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Introduction to Neural Networks

Introduction to Neural Networks

Convolutional neural networks can learn features through supervised learning and can be categorized into three different types:

  1. Classification
  2. Object detection
  3. Segmentation

The underlying basis of all these neural networks is the convolutional layer.

A classification CNN takes in an input image and outputs a distribution of class scores. This is done by feeding the input image through convolutional layers, which is the backbone of a CNN. These layers are used to filter the input image, and the filters are also known as convolution kernels. A kernel has a certain (small) size and one or more channels, specifying its depth. Each filter extracts different features from an image, such as edges or colors. The output of a given convolutional layer is a set of feature maps (also called activation maps), which are filtered versions of an original input image. As a CNN trains it updates the weights that define the image filters in this convolutional layer using back propagation.

Activation Function

Activation functions, such as ReLU's, are typically placed after a convolutional layer to slightly transform the output so that it's more efficient to perform backpropagation and effectively train the network.

References

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