.. _`Threshold image`:

.. _`syip.threshold`:

Threshold image
~~~~~~~~~~~~~~~

.. image:: image_threshold.svg
   :width: 48


Applies a threshold to an image giving a boolean output

*Algorithms*:


  - `adaptive`_

    Applies an adaptive threshold to an array.



    Also known as local or dynamic thresholding where the threshold value is the weighted mean for the local neighborhood of a pixel subtracted by a constant.

    **threshold method:**
      Method used for calculating adaptive threshold

    **kernel size:**
      Size of blocks used during threshold check.

      Must be an odd number. (default 3)

    **offset:**
      Constant subtracted from weighted mean of neighborhood to calculate the local threshold value. (default 0.0)

    **sigma:**
      Standard deviation of gaussian kernel when method gaussian is used.


  - `automatic`_

    Performs global thresholding based a selection of automatic algorithms with none or few parameters

    **auto threshold method:**
      Method used for calculating threshold


  - *basic*

    Compares each channel with a threshold

    **threshold:**
      Threshold value to compare with


.. _adaptive: http://scikit-image.org/docs/0.13.x/api/skimage.filters.html#skimage.filters.threshold_local
.. _automatic: http://scikit-image.org/docs/0.13.x/api/skimage.filters.html

*Input ports*:
    **source** : image

        source image to filter

*Output ports*:
    **result** : image

        result after filtering



*Configuration*:
    **Algorithm** (algorithm)
        (no description)
    **threshold method** (threshold method)
        (no description)
    **auto threshold method** (auto threshold method)
        (no description)
    **offset** (offset)
        (no description)
    **threshold** (threshold)
        (no description)
    **kernel size** (kernel size)
        (no description)
    **sigma** (sigma)
        (no description)

.. automodule:: node_threshold

.. class:: ThresholdImage