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