What are the applications of autoencoders?

Data compression is utilized in computer vision, networks, architecture, and many other domains. Artificial Intelligence encompasses a wide range of technologies and techniques that enable computer systems to address challenges like Data Compression. Autoencoders are unsupervised neural networks that compress data via machine learning.

What is an autoencoder?

An autoencoder (AE) is an unsupervised artificial neural network that provides compression and other functions in machine learning. The Autoencoder's primary function is to reconstruct an output from the input using a feedforward approach. The input is compressed before being decompressed as output, which is generally identical to the original input. It's like an autoencoder to measure and compare similar inputs and outputs for execution results.

An autoencoder is also known as a diabolo network or an auto associator.

An encoder, a code, and a decoder are the three main components of an autoencoder. The initial data is transformed into a coded result, then expanded into a finished output by the network's succeeding layers. Examining a "denoising" autoencoder is one approach to learning about autoencoders. The denoising autoencoder refines the production by combining it with a noisy input to recreate something that represents the original set of inputs. Image processing, classification, and other parts of machine learning benefit from autoencoders.

Autoencoder architecture

There are three parts to an autoencoder −

  • Encoder − An encoder is a wholly integrated, feedforward neural network that compresses the input image into a latent space representation and encodes it in a lower dimension as a compressed representation. The compressed image is a deformed reproduction of the original image.

  • Code − This segment of the network stores the reduced representation of the input delivered to the decoder.

  • Decoder − The decoder, like the encoder, is a feedforward network with the same structure as the encoder. This network is responsible for reassembling the code supplied to its original dimensions.

Types of Autoencoders

Convolution Autoencoders

The idea that a signal might be viewed as a sum of other signals is ignored by autoencoders in their traditional construction. This discovery is exploited by convolutional autoencoders, which use the convolution operator. They learn to encode the input as a series of basic signals and then reconstruct the input from these signals by altering the image's geometry or reflectance.

Sparse Autoencoders

Sparse autoencoders provide another way to introduce an information bottleneck without reducing the number of nodes in our hidden layers. Instead, we'll design our loss function to penalize activations within a layer.

Deep Autoencoder

The Deep Autoencoder is an expansion of the ordinary Autoencoder. The Deep Autoencoder's first layer is used for first-order features in the raw input. Second-order features relating to patterns in the appearance of first-order characteristics are represented in the second layer. The Deep Autoencoder's deeper layers are more likely to learn higher-order features.

A deep autoencoder is made up of two symmetrical deep-belief networks:

  • The first four or five shallow layers represent the encoding half of the net, and the second four or five external layers represent the decoding half of the net.

  • The decoding half comprises the second set of four or five layers.

Contractive autoencoder

A contractive autoencoder is a deep learning approach that aids the encoding of unlabeled training input by a neural network. This is achieved by creating a loss term that Large derivatives of our hidden layer activations are penalized compared to the input training samples. Effectively punishing situations when a slight change in the input leads to a considerable difference in the encoding space.

The use of autoencoders

So far, we've seen a wide range of autoencoders, each of which excels at a distinct task. Let's take a look at some of the things they can do.

Compression of data

Even though autoencoders are meant to compress data, they are rarely employed for this reason in practice. The following are the reasons −

  • Lossy compression  − The Autoencoder's output is not identical to the input, but it is a near but degraded representation. They are not the best option for lossless compression.

  • Data-specific − Autoencoders can only compress data identical to the data on which they were trained. They differ from traditional data compression algorithms like jpeg or gzip in that they learn features relevant to the provided training data. As a result, we can't anticipate a landscape photo to be compressed by an autoencoder trained on handwritten digits.

Autoencoders are rarely used for compression because we now have more efficient and straightforward algorithms as jpeg, LZMA, and LZSS (used in WinRAR in conjunction with Huffman coding). Autoencoders have been used for picture denoising and dimensionality reduction in recent years. Image denoising is used to gain accurate information about the image's content.

Reduction of Dimensionality

The autoencoders reduce the input to a reduced representation stored in the middle layer called code. By separating this layer from the model, the information from the input has been compressed, and each node can now be handled as a variable. As a result, we may determine that by deleting the decoder, an autoencoder with the coding layer as the output can be used for dimensionality reduction.

Extraction of Features

Autoencoders' encoding segment aids in the learning of critical hidden features present in the input data, reducing the reconstruction error. A new set of unique feature combinations is formed during the encoding process.

Image Production

The VAE (Variational Autoencoder) is a generative model used to produce images that the model has not yet seen. The concept is that the system will generate similar images based on input photographs such as faces or scenery. The purpose is to:

  • Create new animated characters

  • Create fictitious human images

  • Colourization of an image

One of the purposes of autoencoders is to convert a black-and-white image to a colored image. A colorful image can also be converted to grayscale.

Updated on: 16-Mar-2022

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