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+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+
+.. _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.