.. _`Color range conversion`:

.. _`syip.color_range_conversion`:

Color range conversion
~~~~~~~~~~~~~~~~~~~~~~

.. image:: image_color_range.svg
   :width: 48


Changes the range and distribution of values for all pixels

:Algorithms:


  - `adaptive histogram`_

    Improves contrast by stretching and equalizing the histogramin a sliding window over the image

    **bins:**
      Number of bins in computed histogram (default 256)

    **adaptive kernel size:**
      Size of the sliding window. Must evenly divide both image width and height.

    **sigma:**
      Clipping limit (normalized between 0 and 1). Higher values give more contrast. (default 1.0)


  - `gamma correction`_

    Applies the correction:  Vout = scale Vin^gamma

    Processes each channel separately

    **scale:**
      Constant scale factor applied after gamma correction

    **gamma:**
      Gamma factor applied to image.

      <1 increases intensities of mid-tones,

      >1 decreases intensities of mid-tones


  - `histogram equalization`_

    Improves contrast by stretching and equalizing the histogram

    **bins:**
      Number of bins in computed histogram (default 256)


  - `log correction`_

    Applies the correction:  Vout = scale log(1 + Vin)

    Processes each channel separately

    **scale:**
      Constant scale factor applied after gamma correction

    **inverse:**
      Perform inverse log-correction instead (default false):

      Vout = scale (2^Vin - 1)


  - `sigmoid`_

    Performs Sigmoid correction on input image. Also known as contrast adjustment.

    Vout = 1/(1+exp(gain*(cutoff-Vin)))

    Processes each channel separately

    **inverse:**
      Perform negative sigmoid correction instead (default false)

    **cutoff:**
      Shifts the characteristic curve for the sigmoid horizontally(default 0.5)

    **gain:**
      Gain of sigmoid, affects rise time of curve (default 10.0)


.. _adaptive histogram: http://scikit-image.org/docs/0.13.x/api/skimage.exposure.html#skimage.exposure.equalize_adapthist
.. _gamma correction: http://scikit-image.org/docs/0.13.x/api/skimage.exposure.html#skimage.exposure.adjust_gamma
.. _histogram equalization: http://scikit-image.org/docs/0.13.x/api/skimage.exposure.html#skimage.exposure.equalize_hist
.. _log correction: http://scikit-image.org/docs/0.13.x/api/skimage.exposure.html#skimage.exposure.adjust_log
.. _sigmoid: http://scikit-image.org/docs/0.13.x/api/skimage.exposure.html#skimage.exposure.adjust_sigmoid

:Inputs:
    **source** : image

        source image to filter

:Outputs:
    **result** : image

        result after filtering

*Ports*:

    **Inputs**:

        :source: image

            source image to filter

    **Outputs**:

        :result: image

            result after filtering

*Configuration*:

    **algorithm**
        (no description)
    **gamma**
        (no description)
    **inverse**
        (no description)
    **adaptive kernel size**
        (no description)
    **cutoff**
        (no description)
    **scale**
        (no description)
    **gain**
        (no description)
    **sigma**
        (no description)
    **bins**
        (no description)

.. automodule:: node_colors

.. class:: ColorRangeConversion