# What is the scope of mutual information

**URL:** <https://discourse.itk.org/t/what-is-the-scope-of-mutual-information/5811>\
**Category:** Uncategorized\
**Created:** [March 19, 2023, 9:08am UTC](https://discourse.itk.org/t/what-is-the-scope-of-mutual-information/5811 "2023-03-19T09:08:16Z")\
**Posts on this page:** 1\
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**Author:** ![zivy](https://discourse.itk.org/user_avatar/discourse.itk.org/zivy/32/1726_2.png) [@zivy](https://discourse.itk.org/u/zivy)\
**Post date:** [March 19, 2023, 11:49pm UTC](https://discourse.itk.org/t/what-is-the-scope-of-mutual-information/5811/2 "2023-03-19T23:49:34Z")

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Hello @ljjiayou,

The range for mutual information is bound from below by zero, when the two variables are independent. It is bound from above by log(min(cardinality(X), cardinality(Y))), when the values in X and Y are equally likely.

Note that in ITK we use the negative of MI, because similarity measures are minimized.

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