.. _regionremoval:

regionremoval
*************


**Syntax:** :code:`regionremoval(image, volume threshold, connectivity, allow multi-threading)`

Removes nonzero foreground regions smaller than given threshold. This command supports only binary images (where regions are separated by backround).

This command can be used in the distributed processing mode. Use :ref:`distribute` command to change processing mode from local to distributed.

Arguments
---------

image [input & output]
~~~~~~~~~~~~~~~~~~~~~~

**Data type:** uint8 image, uint16 image, uint32 image, uint64 image, int8 image, int16 image, int32 image, int64 image, float32 image

Image to process.

volume threshold [input]
~~~~~~~~~~~~~~~~~~~~~~~~

**Data type:** positive integer

**Default value:** 600

All nonzero regions consisting of less than this many pixels are removed.

connectivity [input]
~~~~~~~~~~~~~~~~~~~~

**Data type:** connectivity

**Default value:** Nearest

Connectivity of the particles. Can be Nearest for connectivity to nearest neighbours only, or All for connectivity to all neighbours.

allow multi-threading [input]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

**Data type:** boolean

**Default value:** True

Set to true to allow multi-threaded processing. Set to false to use single-threaded processing. Single-threaded processing is often faster if it is known in advance that there are only a few particles or if the image is small. This argument has no effect in the distributed processing mode. There, the processing is always multi-threaded.

See also
--------

:ref:`openingfilter`, :ref:`closingfilter`, :ref:`analyzeparticles`