.. _ComputeImagesStatistics: 

ComputeImagesStatistics
=======================





Computes global mean and standard deviation for each band from a set of images and optionally saves the results in an XML file.

Description
-----------

This application computes a global mean and standard deviation for each band of a set of images and optionally saves the results in an XML file. The output XML is intended to be used as an input for the :ref:`TrainImagesClassifier` application to normalize samples before learning. You can also normalize the image with the XML file in the :ref:`ImageClassifier` application.



Parameters
----------

.. contents:: :local:

.. |br| raw:: html

   <br />

.. |em| raw:: html

   &emsp;

**Input images** :code:`-il image1 image2...` *Mandatory* |br|
List of input image filenames.

**Background Value** :code:`-bv float` |br|
Background value to ignore in computation of statistics.

Optional outputs
^^^^^^^^^^^^^^^^





**Output XML file** :code:`-out.xml filename [dtype]` |br|
XML filename where the statistics are saved for future reuse.

**Mean pixel Value** :code:`-out.mean string` |br|
Mean pixel value.

**Min pixel Value** :code:`-out.min string` |br|
Minimum pixel value.

**Max pixel Value** :code:`-out.max string` |br|
Maximum pixel value.

**Standard deviation of pixel Value** :code:`-out.std string` |br|
Standard deviation of pixel value.



------------

**Available RAM (MB)** :code:`-ram int` *Default value: 256* |br|
Available memory for processing (in MB).



Examples
--------

From the command-line:

.. code-block:: bash

    otbcli_ComputeImagesStatistics -il QB_1_ortho.tif -out.xml EstimateImageStatisticsQB1.xml


From Python:

.. code-block:: python

	import otbApplication

	app = otbApplication.Registry.CreateApplication("ComputeImagesStatistics")

	app.SetParameterStringList("il", ['QB_1_ortho.tif'])
	app.SetParameterString("out.xml", "EstimateImageStatisticsQB1.xml")

	app.ExecuteAndWriteOutput()



Limitations
-----------

Each image of the set must contain the same bands as the others (i.e. same types, in the same order).

See also
--------

| Documentation of the :ref:`TrainImagesClassifier` and :ref:`ImageClassifier` application.