Body: <p>From the architecture table of the <a href="https://arxiv.org/abs/1704.04861" rel="nofollow noreferrer">first MobileNet paper</a>, a depthwise convolution with stride 2 and an input of 7x7x1024 is followed by a pointwise convolution with the same input dimensions, 7x7x1024.</p>
  <p>Shouldn't the pointwise layer's input be 4x4x1024 if the depthwise conv. layer was stride 2? (Assumming padding of 1)</p>
  <p>Is this an error on the author's side? Or are there something that I've missed between these layers?
  I've checked implementations of MobileNet V1 and it seems that everyone just treated this depthwise layer's stride as 1.</p>
  <p><a href="https://i.sstatic.net/DGVZ5.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/DGVZ5.png" alt="enter image description here" /></a></p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-02-14T10:19:56.797Z
Comments.Text: It depends if there is zero padding or not. There was probably some padding.
Comments.UserDisplayName: Brale
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-02-15T10:23:49.817Z
Comments.Text: @Brale from the source code it seems that the padding is always of form `valid` - https://github.com/tensorflow/models/blob/master/research/slim/nets/mobilenet_v1.py
Comments.UserDisplayName: spiridon_the_sun_rotator
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-02-15T12:58:10.083Z
Comments.Text: @spiridon_the_sun_rotator I see. Then I assume there would be padding of 4 on each side, making the input at least 15x15. This does mean that roughly 30% of output values are zeros... I don't think I understand why they would have made such design choice.
Comments.UserDisplayName: Jong Seok Park
Tags: <convolutional-neural-networks><convolutional-layers>
Title: Error in MobileNet V1 Architecture?
UserDisplayName: Jong Seok Park
ThreadText: # Error in MobileNet V1 Architecture?
  
  (Asked by: username_0 on 2021-02-14)
  
  From the architecture table of the [first MobileNet paper](https://arxiv.org/abs/1704.04861), a depthwise convolution with stride 2 and an input of 7x7x1024 is followed by a pointwise convolution with the same input dimensions, 7x7x1024.
  
  Shouldn't the pointwise layer's input be 4x4x1024 if the depthwise conv. layer was stride 2? (Assumming padding of 1)
  
  Is this an error on the author's side? Or are there something that I've missed between these layers?
  I've checked implementations of MobileNet V1 and it seems that everyone just treated this depthwise layer's stride as 1.
  
  [![enter image description here](https://i.sstatic.net/DGVZ5.png)](https://i.sstatic.net/DGVZ5.png)
  
  **Tags:** convolutional-neural-networks, convolutional-layers
  > **Comments:**
  > **username_1**: It depends if there is zero padding or not. There was probably some padding.  
  > **username_2**: @Brale from the source code it seems that the padding is always of form `valid` - https://github.com/tensorflow/models/blob/master/research/slim/nets/mobilenet_v1.py  
  > **username_0**: @spiridon_the_sun_rotator I see. Then I assume there would be padding of 4 on each side, making the input at least 15x15. This does mean that roughly 30% of output values are zeros... I don't think I understand why they would have made such design choice.  
  
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  ## 0 answers
  
  