EdgeExtraction - Edge Feature Extraction
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This application computes edge features on every pixel of the input image selected channel

Detailed description
--------------------

This application computes edge features on a selected channel of the input.It uses different filter such as gradient, Sobel and Touzi

Parameters
----------

This section describes in details the parameters available for this application. Table [#]_ presents a summary of these parameters and the parameters keys to be used in command-line and programming languages. Application key is *EdgeExtraction* .

.. [#] Table: Parameters table for Edge Feature Extraction.

+--------------------+----------------------------------+--------------------------+
|Parameter Key       |Parameter Name                    |Parameter Type            |
+====================+==================================+==========================+
|in                  |Input Image                       |Input image               |
+--------------------+----------------------------------+--------------------------+
|channel             |Selected Channel                  |Int                       |
+--------------------+----------------------------------+--------------------------+
|ram                 |Available RAM (Mb)                |Int                       |
+--------------------+----------------------------------+--------------------------+
|filter              |Edge feature                      |Choices                   |
+--------------------+----------------------------------+--------------------------+
|filter gradient     |Gradient                          | *Choice*                 |
+--------------------+----------------------------------+--------------------------+
|filter sobel        |Sobel                             | *Choice*                 |
+--------------------+----------------------------------+--------------------------+
|filter touzi        |Touzi                             | *Choice*                 |
+--------------------+----------------------------------+--------------------------+
|filter.touzi.xradius|The X radius of the neighborhood. |Int                       |
+--------------------+----------------------------------+--------------------------+
|filter.touzi.yradius|The Y radius of the neighborhood. |Int                       |
+--------------------+----------------------------------+--------------------------+
|out                 |Feature Output Image              |Output image              |
+--------------------+----------------------------------+--------------------------+
|inxml               |Load otb application from xml file|XML input parameters file |
+--------------------+----------------------------------+--------------------------+
|outxml              |Save otb application to xml file  |XML output parameters file|
+--------------------+----------------------------------+--------------------------+

**Input Image**: The input image on which the features are computed.

**Selected Channel**: The selected channel index.

**Available RAM (Mb)**: Available memory for processing (in MB).

**Edge feature**: Choice of edge feature. Available choices are: 

- **Gradient**: This filter computes the gradient magnitude of the image at each pixel.
- **Sobel**: This filter uses the Sobel operator to calculate the image gradient and then finds the magnitude of this gradient vector.
- **Touzi**: This filter is more suited for radar images. It has a spatial parameter to avoid speckle noise perturbations. The larger the radius is, less sensible to the speckle noise the filter is, but micro edge will be missed.

 * **The X radius of the neighborhood.**
 * **The Y radius of the neighborhood.**


**Feature Output Image**: Output image containing the edge features.

**Load otb application from xml file**: Load otb application from xml file.

**Save otb application to xml file**: Save otb application to xml file.



Example
-------

To run this example in command-line, use the following: 
::

	otbcli_EdgeExtraction -in qb_RoadExtract.tif -channel 1 -out Edges.tif

To run this example from Python, use the following code snippet: 

::

	#!/usr/bin/python

	# Import the otb applications package
	import otbApplication

	# The following line creates an instance of the EdgeExtraction application 
	EdgeExtraction = otbApplication.Registry.CreateApplication("EdgeExtraction")

	# The following lines set all the application parameters:
	EdgeExtraction.SetParameterString("in", "qb_RoadExtract.tif")

	EdgeExtraction.SetParameterInt("channel", 1)

	EdgeExtraction.SetParameterString("out", "Edges.tif")

	# The following line execute the application
	EdgeExtraction.ExecuteAndWriteOutput()

Limitations
~~~~~~~~~~~

None

Authors
~~~~~~~

This application has been written by OTB-Team.

See Also
~~~~~~~~

These additional resources can be useful for further information: 
  | otb class