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# copyright (c) 2024 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.
"""
This code is refer from:
https://github.com/THU-MIG/RepViT
"""
import paddle.nn as nn
import paddle
from paddle.nn.initializer import TruncatedNormal, Constant, Normal
trunc_normal_ = TruncatedNormal(std=0.02)
normal_ = Normal
zeros_ = Constant(value=0.0)
ones_ = Constant(value=1.0)
def _make_divisible(v, divisor, min_value=None):
"""
This function is taken from the original tf repo.
It ensures that all layers have a channel number that is divisible by 8
It can be seen here:
https://github.com/tensorflow/models/blob/master/research/slim/nets/mobilenet/mobilenet.py
:param v:
:param divisor:
:param min_value:
:return:
"""
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
# from timm.models.layers import SqueezeExcite
def make_divisible(v, divisor=8, min_value=None, round_limit=0.9):
min_value = min_value or 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 < round_limit * v:
new_v += divisor
return new_v
class SEModule(nn.Layer):
"""SE Module as defined in original SE-Nets with a few additions
Additions include:
* divisor can be specified to keep channels % div == 0 (default: 8)
* reduction channels can be specified directly by arg (if rd_channels is set)
* reduction channels can be specified by float rd_ratio (default: 1/16)
* global max pooling can be added to the squeeze aggregation
* customizable activation, normalization, and gate layer
"""
def __init__(
self,
channels,
rd_ratio=1.0 / 16,
rd_channels=None,
rd_divisor=8,
act_layer=nn.ReLU,
):
super(SEModule, self).__init__()
if not rd_channels:
rd_channels = make_divisible(
channels * rd_ratio, rd_divisor, round_limit=0.0
)
self.fc1 = nn.Conv2D(channels, rd_channels, kernel_size=1, bias_attr=True)
self.act = act_layer()
self.fc2 = nn.Conv2D(rd_channels, channels, kernel_size=1, bias_attr=True)
def forward(self, x):
x_se = x.mean((2, 3), keepdim=True)
x_se = self.fc1(x_se)
x_se = self.act(x_se)
x_se = self.fc2(x_se)
return x * nn.functional.sigmoid(x_se)
class Conv2D_BN(nn.Sequential):
def __init__(
self,
a,
b,
ks=1,
stride=1,
pad=0,
dilation=1,
groups=1,
bn_weight_init=1,
resolution=-10000,
):
super().__init__()
self.add_sublayer(
"c", nn.Conv2D(a, b, ks, stride, pad, dilation, groups, bias_attr=False)
)
self.add_sublayer("bn", nn.BatchNorm2D(b))
if bn_weight_init == 1:
ones_(self.bn.weight)
else:
zeros_(self.bn.weight)
zeros_(self.bn.bias)
@paddle.no_grad()
def fuse(self):
c, bn = self.c, self.bn
w = bn.weight / (bn._variance + bn._epsilon) ** 0.5
w = c.weight * w[:, None, None, None]
b = bn.bias - bn._mean * bn.weight / (bn._variance + bn._epsilon) ** 0.5
m = nn.Conv2D(
w.shape[1] * self.c._groups,
w.shape[0],
w.shape[2:],
stride=self.c._stride,
padding=self.c._padding,
dilation=self.c._dilation,
groups=self.c._groups,
)
m.weight.set_value(w)
m.bias.set_value(b)
return m
class Residual(nn.Layer):
def __init__(self, m, drop=0.0):
super().__init__()
self.m = m
self.drop = drop
def forward(self, x):
if self.training and self.drop > 0:
return (
x
+ self.m(x)
* paddle.rand(x.size(0), 1, 1, 1)
.ge_(self.drop)
.div(1 - self.drop)
.detach()
)
else:
return x + self.m(x)
@paddle.no_grad()
def fuse(self):
if isinstance(self.m, Conv2D_BN):
m = self.m.fuse()
assert m._groups == m.in_channels
identity = paddle.ones([m.weight.shape[0], m.weight.shape[1], 1, 1])
identity = nn.functional.pad(identity, [1, 1, 1, 1])
m.weight += identity
return m
elif isinstance(self.m, nn.Conv2D):
m = self.m
assert m._groups != m.in_channels
identity = paddle.ones([m.weight.shape[0], m.weight.shape[1], 1, 1])
identity = nn.functional.pad(identity, [1, 1, 1, 1])
m.weight += identity
return m
else:
return self
class RepVGGDW(nn.Layer):
def __init__(self, ed) -> None:
super().__init__()
self.conv = Conv2D_BN(ed, ed, 3, 1, 1, groups=ed)
self.conv1 = nn.Conv2D(ed, ed, 1, 1, 0, groups=ed)
self.dim = ed
self.bn = nn.BatchNorm2D(ed)
def forward(self, x):
return self.bn((self.conv(x) + self.conv1(x)) + x)
@paddle.no_grad()
def fuse(self):
conv = self.conv.fuse()
conv1 = self.conv1
conv_w = conv.weight
conv_b = conv.bias
conv1_w = conv1.weight
conv1_b = conv1.bias
conv1_w = nn.functional.pad(conv1_w, [1, 1, 1, 1])
identity = nn.functional.pad(
paddle.ones([conv1_w.shape[0], conv1_w.shape[1], 1, 1]), [1, 1, 1, 1]
)
final_conv_w = conv_w + conv1_w + identity
final_conv_b = conv_b + conv1_b
conv.weight.set_value(final_conv_w)
conv.bias.set_value(final_conv_b)
bn = self.bn
w = bn.weight / (bn._variance + bn._epsilon) ** 0.5
w = conv.weight * w[:, None, None, None]
b = (
bn.bias
+ (conv.bias - bn._mean) * bn.weight / (bn._variance + bn._epsilon) ** 0.5
)
conv.weight.set_value(w)
conv.bias.set_value(b)
return conv
class RepViTBlock(nn.Layer):
def __init__(self, inp, hidden_dim, oup, kernel_size, stride, use_se, use_hs):
super(RepViTBlock, self).__init__()
self.identity = stride == 1 and inp == oup
assert hidden_dim == 2 * inp
if stride != 1:
self.token_mixer = nn.Sequential(
Conv2D_BN(
inp, inp, kernel_size, stride, (kernel_size - 1) // 2, groups=inp
),
SEModule(inp, 0.25) if use_se else nn.Identity(),
Conv2D_BN(inp, oup, ks=1, stride=1, pad=0),
)
self.channel_mixer = Residual(
nn.Sequential(
# pw
Conv2D_BN(oup, 2 * oup, 1, 1, 0),
nn.GELU() if use_hs else nn.GELU(),
# pw-linear
Conv2D_BN(2 * oup, oup, 1, 1, 0, bn_weight_init=0),
)
)
else:
assert self.identity
self.token_mixer = nn.Sequential(
RepVGGDW(inp),
SEModule(inp, 0.25) if use_se else nn.Identity(),
)
self.channel_mixer = Residual(
nn.Sequential(
# pw
Conv2D_BN(inp, hidden_dim, 1, 1, 0),
nn.GELU() if use_hs else nn.GELU(),
# pw-linear
Conv2D_BN(hidden_dim, oup, 1, 1, 0, bn_weight_init=0),
)
)
def forward(self, x):
return self.channel_mixer(self.token_mixer(x))
class RepViT(nn.Layer):
def __init__(self, cfgs, in_channels=3, out_indices=None):
super(RepViT, self).__init__()
# setting of inverted residual blocks
self.cfgs = cfgs
# building first layer
input_channel = self.cfgs[0][2]
patch_embed = nn.Sequential(
Conv2D_BN(in_channels, input_channel // 2, 3, 2, 1),
nn.GELU(),
Conv2D_BN(input_channel // 2, input_channel, 3, 2, 1),
)
layers = [patch_embed]
# building inverted residual blocks
block = RepViTBlock
for k, t, c, use_se, use_hs, s in self.cfgs:
output_channel = _make_divisible(c, 8)
exp_size = _make_divisible(input_channel * t, 8)
layers.append(
block(input_channel, exp_size, output_channel, k, s, use_se, use_hs)
)
input_channel = output_channel
self.features = nn.LayerList(layers)
self.out_indices = out_indices
if out_indices is not None:
self.out_channels = [self.cfgs[ids - 1][2] for ids in out_indices]
else:
self.out_channels = self.cfgs[-1][2]
def forward(self, x):
if self.out_indices is not None:
return self.forward_det(x)
return self.forward_rec(x)
def forward_det(self, x):
outs = []
for i, f in enumerate(self.features):
x = f(x)
if i in self.out_indices:
outs.append(x)
return outs
def forward_rec(self, x):
for f in self.features:
x = f(x)
h = x.shape[2]
x = nn.functional.avg_pool2d(x, [h, 2])
return x
def RepSVTR(in_channels=3):
"""
Constructs a MobileNetV3-Large model
"""
# k, t, c, SE, HS, s
cfgs = [
[3, 2, 96, 1, 0, 1],
[3, 2, 96, 0, 0, 1],
[3, 2, 96, 0, 0, 1],
[3, 2, 192, 0, 1, (2, 1)],
[3, 2, 192, 1, 1, 1],
[3, 2, 192, 0, 1, 1],
[3, 2, 192, 1, 1, 1],
[3, 2, 192, 0, 1, 1],
[3, 2, 192, 1, 1, 1],
[3, 2, 192, 0, 1, 1],
[3, 2, 384, 0, 1, (2, 1)],
[3, 2, 384, 1, 1, 1],
[3, 2, 384, 0, 1, 1],
]
return RepViT(cfgs, in_channels=in_channels)
def RepSVTR_det(in_channels=3, out_indices=[2, 5, 10, 13]):
"""
Constructs a MobileNetV3-Large model
"""
# k, t, c, SE, HS, s
cfgs = [
[3, 2, 48, 1, 0, 1],
[3, 2, 48, 0, 0, 1],
[3, 2, 96, 0, 0, 2],
[3, 2, 96, 1, 0, 1],
[3, 2, 96, 0, 0, 1],
[3, 2, 192, 0, 1, 2],
[3, 2, 192, 1, 1, 1],
[3, 2, 192, 0, 1, 1],
[3, 2, 192, 1, 1, 1],
[3, 2, 192, 0, 1, 1],
[3, 2, 384, 0, 1, 2],
[3, 2, 384, 1, 1, 1],
[3, 2, 384, 0, 1, 1],
]
return RepViT(cfgs, in_channels=in_channels, out_indices=out_indices)