Answers.Body: <p>You wouldn't, normally. A <a href="https://en.wikipedia.org/wiki/Hidden_Markov_model" rel="nofollow noreferrer">HMM</a> is used to model <em>sequences of observations</em>, and it would not make sense to use it for image recognition. Unless they are sequential, such as strokes in handwriting.</p>
  
  <p>HMMs are typically used in fields such as speech recognition and part-of-speech tagging. Here you observe a sequence of events that you want to fit to a model in order to classify the individual observations.</p>
  
  <p>For training a HMM you would use something like the <a href="https://en.wikipedia.org/wiki/Baum%E2%80%93Welch_algorithm" rel="nofollow noreferrer">Baum-Welch Algorithm</a>; for finding the most likely sequence (ie the recognition process) the <a href="https://en.wikipedia.org/wiki/Viterbi_algorithm" rel="nofollow noreferrer">Viterbi Algorithm</a> is used.</p>
  
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Body: <p>How could I use a 16x16 image as an input in a HMM? And at the same time how would I train it? Can I use backpropagation?</p>
  
Tags: <image-recognition><backpropagation><markov-chain><hidden-markov-model>
Title: How can I use a Hidden Markov Model to recognize images?
UserDisplayName: david david
ThreadText: # How can I use a Hidden Markov Model to recognize images?
  
  (Asked by: username_0 on 2020-04-05)
  
  How could I use a 16x16 image as an input in a HMM? And at the same time how would I train it? Can I use backpropagation?
  
  **Tags:** image-recognition, backpropagation, markov-chain, hidden-markov-model
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2020-04-05. Score: 5 | Accepted answer
  
  You wouldn't, normally. A [HMM](https://en.wikipedia.org/wiki/Hidden_Markov_model) is used to model *sequences of observations*, and it would not make sense to use it for image recognition. Unless they are sequential, such as strokes in handwriting.
  
  HMMs are typically used in fields such as speech recognition and part-of-speech tagging. Here you observe a sequence of events that you want to fit to a model in order to classify the individual observations.
  
  For training a HMM you would use something like the [Baum-Welch Algorithm](https://en.wikipedia.org/wiki/Baum%E2%80%93Welch_algorithm); for finding the most likely sequence (ie the recognition process) the [Viterbi Algorithm](https://en.wikipedia.org/wiki/Viterbi_algorithm) is used.
  
  > **Comments:**
  > **username_2**: Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/118182/discussion-on-answer-by-username_1-username_1-how-can-i-use-a-hidden-markov-model-to-reco).  
  
  ---
  
  