You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
pytorch-image-models/timm/models/davit.py

687 lines
22 KiB

""" DaViT: Dual Attention Vision Transformers
As described in https://arxiv.org/abs/2204.03645
Input size invariant transformer architecture that combines channel and spacial
attention in each block. The attention mechanisms used are linear in complexity.
DaViT model defs and weights adapted from https://github.com/dingmyu/davit, original copyright below
"""
# Copyright (c) 2022 Mingyu Ding
# All rights reserved.
# This source code is licensed under the MIT license
import itertools
from collections import OrderedDict
from functools import partial
from typing import Tuple
import torch
import torch.nn as nn
import torch.nn.functional as F
from torch import Tensor
from timm.data import IMAGENET_DEFAULT_MEAN, IMAGENET_DEFAULT_STD
from timm.layers import DropPath, to_2tuple, trunc_normal_, SelectAdaptivePool2d, Mlp, LayerNorm2d, get_norm_layer
from timm.layers import NormMlpClassifierHead, ClassifierHead
from ._builder import build_model_with_cfg
from ._features_fx import register_notrace_function
from ._manipulate import checkpoint_seq
from ._pretrained import generate_default_cfgs
from ._registry import register_model
__all__ = ['DaViT']
class ConvPosEnc(nn.Module):
def __init__(self, dim: int, k: int = 3, act: bool = False):
super(ConvPosEnc, self).__init__()
self.proj = nn.Conv2d(dim, dim, k, 1, k // 2, groups=dim)
self.act = nn.GELU() if act else nn.Identity()
def forward(self, x: Tensor):
feat = self.proj(x)
x = x + self.act(feat)
return x
class Stem(nn.Module):
""" Size-agnostic implementation of 2D image to patch embedding,
allowing input size to be adjusted during model forward operation
"""
def __init__(
self,
in_chs=3,
out_chs=96,
stride=4,
norm_layer=LayerNorm2d,
):
super().__init__()
stride = to_2tuple(stride)
self.stride = stride
self.in_chs = in_chs
self.out_chs = out_chs
assert stride[0] == 4 # only setup for stride==4
self.conv = nn.Conv2d(
in_chs,
out_chs,
kernel_size=7,
stride=stride,
padding=3,
)
self.norm = norm_layer(out_chs)
def forward(self, x: Tensor):
B, C, H, W = x.shape
x = F.pad(x, (0, (self.stride[1] - W % self.stride[1]) % self.stride[1]))
x = F.pad(x, (0, 0, 0, (self.stride[0] - H % self.stride[0]) % self.stride[0]))
x = self.conv(x)
x = self.norm(x)
return x
class Downsample(nn.Module):
def __init__(
self,
in_chs,
out_chs,
norm_layer=LayerNorm2d,
):
super().__init__()
self.in_chs = in_chs
self.out_chs = out_chs
self.norm = norm_layer(in_chs)
self.conv = nn.Conv2d(
in_chs,
out_chs,
kernel_size=2,
stride=2,
padding=0,
)
def forward(self, x: Tensor):
B, C, H, W = x.shape
x = self.norm(x)
x = F.pad(x, (0, (2 - W % 2) % 2))
x = F.pad(x, (0, 0, 0, (2 - H % 2) % 2))
x = self.conv(x)
return x
class ChannelAttention(nn.Module):
def __init__(self, dim, num_heads=8, qkv_bias=False):
super().__init__()
self.num_heads = num_heads
head_dim = dim // num_heads
self.scale = head_dim ** -0.5
self.qkv = nn.Linear(dim, dim * 3, bias=qkv_bias)
self.proj = nn.Linear(dim, dim)
def forward(self, x: Tensor):
B, N, C = x.shape
qkv = self.qkv(x).reshape(B, N, 3, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4)
q, k, v = qkv.unbind(0)
k = k * self.scale
attention = k.transpose(-1, -2) @ v
attention = attention.softmax(dim=-1)
x = (attention @ q.transpose(-1, -2)).transpose(-1, -2)
x = x.transpose(1, 2).reshape(B, N, C)
x = self.proj(x)
return x
class ChannelBlock(nn.Module):
def __init__(
self,
dim,
num_heads,
mlp_ratio=4.,
qkv_bias=False,
drop_path=0.,
act_layer=nn.GELU,
norm_layer=nn.LayerNorm,
ffn=True,
cpe_act=False,
):
super().__init__()
self.cpe1 = ConvPosEnc(dim=dim, k=3, act=cpe_act)
self.ffn = ffn
self.norm1 = norm_layer(dim)
self.attn = ChannelAttention(dim, num_heads=num_heads, qkv_bias=qkv_bias)
self.drop_path1 = DropPath(drop_path) if drop_path > 0. else nn.Identity()
self.cpe2 = ConvPosEnc(dim=dim, k=3, act=cpe_act)
if self.ffn:
self.norm2 = norm_layer(dim)
self.mlp = Mlp(
in_features=dim,
hidden_features=int(dim * mlp_ratio),
act_layer=act_layer,
)
self.drop_path2 = DropPath(drop_path) if drop_path > 0. else nn.Identity()
else:
self.norm2 = None
self.mlp = None
self.drop_path2 = None
def forward(self, x: Tensor):
B, C, H, W = x.shape
x = self.cpe1(x).flatten(2).transpose(1, 2)
cur = self.norm1(x)
cur = self.attn(cur)
x = x + self.drop_path1(cur)
x = self.cpe2(x.transpose(1, 2).view(B, C, H, W))
if self.mlp is not None:
x = x.flatten(2).transpose(1, 2)
x = x + self.drop_path2(self.mlp(self.norm2(x)))
x = x.transpose(1, 2).view(B, C, H, W)
return x
def window_partition(x: Tensor, window_size: Tuple[int, int]):
"""
Args:
x: (B, H, W, C)
window_size (int): window size
Returns:
windows: (num_windows*B, window_size, window_size, C)
"""
B, H, W, C = x.shape
x = x.view(B, H // window_size[0], window_size[0], W // window_size[1], window_size[1], C)
windows = x.permute(0, 1, 3, 2, 4, 5).contiguous().view(-1, window_size[0], window_size[1], C)
return windows
@register_notrace_function # reason: int argument is a Proxy
def window_reverse(windows: Tensor, window_size: Tuple[int, int], H: int, W: int):
"""
Args:
windows: (num_windows*B, window_size, window_size, C)
window_size (int): Window size
H (int): Height of image
W (int): Width of image
Returns:
x: (B, H, W, C)
"""
C = windows.shape[-1]
x = windows.view(-1, H // window_size[0], W // window_size[1], window_size[0], window_size[1], C)
x = x.permute(0, 1, 3, 2, 4, 5).contiguous().view(-1, H, W, C)
return x
class WindowAttention(nn.Module):
r""" Window based multi-head self attention (W-MSA) module with relative position bias.
It supports both of shifted and non-shifted window.
Args:
dim (int): Number of input channels.
window_size (tuple[int]): The height and width of the window.
num_heads (int): Number of attention heads.
qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
"""
def __init__(self, dim, window_size, num_heads, qkv_bias=True):
super().__init__()
self.dim = dim
self.window_size = window_size
self.num_heads = num_heads
head_dim = dim // num_heads
self.scale = head_dim ** -0.5
self.qkv = nn.Linear(dim, dim * 3, bias=qkv_bias)
self.proj = nn.Linear(dim, dim)
self.softmax = nn.Softmax(dim=-1)
def forward(self, x: Tensor):
B_, N, C = x.shape
qkv = self.qkv(x).reshape(B_, N, 3, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4)
q, k, v = qkv.unbind(0)
q = q * self.scale
attn = (q @ k.transpose(-2, -1))
attn = self.softmax(attn)
x = (attn @ v).transpose(1, 2).reshape(B_, N, C)
x = self.proj(x)
return x
class SpatialBlock(nn.Module):
r""" Windows Block.
Args:
dim (int): Number of input channels.
num_heads (int): Number of attention heads.
window_size (int): Window size.
mlp_ratio (float): Ratio of mlp hidden dim to embedding dim.
qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
drop_path (float, optional): Stochastic depth rate. Default: 0.0
act_layer (nn.Module, optional): Activation layer. Default: nn.GELU
norm_layer (nn.Module, optional): Normalization layer. Default: nn.LayerNorm
"""
def __init__(
self,
dim,
num_heads,
window_size=7,
mlp_ratio=4.,
qkv_bias=True,
drop_path=0.,
act_layer=nn.GELU,
norm_layer=nn.LayerNorm,
ffn=True,
cpe_act=False,
):
super().__init__()
self.dim = dim
self.ffn = ffn
self.num_heads = num_heads
self.window_size = to_2tuple(window_size)
self.mlp_ratio = mlp_ratio
self.cpe1 = ConvPosEnc(dim=dim, k=3, act=cpe_act)
self.norm1 = norm_layer(dim)
self.attn = WindowAttention(
dim,
self.window_size,
num_heads=num_heads,
qkv_bias=qkv_bias,
)
self.drop_path1 = DropPath(drop_path) if drop_path > 0. else nn.Identity()
self.cpe2 = ConvPosEnc(dim=dim, k=3, act=cpe_act)
if self.ffn:
self.norm2 = norm_layer(dim)
mlp_hidden_dim = int(dim * mlp_ratio)
self.mlp = Mlp(
in_features=dim,
hidden_features=mlp_hidden_dim,
act_layer=act_layer,
)
self.drop_path2 = DropPath(drop_path) if drop_path > 0. else nn.Identity()
else:
self.norm2 = None
self.mlp = None
self.drop_path1 = None
def forward(self, x: Tensor):
B, C, H, W = x.shape
shortcut = self.cpe1(x).flatten(2).transpose(1, 2)
x = self.norm1(shortcut)
x = x.view(B, H, W, C)
pad_l = pad_t = 0
pad_r = (self.window_size[1] - W % self.window_size[1]) % self.window_size[1]
pad_b = (self.window_size[0] - H % self.window_size[0]) % self.window_size[0]
x = F.pad(x, (0, 0, pad_l, pad_r, pad_t, pad_b))
_, Hp, Wp, _ = x.shape
x_windows = window_partition(x, self.window_size)
x_windows = x_windows.view(-1, self.window_size[0] * self.window_size[1], C)
# W-MSA/SW-MSA
attn_windows = self.attn(x_windows)
# merge windows
attn_windows = attn_windows.view(-1, self.window_size[0], self.window_size[1], C)
x = window_reverse(attn_windows, self.window_size, Hp, Wp)
# if pad_r > 0 or pad_b > 0:
x = x[:, :H, :W, :].contiguous()
x = x.view(B, H * W, C)
x = shortcut + self.drop_path1(x)
x = self.cpe2(x.transpose(1, 2).view(B, C, H, W))
if self.mlp is not None:
x = x.flatten(2).transpose(1, 2)
x = x + self.drop_path2(self.mlp(self.norm2(x)))
x = x.transpose(1, 2).view(B, C, H, W)
return x
class DaViTStage(nn.Module):
def __init__(
self,
in_chs,
out_chs,
depth=1,
downsample=True,
attn_types=('spatial', 'channel'),
num_heads=3,
window_size=7,
mlp_ratio=4,
qkv_bias=True,
drop_path_rates=(0, 0),
norm_layer=LayerNorm2d,
norm_layer_cl=nn.LayerNorm,
ffn=True,
cpe_act=False
):
super().__init__()
self.grad_checkpointing = False
# downsample embedding layer at the beginning of each stage
if downsample:
self.downsample = Downsample(in_chs, out_chs, norm_layer=norm_layer)
else:
self.downsample = nn.Identity()
'''
repeating alternating attention blocks in each stage
default: (spatial -> channel) x depth
potential opportunity to integrate with a more general version of ByobNet/ByoaNet
since the logic is similar
'''
stage_blocks = []
for block_idx in range(depth):
dual_attention_block = []
for attn_idx, attn_type in enumerate(attn_types):
if attn_type == 'spatial':
dual_attention_block.append(SpatialBlock(
dim=out_chs,
num_heads=num_heads,
mlp_ratio=mlp_ratio,
qkv_bias=qkv_bias,
drop_path=drop_path_rates[block_idx],
norm_layer=norm_layer_cl,
ffn=ffn,
cpe_act=cpe_act,
window_size=window_size,
))
elif attn_type == 'channel':
dual_attention_block.append(ChannelBlock(
dim=out_chs,
num_heads=num_heads,
mlp_ratio=mlp_ratio,
qkv_bias=qkv_bias,
drop_path=drop_path_rates[block_idx],
norm_layer=norm_layer_cl,
ffn=ffn,
cpe_act=cpe_act
))
stage_blocks.append(nn.Sequential(*dual_attention_block))
self.blocks = nn.Sequential(*stage_blocks)
@torch.jit.ignore
def set_grad_checkpointing(self, enable=True):
self.grad_checkpointing = enable
def forward(self, x: Tensor):
x = self.downsample(x)
if self.grad_checkpointing and not torch.jit.is_scripting():
x = checkpoint_seq(self.blocks, x)
else:
x = self.blocks(x)
return x
class DaViT(nn.Module):
r""" DaViT
A PyTorch implementation of `DaViT: Dual Attention Vision Transformers` - https://arxiv.org/abs/2204.03645
Supports arbitrary input sizes and pyramid feature extraction
Args:
in_chans (int): Number of input image channels. Default: 3
num_classes (int): Number of classes for classification head. Default: 1000
depths (tuple(int)): Number of blocks in each stage. Default: (1, 1, 3, 1)
embed_dims (tuple(int)): Patch embedding dimension. Default: (96, 192, 384, 768)
num_heads (tuple(int)): Number of attention heads in different layers. Default: (3, 6, 12, 24)
window_size (int): Window size. Default: 7
mlp_ratio (float): Ratio of mlp hidden dim to embedding dim. Default: 4
qkv_bias (bool): If True, add a learnable bias to query, key, value. Default: True
drop_path_rate (float): Stochastic depth rate. Default: 0.1
norm_layer (nn.Module): Normalization layer. Default: nn.LayerNorm.
"""
def __init__(
self,
in_chans=3,
depths=(1, 1, 3, 1),
embed_dims=(96, 192, 384, 768),
num_heads=(3, 6, 12, 24),
window_size=7,
mlp_ratio=4,
qkv_bias=True,
norm_layer='layernorm2d',
norm_layer_cl='layernorm',
norm_eps=1e-5,
attn_types=('spatial', 'channel'),
ffn=True,
cpe_act=False,
drop_rate=0.,
attn_drop_rate=0.,
drop_path_rate=0.,
num_classes=1000,
global_pool='avg',
head_norm_first=False,
):
super().__init__()
num_stages = len(embed_dims)
assert num_stages == len(num_heads) == len(depths)
norm_layer = partial(get_norm_layer(norm_layer), eps=norm_eps)
norm_layer_cl = partial(get_norm_layer(norm_layer_cl), eps=norm_eps)
self.num_classes = num_classes
self.num_features = embed_dims[-1]
self.drop_rate = drop_rate
self.grad_checkpointing = False
self.feature_info = []
self.stem = Stem(in_chans, embed_dims[0], norm_layer=norm_layer)
in_chs = embed_dims[0]
dpr = [x.tolist() for x in torch.linspace(0, drop_path_rate, sum(depths)).split(depths)]
stages = []
for stage_idx in range(num_stages):
out_chs = embed_dims[stage_idx]
stage = DaViTStage(
in_chs,
out_chs,
depth=depths[stage_idx],
downsample=stage_idx > 0,
attn_types=attn_types,
num_heads=num_heads[stage_idx],
window_size=window_size,
mlp_ratio=mlp_ratio,
qkv_bias=qkv_bias,
drop_path_rates=dpr[stage_idx],
norm_layer=norm_layer,
norm_layer_cl=norm_layer_cl,
ffn=ffn,
cpe_act=cpe_act,
)
in_chs = out_chs
stages.append(stage)
self.feature_info += [dict(num_chs=out_chs, reduction=2, module=f'stages.{stage_idx}')]
self.stages = nn.Sequential(*stages)
# if head_norm_first == true, norm -> global pool -> fc ordering, like most other nets
# otherwise pool -> norm -> fc, the default DaViT order, similar to ConvNeXt
# FIXME generalize this structure to ClassifierHead
if head_norm_first:
self.norm_pre = norm_layer(self.num_features)
self.head = ClassifierHead(
self.num_features,
num_classes,
pool_type=global_pool,
drop_rate=self.drop_rate,
)
else:
self.norm_pre = nn.Identity()
self.head = NormMlpClassifierHead(
self.num_features,
num_classes,
pool_type=global_pool,
drop_rate=self.drop_rate,
norm_layer=norm_layer,
)
self.apply(self._init_weights)
def _init_weights(self, m):
if isinstance(m, nn.Linear):
trunc_normal_(m.weight, std=.02)
if isinstance(m, nn.Linear) and m.bias is not None:
nn.init.constant_(m.bias, 0)
@torch.jit.ignore
def set_grad_checkpointing(self, enable=True):
self.grad_checkpointing = enable
for stage in self.stages:
stage.set_grad_checkpointing(enable=enable)
@torch.jit.ignore
def get_classifier(self):
return self.head.fc
def reset_classifier(self, num_classes, global_pool=None):
self.head.reset(num_classes, global_pool=global_pool)
def forward_features(self, x):
x = self.stem(x)
if self.grad_checkpointing and not torch.jit.is_scripting():
x = checkpoint_seq(self.stages, x)
else:
x = self.stages(x)
x = self.norm_pre(x)
return x
def forward_head(self, x, pre_logits: bool = False):
x = self.head.global_pool(x)
x = self.head.norm(x)
x = self.head.flatten(x)
x = self.head.drop(x)
return x if pre_logits else self.head.fc(x)
def forward(self, x):
x = self.forward_features(x)
x = self.forward_head(x)
return x
def checkpoint_filter_fn(state_dict, model):
""" Remap MSFT checkpoints -> timm """
if 'head.fc.weight' in state_dict:
return state_dict # non-MSFT checkpoint
if 'state_dict' in state_dict:
state_dict = state_dict['state_dict']
import re
out_dict = {}
for k, v in state_dict.items():
k = re.sub(r'patch_embeds.([0-9]+)', r'stages.\1.downsample', k)
k = re.sub(r'main_blocks.([0-9]+)', r'stages.\1.blocks', k)
k = k.replace('downsample.proj', 'downsample.conv')
k = k.replace('stages.0.downsample', 'stem')
k = k.replace('head.', 'head.fc.')
k = k.replace('norms.', 'head.norm.')
k = k.replace('cpe.0', 'cpe1')
k = k.replace('cpe.1', 'cpe2')
out_dict[k] = v
return out_dict
def _create_davit(variant, pretrained=False, **kwargs):
default_out_indices = tuple(i for i, _ in enumerate(kwargs.get('depths', (1, 1, 3, 1))))
out_indices = kwargs.pop('out_indices', default_out_indices)
model = build_model_with_cfg(
DaViT,
variant,
pretrained,
pretrained_filter_fn=checkpoint_filter_fn,
feature_cfg=dict(flatten_sequential=True, out_indices=out_indices),
**kwargs)
return model
def _cfg(url='', **kwargs):
return {
'url': url,
'num_classes': 1000, 'input_size': (3, 224, 224), 'pool_size': (7, 7),
'crop_pct': 0.95, 'interpolation': 'bicubic',
'mean': IMAGENET_DEFAULT_MEAN, 'std': IMAGENET_DEFAULT_STD,
'first_conv': 'stem.conv', 'classifier': 'head.fc',
**kwargs
}
# TODO contact authors to get larger pretrained models
default_cfgs = generate_default_cfgs({
# official microsoft weights from https://github.com/dingmyu/davit
'davit_tiny.msft_in1k': _cfg(
hf_hub_id='timm/'),
'davit_small.msft_in1k': _cfg(
hf_hub_id='timm/'),
'davit_base.msft_in1k': _cfg(
hf_hub_id='timm/'),
'davit_large': _cfg(),
'davit_huge': _cfg(),
'davit_giant': _cfg(),
})
@register_model
def davit_tiny(pretrained=False, **kwargs):
model_kwargs = dict(
depths=(1, 1, 3, 1), embed_dims=(96, 192, 384, 768), num_heads=(3, 6, 12, 24), **kwargs)
return _create_davit('davit_tiny', pretrained=pretrained, **model_kwargs)
@register_model
def davit_small(pretrained=False, **kwargs):
model_kwargs = dict(
depths=(1, 1, 9, 1), embed_dims=(96, 192, 384, 768), num_heads=(3, 6, 12, 24), **kwargs)
return _create_davit('davit_small', pretrained=pretrained, **model_kwargs)
@register_model
def davit_base(pretrained=False, **kwargs):
model_kwargs = dict(
depths=(1, 1, 9, 1), embed_dims=(128, 256, 512, 1024), num_heads=(4, 8, 16, 32), **kwargs)
return _create_davit('davit_base', pretrained=pretrained, **model_kwargs)
@register_model
def davit_large(pretrained=False, **kwargs):
model_kwargs = dict(
depths=(1, 1, 9, 1), embed_dims=(192, 384, 768, 1536), num_heads=(6, 12, 24, 48), **kwargs)
return _create_davit('davit_large', pretrained=pretrained, **model_kwargs)
@register_model
def davit_huge(pretrained=False, **kwargs):
model_kwargs = dict(
depths=(1, 1, 9, 1), embed_dims=(256, 512, 1024, 2048), num_heads=(8, 16, 32, 64), **kwargs)
return _create_davit('davit_huge', pretrained=pretrained, **model_kwargs)
@register_model
def davit_giant(pretrained=False, **kwargs):
model_kwargs = dict(
depths=(1, 1, 12, 3), embed_dims=(384, 768, 1536, 3072), num_heads=(12, 24, 48, 96), **kwargs)
return _create_davit('davit_giant', pretrained=pretrained, **model_kwargs)