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94 lines
3.3 KiB
94 lines
3.3 KiB
.. 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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