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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.