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+.. Permission is granted to copy, distribute and/or modify this
+.. document under the terms of the GNU Free Documentation License,
+.. Version 1.1 or any later version published by the Free Software
+.. Foundation, with no Invariant Sections, no Front-Cover Texts
+.. and no Back-Cover Texts. A copy of the license is included at
+.. Documentation/userspace-api/media/fdl-appendix.rst.
+..
+.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
+
+.. _image-process-controls:
+
+*******************************
+Image Process Control Reference
+*******************************
+
+The Image Process control class is intended for low-level control of
+image processing functions. Unlike ``V4L2_CID_IMAGE_SOURCE_CLASS``, the
+controls in this class affect processing the image, and do not control
+capturing of it.
+
+
+.. _image-process-control-id:
+
+Image Process Control IDs
+=========================
+
+``V4L2_CID_IMAGE_PROC_CLASS (class)``
+    The IMAGE_PROC class descriptor.
+
+``V4L2_CID_LINK_FREQ (integer menu)``
+    Data bus frequency. Together with the media bus pixel code, bus type
+    (clock cycles per sample), the data bus frequency defines the pixel
+    rate (``V4L2_CID_PIXEL_RATE``) in the pixel array (or possibly
+    elsewhere, if the device is not an image sensor). The frame rate can
+    be calculated from the pixel clock, image width and height and
+    horizontal and vertical blanking. While the pixel rate control may
+    be defined elsewhere than in the subdev containing the pixel array,
+    the frame rate cannot be obtained from that information. This is
+    because only on the pixel array it can be assumed that the vertical
+    and horizontal blanking information is exact: no other blanking is
+    allowed in the pixel array. The selection of frame rate is performed
+    by selecting the desired horizontal and vertical blanking. The unit
+    of this control is Hz.
+
+``V4L2_CID_PIXEL_RATE (64-bit integer)``
+    Pixel rate in the source pads of the subdev. This control is
+    read-only and its unit is pixels / second.
+
+``V4L2_CID_TEST_PATTERN (menu)``
+    Some capture/display/sensor devices have the capability to generate
+    test pattern images. These hardware specific test patterns can be
+    used to test if a device is working properly.
+
+``V4L2_CID_DEINTERLACING_MODE (menu)``
+    The video deinterlacing mode (such as Bob, Weave, ...). The menu items are
+    driver specific and are documented in :ref:`uapi-v4l-drivers`.
+
+``V4L2_CID_DIGITAL_GAIN (integer)``
+    Digital gain is the value by which all colour components
+    are multiplied by. Typically the digital gain applied is the
+    control value divided by e.g. 0x100, meaning that to get no
+    digital gain the control value needs to be 0x100. The no-gain
+    configuration is also typically the default.