pytorch-image-models/timm/models/nextvit.py

689 lines
22 KiB
Python

""" Next-ViT
As described in https://arxiv.org/abs/2207.05501
Next-ViT model defs and weights adapted from https://github.com/bytedance/Next-ViT, original copyright below
"""
# Copyright (c) ByteDance Inc. All rights reserved.
from functools import partial
from typing import Optional
import torch
import torch.nn.functional as F
from torch import nn
from timm.data import IMAGENET_DEFAULT_MEAN, IMAGENET_DEFAULT_STD
from timm.layers import DropPath, trunc_normal_, ConvMlp, get_norm_layer, get_act_layer, use_fused_attn
from timm.layers import ClassifierHead
from ._builder import build_model_with_cfg
from ._features_fx import register_notrace_function
from ._manipulate import checkpoint_seq
from ._registry import generate_default_cfgs, register_model
__all__ = ['NextViT']
def merge_pre_bn(module, pre_bn_1, pre_bn_2=None):
""" Merge pre BN to reduce inference runtime.
"""
weight = module.weight.data
if module.bias is None:
zeros = torch.zeros(module.out_chs, device=weight.device).type(weight.type())
module.bias = nn.Parameter(zeros)
bias = module.bias.data
if pre_bn_2 is None:
assert pre_bn_1.track_running_stats is True, "Unsupported bn_module.track_running_stats is False"
assert pre_bn_1.affine is True, "Unsupported bn_module.affine is False"
scale_invstd = pre_bn_1.running_var.add(pre_bn_1.eps).pow(-0.5)
extra_weight = scale_invstd * pre_bn_1.weight
extra_bias = pre_bn_1.bias - pre_bn_1.weight * pre_bn_1.running_mean * scale_invstd
else:
assert pre_bn_1.track_running_stats is True, "Unsupported bn_module.track_running_stats is False"
assert pre_bn_1.affine is True, "Unsupported bn_module.affine is False"
assert pre_bn_2.track_running_stats is True, "Unsupported bn_module.track_running_stats is False"
assert pre_bn_2.affine is True, "Unsupported bn_module.affine is False"
scale_invstd_1 = pre_bn_1.running_var.add(pre_bn_1.eps).pow(-0.5)
scale_invstd_2 = pre_bn_2.running_var.add(pre_bn_2.eps).pow(-0.5)
extra_weight = scale_invstd_1 * pre_bn_1.weight * scale_invstd_2 * pre_bn_2.weight
extra_bias = (
scale_invstd_2 * pre_bn_2.weight
* (pre_bn_1.bias - pre_bn_1.weight * pre_bn_1.running_mean * scale_invstd_1 - pre_bn_2.running_mean)
+ pre_bn_2.bias
)
if isinstance(module, nn.Linear):
extra_bias = weight @ extra_bias
weight.mul_(extra_weight.view(1, weight.size(1)).expand_as(weight))
elif isinstance(module, nn.Conv2d):
assert weight.shape[2] == 1 and weight.shape[3] == 1
weight = weight.reshape(weight.shape[0], weight.shape[1])
extra_bias = weight @ extra_bias
weight.mul_(extra_weight.view(1, weight.size(1)).expand_as(weight))
weight = weight.reshape(weight.shape[0], weight.shape[1], 1, 1)
bias.add_(extra_bias)
module.weight.data = weight
module.bias.data = bias
class ConvNormAct(nn.Module):
def __init__(
self,
in_chs,
out_chs,
kernel_size=3,
stride=1,
groups=1,
norm_layer=nn.BatchNorm2d,
act_layer=nn.ReLU,
):
super(ConvNormAct, self).__init__()
self.conv = nn.Conv2d(
in_chs, out_chs, kernel_size=kernel_size, stride=stride,
padding=1, groups=groups, bias=False)
self.norm = norm_layer(out_chs)
self.act = act_layer()
def forward(self, x):
x = self.conv(x)
x = self.norm(x)
x = self.act(x)
return x
def _make_divisible(v, divisor, min_value=None):
if min_value is None:
min_value = divisor
new_v = max(min_value, int(v + divisor / 2) // divisor * divisor)
# Make sure that round down does not go down by more than 10%.
if new_v < 0.9 * v:
new_v += divisor
return new_v
class PatchEmbed(nn.Module):
def __init__(self,
in_chs,
out_chs,
stride=1,
norm_layer = nn.BatchNorm2d,
):
super(PatchEmbed, self).__init__()
if stride == 2:
self.pool = nn.AvgPool2d((2, 2), stride=2, ceil_mode=True, count_include_pad=False)
self.conv = nn.Conv2d(in_chs, out_chs, kernel_size=1, stride=1, bias=False)
self.norm = norm_layer(out_chs)
elif in_chs != out_chs:
self.pool = nn.Identity()
self.conv = nn.Conv2d(in_chs, out_chs, kernel_size=1, stride=1, bias=False)
self.norm = norm_layer(out_chs)
else:
self.pool = nn.Identity()
self.conv = nn.Identity()
self.norm = nn.Identity()
def forward(self, x):
return self.norm(self.conv(self.pool(x)))
class ConvAttention(nn.Module):
"""
Multi-Head Convolutional Attention
"""
def __init__(self, out_chs, head_dim, norm_layer = nn.BatchNorm2d, act_layer = nn.ReLU):
super(ConvAttention, self).__init__()
self.group_conv3x3 = nn.Conv2d(
out_chs, out_chs,
kernel_size=3, stride=1, padding=1, groups=out_chs // head_dim, bias=False
)
self.norm = norm_layer(out_chs)
self.act = act_layer()
self.projection = nn.Conv2d(out_chs, out_chs, kernel_size=1, bias=False)
def forward(self, x):
out = self.group_conv3x3(x)
out = self.norm(out)
out = self.act(out)
out = self.projection(out)
return out
class NextConvBlock(nn.Module):
"""
Next Convolution Block
"""
def __init__(
self,
in_chs,
out_chs,
stride=1,
drop_path=0.,
drop=0.,
head_dim=32,
mlp_ratio=3.,
norm_layer=nn.BatchNorm2d,
act_layer=nn.ReLU
):
super(NextConvBlock, self).__init__()
self.in_chs = in_chs
self.out_chs = out_chs
assert out_chs % head_dim == 0
self.patch_embed = PatchEmbed(in_chs, out_chs, stride, norm_layer=norm_layer)
self.mhca = ConvAttention(
out_chs,
head_dim,
norm_layer=norm_layer,
act_layer=act_layer,
)
self.attn_drop_path = DropPath(drop_path)
self.norm = norm_layer(out_chs)
self.mlp = ConvMlp(
out_chs,
hidden_features=int(out_chs * mlp_ratio),
drop=drop,
bias=True,
act_layer=act_layer,
)
self.mlp_drop_path = DropPath(drop_path)
self.is_fused = False
@torch.no_grad()
def reparameterize(self):
if not self.is_fused:
merge_pre_bn(self.mlp.fc1, self.norm)
self.norm = nn.Identity()
self.is_fused = True
def forward(self, x):
x = self.patch_embed(x)
x = x + self.attn_drop_path(self.mhca(x))
out = self.norm(x)
x = x + self.mlp_drop_path(self.mlp(out))
return x
class EfficientAttention(nn.Module):
"""
Efficient Multi-Head Self Attention
"""
fused_attn: torch.jit.Final[bool]
def __init__(
self,
dim,
out_dim=None,
head_dim=32,
qkv_bias=True,
attn_drop=0.,
proj_drop=0.,
sr_ratio=1,
norm_layer=nn.BatchNorm1d,
):
super().__init__()
self.dim = dim
self.out_dim = out_dim if out_dim is not None else dim
self.num_heads = self.dim // head_dim
self.head_dim = head_dim
self.scale = head_dim ** -0.5
self.fused_attn = use_fused_attn()
self.q = nn.Linear(dim, self.dim, bias=qkv_bias)
self.k = nn.Linear(dim, self.dim, bias=qkv_bias)
self.v = nn.Linear(dim, self.dim, bias=qkv_bias)
self.proj = nn.Linear(self.dim, self.out_dim)
self.attn_drop = nn.Dropout(attn_drop)
self.proj_drop = nn.Dropout(proj_drop)
self.sr_ratio = sr_ratio
self.N_ratio = sr_ratio ** 2
if sr_ratio > 1:
self.sr = nn.AvgPool1d(kernel_size=self.N_ratio, stride=self.N_ratio)
self.norm = norm_layer(dim)
else:
self.sr = None
self.norm = None
def forward(self, x):
B, N, C = x.shape
q = self.q(x).reshape(B, N, self.num_heads, self.head_dim).permute(0, 2, 1, 3)
if self.sr is not None:
x = self.sr(x.transpose(1, 2))
x = self.norm(x).transpose(1, 2)
k = self.k(x).reshape(B, -1, self.num_heads, self.head_dim).transpose(1, 2)
v = self.v(x).reshape(B, -1, self.num_heads, self.head_dim).transpose(1, 2)
if self.fused_attn:
x = F.scaled_dot_product_attention(
q, k, v,
dropout_p=self.attn_drop.p if self.training else 0.,
)
else:
q = q * self.scale
attn = q @ k.transpose(-1, -2)
attn = attn.softmax(dim=-1)
attn = self.attn_drop(attn)
x = attn @ v
x = x.transpose(1, 2).reshape(B, N, C)
x = self.proj(x)
x = self.proj_drop(x)
return x
class NextTransformerBlock(nn.Module):
"""
Next Transformer Block
"""
def __init__(
self,
in_chs,
out_chs,
drop_path,
stride=1,
sr_ratio=1,
mlp_ratio=2,
head_dim=32,
mix_block_ratio=0.75,
attn_drop=0.,
drop=0.,
norm_layer=nn.BatchNorm2d,
act_layer=nn.ReLU,
):
super(NextTransformerBlock, self).__init__()
self.in_chs = in_chs
self.out_chs = out_chs
self.mix_block_ratio = mix_block_ratio
self.mhsa_out_chs = _make_divisible(int(out_chs * mix_block_ratio), 32)
self.mhca_out_chs = out_chs - self.mhsa_out_chs
self.patch_embed = PatchEmbed(in_chs, self.mhsa_out_chs, stride)
self.norm1 = norm_layer(self.mhsa_out_chs)
self.e_mhsa = EfficientAttention(
self.mhsa_out_chs,
head_dim=head_dim,
sr_ratio=sr_ratio,
attn_drop=attn_drop,
proj_drop=drop,
)
self.mhsa_drop_path = DropPath(drop_path * mix_block_ratio)
self.projection = PatchEmbed(self.mhsa_out_chs, self.mhca_out_chs, stride=1, norm_layer=norm_layer)
self.mhca = ConvAttention(
self.mhca_out_chs,
head_dim=head_dim,
norm_layer=norm_layer,
act_layer=act_layer,
)
self.mhca_drop_path = DropPath(drop_path * (1 - mix_block_ratio))
self.norm2 = norm_layer(out_chs)
self.mlp = ConvMlp(
out_chs,
hidden_features=int(out_chs * mlp_ratio),
act_layer=act_layer,
drop=drop,
)
self.mlp_drop_path = DropPath(drop_path)
self.is_fused = False
@torch.no_grad()
def reparameterize(self):
if not self.is_fused:
merge_pre_bn(self.e_mhsa.q, self.norm1)
if self.e_mhsa.norm is not None:
merge_pre_bn(self.e_mhsa.k, self.norm1, self.e_mhsa.norm)
merge_pre_bn(self.e_mhsa.v, self.norm1, self.e_mhsa.norm)
self.e_mhsa.norm = nn.Identity()
else:
merge_pre_bn(self.e_mhsa.k, self.norm1)
merge_pre_bn(self.e_mhsa.v, self.norm1)
self.norm1 = nn.Identity()
merge_pre_bn(self.mlp.fc1, self.norm2)
self.norm2 = nn.Identity()
self.is_fused = True
def forward(self, x):
x = self.patch_embed(x)
B, C, H, W = x.shape
out = self.norm1(x)
out = out.reshape(B, C, -1).transpose(-1, -2)
out = self.mhsa_drop_path(self.e_mhsa(out))
x = x + out.transpose(-1, -2).reshape(B, C, H, W)
out = self.projection(x)
out = out + self.mhca_drop_path(self.mhca(out))
x = torch.cat([x, out], dim=1)
out = self.norm2(x)
x = x + self.mlp_drop_path(self.mlp(out))
return x
class NextStage(nn.Module):
def __init__(
self,
in_chs,
block_chs,
block_types,
stride=2,
sr_ratio=1,
mix_block_ratio=1.0,
drop=0.,
attn_drop=0.,
drop_path=0.,
head_dim=32,
norm_layer=nn.BatchNorm2d,
act_layer=nn.ReLU,
):
super().__init__()
self.grad_checkpointing = False
blocks = []
for block_idx, block_type in enumerate(block_types):
stride = stride if block_idx == 0 else 1
out_chs = block_chs[block_idx]
block_type = block_types[block_idx]
dpr = drop_path[block_idx] if isinstance(drop_path, (list, tuple)) else drop_path
if block_type is NextConvBlock:
layer = NextConvBlock(
in_chs,
out_chs,
stride=stride,
drop_path=dpr,
drop=drop,
head_dim=head_dim,
norm_layer=norm_layer,
act_layer=act_layer,
)
blocks.append(layer)
elif block_type is NextTransformerBlock:
layer = NextTransformerBlock(
in_chs,
out_chs,
drop_path=dpr,
stride=stride,
sr_ratio=sr_ratio,
head_dim=head_dim,
mix_block_ratio=mix_block_ratio,
attn_drop=attn_drop,
drop=drop,
norm_layer=norm_layer,
act_layer=act_layer,
)
blocks.append(layer)
in_chs = out_chs
self.blocks = nn.Sequential(*blocks)
@torch.jit.ignore
def set_grad_checkpointing(self, enable=True):
self.grad_checkpointing = enable
def forward(self, 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 NextViT(nn.Module):
def __init__(
self,
in_chans,
num_classes=1000,
global_pool='avg',
stem_chs=(64, 32, 64),
depths=(3, 4, 10, 3),
strides=(1, 2, 2, 2),
sr_ratios=(8, 4, 2, 1),
drop_path_rate=0.1,
attn_drop_rate=0.,
drop_rate=0.,
head_dim=32,
mix_block_ratio=0.75,
norm_layer=nn.BatchNorm2d,
act_layer=None,
):
super(NextViT, self).__init__()
self.grad_checkpointing = False
self.num_classes = num_classes
norm_layer = get_norm_layer(norm_layer)
if act_layer is None:
act_layer = partial(nn.ReLU, inplace=True)
else:
act_layer = get_act_layer(act_layer)
self.stage_out_chs = [
[96] * (depths[0]),
[192] * (depths[1] - 1) + [256],
[384, 384, 384, 384, 512] * (depths[2] // 5),
[768] * (depths[3] - 1) + [1024]
]
self.feature_info = [dict(
num_chs=sc[-1],
reduction=2**(i + 2),
module=f'stages.{i}'
) for i, sc in enumerate(self.stage_out_chs)]
# Next Hybrid Strategy
self.stage_block_types = [
[NextConvBlock] * depths[0],
[NextConvBlock] * (depths[1] - 1) + [NextTransformerBlock],
[NextConvBlock, NextConvBlock, NextConvBlock, NextConvBlock, NextTransformerBlock] * (depths[2] // 5),
[NextConvBlock] * (depths[3] - 1) + [NextTransformerBlock]]
self.stem = nn.Sequential(
ConvNormAct(in_chans, stem_chs[0], kernel_size=3, stride=2, norm_layer=norm_layer, act_layer=act_layer),
ConvNormAct(stem_chs[0], stem_chs[1], kernel_size=3, stride=1, norm_layer=norm_layer, act_layer=act_layer),
ConvNormAct(stem_chs[1], stem_chs[2], kernel_size=3, stride=1, norm_layer=norm_layer, act_layer=act_layer),
ConvNormAct(stem_chs[2], stem_chs[2], kernel_size=3, stride=2, norm_layer=norm_layer, act_layer=act_layer),
)
in_chs = out_chs = stem_chs[-1]
stages = []
idx = 0
dpr = [x.tolist() for x in torch.linspace(0, drop_path_rate, sum(depths)).split(depths)]
for stage_idx in range(len(depths)):
stage = NextStage(
in_chs=in_chs,
block_chs=self.stage_out_chs[stage_idx],
block_types=self.stage_block_types[stage_idx],
stride=strides[stage_idx],
sr_ratio=sr_ratios[stage_idx],
mix_block_ratio=mix_block_ratio,
head_dim=head_dim,
drop=drop_rate,
attn_drop=attn_drop_rate,
drop_path=dpr[stage_idx],
norm_layer=norm_layer,
act_layer=act_layer,
)
in_chs = out_chs = self.stage_out_chs[stage_idx][-1]
stages += [stage]
idx += depths[stage_idx]
self.num_features = self.head_hidden_size = out_chs
self.stages = nn.Sequential(*stages)
self.norm = norm_layer(out_chs)
self.head = ClassifierHead(pool_type=global_pool, in_features=out_chs, num_classes=num_classes)
self.stage_out_idx = [sum(depths[:idx + 1]) - 1 for idx in range(len(depths))]
self._initialize_weights()
def _initialize_weights(self):
for n, m in self.named_modules():
if isinstance(m, nn.Linear):
trunc_normal_(m.weight, std=.02)
if hasattr(m, 'bias') and m.bias is not None:
nn.init.constant_(m.bias, 0)
elif isinstance(m, nn.Conv2d):
trunc_normal_(m.weight, std=.02)
if hasattr(m, 'bias') and m.bias is not None:
nn.init.constant_(m.bias, 0)
@torch.jit.ignore
def group_matcher(self, coarse=False):
return dict(
stem=r'^stem', # stem and embed
blocks=r'^stages\.(\d+)' if coarse else [
(r'^stages\.(\d+)\.blocks\.(\d+)', None),
(r'^norm', (99999,)),
]
)
@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) -> nn.Module:
return self.head.fc
def reset_classifier(self, num_classes: int, global_pool: Optional[str] = None):
self.head.reset(num_classes, pool_type=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(x)
return x
def forward_head(self, x, pre_logits: bool = False):
return self.head(x, pre_logits=pre_logits) if pre_logits else self.head(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 original checkpoints -> timm """
if 'head.fc.weight' in state_dict:
return state_dict # non-original
D = model.state_dict()
out_dict = {}
# remap originals based on order
for ka, kb, va, vb in zip(D.keys(), state_dict.keys(), D.values(), state_dict.values()):
out_dict[ka] = vb
return out_dict
def _create_nextvit(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(
NextViT,
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.0.conv', 'classifier': 'head.fc',
**kwargs
}
default_cfgs = generate_default_cfgs({
'nextvit_small.bd_in1k': _cfg(
hf_hub_id='timm/',
),
'nextvit_base.bd_in1k': _cfg(
hf_hub_id='timm/',
),
'nextvit_large.bd_in1k': _cfg(
hf_hub_id='timm/',
),
'nextvit_small.bd_in1k_384': _cfg(
hf_hub_id='timm/',
input_size=(3, 384, 384), pool_size=(12, 12), crop_pct=1.0,
),
'nextvit_base.bd_in1k_384': _cfg(
hf_hub_id='timm/',
input_size=(3, 384, 384), pool_size=(12, 12), crop_pct=1.0,
),
'nextvit_large.bd_in1k_384': _cfg(
hf_hub_id='timm/',
input_size=(3, 384, 384), pool_size=(12, 12), crop_pct=1.0,
),
'nextvit_small.bd_ssld_6m_in1k': _cfg(
hf_hub_id='timm/',
),
'nextvit_base.bd_ssld_6m_in1k': _cfg(
hf_hub_id='timm/',
),
'nextvit_large.bd_ssld_6m_in1k': _cfg(
hf_hub_id='timm/',
),
'nextvit_small.bd_ssld_6m_in1k_384': _cfg(
hf_hub_id='timm/',
input_size=(3, 384, 384), pool_size=(12, 12), crop_pct=1.0,
),
'nextvit_base.bd_ssld_6m_in1k_384': _cfg(
hf_hub_id='timm/',
input_size=(3, 384, 384), pool_size=(12, 12), crop_pct=1.0,
),
'nextvit_large.bd_ssld_6m_in1k_384': _cfg(
hf_hub_id='timm/',
input_size=(3, 384, 384), pool_size=(12, 12), crop_pct=1.0,
),
})
@register_model
def nextvit_small(pretrained=False, **kwargs):
model_args = dict(depths=(3, 4, 10, 3), drop_path_rate=0.1)
model = _create_nextvit(
'nextvit_small', pretrained=pretrained, **dict(model_args, **kwargs))
return model
@register_model
def nextvit_base(pretrained=False, **kwargs):
model_args = dict(depths=(3, 4, 20, 3), drop_path_rate=0.2)
model = _create_nextvit(
'nextvit_base', pretrained=pretrained, **dict(model_args, **kwargs))
return model
@register_model
def nextvit_large(pretrained=False, **kwargs):
model_args = dict(depths=(3, 4, 30, 3), drop_path_rate=0.2)
model = _create_nextvit(
'nextvit_large', pretrained=pretrained, **dict(model_args, **kwargs))
return model