EntropyFilter[data,r]
filters data by replacing every value by the entropy value in its range-r neighborhood.
EntropyFilter[data,{r1,r2,…}]
uses ri for filtering the dimension in data.


EntropyFilter
EntropyFilter[data,r]
filters data by replacing every value by the entropy value in its range-r neighborhood.
EntropyFilter[data,{r1,r2,…}]
uses ri for filtering the dimension in data.
Details

- EntropyFilter returns the local randomness of a signal, commonly used to measure textures in an image. The size of the neighborhood is dependent on the value of r.
- The function applied to each range-r neighborhood is Entropy.
- The data can be any of the following:
-
list arbitrary-rank numerical array tseries temporal data such as TimeSeries, TemporalData, … image arbitrary Image or Image3D object audio an Audio object video a Video object - EntropyFilter[data,{r1,r2,…}] computes the entropy value in
blocks centered on each sample.
- EntropyFilter assumes the index coordinate system for lists and images.
- At the data boundaries, EntropyFilter uses smaller neighborhoods.


Examples
open all close allBasic Examples (3)
Apply an entropy filter to a vector of numbers:
Filter a TimeSeries:
Scope (11)
Data (7)
Apply a moving entropy filter to a vector:
Entropy filtering of a 2D array:
Filter an Audio signal:
Filtering a 2D grayscale image:
Applications (3)
Properties & Relations (2)
Entropy filtering is the same as ArrayFilter with function Entropy:
Entropy filtering is the same as ImageFilter with function Entropy:
Possible Issues (1)
The discrete entropy measure does not apply to real-valued images, since distinct pixel values are unlikely to occur more than once:
Use ColorQuantize to limit the number of possible pixel values:
History
Introduced in 2008 (7.0) | Updated in 2012 (9.0) ▪ 2015 (10.2) ▪ 2016 (11.0) ▪ 2025 (14.3)
Text
Wolfram Research (2008), EntropyFilter, Wolfram Language function, https://reference.wolfram.com/language/ref/EntropyFilter.html (updated 2025).
CMS
Wolfram Language. 2008. "EntropyFilter." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2025. https://reference.wolfram.com/language/ref/EntropyFilter.html.
APA
Wolfram Language. (2008). EntropyFilter. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/EntropyFilter.html
BibTeX
@misc{reference.wolfram_2025_entropyfilter, author="Wolfram Research", title="{EntropyFilter}", year="2025", howpublished="\url{https://reference.wolfram.com/language/ref/EntropyFilter.html}", note=[Accessed: 13-August-2025]}
BibLaTeX
@online{reference.wolfram_2025_entropyfilter, organization={Wolfram Research}, title={EntropyFilter}, year={2025}, url={https://reference.wolfram.com/language/ref/EntropyFilter.html}, note=[Accessed: 13-August-2025]}