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Properties
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Header
======

.. figure:: /images/compositing_introduction_header.png

   Compositing Specific Options.

Use Nodes
   Enables basic compositing set up with a :doc:`Render Layer Node </compositing/types/input/render_layers>`
   and a :doc:`Composite Node </compositing/types/output/composite>`.
Backdrop
   Enables the use of a backdrop using a :doc:`Viewer Node </compositing/types/output/viewer>`.

   Backdrop Channels
      See below.
Auto Render
   Re-render and composite changed layer when edits to the 3D scene are made.


Backdrop
========

.. admonition:: Reference
   :class: refbox

   | Panel:    :menuselection:`Properties editors --> Backdrop`

.. figure:: /images/compositing_introduction_backdrop.png
   :align: right

   Backdrop Options.

Backdrop Channels
   Set the image to be displayed with *Color*, *Color and Alpha*, or just *Alpha*.
Zoom
   Sets how big the backdrop image is.
Offset
   Change the screen space position of the backdrop,
   or click the *Move* button, or shortcut :kbd:`Alt-MMB` to manually move it.
Fit
   Automatically scales the backdrop to fit the size of the Node editor.


Performance
===========

.. admonition:: Reference
   :class: refbox

   | Panel:    :menuselection:`Properties editors --> Performance`

.. figure:: /images/compositing_introduction_performance.png
   :align: right

   Performance Settings.

This panel help you to tweak the performance of the compositor.

Render
   Sets the quality when doing the final render.
Edit
   Sets the quality when making edits.
Chunk Size
   Max size of a title (smaller values give a better distribution of multiple threads, but more overhead).
OpenCL
   This allows the use of an OpenCL platform to aid in rendering.
   Generally, this should be enabled unless your hardware does not have good OpenCL support.
Buffer Groups
   Enables buffering of group nodes to increase the speed at the cost of more memory.
Two Pass
   Use two pass execution during editing: first calculate fast nodes, the second pass calculate all nodes.
Viewer Border
   This allows to set an area of interest for the backdrop and preview.
   The border is started by :kbd:`Ctrl-B` and finished by selection of a rectangular area.
   :kbd:`Ctrl-Alt-B` discards the border back to a full preview.
   This is only a preview option, final compositing during a render ignores this border.
Highlight
   Highlights the nodes that are being calculated by the compositor.