PaddleClas/ppcls/arch/backbone/model_zoo/cswin_transformer.py

652 lines
23 KiB
Python

# copyright (c) 2021 PaddlePaddle Authors. All Rights Reserve.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Code was based on https://github.com/BR-IDL/PaddleViT/blob/develop/image_classification/CSwin/cswin.py
# reference: https://arxiv.org/abs/2107.00652
import copy
import numpy as np
import paddle
import paddle.nn as nn
from .vision_transformer import trunc_normal_, zeros_, ones_, to_2tuple, DropPath, Identity
from ....utils.save_load import load_dygraph_pretrain, load_dygraph_pretrain_from_url
MODEL_URLS = {
"CSWinTransformer_tiny_224":
"https://paddle-imagenet-models-name.bj.bcebos.com/dygraph/CSWinTransformer_tiny_224_pretrained.pdparams",
"CSWinTransformer_small_224":
"https://paddle-imagenet-models-name.bj.bcebos.com/dygraph/CSWinTransformer_small_224_pretrained.pdparams",
"CSWinTransformer_base_224":
"https://paddle-imagenet-models-name.bj.bcebos.com/dygraph/CSWinTransformer_base_224_pretrained.pdparams",
"CSWinTransformer_large_224":
"https://paddle-imagenet-models-name.bj.bcebos.com/dygraph/CSWinTransformer_large_224_pretrained.pdparams",
"CSWinTransformer_base_384":
"https://paddle-imagenet-models-name.bj.bcebos.com/dygraph/CSWinTransformer_base_384_pretrained.pdparams",
"CSWinTransformer_large_384":
"https://paddle-imagenet-models-name.bj.bcebos.com/dygraph/CSWinTransformer_large_384_pretrained.pdparams",
}
__all__ = list(MODEL_URLS.keys())
class PatchEmbedding(nn.Layer):
"""CSwin Patch Embedding
This patch embedding has a 7x7 conv + layernorm, the output tensor
is reshaped to [Batch, H*W, embed_dim]. Note that the patch is applied
by a conv with overlap (using patch_stride).
Args:
patch_stride: int, patch stride size, default: 4
in_channels: int, number of channels of input image, default: 3
embed_dim: int, output feature dimension, default: 96
"""
def __init__(self, patch_stride=4, in_channels=3, embed_dim=96):
super().__init__()
self.patch_embed = nn.Conv2D(
in_channels=in_channels,
out_channels=embed_dim,
kernel_size=7,
stride=patch_stride,
padding=2)
self.norm = nn.LayerNorm(embed_dim)
def forward(self, x):
x = self.patch_embed(
x) # [batch, embed_dim, h, w], h = w = image_size / 4
x = x.flatten(start_axis=2, stop_axis=-1) # [batch, embed_dim, h*w]
x = x.transpose([0, 2, 1]) # [batch, h*w, embed_dim]
x = self.norm(x)
return x
class Mlp(nn.Layer):
""" MLP module
Impl using nn.Linear and activation is GELU, dropout is applied.
Ops: fc -> act -> dropout -> fc -> dropout
Attributes:
fc1: nn.Linear
fc2: nn.Linear
act: GELU
dropout1: dropout after fc1
dropout2: dropout after fc2
"""
def __init__(self, in_features, hidden_features, dropout):
super().__init__()
self.fc1 = nn.Linear(in_features, hidden_features)
self.fc2 = nn.Linear(hidden_features, in_features)
self.act = nn.GELU()
self.dropout = nn.Dropout(dropout)
def forward(self, x):
x = self.fc1(x)
x = self.act(x)
x = self.dropout(x)
x = self.fc2(x)
x = self.dropout(x)
return x
def img2windows(img, h_split, w_split):
"""Convert input tensor into split stripes
Args:
img: tensor, image tensor with shape [B, C, H, W]
h_split: int, splits width in height direction
w_split: int, splits width in width direction
Returns:
out: tensor, splitted image
"""
B, C, H, W = img.shape
out = img.reshape([B, C, H // h_split, h_split, W // w_split, w_split])
out = out.transpose(
[0, 2, 4, 3, 5, 1]) # [B, H//h_split, W//w_split, h_split, w_split, C]
out = out.reshape([-1, h_split * w_split,
C]) # [B, H//h_split, W//w_split, h_split*w_split, C]
return out
def windows2img(img_splits, h_split, w_split, img_h, img_w):
"""Convert splitted stripes back
Args:
img_splits: tensor, image tensor with shape [B, C, H, W]
h_split: int, splits width in height direction
w_split: int, splits width in width direction
img_h: int, original tensor height
img_w: int, original tensor width
Returns:
img: tensor, original tensor
"""
B = paddle.to_tensor(img_splits.shape[0] //
(img_h // h_split * img_w // w_split), "int32")
img = img_splits.reshape([
B, img_h // h_split, img_w // w_split, h_split, w_split,
img_splits.shape[-1]
])
img = img.transpose(
[0, 1, 3, 2, 4,
5]) #[B,img_h//h_split, h_split, img_w//w_split, w_split,C]
img = img.reshape(
[B, img_h, img_w, img_splits.shape[-1]]) # [B, img_h, img_w, C]
return img
class LePEAttention(nn.Layer):
"""Cross Shaped Window self-attention with Locally enhanced positional encoding"""
def __init__(self,
dim,
resolution,
h_split=7,
w_split=7,
num_heads=8,
attention_dropout=0.,
dropout=0.,
qk_scale=None):
super().__init__()
self.dim = dim
self.resolution = resolution
self.num_heads = num_heads
self.dim_head = dim // num_heads
self.scale = qk_scale or self.dim_head**-0.5
self.h_split = h_split
self.w_split = w_split
self.get_v = nn.Conv2D(
in_channels=dim,
out_channels=dim,
kernel_size=3,
stride=1,
padding=1,
groups=dim)
self.softmax = nn.Softmax(axis=-1)
self.attn_dropout = nn.Dropout(attention_dropout)
def im2cswin(self, x):
B, HW, C = x.shape
H = W = int(np.sqrt(HW))
x = x.transpose([0, 2, 1]) # [B, C, H*W]
x = x.reshape([B, C, H, W]) # [B, C, H, W]
x = img2windows(x, self.h_split, self.w_split)
x = x.reshape(
[-1, self.h_split * self.w_split, self.num_heads, self.dim_head])
x = x.transpose([0, 2, 1, 3])
return x
def get_lepe(self, x, func):
"""Locally Enhanced Positional Encoding (LePE)
This module applies a depthwise conv on V and returns the lepe
Args:
x: tensor, the input tensor V
func: nn.Layer, a depth wise conv of kernel 3 stride 1 and padding 1
"""
B, HW, C = x.shape
H = W = int(np.sqrt(HW))
h_split = self.h_split
w_split = self.w_split
x = x.transpose([0, 2, 1]) # [B, C, H*W]
x = x.reshape([B, C, H, W]) # [B, C, H, W]
x = x.reshape([B, C, H // h_split, h_split, W // w_split, w_split])
x = x.transpose(
[0, 2, 4, 1, 3,
5]) # [B, H//h_split, W//w_split, C, h_split, w_split]
x = x.reshape(
[-1, C, h_split,
w_split]) # [B*(H//h_split)*(W//w_split), h_split, w_split]
lepe = func(x) # depth wise conv does not change shape
#lepe = lepe.reshape([-1, self.num_heads, C // self.num_heads, h_split * w_split])
lepe = lepe.reshape(
[-1, self.num_heads, self.dim_head, h_split * w_split])
lepe = lepe.transpose(
[0, 1, 3, 2]) # [B, num_heads, h_spllit*w_split, dim_head]
x = x.reshape([-1, self.num_heads, self.dim_head, h_split * w_split])
x = x.transpose(
[0, 1, 3, 2]) # [B, num_heads, h_split*wsplit, dim_head]
return x, lepe
def forward(self, q, k, v):
B, HW, C = q.shape
H = W = self.resolution
q = self.im2cswin(q)
k = self.im2cswin(k)
v, lepe = self.get_lepe(v, self.get_v)
q = q * self.scale
attn = paddle.matmul(q, k, transpose_y=True)
attn = self.softmax(attn)
attn = self.attn_dropout(attn)
z = paddle.matmul(attn, v)
z = z + lepe
z = z.transpose([0, 2, 1, 3])
z = z.reshape([-1, self.h_split * self.w_split, C])
z = windows2img(z, self.h_split, self.w_split, H, W)
z = z.reshape([B, z.shape[1] * z.shape[2], C])
return z
class CSwinBlock(nn.Layer):
"""CSwin Block
CSwin block contains a LePE attention modual, a linear projection,
a mlp layer, and related norms layers. In the first 3 stages, the
LePE attention moduals used 2 branches, where horizontal and
vertical split stripes are used for self attention and a concat
op is applied to combine the outputs. The last stage does not
have branche in LePE attention.
Args:
dim: int, input feature dimension
input_resolution: int, input feature spatial size.
num_heads: int, num of attention heads in current stage
split_size: int, the split size in current stage
mlp_ratio: float, mlp ratio, mlp_hidden_dim = mlp_ratio * mlp_in_dim, default: 4.
qkv_bias: bool, if set True, qkv projection will have bias, default: True
qk_scale: float, if set, replace the orig qk_scale (dim_head ** -0.5), default: None
dropout: float, dropout rate for linear projection, default: 0
attention_dropout: float, dropout rate for attention, default: 0
droppath: float, drop path rate, default: 0
split_heads: bool, if True, split heads is applied (True for 1,2,3 stages), default: True
"""
def __init__(self,
dim,
input_resolution,
num_heads,
split_size=7,
mlp_ratio=4.,
qkv_bias=False,
qk_scale=None,
attention_dropout=0.,
dropout=0.,
droppath=0.,
split_heads=True):
super().__init__()
self.dim = dim
# NOTE: here assume image_h == imgae_w
self.input_resolution = (input_resolution, input_resolution)
self.num_heads = num_heads
self.dim_head = dim // num_heads
self.mlp_ratio = mlp_ratio
self.split_size = split_size
self.norm1 = nn.LayerNorm(dim)
self.qkv = nn.Linear(
dim, dim * 3, bias_attr=None if qkv_bias else False)
self.attns = nn.LayerList()
self.split_heads = split_heads
num_branches = 2 if split_heads else 1
if split_heads: # first 3 stages
splits = [self.input_resolution[0],
self.split_size] # horizantal splits
else: # last stage
splits = [self.input_resolution[0], self.input_resolution[0]]
for _ in range(num_branches):
attn = LePEAttention(
dim=dim // num_branches,
resolution=input_resolution,
h_split=splits[0],
w_split=splits[1],
num_heads=num_heads // num_branches,
qk_scale=qk_scale,
attention_dropout=attention_dropout,
dropout=dropout)
self.attns.append(copy.deepcopy(attn))
# switch splits from horizantal to vertical
# NOTE: may need to change for different H and W
splits[0], splits[1] = splits[1], splits[0]
self.proj = nn.Linear(dim, dim)
self.drop_path = DropPath(droppath) if droppath > 0. else Identity()
self.norm2 = nn.LayerNorm(dim)
self.mlp = Mlp(in_features=dim,
hidden_features=int(dim * mlp_ratio),
dropout=dropout)
def chunk_qkv(self, x, chunks=1, axis=-1):
x = x.chunk(chunks, axis=axis)
return x
def forward(self, x):
H, W = self.input_resolution
B, HW, C = x.shape
# cswin attention
h = x
x = self.norm1(x)
qkv = self.qkv(x).chunk(3, axis=-1) # qkv is a tuple of [q, k, v]
if self.split_heads:
q, k, v = map(self.chunk_qkv, qkv,
(2, 2, 2)) # map requries list/tuple inputs
else:
q, k, v = map(lambda x: [x], qkv)
if self.split_heads: # first 3 stages
h_attn = self.attns[0](q[0], k[0], v[0])
w_attn = self.attns[1](q[1], k[1], v[1])
attn = paddle.concat([h_attn, w_attn], axis=2)
else: # last stage
attn = self.attns[0](q[0], k[0], v[0])
attn = self.proj(attn)
attn = self.drop_path(attn)
x = h + attn
# mlp + residual
h = x
x = self.norm2(x)
x = self.mlp(x)
x = self.drop_path(x)
x = h + x
return x
class MergeBlock(nn.Layer):
def __init__(self, dim_in, dim_out):
super().__init__()
self.conv = nn.Conv2D(
in_channels=dim_in,
out_channels=dim_out,
kernel_size=3,
stride=2,
padding=1)
self.norm = nn.LayerNorm(dim_out)
def forward(self, x):
B, HW, C = x.shape
H = W = int(np.sqrt(HW))
x = x.transpose([0, 2, 1]) # [B, C, HW]
x = x.reshape([B, C, H, W]) # [B, C, H, W]
x = self.conv(x)
new_shape = [x.shape[0], x.shape[1],
x.shape[2] * x.shape[3]] # [B, C', H*W]
x = x.reshape(new_shape) # [B, C', H*W]
x = x.transpose([0, 2, 1]) # [B, H*W, C']
x = self.norm(x)
return x
class CSwinStage(nn.Layer):
""" CSwin Stage, each stage contains multi blocks
CSwin has 4 stages, the first 3 stages are using head split. The last
stage does not have head split. There is a merge block between each
2 stages.
Args:
dim: int, input feature dimension
depth: int, number of blocks in current stage
num_heads: int, num of attention heads in current stage
split_size: int, the split size in current stage
mlp_ratio: float, mlp ratio, mlp_hidden_dim = mlp_ratio * mlp_in_dim, default: 4.
qkv_bias: bool, if set True, qkv projection will have bias, default: True
qk_scale: float, if set, replace the orig qk_scale (dim_head ** -0.5), default: None
dropout: float, dropout rate for linear projection, default: 0
attention_dropout: float, dropout rate for attention, default: 0
droppath: float, drop path rate, default: 0
last_stage: bool, if current stage is the last stage, default: False
"""
def __init__(self,
dim,
input_resolution,
depth,
num_heads,
split_size,
mlp_ratio=4.,
qkv_bias=True,
qk_scale=None,
dropout=0.,
attention_dropout=0.,
droppath=0.,
last_stage=False):
super().__init__()
self.blocks = nn.LayerList()
for i in range(depth):
block = CSwinBlock(
dim=dim,
input_resolution=input_resolution,
num_heads=num_heads,
split_size=split_size,
mlp_ratio=mlp_ratio,
qkv_bias=qkv_bias,
qk_scale=qk_scale,
attention_dropout=attention_dropout,
dropout=dropout,
droppath=droppath[i]
if isinstance(droppath, list) else droppath,
split_heads=not last_stage)
self.blocks.append(copy.deepcopy(block))
# last stage does not need merge layer
self.merge = MergeBlock(
dim_in=dim, dim_out=dim * 2) if not last_stage else Identity()
def forward(self, x):
for block in self.blocks:
x = block(x)
x = self.merge(x)
return x
class CSwinTransformer(nn.Layer):
"""CSwin Transformer class
Args:
image_size: int, input image size, default: 224
patch_stride: int, stride for patch embedding, default: 4
in_channels: int, num of channels of input image, default: 3
num_classes: int, num of classes, default: 1000
embed_dim: int, embedding dim (patch embed out dim), default: 96
depths: list/tuple(int), number of blocks in each stage, default: [2, 4, 32, 2]
splits: list/tuple(int), the split number in each stage, default: [1, 2, 7, 7]
num_heads: list/tuple(int), num of attention heads in each stage, default: [4, 8, 16, 32]
mlp_ratio: float, mlp ratio, mlp_hidden_dim = mlp_ratio * mlp_in_dim, default: 4.
qkv_bias: bool, if set True, qkv projection will have bias, default: True
qk_scale: float, if set, replace the orig qk_scale (dim_head ** -0.5), default: None
dropout: float, dropout rate for linear projection, default: 0
attention_dropout: float, dropout rate for attention, default: 0
droppath: float, drop path rate, default: 0
"""
def __init__(self,
image_size=224,
patch_stride=4,
in_channels=3,
class_num=1000,
embed_dim=96,
depths=[2, 4, 32, 2],
splits=[1, 2, 7, 7],
num_heads=[4, 8, 16, 32],
mlp_ratio=4.,
qkv_bias=True,
qk_scale=None,
dropout=0.,
attention_dropout=0.,
droppath=0.):
super().__init__()
# token embedding
self.patch_embedding = PatchEmbedding(
patch_stride=patch_stride,
in_channels=in_channels,
embed_dim=embed_dim)
# drop path decay by stage
depth_decay = [
x.item() for x in paddle.linspace(0, droppath, sum(depths))
]
dim = embed_dim
resolution = image_size // 4
self.stages = nn.LayerList()
num_stages = len(depths)
# construct CSwin stages: each stage has multiple blocks
for stage_idx in range(num_stages):
stage = CSwinStage(
dim=dim,
input_resolution=resolution,
depth=depths[stage_idx],
num_heads=num_heads[stage_idx],
split_size=splits[stage_idx],
mlp_ratio=mlp_ratio,
qkv_bias=qkv_bias,
qk_scale=qk_scale,
dropout=dropout,
attention_dropout=attention_dropout,
droppath=depth_decay[sum(depths[:stage_idx]):sum(
depths[:stage_idx + 1])],
last_stage=stage_idx == num_stages - 1)
self.stages.append(stage)
if stage_idx != num_stages - 1:
dim = dim * 2
resolution = resolution // 2
# last norm and classification head layers
self.norm = nn.LayerNorm(dim)
self.head = nn.Linear(dim, class_num)
self.apply(self._init_weights)
def _init_weights(self, m):
if isinstance(m, nn.Linear):
trunc_normal_(m.weight)
if isinstance(m, nn.Linear) and m.bias is not None:
zeros_(m.bias)
elif isinstance(m, nn.LayerNorm):
zeros_(m.bias)
ones_(m.weight)
def forward_features(self, x):
x = self.patch_embedding(x)
for stage in self.stages:
x = stage(x)
x = self.norm(x)
return paddle.mean(x, axis=1)
def forward(self, x):
x = self.forward_features(x)
x = self.head(x)
return x
def _load_pretrained(pretrained, model, model_url, use_ssld=False):
if pretrained is False:
pass
elif pretrained is True:
load_dygraph_pretrain_from_url(model, model_url, use_ssld=use_ssld)
elif isinstance(pretrained, str):
load_dygraph_pretrain(model, pretrained)
else:
raise RuntimeError(
"pretrained type is not available. Please use `string` or `boolean` type."
)
def CSWinTransformer_tiny_224(pretrained=False, use_ssld=False, **kwargs):
model = CSwinTransformer(
image_size=224,
embed_dim=64,
depths=[1, 2, 21, 1],
splits=[1, 2, 7, 7],
num_heads=[2, 4, 8, 16],
droppath=0.2,
**kwargs)
_load_pretrained(
pretrained,
model,
MODEL_URLS["CSWinTransformer_tiny_224"],
use_ssld=use_ssld)
return model
def CSWinTransformer_small_224(pretrained=False, use_ssld=False, **kwargs):
model = CSwinTransformer(
image_size=224,
embed_dim=64,
depths=[2, 4, 32, 2],
splits=[1, 2, 7, 7],
num_heads=[2, 4, 8, 16],
droppath=0.4,
**kwargs)
_load_pretrained(
pretrained,
model,
MODEL_URLS["CSWinTransformer_small_224"],
use_ssld=use_ssld)
return model
def CSWinTransformer_base_224(pretrained=False, use_ssld=False, **kwargs):
model = CSwinTransformer(
image_size=224,
embed_dim=96,
depths=[2, 4, 32, 2],
splits=[1, 2, 7, 7],
num_heads=[4, 8, 16, 32],
droppath=0.5,
**kwargs)
_load_pretrained(
pretrained,
model,
MODEL_URLS["CSWinTransformer_base_224"],
use_ssld=use_ssld)
return model
def CSWinTransformer_base_384(pretrained=False, use_ssld=False, **kwargs):
model = CSwinTransformer(
image_size=384,
embed_dim=96,
depths=[2, 4, 32, 2],
splits=[1, 2, 12, 12],
num_heads=[4, 8, 16, 32],
droppath=0.5,
**kwargs)
_load_pretrained(
pretrained,
model,
MODEL_URLS["CSWinTransformer_base_384"],
use_ssld=use_ssld)
return model
def CSWinTransformer_large_224(pretrained=False, use_ssld=False, **kwargs):
model = CSwinTransformer(
image_size=224,
embed_dim=144,
depths=[2, 4, 32, 2],
splits=[1, 2, 7, 7],
num_heads=[6, 12, 24, 24],
droppath=0.5,
**kwargs)
_load_pretrained(
pretrained,
model,
MODEL_URLS["CSWinTransformer_large_224"],
use_ssld=use_ssld)
return model
def CSWinTransformer_large_384(pretrained=False, use_ssld=False, **kwargs):
model = CSwinTransformer(
image_size=384,
embed_dim=144,
depths=[2, 4, 32, 2],
splits=[1, 2, 12, 12],
num_heads=[6, 12, 24, 24],
droppath=0.5,
**kwargs)
_load_pretrained(
pretrained,
model,
MODEL_URLS["CSWinTransformer_large_384"],
use_ssld=use_ssld)
return model