we attempt to prepare a really deep neural community mannequin, one problem that we would encounter is the vanishing gradient downside. That is primarily an issue the place the load replace of a mannequin throughout coaching slows down and even stops, therefore inflicting the mannequin to not enhance. When a community may be very deep, the gradient computation throughout backpropagation includes multiplying many by-product phrases collectively by means of the chain rule. Do not forget that if we multiply small numbers (usually lower than 1) too many occasions, it can make the ensuing numbers turning into extraordinarily small. Within the case of neural networks, these numbers are used as the idea of the load replace. So, if the gradient may be very small, then the load replace can be very sluggish, inflicting the coaching to be sluggish as properly.
To deal with this vanishing gradient downside, we are able to really use shortcut paths in order that the gradients can stream extra simply by means of a deep community. Some of the well-liked architectures that makes an attempt to resolve that is ResNet, the place it implements skip connections that soar over a number of layers within the community. This concept is adopted by DenseNet, the place the skip connections are applied way more aggressively, making it higher than ResNet in dealing with the vanishing gradient downside. On this article I wish to discuss how precisely DenseNet works and implement the structure from scratch.
The DenseNet Structure
Dense Block
DenseNet was initially proposed in a paper titled “Densely Related Convolutional Networks” written by Gao Huang et al. again in 2016 [1]. The principle thought of DenseNet is certainly to resolve the vanishing gradient downside. The explanation that it performs higher than ResNet is due to the shortcut paths branching out from a single layer to all different subsequent layers. To raised illustrate this concept, you possibly can see in Determine 1 under that the enter tensor x₀ is forwarded to H₁, H₂, H₃, H₄, and the transition layers. We do the identical factor to all layers inside this block, making all tensors related densely — therefore the title DenseNet. With all these shortcut connections, info can stream seamlessly between layers. Not solely that, however this mechanism additionally permits function reuse the place every layer can instantly profit from the options produced by all earlier layers.
In a normal CNN, if we now have L layers, we can even have L connections. Assuming that the above illustration is only a conventional 5-layer CNN, we mainly solely have the 5 straight arrows popping out from every tensor. In DenseNet, if we now have L layers, we may have L(L+1)/2 connections. So within the above case we mainly acquired 5(5+1)/2 = 15 connections in whole. You may confirm this by manually tallying the arrows one after the other: 5 crimson arrows, 4 inexperienced arrows, 3 purple arrows, 2 yellow arrows, and 1 brown arrow.
One other key distinction between ResNet and DenseNet is how they mix info from totally different layers. In ResNet, we mix info from two tensors by element-wise summation, which may mathematically be outlined in Determine 2 under. As a substitute of performing element-wise summation, DenseNet combines info by channel-wise concatenation as expressed in Determine 3. With this mechanism, the function maps produced by all earlier layers are concatenated with the output of the present layer earlier than finally getting used because the enter of the next layer.
Performing channel-wise concatenation like this really has a aspect impact: the variety of function maps grows as we get deeper into the community. Within the instance I confirmed you in Determine 1, we initially have an enter tensor of 6 channels. The H₁ layer processes this tensor and produces a 4-channel tensor. These two tensors are then concatenated earlier than being forwarded to H₂. This primarily implies that the H₂ layer accepts 10 channels. Following the identical sample, we are going to later have the H₃, H₄, and the transition layers to just accept tensors of 14, 18, and 22 channels, respectively. That is really an instance of a DenseNet that makes use of the development fee parameter of 4, that means that every layer produces 4 new function maps. Afterward, we are going to use okay to indicate this parameter as advised within the authentic paper.
Regardless of having such advanced connections, DenseNet is definitely much more environment friendly as in comparison with the normal CNN by way of the variety of parameters. Let’s do some little bit of math to show this. The construction given in Determine 1 consists of 4 conv layers (let’s ignore the transition layer for now). To compute what number of parameters a convolution layer has, we are able to merely calculate input_channels × kernel_height × kernel_width × output_channels. Assuming that each one these convolutions use 3×3 kernel, our layers within the DenseNet structure would have the next variety of parameters:
- H₁ → 6×3×3×4 = 216
- H₂ → 10×3×3×4 = 360
- H₃ → 14×3×3×4 = 504
- H₄ → 18×3×3×4 = 648
By summing these 4 numbers, we may have 1,728 params in whole. Observe that this quantity doesn’t embody the bias time period. Now if we attempt to create the very same construction with a standard CNN, we would require the next variety of params for every layer:
- H₁ → 6×3×3×10 = 540
- H₂ → 10×3×3×14 = 1,260
- H₃ → 14×3×3×18 = 2,268
- H₄ → 18×3×3×22 = 3,564
Summing these up, a standard CNN hits 7,632 params — that’s over 4× increased! With this parameter depend in thoughts, we are able to clearly see that DenseNet is certainly way more light-weight than conventional CNNs. The explanation why DenseNet may be so environment friendly is due to the function reuse mechanism, the place as a substitute of computing all function maps from scratch, it solely computes okay function maps and concatenate them with the prevailing function maps from the earlier layers.
Transition Layer
The construction I confirmed you earlier is definitely simply the principle constructing block of the DenseNet mannequin, which is known as the dense block. Determine 4 under reveals how these constructing blocks are assembled, the place three of them are related by the so-called transition layers. Every transition layer consists of a convolution adopted by a pooling layer. This element has two essential duties: first, to scale back the spatial dimension of the tensor, and second, to scale back the variety of channels. The discount in spatial dimension is commonplace follow when setting up CNN-based mannequin, the place the deeper function maps ought to usually have decrease dimension than that of the shallower ones. In the meantime, decreasing the variety of channels is critical as a result of they may drastically enhance as a result of channel-wise concatenation mechanism executed inside every layer within the dense block.
To know how the transition layer reduces channels, we have to have a look at the compression issue parameter. This parameter, which the authors seek advice from as θ (theta), ought to have the worth of someplace between 0 and 1. Suppose we set θ to 0.2, then the variety of channels to be forwarded to the subsequent dense block will solely be 20% of the overall variety of channels produced by the present dense block.
The Total DenseNet Structure
As we now have understood the dense block and the transition layer, we are able to now transfer on to the whole DenseNet structure proven in Determine 5 under. It initially accepts an RGB picture of measurement 224×224, which is then processed by a 7×7 conv and a 3×3 maxpooling layer. Needless to say these two layers use the stride of two, inflicting the spatial dimension to shrink to 112×112 and 56×56, respectively. At this level the tensor is able to be handed by means of the primary dense block which consists of 6 bottleneck blocks — I’ll discuss extra about this element very quickly. The ensuing output will then be forwarded to the primary transition layer, adopted by the second dense block, and so forth till we finally attain the worldwide common pooling layer. Lastly, we go the tensor to the fully-connected layer which is accountable for making class predictions.
There are literally a number of extra particulars I would like to clarify concerning the structure above. First, the variety of function maps produced in every step isn’t explicitly talked about. That is primarily as a result of the structure is adaptive in line with the okay and θ parameters. The one layer with a set quantity is the very first convolution layer (the 7×7 one), which produces 64 function maps (not displayed within the determine). Second, it’s also vital to notice that each convolution layer proven within the structure follows the BN-ReLU-conv-dropout sequence, apart from the 7×7 convolution which doesn’t embody the dropout layer. Third, the authors applied a number of DenseNet variants, which they seek advice from as DenseNet (the vanilla one), DenseNet-B (the variant that makes use of bottleneck blocks), DenseNet-C (the one which makes use of compression issue θ), and DenseNet-BC (the variant that employs each). The structure given in Determine 5 is the DenseNet-B (or DenseNet-BC) variant.
The so-called bottleneck block itself is the stack of 1×1 and three×3 convolutions. The 1×1 conv is used to scale back the variety of channels to 4okay earlier than finally being shrunk additional to okay by the next 3×3 conv. The explanation for it’s because 3×3 convolution is computationally costly on tensors with many channels. So to make the computation quicker, we have to cut back the channels first utilizing the 1×1 conv. Later within the coding part we’re going to implement this DenseNet-BC variant. Nevertheless, if you wish to implement the usual DenseNet (or DenseNet-C) as a substitute, you possibly can merely omit the 1×1 conv so that every dense block solely includes 3×3 convolutions.
Some Experimental Outcomes
It’s seen within the paper that the authors carried out a lot of experiments evaluating DenseNet with different fashions. On this part I’m going to indicate you some fascinating issues they found.
The primary experimental end result I discovered fascinating is that DenseNet really has significantly better efficiency than ResNet. Determine 6 above reveals that it persistently outperforms ResNet throughout all community depths. When evaluating variants with related accuracy, DenseNet is definitely much more environment friendly. Let’s take a more in-depth have a look at the DenseNet-201 variant. Right here you possibly can see that the validation error is almost the identical as ResNet-101. Regardless of being 2× deeper (201 vs 101 layers), it’s roughly 2× smaller by way of each parameters and FLOPs (floating level operations).
Subsequent, the authors additionally carried out ablation research concerning the usage of bottleneck layer and compression issue. We are able to see in Determine 7 above that using each the bottleneck layer inside the dense block and performing channel depend discount within the transition layer permits the mannequin to realize increased accuracy (DenseNet-BC). It may appear a bit counterintuitive to see that the discount within the variety of channels as a result of compression issue improves the accuracy as a substitute. In truth, in deep studying, too many options may as a substitute damage accuracy attributable to info redundancy. So, decreasing the variety of channels may be perceived as a regularization mechanism which may forestall the mannequin from overfitting, permitting it to acquire increased validation accuracy.
DenseNet From Scratch
As we now have understood the underlying principle behind DenseNet, we are able to now implement the structure from scratch. What we have to do first is to import the required modules and initializing the configurable variables. Within the Codeblock 1 under, the okay and θ we mentioned earlier are denoted as GROWTH and COMPRESSION, which the values are set to 12 and 0.5, respectively. These two values are the defaults given within the paper, which we are able to positively change if we need to. Subsequent, right here I additionally initialize the REPEATS record to retailer the variety of bottleneck blocks inside every dense block.
# Codeblock 1
import torch
import torch.nn as nn
GROWTH = 12
COMPRESSION = 0.5
REPEATS = [6, 12, 24, 16]Bottleneck Implementation
Now let’s check out the Bottleneck class under to see how I implement the stack of 1×1 and three×3 convolutions. Beforehand I’ve talked about that every convolution layer follows the BN-ReLU-Conv-dropout construction, so right here we have to initialize all these layers within the __init__() methodology.
The 2 convolution layers are initialized as conv0 and conv1, every with their corresponding batch normalization layers. Don’t overlook to set the out_channels parameter of the conv0 layer to GROWTH*4 as a result of we would like it to return 4okay function maps (see the road marked with #(1)). This variety of function maps will then be shrunk even additional by the conv1 layer to okay by setting the out_channels to GROWTH (#(2)). As all layers have been initialized, we are able to now outline the stream within the ahead() methodology. Simply understand that on the finish of the method we now have to concatenate the ensuing tensor (out) with the unique one (x) to implement the skip-connection (#(3)).
# Codeblock 2
class Bottleneck(nn.Module):
def __init__(self, in_channels):
tremendous().__init__()
self.relu = nn.ReLU()
self.dropout = nn.Dropout(p=0.2)
self.bn0 = nn.BatchNorm2d(num_features=in_channels)
self.conv0 = nn.Conv2d(in_channels=in_channels,
out_channels=GROWTH*4, #(1)
kernel_size=1,
padding=0,
bias=False)
self.bn1 = nn.BatchNorm2d(num_features=GROWTH*4)
self.conv1 = nn.Conv2d(in_channels=GROWTH*4,
out_channels=GROWTH, #(2)
kernel_size=3,
padding=1,
bias=False)
def ahead(self, x):
print(f'originalt: {x.measurement()}')
out = self.dropout(self.conv0(self.relu(self.bn0(x))))
print(f'after conv0t: {out.measurement()}')
out = self.dropout(self.conv1(self.relu(self.bn1(out))))
print(f'after conv1t: {out.measurement()}')
concatenated = torch.cat((out, x), dim=1) #(3)
print(f'after concatt: {concatenated.measurement()}')
return concatenatedWith a view to verify if our Bottleneck class works correctly, we are going to now create one which accepts 64 function maps and go a dummy tensor by means of it. The bottleneck layer I instantiate under primarily corresponds to the very first bottleneck inside the primary dense block (refer again to Determine 5 if you happen to’re uncertain). So, to simulate precise the stream of the community, we’re going to go a tensor of measurement 64×56×56, which is basically the form produced by the three×3 maxpooling layer.
# Codeblock 3
bottleneck = Bottleneck(in_channels=64)
x = torch.randn(1, 64, 56, 56)
x = bottleneck(x)As soon as the above code is run, we are going to get the next output seem on our display.
# Codeblock 3 Output
authentic : torch.Dimension([1, 64, 56, 56])
after conv0 : torch.Dimension([1, 48, 56, 56]) #(1)
after conv1 : torch.Dimension([1, 12, 56, 56]) #(2)
after concat : torch.Dimension([1, 76, 56, 56])Right here we are able to see that our conv0 layer efficiently lowered the function maps from 64 to 48 (#(1)), the place 48 is the 4okay (keep in mind that our okay is 12). This 48-channel tensor is then processed by the conv1 layer, which reduces the variety of function maps even additional to okay (#(2)). This output tensor is then concatenated with the unique one, leading to a tensor of 64+12 = 76 function maps. And right here is definitely the place the sample begins. Later within the dense block, if we repeat this bottleneck a number of occasions, then we may have every layer produce:
- second layer → 64+(2×12) = 88 function maps
- third layer → 64+(3×12) = 100 function maps
- fourth layer → 64+(4×12) = 112 function maps
- and so forth …
Dense Block Implementation
Now let’s really create the DenseBlock class to retailer the sequence of Bottleneck situations. Have a look at the Codeblock 4 under to see how I try this. The way in which to do it’s fairly simple, we are able to simply initialize a module record (#(1)) after which append the bottleneck blocks one after the other (#(3)). Observe that we have to maintain observe of the variety of enter channels of every bottleneck utilizing the current_in_channels variable (#(2)). Lastly, within the ahead() methodology we are able to merely go the tensor sequentially.
# Codeblock 4
class DenseBlock(nn.Module):
def __init__(self, in_channels, repeats):
tremendous().__init__()
self.bottlenecks = nn.ModuleList() #(1)
for i in vary(repeats):
current_in_channels = in_channels + i*GROWTH #(2)
self.bottlenecks.append(Bottleneck(in_channels=current_in_channels)) #(3)
def ahead(self, x):
for i, bottleneck in enumerate(self.bottlenecks):
x = bottleneck(x)
print(f'after bottleneck #{i}t: {x.measurement()}')
return xWe are able to check the code above by simulating the primary dense block within the community. You may see in Determine 5 that it accommodates 6 bottleneck blocks, so within the Codeblock 5 under I set the repeats parameter to that quantity (#(1)). We are able to see within the ensuing output that the enter tensor, which initially has the form of 64×56×56, is remodeled to 136×56×56. The 136 function maps come from 64+(6×12), which follows the sample I gave you earlier.
# Codeblock 5
dense_block = DenseBlock(in_channels=64, repeats=6) #(1)
x = torch.randn(1, 64, 56, 56)
x = dense_block(x)# Codeblock 5 Output
after bottleneck #0 : torch.Dimension([1, 76, 56, 56])
after bottleneck #1 : torch.Dimension([1, 88, 56, 56])
after bottleneck #2 : torch.Dimension([1, 100, 56, 56])
after bottleneck #3 : torch.Dimension([1, 112, 56, 56])
after bottleneck #4 : torch.Dimension([1, 124, 56, 56])
after bottleneck #5 : torch.Dimension([1, 136, 56, 56])Transition Layer
The following element we’re going to implement is the transition layer, which is proven in Codeblock 6 under. Much like the convolution layers within the bottleneck blocks, right here we additionally use the BN-ReLU-conv-dropout construction, but this one is with an extra common pooling layer on the finish (#(1)). Don’t overlook to set the stride of this pooling layer to 2 to scale back the spatial dimension by half.
# Codeblock 6
class Transition(nn.Module):
def __init__(self, in_channels, out_channels):
tremendous().__init__()
self.bn = nn.BatchNorm2d(num_features=in_channels)
self.relu = nn.ReLU()
self.conv = nn.Conv2d(in_channels=in_channels,
out_channels=out_channels,
kernel_size=1,
padding=0,
bias=False)
self.dropout = nn.Dropout(p=0.2)
self.pool = nn.AvgPool2d(kernel_size=2, stride=2) #(1)
def ahead(self, x):
print(f'originalt: {x.measurement()}')
out = self.pool(self.dropout(self.conv(self.relu(self.bn(x)))))
print(f'after transition: {out.measurement()}')
return outNow let’s check out the testing code within the Codeblock 7 under to see how a tensor transforms as it’s handed by means of the above community. On this instance I’m attempting to simulate the very first transition layer, i.e., the one proper after the primary dense block. That is primarily the rationale that I set this layer to just accept 136 channels. Beforehand I discussed that this layer is used to shrink the channel dimension by means of the θ parameter, so to implement it we are able to merely multiply the variety of enter function maps with the COMPRESSION variable for the out_channels parameter.
# Codeblock 7
transition = Transition(in_channels=136, out_channels=int(136*COMPRESSION))
x = torch.randn(1, 136, 56, 56)
x = transition(x)As soon as above code is run, we must always get hold of the next output. Right here you possibly can see that the spatial dimension of the enter tensor shrinks from 56×56 to twenty-eight×28, whereas the variety of channels additionally reduces from 136 to 68. This primarily signifies that our transition layer implementation is right.
# Codeblock 7 Output
authentic : torch.Dimension([1, 136, 56, 56])
after transition : torch.Dimension([1, 68, 28, 28])The Total DenseNet Structure
As we now have efficiently applied the principle elements of the DenseNet mannequin, we are actually going to assemble your complete structure. Right here I separate the __init__() and the ahead() strategies into two codeblocks as they’re fairly lengthy. Simply be sure that you set Codeblock 8a and 8b inside the similar pocket book cell if you wish to run it by yourself.
# Codeblock 8a
class DenseNet(nn.Module):
def __init__(self):
tremendous().__init__()
self.first_conv = nn.Conv2d(in_channels=3,
out_channels=64,
kernel_size=7, #(1)
stride=2, #(2)
padding=3, #(3)
bias=False)
self.first_pool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1) #(4)
channel_count = 64
# Dense block #0
self.dense_block_0 = DenseBlock(in_channels=channel_count,
repeats=REPEATS[0]) #(5)
channel_count = int(channel_count+REPEATS[0]*GROWTH) #(6)
self.transition_0 = Transition(in_channels=channel_count,
out_channels=int(channel_count*COMPRESSION))
channel_count = int(channel_count*COMPRESSION) #(7)
# Dense block #1
self.dense_block_1 = DenseBlock(in_channels=channel_count,
repeats=REPEATS[1])
channel_count = int(channel_count+REPEATS[1]*GROWTH)
self.transition_1 = Transition(in_channels=channel_count,
out_channels=int(channel_count*COMPRESSION))
channel_count = int(channel_count*COMPRESSION)
# # Dense block #2
self.dense_block_2 = DenseBlock(in_channels=channel_count,
repeats=REPEATS[2])
channel_count = int(channel_count+REPEATS[2]*GROWTH)
self.transition_2 = Transition(in_channels=channel_count,
out_channels=int(channel_count*COMPRESSION))
channel_count = int(channel_count*COMPRESSION)
# Dense block #3
self.dense_block_3 = DenseBlock(in_channels=channel_count,
repeats=REPEATS[3])
channel_count = int(channel_count+REPEATS[3]*GROWTH)
self.avgpool = nn.AdaptiveAvgPool2d(output_size=(1,1)) #(8)
self.fc = nn.Linear(in_features=channel_count, out_features=1000) #(9)What we do first within the __init__() methodology above is to initialize the first_conv and the first_pool layers. Needless to say these two layers neither belong to the dense block nor the transition layer, so we have to manually initialize them as nn.Conv2d and nn.MaxPool2d situations. In truth, these two preliminary layers are fairly distinctive. The convolution layer makes use of a really massive kernel of measurement 7×7 (#(1)) with the stride of two (#(2)). So, not solely capturing info from massive space, however this layer additionally performs spatial downsampling in-place. Right here we additionally must set the padding to three (#(3)) to compensate for the big kernel in order that the spatial dimension doesn’t get lowered an excessive amount of. Subsequent, the pooling layer is totally different from those within the transition layer, the place we use 3×3 maxpooling quite than 2×2 common pooling (#(4)).
As the primary two layers are executed, what we do subsequent is to initialize the dense blocks and the transition layers. The concept is fairly simple, the place we have to initialize the dense blocks consisting of a number of bottleneck blocks (which the quantity bottlenecks is handed by means of the repeats parameter (#(5))). Keep in mind to maintain observe of the channel depend of every step (#(6,7)) in order that we are able to match the enter form of the next layer with the output form of the earlier one. After which we mainly do the very same factor for the remaining dense blocks and the transition layers.
As we now have reached the final dense block, we now initialize the worldwide common pooling layer (#(8)), which is accountable for taking the typical worth throughout the spatial dimension, earlier than finally initializing the classification head (#(9)). Lastly, as all layers have been initialized, we are able to now join all of them contained in the ahead() methodology under.
# Codeblock 8b
def ahead(self, x):
print(f'originaltt: {x.measurement()}')
x = self.first_conv(x)
print(f'after first_convt: {x.measurement()}')
x = self.first_pool(x)
print(f'after first_poolt: {x.measurement()}')
x = self.dense_block_0(x)
print(f'after dense_block_0t: {x.measurement()}')
x = self.transition_0(x)
print(f'after transition_0t: {x.measurement()}')
x = self.dense_block_1(x)
print(f'after dense_block_1t: {x.measurement()}')
x = self.transition_1(x)
print(f'after transition_1t: {x.measurement()}')
x = self.dense_block_2(x)
print(f'after dense_block_2t: {x.measurement()}')
x = self.transition_2(x)
print(f'after transition_2t: {x.measurement()}')
x = self.dense_block_3(x)
print(f'after dense_block_3t: {x.measurement()}')
x = self.avgpool(x)
print(f'after avgpooltt: {x.measurement()}')
x = torch.flatten(x, start_dim=1)
print(f'after flattentt: {x.measurement()}')
x = self.fc(x)
print(f'after fctt: {x.measurement()}')
return xThat’s mainly the entire implementation of the DenseNet structure. We are able to check if it really works correctly by working the Codeblock 9 under. Right here we go the x tensor by means of the community, during which it simulates a batch of a single 224×224 RGB picture.
# Codeblock 9
densenet = DenseNet()
x = torch.randn(1, 3, 224, 224)
x = densenet(x)And under is what the output appears to be like like. Right here I deliberately print out the tensor form after every step to be able to clearly see how the tensor transforms all through your complete community. Regardless of having so many layers, that is really the smallest DenseNet variant, i.e., DenseNet-121. You may really make the mannequin even bigger by altering the values within the REPEATS record in line with the variety of bottleneck blocks inside every dense block given in Determine 5.
# Codeblock 9 Output
authentic : torch.Dimension([1, 3, 224, 224])
after first_conv : torch.Dimension([1, 64, 112, 112])
after first_pool : torch.Dimension([1, 64, 56, 56])
after bottleneck #0 : torch.Dimension([1, 76, 56, 56])
after bottleneck #1 : torch.Dimension([1, 88, 56, 56])
after bottleneck #2 : torch.Dimension([1, 100, 56, 56])
after bottleneck #3 : torch.Dimension([1, 112, 56, 56])
after bottleneck #4 : torch.Dimension([1, 124, 56, 56])
after bottleneck #5 : torch.Dimension([1, 136, 56, 56])
after dense_block_0 : torch.Dimension([1, 136, 56, 56])
after transition_0 : torch.Dimension([1, 68, 28, 28])
after bottleneck #0 : torch.Dimension([1, 80, 28, 28])
after bottleneck #1 : torch.Dimension([1, 92, 28, 28])
after bottleneck #2 : torch.Dimension([1, 104, 28, 28])
after bottleneck #3 : torch.Dimension([1, 116, 28, 28])
after bottleneck #4 : torch.Dimension([1, 128, 28, 28])
after bottleneck #5 : torch.Dimension([1, 140, 28, 28])
after bottleneck #6 : torch.Dimension([1, 152, 28, 28])
after bottleneck #7 : torch.Dimension([1, 164, 28, 28])
after bottleneck #8 : torch.Dimension([1, 176, 28, 28])
after bottleneck #9 : torch.Dimension([1, 188, 28, 28])
after bottleneck #10 : torch.Dimension([1, 200, 28, 28])
after bottleneck #11 : torch.Dimension([1, 212, 28, 28])
after dense_block_1 : torch.Dimension([1, 212, 28, 28])
after transition_1 : torch.Dimension([1, 106, 14, 14])
after bottleneck #0 : torch.Dimension([1, 118, 14, 14])
after bottleneck #1 : torch.Dimension([1, 130, 14, 14])
after bottleneck #2 : torch.Dimension([1, 142, 14, 14])
after bottleneck #3 : torch.Dimension([1, 154, 14, 14])
after bottleneck #4 : torch.Dimension([1, 166, 14, 14])
after bottleneck #5 : torch.Dimension([1, 178, 14, 14])
after bottleneck #6 : torch.Dimension([1, 190, 14, 14])
after bottleneck #7 : torch.Dimension([1, 202, 14, 14])
after bottleneck #8 : torch.Dimension([1, 214, 14, 14])
after bottleneck #9 : torch.Dimension([1, 226, 14, 14])
after bottleneck #10 : torch.Dimension([1, 238, 14, 14])
after bottleneck #11 : torch.Dimension([1, 250, 14, 14])
after bottleneck #12 : torch.Dimension([1, 262, 14, 14])
after bottleneck #13 : torch.Dimension([1, 274, 14, 14])
after bottleneck #14 : torch.Dimension([1, 286, 14, 14])
after bottleneck #15 : torch.Dimension([1, 298, 14, 14])
after bottleneck #16 : torch.Dimension([1, 310, 14, 14])
after bottleneck #17 : torch.Dimension([1, 322, 14, 14])
after bottleneck #18 : torch.Dimension([1, 334, 14, 14])
after bottleneck #19 : torch.Dimension([1, 346, 14, 14])
after bottleneck #20 : torch.Dimension([1, 358, 14, 14])
after bottleneck #21 : torch.Dimension([1, 370, 14, 14])
after bottleneck #22 : torch.Dimension([1, 382, 14, 14])
after bottleneck #23 : torch.Dimension([1, 394, 14, 14])
after dense_block_2 : torch.Dimension([1, 394, 14, 14])
after transition_2 : torch.Dimension([1, 197, 7, 7])
after bottleneck #0 : torch.Dimension([1, 209, 7, 7])
after bottleneck #1 : torch.Dimension([1, 221, 7, 7])
after bottleneck #2 : torch.Dimension([1, 233, 7, 7])
after bottleneck #3 : torch.Dimension([1, 245, 7, 7])
after bottleneck #4 : torch.Dimension([1, 257, 7, 7])
after bottleneck #5 : torch.Dimension([1, 269, 7, 7])
after bottleneck #6 : torch.Dimension([1, 281, 7, 7])
after bottleneck #7 : torch.Dimension([1, 293, 7, 7])
after bottleneck #8 : torch.Dimension([1, 305, 7, 7])
after bottleneck #9 : torch.Dimension([1, 317, 7, 7])
after bottleneck #10 : torch.Dimension([1, 329, 7, 7])
after bottleneck #11 : torch.Dimension([1, 341, 7, 7])
after bottleneck #12 : torch.Dimension([1, 353, 7, 7])
after bottleneck #13 : torch.Dimension([1, 365, 7, 7])
after bottleneck #14 : torch.Dimension([1, 377, 7, 7])
after bottleneck #15 : torch.Dimension([1, 389, 7, 7])
after dense_block_3 : torch.Dimension([1, 389, 7, 7])
after avgpool : torch.Dimension([1, 389, 1, 1])
after flatten : torch.Dimension([1, 389])
after fc : torch.Dimension([1, 1000])Ending
I feel that’s just about every thing concerning the principle and the implementation of the DenseNet mannequin. It’s also possible to discover all of the codes above in my GitHub repo [2]. See ya in my subsequent article!
References
[1] Gao Huang et al. Densely Related Convolutional Networks. Arxiv. https://arxiv.org/abs/1608.06993 [Accessed September 18, 2025].
[2] MuhammadArdiPutra. DenseNet. GitHub. https://github.com/MuhammadArdiPutra/medium_articles/blob/essential/DenseNet.ipynb [Accessed September 18, 2025].
