type': 'Constant', 'val': 1, 'layer': ['_BatchNorm', 'GroupNorm']}], drop_path_rate=0.0)[source]¶
ResNet backbone.
Please refer to the paper for details.
- Parameters:
depth (int) – Network depth, from {18, 34, 50, 101, 152}.
in_channels (int) – Number of input image channels. Default: 3.
stem_channels (int) – Output channels of the stem layer. Default: 64.
base_channels (int) – Middle channels of the first stage. Default: 64.
num_stages (int) – Stages of the network. Default: 4.
strides (Sequence[int]) – Strides of the first block of each stage. Default:
(1, 2, 2, 2).dilations (Sequence[int]) – Dilation of each stage. Default:
(1, 1, 1, 1).out_indices (Sequence[int]) – Output from which stages. Default:
(3, ).style (str) – pytorch or caffe. If set to “pytorch”, the stride-two layer is the 3x3 conv layer, otherwise the stride-two layer is the first 1x1 conv layer.
deep_stem (bool) – Replace 7x7 conv in input stem with 3 3x3 conv. Default: False.
avg_down (bool) – Use AvgPool instead of stride conv when downsampling in the bottleneck. Default: False.
frozen_stages (int) – Stages to be frozen (stop grad and set eval mode). -1 means not freezing any parameters. Default: -1.
conv_cfg (dict | None) – The config dict for conv layers. Default: None.
norm_cfg (dict) – The config dict for norm layers.
norm_eval (bool) – Whether to set norm layers to eval mode, namely, freeze running stats (mean and var). Note: Effect on Batch Norm and its variants only. Default: False.
with_cp (bool) – Use checkpoint or not. Using checkpoint will save some memory while slowing down the training speed. Default: False.
zero_init_residual (bool) – Whether to use zero init for last norm layer in resblocks to let them behave as identity. Default: True.
Example
>>> from mmpretrain.models import ResNet >>> import torch >>> self = ResNet(depth=18) >>> self.eval() >>> inputs = torch.rand(1, 3, 32, 32) >>> level_outputs = self.forward(inputs) >>> for level_out in level_outputs: ... print(tuple(level_out.shape)) (1, 64, 8, 8) (1, 128, 4, 4) (1, 256, 2, 2) (1, 512, 1, 1)