File size: 5,967 Bytes
3b96cb1
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
# Copyright (c) OpenMMLab. All rights reserved.
import math
from typing import Optional

import torch
import torch.nn as nn
from mmengine.model import BaseModule

from mmpretrain.registry import MODELS
from ..utils import build_norm_layer


def is_pow2n(x):
    return x > 0 and (x & (x - 1) == 0)


class ConvBlock2x(BaseModule):
    """The definition of convolution block."""

    def __init__(self,
                 in_channels: int,
                 out_channels: int,
                 mid_channels: int,
                 norm_cfg: dict,
                 act_cfg: dict,
                 last_act: bool,
                 init_cfg: Optional[dict] = None) -> None:
        super().__init__(init_cfg=init_cfg)

        self.conv1 = nn.Conv2d(in_channels, mid_channels, 3, 1, 1, bias=False)
        self.norm1 = build_norm_layer(norm_cfg, mid_channels)
        self.activate1 = MODELS.build(act_cfg)

        self.conv2 = nn.Conv2d(mid_channels, out_channels, 3, 1, 1, bias=False)
        self.norm2 = build_norm_layer(norm_cfg, out_channels)
        self.activate2 = MODELS.build(act_cfg) if last_act else nn.Identity()

    def forward(self, x: torch.Tensor):
        out = self.conv1(x)
        out = self.norm1(out)
        out = self.activate1(out)

        out = self.conv2(out)
        out = self.norm2(out)
        out = self.activate2(out)
        return out


class DecoderConvModule(BaseModule):
    """The convolution module of decoder with upsampling."""

    def __init__(self,
                 in_channels: int,
                 out_channels: int,
                 mid_channels: int,
                 kernel_size: int = 4,
                 scale_factor: int = 2,
                 num_conv_blocks: int = 1,
                 norm_cfg: dict = dict(type='SyncBN'),
                 act_cfg: dict = dict(type='ReLU6'),
                 last_act: bool = True,
                 init_cfg: Optional[dict] = None):
        super().__init__(init_cfg=init_cfg)

        assert (kernel_size - scale_factor >= 0) and\
               (kernel_size - scale_factor) % 2 == 0,\
               f'kernel_size should be greater than or equal to scale_factor '\
               f'and (kernel_size - scale_factor) should be even numbers, '\
               f'while the kernel size is {kernel_size} and scale_factor is '\
               f'{scale_factor}.'

        padding = (kernel_size - scale_factor) // 2
        self.upsample = nn.ConvTranspose2d(
            in_channels,
            in_channels,
            kernel_size=kernel_size,
            stride=scale_factor,
            padding=padding,
            bias=True)

        conv_blocks_list = [
            ConvBlock2x(
                in_channels=in_channels,
                out_channels=out_channels,
                mid_channels=mid_channels,
                norm_cfg=norm_cfg,
                last_act=last_act,
                act_cfg=act_cfg) for _ in range(num_conv_blocks)
        ]
        self.conv_blocks = nn.Sequential(*conv_blocks_list)

    def forward(self, x):
        x = self.upsample(x)
        return self.conv_blocks(x)


@MODELS.register_module()
class SparKLightDecoder(BaseModule):
    """The decoder for SparK, which upsamples the feature maps.

    Args:
        feature_dim (int): The dimension of feature map.
        upsample_ratio (int): The ratio of upsample, equal to downsample_raito
            of the algorithm.
        mid_channels (int): The middle channel of `DecoderConvModule`. Defaults
            to 0.
        kernel_size (int): The kernel size of `ConvTranspose2d` in
            `DecoderConvModule`. Defaults to 4.
        scale_factor (int): The scale_factor of `ConvTranspose2d` in
            `DecoderConvModule`. Defaults to 2.
        num_conv_blocks (int): The number of convolution blocks in
            `DecoderConvModule`. Defaults to 1.
        norm_cfg (dict): Normalization config. Defaults to dict(type='SyncBN').
        act_cfg (dict): Activation config. Defaults to dict(type='ReLU6').
        last_act (bool): Whether apply the last activation in
            `DecoderConvModule`. Defaults to False.
        init_cfg (dict or list[dict], optional): Initialization config dict.
    """

    def __init__(
        self,
        feature_dim: int,
        upsample_ratio: int,
        mid_channels: int = 0,
        kernel_size: int = 4,
        scale_factor: int = 2,
        num_conv_blocks: int = 1,
        norm_cfg: dict = dict(type='SyncBN'),
        act_cfg: dict = dict(type='ReLU6'),
        last_act: bool = False,
        init_cfg: Optional[dict] = [
            dict(type='Kaiming', layer=['Conv2d', 'ConvTranspose2d']),
            dict(type='TruncNormal', std=0.02, layer=['Linear']),
            dict(
                type='Constant',
                val=1,
                layer=['_BatchNorm', 'LayerNorm', 'SyncBatchNorm'])
        ],
    ):
        super().__init__(init_cfg=init_cfg)
        self.feature_dim = feature_dim

        assert is_pow2n(upsample_ratio)
        n = round(math.log2(upsample_ratio))
        channels = [feature_dim // 2**i for i in range(n + 1)]

        self.decoder = nn.ModuleList([
            DecoderConvModule(
                in_channels=c_in,
                out_channels=c_out,
                mid_channels=c_in if mid_channels == 0 else mid_channels,
                kernel_size=kernel_size,
                scale_factor=scale_factor,
                num_conv_blocks=num_conv_blocks,
                norm_cfg=norm_cfg,
                act_cfg=act_cfg,
                last_act=last_act)
            for (c_in, c_out) in zip(channels[:-1], channels[1:])
        ])
        self.proj = nn.Conv2d(
            channels[-1], 3, kernel_size=1, stride=1, bias=True)

    def forward(self, to_dec):
        x = 0
        for i, d in enumerate(self.decoder):
            if i < len(to_dec) and to_dec[i] is not None:
                x = x + to_dec[i]
            x = self.decoder[i](x)
        return self.proj(x)