# Mattes mutual information

**URL:** <https://discourse.itk.org/t/mattes-mutual-information/238>\
**Category:** Uncategorized\
**Created:** [September 29, 2017, 11:24am UTC](https://discourse.itk.org/t/mattes-mutual-information/238 "2017-09-29T11:24:12Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![c.spanakis83](https://discourse.itk.org/user_avatar/discourse.itk.org/c.spanakis83/32/737_2.png) [@c.spanakis83](https://discourse.itk.org/u/c.spanakis83)\
**Post date:** [September 29, 2017, 11:24am UTC](https://discourse.itk.org/t/mattes-mutual-information/238/1 "2017-09-29T11:24:13Z")

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Hello. I want to understand mattes mutual information but i cannot understand the purpose of  
the functions:

SetUseAllPixels()  
SetUseSequentialSampling() and  
SetNumberOfSpatialSamples()

and how they affect Mutual information and the duration of its evaluation.

Can anyone help me please?

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**Author:** ![matt.mccormick](https://discourse.itk.org/user_avatar/discourse.itk.org/matt.mccormick/32/7_2.png) [@matt.mccormick](https://discourse.itk.org/u/matt.mccormick)\
**Post date:** [October 2, 2017, 8:18pm UTC](https://discourse.itk.org/t/mattes-mutual-information/238/2 "2017-10-02T20:18:53Z")

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Hi @c.spanakis83,

These parameters are related to the computation of the joint histogram, which is [used to compute mutual information](https://courses.cs.washington.edu/courses/cse577/11au/notes/Z5-Mutual-Information.pptx).