# Tag Info

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3D CNN's are used when you want to extract features in 3 Dimensions or establish a relationship between 3 dimensions. Essentially its the same as 2D convolutions but the kernel movement is now 3-Dimensional causing a better capture of dependencies within the 3 dimensions and a difference in output dimensions post convolution. The kernel on convolution ...

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3D convolutions should when you want to extract spatial features from your input on three dimensions. For Computer Vision, they are typically used on volumetric images, which are 3D. Some examples are classifying 3D rendered images and medical image segmentation

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NOTE: All the observations and results are from the paper The Lottery Ticket Hypothesis: Finding Sparse, Trainable Neural Networks. To answer your questions one by one: Yes there are ways to determine which filters have more impact on the output. Its a very naive way but works very good in practice. Filters with small weights impact output less (according ...

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I haven't seen it as you describe and I don't think it would be much useful. Pooling layers are being gradually phased out of networks, because they don't seem to be that useful anymore. With the emergence of more and more conv-only architectures, I don't see that likely.

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I have had similar thoughts about neural networks before. Convolution layers are layers of two dimensional nodes effectively passing the spacial data so why don't we use two dimensional hidden layers to receive information out of them. I'm sure someone has used this type of implementation before. I believe the papers bellow are using this. Part of the ...

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For a 3 channel image (RGB), each filter in a convolutional layer computes a feature map which is essentially a single channel image. Typically, 2D convolutional filters are used for multichannel images. This can be a single filter applied to each layer or a seperate filter per layer. These filters are looking for features which are independent of the color,...

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In most modern neural network frameworks, the update rules for training can be selectively applied to some parameters and not others. How to do that is dependent on the framework. Some will have the concept of "freezing" a layer, preventing parameters in it being updated. Keras does this for example. Others will do the opposite and expect you to provide a ...

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I'd suggest you better understand edge detectors such as Robert or Sobel operators first to understand better how convolution operation on images extract features by constant value kernels. Would personally recommend Gonzales and Woods for this, as it gives a pure mathematical explanation to how and why these features are extracted. Essentially the ...

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About the images inside the CNN layers: I really recommend this article since there is no one short answer to this question and it probably will be better to experiment with it. About the RGB input images: When needed to train on RGB pictures it is not advised to split the RGB channels, you can think of it by trying to identify a fictional cat with red ears,...

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The pooling operation in a CNN is applied independently to each layer and the resulting feature maps are disjoint. This is the very reason that in most schematics depicting a certain CNN architecture, we obtain three output maps from an input image (corresponding to the convolutions and pooling operations performed on the RGB channels separately). Each ...

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Does the next convolutional filter have a depth of 40? So the filter dimensions would be 3x3x40? Yes. The depth of the next layer $l$ (which corresponds to the number of feature maps) will be 40. If you apply $8$ kernels with a $3\times 3$ window to $l$, then the number of features maps (or the depth) of layer $l+1$ will be $8$. Each of these $8$ kernels ...

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You are partially correct. On CNNs the output shape per layer is defined by the amount of filters used, and the application of the filters (dilation, stride, padding, etc.). CNNs shapes In your example, your input is 30 x 30 x 3. Assuming stride of 1, no padding, and no dilation on the filter, you will get a spatial shape equal to your input, that is ...

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As a rule of thumb for image data augmentation, look at the augmented images: Can you correctly classify or measure your target label from the augmented images? Could something similar to the augmented images appear in the environment where you want to run inferences on previously unseen inputs? For your suggested augmentation of shuffling the channels, it ...

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Read on Fully Convolutional Networks (FCN). There is a lot of papers on the subject, first was "Fully Convolutional Networks for Semantic Segmentation" by Long. The idea is quite close to what you describe - preserve spatial locality in the layers. In FCN there is no fully connected layer. Instead there is average pooling on top of last low-resolution/high-...

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Yes you can vectorize a CNN. See this github file for details: https://github.com/parasdahal/deepnet/blob/master/deepnet/layers.py After looking through it it basically transposes the input to some dimension and apply matrix multiplication to the weight with some other kind of transfromation. Pls refer to the github repository for details. Hope this can ...

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MaxPooling pools together information. Imagine you have 2 convolutional layers $(F_1, F_2)$ respectively, each with a 3x3 kernel and a stride of $1$. Also, imagine your input is $I$ is of shape $(w,h)$. Let's call a max-pooling layer $M$ is of size $(2,2)$. Note: I'm ignoring channels because, for these purposes, it's not necessary and can be extended to ...

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If you have a $h_i \times w_i \times d_i$ input, where $h_i, w_i$ and $d_i$ respectively refer to the height, width and depth of the input, then we usually apply $m$ $h_k \times w_k \times d_i$ kernels (or filters) to this input (with the appropriate stride and padding), where $m$ is usually a hyper-parameter. So, after the application of $m$ kernels, you ...

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They are not the same thing. asymmetric convolutions work by taking the x and y axes of the image separately. For example performing a convolution with an $(n \times 1)$ kernel before one with a $(1 \times n)$ kernel. On the other-hand depth-wise separable convolutions separate the spatial and channel components of a 2D convolution. It will first ...

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