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+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+
+.. _image-source-controls:
+
+******************************
+Image Source Control Reference
+******************************
+
+The Image Source control class is intended for low-level control of
+image source devices such as image sensors. The devices feature an
+analogue to digital converter and a bus transmitter to transmit the
+image data out of the device.
+
+
+.. _image-source-control-id:
+
+Image Source Control IDs
+========================
+
+``V4L2_CID_IMAGE_SOURCE_CLASS (class)``
+    The IMAGE_SOURCE class descriptor.
+
+``V4L2_CID_VBLANK (integer)``
+    Vertical blanking. The idle period after every frame during which no
+    image data is produced. The unit of vertical blanking is a line.
+    Every line has length of the image width plus horizontal blanking at
+    the pixel rate defined by ``V4L2_CID_PIXEL_RATE`` control in the
+    same sub-device.
+
+``V4L2_CID_HBLANK (integer)``
+    Horizontal blanking. The idle period after every line of image data
+    during which no image data is produced. The unit of horizontal
+    blanking is pixels.
+
+``V4L2_CID_ANALOGUE_GAIN (integer)``
+    Analogue gain is gain affecting all colour components in the pixel
+    matrix. The gain operation is performed in the analogue domain
+    before A/D conversion.
+
+``V4L2_CID_TEST_PATTERN_RED (integer)``
+    Test pattern red colour component.
+
+``V4L2_CID_TEST_PATTERN_GREENR (integer)``
+    Test pattern green (next to red) colour component.
+
+``V4L2_CID_TEST_PATTERN_BLUE (integer)``
+    Test pattern blue colour component.
+
+``V4L2_CID_TEST_PATTERN_GREENB (integer)``
+    Test pattern green (next to blue) colour component.
+
+``V4L2_CID_UNIT_CELL_SIZE (struct)``
+    This control returns the unit cell size in nanometers. The struct
+    :c:type:`v4l2_area` provides the width and the height in separate
+    fields to take into consideration asymmetric pixels.
+    This control does not take into consideration any possible hardware
+    binning.
+    The unit cell consists of the whole area of the pixel, sensitive and
+    non-sensitive.
+    This control is required for automatic calibration of sensors/cameras.
+
+.. c:type:: v4l2_area
+
+.. flat-table:: struct v4l2_area
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - __u32
+      - ``width``
+      - Width of the area.
+    * - __u32
+      - ``height``
+      - Height of the area.
+
+``V4L2_CID_NOTIFY_GAINS (integer array)``
+    The sensor is notified what gains will be applied to the different
+    colour channels by subsequent processing (such as by an ISP). The
+    sensor is merely informed of these values in case it performs
+    processing that requires them, but it does not apply them itself to
+    the output pixels.
+
+    Currently it is defined only for Bayer sensors, and is an array
+    control taking 4 gain values, being the gains for each of the
+    Bayer channels. The gains are always in the order B, Gb, Gr and R,
+    irrespective of the exact Bayer order of the sensor itself.
+
+    The use of an array allows this control to be extended to sensors
+    with, for example, non-Bayer CFAs (colour filter arrays).
+
+    The units for the gain values are linear, with the default value
+    representing a gain of exactly 1.0. For example, if this default value
+    is reported as being (say) 128, then a value of 192 would represent
+    a gain of exactly 1.5.