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by opsy2 1862 days ago
How is entropy defined in this context?

Clearly there is human-derived input in the system (otherwise... What's the point just crop randomly)

2 comments

Here is the code:

https://github.com/reddit-archive/reddit/blob/753b17407e9a9d...

But in short, it's a histogram of the values of the pixels.

Which is not really image entropy at all, as it totally neglects spatial structure. You could sort an image and get the same entropy using the histogram approach.
"Entropy" in this context also left me wondering. Perhaps "variance" or "deviation from the mean"?

Thanks for the insights!

Entropy usually boils down to "sum p * log(p) for all p (and possibly normalize)", assuming you have discrete probabilities p. It is not related to variance or mean.
Randomness in pixel values