BandMath - Band Math
^^^^^^^^^^^^^^^^^^^^

Outputs a monoband image which is the result of a mathematical operation on several multi-band images.

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

This application performs a mathematical operation on several multi-band images and outputs the result into a monoband image. Evaluation of the mathematical formula is done by the muParser libraries.

muParser version superior to 2.0, provides the '&&' and '||' logical operators, and a ternary operator 'boolean_expression ? if_true : if_false'.

Older versions of muParser (prior to v-2.0) provides only the 'and' and 'or' logical operators, and a ternary operator 'if(; ; )'.

The list of features and operators is available on the muParser website [1].

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 *BandMath* .

.. [#] Table: Parameters table for Band Math.

+-------------+----------------------------------+--------------------------+
|Parameter Key|Parameter Name                    |Parameter Type            |
+=============+==================================+==========================+
|il           |Input image-list                  |Input image list          |
+-------------+----------------------------------+--------------------------+
|out          |Output Image                      |Output image              |
+-------------+----------------------------------+--------------------------+
|ram          |Available RAM (Mb)                |Int                       |
+-------------+----------------------------------+--------------------------+
|exp          |Expression                        |String                    |
+-------------+----------------------------------+--------------------------+
|inxml        |Load otb application from xml file|XML input parameters file |
+-------------+----------------------------------+--------------------------+
|outxml       |Save otb application to xml file  |XML output parameters file|
+-------------+----------------------------------+--------------------------+

- **Input image-list**: Image-list of operands to the mathematical expression.
- **Output Image**: Output image which is the result of the mathematical expressions on input image-list operands.
- **Available RAM (Mb)**: Available memory for processing (in MB).
- **Expression**: The muParser mathematical expression to apply on input images. Use im1b1 as first band of first image, im1b2 for the second band of first image. Use im2b1 as first band of second image, im2b2 for the second band of second image. etc.
- **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_BandMath -il verySmallFSATSW_r.tif verySmallFSATSW_nir.tif verySmallFSATSW.tif -out apTvUtBandMathOutput.tif -exp 'cos( im1b1 ) > cos( im2b1 ) ? im3b1 : im3b2'

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 BandMath application 
	BandMath = otbApplication.Registry.CreateApplication("BandMath")

	# The following lines set all the application parameters:
	BandMath.SetParameterStringList("il", ['verySmallFSATSW_r.tif', 'verySmallFSATSW_nir.tif', 'verySmallFSATSW.tif'])

	BandMath.SetParameterString("out", "apTvUtBandMathOutput.tif")

	BandMath.SetParameterString("exp", "'cos( im1b1 ) > cos( im2b1 ) ? im3b1 : im3b2'")

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

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

None

Authors
~~~~~~~

This application has been written by OTB-Team.

See Also
~~~~~~~~

These additional resources can be useful for further information: 
  | [1] http://muparser.sourceforge.net/