Difference between Shannon entropy and shannon entropy from wavelet packet?

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Beatriz Ruiz
Beatriz Ruiz le 19 Mai 2019
I wanted to calculate the shannon entropy of a signal and I used the command
entropia_sha(1,i)=wentropy(ventana(i,:), 'shannon');
I thought this function used the following formula:
but in the Matlab help the formula applied is:
I don't understand where does this formula come from and what's the connection with the first one.
Thanks.
  3 commentaires
Bala Amala Kannan
Bala Amala Kannan le 10 Jan 2020
You can find this formula in this literature:
https://www.spiedigitallibrary.org/journals/journal-of-biomedical-optics/volume-21/issue-9/096007/Retinal-image-quality-assessment-based-on-image-clarity-and-content/10.1117/1.JBO.21.9.096007.full?SSO=1.
In section 4.1: sharpness, this is the equation for Entropy_subband.
I don't know about the connection between these two equations.

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John Navarro
John Navarro le 29 Nov 2021
I would guess it is because the first equation is evaluating the Shannon entropy of the signal as a series, while the second is evaluating the entropy of the energy of the signal (energy is the square value)

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