.. _`Corner detection`:

.. _`syip.corner_detection`:

Corner detection
~~~~~~~~~~~~~~~~

.. image:: image_corners.svg
   :width: 48


Detects corners in the incoming image

*Algorithms*:


  - `FAST`_

    Corner detection using the FAST (Feature from Accelerated Segment Test) method.

    **n:**
      Number of points out of 16 that should be all brighter ordarker than test point. (default 12)

    **threshold:**
      Threshold used in determining wheter the pixels are darker orbrighter (default 0.15).

      Decrease threshold when more corners are desired


  - `KR`_

    Compute Kitchen-Rosenfeld corner measure response image

    **k:**
      Value outside image borders when method constant is used.

    **border mode:**
      Method for handling values outside the borders


  - `ST`_

    Compute Shi-Tomasi (Kanade-Tomasi) corner measure responseimage. Uses information from auto-correlation matrix

    **sigma:**
      Standard deviation used for the Gaussian kernel, which is used as weighting function for the auto-correlation matrix.


  - `harris`_

    Compute corner harris response image.

    **harris method:**
      Method to compute response image from auto-correlationmatrix

    **k:**
      Sensitivity factor to separate corners from edges, typically in range [0, 0.2]. Small values of k result in detection of sharp corners.

    **eps:**
      Normalisation factor (Nobles corner measure)

    **sigma:**
      Standard deviation used for the Gaussian kernel, which is used as weighting function for the auto-correlation matrix.


  - `moravec`_

    Compute Moravec corner measure response image.



     This is one of the simplest corner detectors and is comparatively fast but has several limitations (e.g. not rotation invariant).

    **window size:**
      Size of window used during calculations


.. _FAST: http://scikit-image.org/docs/0.13.x/api/skimage.feature.html#skimage.feature.corner_fast
.. _KR: http://scikit-image.org/docs/0.13.x/api/skimage.feature.html#skimage.feature.corner_kitchen_rosenfeld
.. _ST: http://scikit-image.org/docs/0.13.x/api/skimage.feature.html#skimage.feature.corner_shi_tomasi
.. _harris: http://scikit-image.org/docs/0.13.x/api/skimage.feature.html#skimage.feature.corner_harris
.. _moravec: http://scikit-image.org/docs/0.13.x/api/skimage.feature.html#skimage.feature.corner_moravec

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

        source image to filter

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

        result after filtering



*Configuration*:
    **Algorithm** (algorithm)
        (no description)
    **border mode** (border mode)
        (no description)
    **eps** (eps)
        (no description)
    **harris method** (harris method)
        (no description)
    **k** (k)
        (no description)
    **n** (n)
        (no description)
    **sigma** (sigma)
        (no description)
    **threshold** (threshold)
        (no description)
    **window size** (window size)
        (no description)

.. automodule:: node_detection_filters

.. class:: CornerDetection