File size: 21,570 Bytes
853e22b
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
# Copyright (c) MONAI Consortium
# 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.

from __future__ import annotations

import math
from collections.abc import Sequence
from typing import Union

import torch
import torch.nn as nn
import torch.nn.functional as F

from monai.networks.blocks.fcn import FCN
from monai.networks.layers.factories import Act, Conv, Norm, Pool

__all__ = ["AHnet", "Ahnet", "AHNet"]


class Bottleneck3x3x1(nn.Module):
    expansion = 4

    def __init__(
        self,
        spatial_dims: int,
        inplanes: int,
        planes: int,
        stride: Sequence[int] | int = 1,
        downsample: nn.Sequential | None = None,
    ) -> None:
        super().__init__()

        conv_type = Conv[Conv.CONV, spatial_dims]
        norm_type: type[nn.BatchNorm2d | nn.BatchNorm3d] = Norm[Norm.BATCH, spatial_dims]
        pool_type: type[nn.MaxPool2d | nn.MaxPool3d] = Pool[Pool.MAX, spatial_dims]
        relu_type: type[nn.ReLU] = Act[Act.RELU]

        self.conv1 = conv_type(inplanes, planes, kernel_size=1, bias=False)
        self.bn1 = norm_type(planes)
        self.conv2 = conv_type(
            planes,
            planes,
            kernel_size=(3, 3, 1)[-spatial_dims:],
            stride=stride,
            padding=(1, 1, 0)[-spatial_dims:],
            bias=False,
        )
        self.bn2 = norm_type(planes)
        self.conv3 = conv_type(planes, planes * 4, kernel_size=1, bias=False)
        self.bn3 = norm_type(planes * 4)
        self.relu = relu_type(inplace=True)
        self.downsample = downsample
        self.stride = stride
        self.pool = pool_type(kernel_size=(1, 1, 2)[-spatial_dims:], stride=(1, 1, 2)[-spatial_dims:])

    def forward(self, x):
        residual = x

        out = self.conv1(x)
        out = self.bn1(out)
        out = self.relu(out)

        out = self.conv2(out)
        out = self.bn2(out)
        out = self.relu(out)

        out = self.conv3(out)
        out = self.bn3(out)

        if self.downsample is not None:
            residual = self.downsample(x)
            if out.size() != residual.size():
                out = self.pool(out)

        out += residual
        out = self.relu(out)

        return out


class Projection(nn.Sequential):

    def __init__(self, spatial_dims: int, num_input_features: int, num_output_features: int):
        super().__init__()

        conv_type = Conv[Conv.CONV, spatial_dims]
        norm_type: type[nn.BatchNorm2d | nn.BatchNorm3d] = Norm[Norm.BATCH, spatial_dims]
        relu_type: type[nn.ReLU] = Act[Act.RELU]

        self.add_module("norm", norm_type(num_input_features))
        self.add_module("relu", relu_type(inplace=True))
        self.add_module("conv", conv_type(num_input_features, num_output_features, kernel_size=1, stride=1, bias=False))


class DenseBlock(nn.Sequential):

    def __init__(
        self,
        spatial_dims: int,
        num_layers: int,
        num_input_features: int,
        bn_size: int,
        growth_rate: int,
        dropout_prob: float,
    ):
        super().__init__()
        for i in range(num_layers):
            layer = Pseudo3DLayer(
                spatial_dims, num_input_features + i * growth_rate, growth_rate, bn_size, dropout_prob
            )
            self.add_module("denselayer%d" % (i + 1), layer)


class UpTransition(nn.Sequential):

    def __init__(
        self, spatial_dims: int, num_input_features: int, num_output_features: int, upsample_mode: str = "transpose"
    ):
        super().__init__()

        conv_type = Conv[Conv.CONV, spatial_dims]
        norm_type: type[nn.BatchNorm2d | nn.BatchNorm3d] = Norm[Norm.BATCH, spatial_dims]
        relu_type: type[nn.ReLU] = Act[Act.RELU]

        self.add_module("norm", norm_type(num_input_features))
        self.add_module("relu", relu_type(inplace=True))
        self.add_module("conv", conv_type(num_input_features, num_output_features, kernel_size=1, stride=1, bias=False))
        if upsample_mode == "transpose":
            conv_trans_type = Conv[Conv.CONVTRANS, spatial_dims]
            self.add_module(
                "up", conv_trans_type(num_output_features, num_output_features, kernel_size=2, stride=2, bias=False)
            )
        else:
            align_corners: bool | None = None
            if upsample_mode in ["trilinear", "bilinear"]:
                align_corners = True
            self.add_module("up", nn.Upsample(scale_factor=2, mode=upsample_mode, align_corners=align_corners))


class Final(nn.Sequential):

    def __init__(
        self, spatial_dims: int, num_input_features: int, num_output_features: int, upsample_mode: str = "transpose"
    ):
        super().__init__()

        conv_type = Conv[Conv.CONV, spatial_dims]
        norm_type: type[nn.BatchNorm2d | nn.BatchNorm3d] = Norm[Norm.BATCH, spatial_dims]
        relu_type: type[nn.ReLU] = Act[Act.RELU]

        self.add_module("norm", norm_type(num_input_features))
        self.add_module("relu", relu_type(inplace=True))
        self.add_module(
            "conv",
            conv_type(
                num_input_features,
                num_output_features,
                kernel_size=(3, 3, 1)[-spatial_dims:],
                stride=1,
                padding=(1, 1, 0)[-spatial_dims:],
                bias=False,
            ),
        )
        if upsample_mode == "transpose":
            conv_trans_type = Conv[Conv.CONVTRANS, spatial_dims]
            self.add_module(
                "up", conv_trans_type(num_output_features, num_output_features, kernel_size=2, stride=2, bias=False)
            )
        else:
            align_corners: bool | None = None
            if upsample_mode in ["trilinear", "bilinear"]:
                align_corners = True
            self.add_module("up", nn.Upsample(scale_factor=2, mode=upsample_mode, align_corners=align_corners))


class Pseudo3DLayer(nn.Module):

    def __init__(self, spatial_dims: int, num_input_features: int, growth_rate: int, bn_size: int, dropout_prob: float):
        super().__init__()
        # 1x1x1

        conv_type = Conv[Conv.CONV, spatial_dims]
        norm_type: type[nn.BatchNorm2d | nn.BatchNorm3d] = Norm[Norm.BATCH, spatial_dims]
        relu_type: type[nn.ReLU] = Act[Act.RELU]

        self.bn1 = norm_type(num_input_features)
        self.relu1 = relu_type(inplace=True)
        self.conv1 = conv_type(num_input_features, bn_size * growth_rate, kernel_size=1, stride=1, bias=False)
        # 3x3x1
        self.bn2 = norm_type(bn_size * growth_rate)
        self.relu2 = relu_type(inplace=True)
        self.conv2 = conv_type(
            bn_size * growth_rate,
            growth_rate,
            kernel_size=(3, 3, 1)[-spatial_dims:],
            stride=1,
            padding=(1, 1, 0)[-spatial_dims:],
            bias=False,
        )
        # 1x1x3
        self.bn3 = norm_type(growth_rate)
        self.relu3 = relu_type(inplace=True)
        self.conv3 = conv_type(
            growth_rate,
            growth_rate,
            kernel_size=(1, 1, 3)[-spatial_dims:],
            stride=1,
            padding=(0, 0, 1)[-spatial_dims:],
            bias=False,
        )
        # 1x1x1
        self.bn4 = norm_type(growth_rate)
        self.relu4 = relu_type(inplace=True)
        self.conv4 = conv_type(growth_rate, growth_rate, kernel_size=1, stride=1, bias=False)
        self.dropout_prob = dropout_prob

    def forward(self, x):
        inx = x
        x = self.bn1(x)
        x = self.relu1(x)
        x = self.conv1(x)

        x = self.bn2(x)
        x = self.relu2(x)
        x3x3x1 = self.conv2(x)

        x = self.bn3(x3x3x1)
        x = self.relu3(x)
        x1x1x3 = self.conv3(x)

        x = x3x3x1 + x1x1x3
        x = self.bn4(x)
        x = self.relu4(x)
        new_features = self.conv4(x)

        self.dropout_prob = 0.0  # Dropout will make trouble!
        # since we use the train mode for inference
        if self.dropout_prob > 0.0:
            new_features = F.dropout(new_features, p=self.dropout_prob, training=self.training)
        return torch.cat([inx, new_features], 1)


class PSP(nn.Module):

    def __init__(self, spatial_dims: int, psp_block_num: int, in_ch: int, upsample_mode: str = "transpose"):
        super().__init__()
        self.up_modules = nn.ModuleList()
        conv_type = Conv[Conv.CONV, spatial_dims]
        pool_type: type[nn.MaxPool2d | nn.MaxPool3d] = Pool[Pool.MAX, spatial_dims]

        self.pool_modules = nn.ModuleList()
        self.project_modules = nn.ModuleList()

        for i in range(psp_block_num):
            size = (2 ** (i + 3), 2 ** (i + 3), 1)[-spatial_dims:]
            self.pool_modules.append(pool_type(kernel_size=size, stride=size))
            self.project_modules.append(
                conv_type(in_ch, 1, kernel_size=(1, 1, 1)[-spatial_dims:], stride=1, padding=(1, 1, 0)[-spatial_dims:])
            )

        self.spatial_dims = spatial_dims
        self.psp_block_num = psp_block_num
        self.upsample_mode = upsample_mode

        if self.upsample_mode == "transpose":
            conv_trans_type = Conv[Conv.CONVTRANS, spatial_dims]
            for i in range(psp_block_num):
                size = (2 ** (i + 3), 2 ** (i + 3), 1)[-spatial_dims:]
                pad_size = (2 ** (i + 3), 2 ** (i + 3), 0)[-spatial_dims:]
                self.up_modules.append(conv_trans_type(1, 1, kernel_size=size, stride=size, padding=pad_size))

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        outputs = []
        if self.upsample_mode == "transpose":
            for project_module, pool_module, up_module in zip(self.project_modules, self.pool_modules, self.up_modules):
                output = up_module(project_module(pool_module(x)))
                outputs.append(output)
        else:
            for project_module, pool_module in zip(self.project_modules, self.pool_modules):
                interpolate_size = x.shape[2:]
                align_corners: Union[bool, None] = None
                if self.upsample_mode in ["trilinear", "bilinear"]:
                    align_corners = True
                output = F.interpolate(
                    project_module(pool_module(x)),
                    size=interpolate_size,
                    mode=self.upsample_mode,
                    align_corners=align_corners,
                )
                outputs.append(output)
        x = torch.cat(outputs, dim=1)
        return x


class AHNet(nn.Module):
    """
    AHNet based on `Anisotropic Hybrid Network <https://arxiv.org/pdf/1711.08580.pdf>`_.
    Adapted from `lsqshr's official code <https://github.com/lsqshr/AH-Net/blob/master/net3d.py>`_.
    Except from the original network that supports 3D inputs, this implementation also supports 2D inputs.
    According to the `tests for deconvolutions <https://github.com/Project-MONAI/MONAI/issues/1023>`_, using
    ``"transpose"`` rather than linear interpolations is faster. Therefore, this implementation sets ``"transpose"``
    as the default upsampling method.

    To meet the requirements of the structure, the input size for each spatial dimension
    (except the last one) should be: divisible by 2 ** (psp_block_num + 3) and no less than 32 in ``transpose`` mode,
    and should be divisible by 32 and no less than 2 ** (psp_block_num + 3) in other upsample modes.
    In addition, the input size for the last spatial dimension should be divisible by 32, and at least one spatial size
    should be no less than 64.

    Args:
        layers: number of residual blocks for 4 layers of the network (layer1...layer4). Defaults to ``(3, 4, 6, 3)``.
        spatial_dims: spatial dimension of the input data. Defaults to 3.
        in_channels: number of input channels for the network. Default to 1.
        out_channels: number of output channels for the network. Defaults to 1.
        psp_block_num: the number of pyramid volumetric pooling modules used at the end of the network before the final
            output layer for extracting multiscale features. The number should be an integer that belongs to [0,4]. Defaults
            to 4.
        upsample_mode: [``"transpose"``, ``"bilinear"``, ``"trilinear"``, ``nearest``]
            The mode of upsampling manipulations.
            Using the last two modes cannot guarantee the model's reproducibility. Defaults to ``transpose``.

            - ``"transpose"``, uses transposed convolution layers.
            - ``"bilinear"``, uses bilinear interpolate.
            - ``"trilinear"``, uses trilinear interpolate.
            - ``"nearest"``, uses nearest interpolate.
        pretrained: whether to load pretrained weights from ResNet50 to initialize convolution layers, default to False.
        progress: If True, displays a progress bar of the download of pretrained weights to stderr.
    """

    def __init__(
        self,
        layers: tuple = (3, 4, 6, 3),
        spatial_dims: int = 3,
        in_channels: int = 1,
        out_channels: int = 1,
        psp_block_num: int = 4,
        upsample_mode: str = "transpose",
        pretrained: bool = False,
        progress: bool = True,
    ):
        self.inplanes = 64
        super().__init__()

        conv_type = Conv[Conv.CONV, spatial_dims]
        conv_trans_type = Conv[Conv.CONVTRANS, spatial_dims]
        norm_type = Norm[Norm.BATCH, spatial_dims]
        pool_type: type[nn.MaxPool2d | nn.MaxPool3d] = Pool[Pool.MAX, spatial_dims]
        relu_type: type[nn.ReLU] = Act[Act.RELU]
        conv2d_type: type[nn.Conv2d] = Conv[Conv.CONV, 2]
        norm2d_type: type[nn.BatchNorm2d] = Norm[Norm.BATCH, 2]

        self.conv2d_type = conv2d_type
        self.norm2d_type = norm2d_type
        self.conv_type = conv_type
        self.norm_type = norm_type
        self.relu_type = relu_type
        self.pool_type = pool_type
        self.spatial_dims = spatial_dims
        self.psp_block_num = psp_block_num
        self.psp: PSP

        if spatial_dims not in [2, 3]:
            raise AssertionError("spatial_dims can only be 2 or 3.")
        if psp_block_num not in [0, 1, 2, 3, 4]:
            raise AssertionError("psp_block_num should be an integer that belongs to [0, 4].")

        self.conv1 = conv_type(
            in_channels,
            64,
            kernel_size=(7, 7, 3)[-spatial_dims:],
            stride=(2, 2, 1)[-spatial_dims:],
            padding=(3, 3, 1)[-spatial_dims:],
            bias=False,
        )
        self.pool1 = pool_type(kernel_size=(1, 1, 2)[-spatial_dims:], stride=(1, 1, 2)[-spatial_dims:])
        self.bn0 = norm_type(64)
        self.relu = relu_type(inplace=True)
        if upsample_mode in ["transpose", "nearest"]:
            # To maintain the determinism, the value of kernel_size and stride should be the same.
            # (you can check this link for reference: https://github.com/Project-MONAI/MONAI/pull/815 )
            self.maxpool = pool_type(kernel_size=(2, 2, 2)[-spatial_dims:], stride=2)
        else:
            self.maxpool = pool_type(kernel_size=(3, 3, 3)[-spatial_dims:], stride=2, padding=1)

        self.layer1 = self._make_layer(Bottleneck3x3x1, 64, layers[0], stride=1)
        self.layer2 = self._make_layer(Bottleneck3x3x1, 128, layers[1], stride=2)
        self.layer3 = self._make_layer(Bottleneck3x3x1, 256, layers[2], stride=2)
        self.layer4 = self._make_layer(Bottleneck3x3x1, 512, layers[3], stride=2)

        # Make the 3D dense decoder layers
        densegrowth = 20
        densebn = 4
        ndenselayer = 3

        num_init_features = 64
        noutres1 = 256
        noutres2 = 512
        noutres3 = 1024
        noutres4 = 2048

        self.up0 = UpTransition(spatial_dims, noutres4, noutres3, upsample_mode)
        self.dense0 = DenseBlock(spatial_dims, ndenselayer, noutres3, densebn, densegrowth, 0.0)
        noutdense = noutres3 + ndenselayer * densegrowth

        self.up1 = UpTransition(spatial_dims, noutdense, noutres2, upsample_mode)
        self.dense1 = DenseBlock(spatial_dims, ndenselayer, noutres2, densebn, densegrowth, 0.0)
        noutdense1 = noutres2 + ndenselayer * densegrowth

        self.up2 = UpTransition(spatial_dims, noutdense1, noutres1, upsample_mode)
        self.dense2 = DenseBlock(spatial_dims, ndenselayer, noutres1, densebn, densegrowth, 0.0)
        noutdense2 = noutres1 + ndenselayer * densegrowth

        self.trans1 = Projection(spatial_dims, noutdense2, num_init_features)
        self.dense3 = DenseBlock(spatial_dims, ndenselayer, num_init_features, densebn, densegrowth, 0.0)
        noutdense3 = num_init_features + densegrowth * ndenselayer

        self.up3 = UpTransition(spatial_dims, noutdense3, num_init_features, upsample_mode)
        self.dense4 = DenseBlock(spatial_dims, ndenselayer, num_init_features, densebn, densegrowth, 0.0)
        noutdense4 = num_init_features + densegrowth * ndenselayer

        self.psp = PSP(spatial_dims, psp_block_num, noutdense4, upsample_mode)
        self.final = Final(spatial_dims, psp_block_num + noutdense4, out_channels, upsample_mode)

        # Initialise parameters
        for m in self.modules():
            if isinstance(m, (conv_type, conv_trans_type)):
                n = m.kernel_size[0] * m.kernel_size[1] * m.out_channels
                m.weight.data.normal_(0, math.sqrt(2.0 / n))
            elif isinstance(m, norm_type):
                m.weight.data.fill_(1)
                m.bias.data.zero_()

        if pretrained:
            net2d = FCN(pretrained=True, progress=progress)
            self.copy_from(net2d)

    def _make_layer(self, block: type[Bottleneck3x3x1], planes: int, blocks: int, stride: int = 1) -> nn.Sequential:
        downsample = None
        if stride != 1 or self.inplanes != planes * block.expansion:
            downsample = nn.Sequential(
                self.conv_type(
                    self.inplanes,
                    planes * block.expansion,
                    kernel_size=1,
                    stride=(stride, stride, 1)[: self.spatial_dims],
                    bias=False,
                ),
                self.pool_type(
                    kernel_size=(1, 1, stride)[: self.spatial_dims], stride=(1, 1, stride)[: self.spatial_dims]
                ),
                self.norm_type(planes * block.expansion),
            )

        layers = []
        layers.append(
            block(self.spatial_dims, self.inplanes, planes, (stride, stride, 1)[: self.spatial_dims], downsample)
        )
        self.inplanes = planes * block.expansion
        for _ in range(1, blocks):
            layers.append(block(self.spatial_dims, self.inplanes, planes))
        return nn.Sequential(*layers)

    def forward(self, x):
        x = self.conv1(x)
        x = self.pool1(x)
        x = self.bn0(x)
        x = self.relu(x)
        conv_x = x
        x = self.maxpool(x)
        pool_x = x

        fm1 = self.layer1(x)
        fm2 = self.layer2(fm1)
        fm3 = self.layer3(fm2)
        fm4 = self.layer4(fm3)

        sum0 = self.up0(fm4) + fm3
        d0 = self.dense0(sum0)

        sum1 = self.up1(d0) + fm2
        d1 = self.dense1(sum1)

        sum2 = self.up2(d1) + fm1
        d2 = self.dense2(sum2)

        sum3 = self.trans1(d2) + pool_x
        d3 = self.dense3(sum3)

        sum4 = self.up3(d3) + conv_x
        d4 = self.dense4(sum4)
        if self.psp_block_num > 0:
            psp = self.psp(d4)
            x = torch.cat((psp, d4), dim=1)
        else:
            x = d4
        return self.final(x)

    def copy_from(self, net):
        # This method only supports for 3D AHNet, the input channel should be 1.
        p2d, p3d = next(net.conv1.parameters()), next(self.conv1.parameters())

        # From 64x3x7x7 -> 64x3x7x7x1 -> 64x1x7x7x3
        weights = p2d.data.unsqueeze(dim=4).permute(0, 4, 2, 3, 1).clone()
        p3d.data = weights.repeat([1, p3d.shape[1], 1, 1, 1])

        # Copy the initial module BN0
        copy_bn_param(net.bn0, self.bn0)

        # Copy layer1 to layer4
        for i in range(1, 5):
            layer_num = "layer" + str(i)

            layer_2d = []
            layer_3d = []
            for m1 in vars(net)["_modules"][layer_num].modules():
                if isinstance(m1, (self.norm2d_type, self.conv2d_type)):
                    layer_2d.append(m1)
            for m2 in vars(self)["_modules"][layer_num].modules():
                if isinstance(m2, (self.norm_type, self.conv_type)):
                    layer_3d.append(m2)

            for m1, m2 in zip(layer_2d, layer_3d):
                if isinstance(m1, self.conv2d_type):
                    copy_conv_param(m1, m2)
                if isinstance(m1, self.norm2d_type):
                    copy_bn_param(m1, m2)


def copy_conv_param(module2d, module3d):
    for p2d, p3d in zip(module2d.parameters(), module3d.parameters()):
        p3d.data[:] = p2d.data.unsqueeze(dim=4).clone()[:]


def copy_bn_param(module2d, module3d):
    for p2d, p3d in zip(module2d.parameters(), module3d.parameters()):
        p3d.data[:] = p2d.data[:]  # Two parameter gamma and beta


AHnet = Ahnet = AHNet