1 .. SPDX-License-Identifier: GFDL-1.1-no-invari 1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2 2
3 .. _image-source-controls: 3 .. _image-source-controls:
4 4
5 ****************************** 5 ******************************
6 Image Source Control Reference 6 Image Source Control Reference
7 ****************************** 7 ******************************
8 8
9 The Image Source control class is intended for 9 The Image Source control class is intended for low-level control of
10 image source devices such as image sensors. Th 10 image source devices such as image sensors. The devices feature an
11 analogue to digital converter and a bus transm 11 analogue to digital converter and a bus transmitter to transmit the
12 image data out of the device. 12 image data out of the device.
13 13
14 14
15 .. _image-source-control-id: 15 .. _image-source-control-id:
16 16
17 Image Source Control IDs 17 Image Source Control IDs
18 ======================== 18 ========================
19 19
20 ``V4L2_CID_IMAGE_SOURCE_CLASS (class)`` 20 ``V4L2_CID_IMAGE_SOURCE_CLASS (class)``
21 The IMAGE_SOURCE class descriptor. 21 The IMAGE_SOURCE class descriptor.
22 22
23 ``V4L2_CID_VBLANK (integer)`` 23 ``V4L2_CID_VBLANK (integer)``
24 Vertical blanking. The idle period after e 24 Vertical blanking. The idle period after every frame during which no
25 image data is produced. The unit of vertic 25 image data is produced. The unit of vertical blanking is a line.
26 Every line has length of the image width p 26 Every line has length of the image width plus horizontal blanking at
27 the pixel rate defined by ``V4L2_CID_PIXEL 27 the pixel rate defined by ``V4L2_CID_PIXEL_RATE`` control in the
28 same sub-device. 28 same sub-device.
29 29
30 ``V4L2_CID_HBLANK (integer)`` 30 ``V4L2_CID_HBLANK (integer)``
31 Horizontal blanking. The idle period after 31 Horizontal blanking. The idle period after every line of image data
32 during which no image data is produced. Th 32 during which no image data is produced. The unit of horizontal
33 blanking is pixels. 33 blanking is pixels.
34 34
35 ``V4L2_CID_ANALOGUE_GAIN (integer)`` 35 ``V4L2_CID_ANALOGUE_GAIN (integer)``
36 Analogue gain is gain affecting all colour 36 Analogue gain is gain affecting all colour components in the pixel
37 matrix. The gain operation is performed in 37 matrix. The gain operation is performed in the analogue domain
38 before A/D conversion. 38 before A/D conversion.
39 39
40 ``V4L2_CID_TEST_PATTERN_RED (integer)`` 40 ``V4L2_CID_TEST_PATTERN_RED (integer)``
41 Test pattern red colour component. 41 Test pattern red colour component.
42 42
43 ``V4L2_CID_TEST_PATTERN_GREENR (integer)`` 43 ``V4L2_CID_TEST_PATTERN_GREENR (integer)``
44 Test pattern green (next to red) colour co 44 Test pattern green (next to red) colour component.
45 45
46 ``V4L2_CID_TEST_PATTERN_BLUE (integer)`` 46 ``V4L2_CID_TEST_PATTERN_BLUE (integer)``
47 Test pattern blue colour component. 47 Test pattern blue colour component.
48 48
49 ``V4L2_CID_TEST_PATTERN_GREENB (integer)`` 49 ``V4L2_CID_TEST_PATTERN_GREENB (integer)``
50 Test pattern green (next to blue) colour c 50 Test pattern green (next to blue) colour component.
51 51
52 ``V4L2_CID_UNIT_CELL_SIZE (struct)`` 52 ``V4L2_CID_UNIT_CELL_SIZE (struct)``
53 This control returns the unit cell size in 53 This control returns the unit cell size in nanometers. The struct
54 :c:type:`v4l2_area` provides the width and 54 :c:type:`v4l2_area` provides the width and the height in separate
55 fields to take into consideration asymmetr 55 fields to take into consideration asymmetric pixels.
56 This control does not take into considerat 56 This control does not take into consideration any possible hardware
57 binning. 57 binning.
58 The unit cell consists of the whole area o 58 The unit cell consists of the whole area of the pixel, sensitive and
59 non-sensitive. 59 non-sensitive.
60 This control is required for automatic cal 60 This control is required for automatic calibration of sensors/cameras.
61 61
62 .. c:type:: v4l2_area 62 .. c:type:: v4l2_area
63 63
64 .. flat-table:: struct v4l2_area 64 .. flat-table:: struct v4l2_area
65 :header-rows: 0 65 :header-rows: 0
66 :stub-columns: 0 66 :stub-columns: 0
67 :widths: 1 1 2 67 :widths: 1 1 2
68 68
69 * - __u32 69 * - __u32
70 - ``width`` 70 - ``width``
71 - Width of the area. 71 - Width of the area.
72 * - __u32 72 * - __u32
73 - ``height`` 73 - ``height``
74 - Height of the area. 74 - Height of the area.
75 75
76 ``V4L2_CID_NOTIFY_GAINS (integer array)`` 76 ``V4L2_CID_NOTIFY_GAINS (integer array)``
77 The sensor is notified what gains will be 77 The sensor is notified what gains will be applied to the different
78 colour channels by subsequent processing ( 78 colour channels by subsequent processing (such as by an ISP). The
79 sensor is merely informed of these values 79 sensor is merely informed of these values in case it performs
80 processing that requires them, but it does 80 processing that requires them, but it does not apply them itself to
81 the output pixels. 81 the output pixels.
82 82
83 Currently it is defined only for Bayer sen 83 Currently it is defined only for Bayer sensors, and is an array
84 control taking 4 gain values, being the ga 84 control taking 4 gain values, being the gains for each of the
85 Bayer channels. The gains are always in th 85 Bayer channels. The gains are always in the order B, Gb, Gr and R,
86 irrespective of the exact Bayer order of t 86 irrespective of the exact Bayer order of the sensor itself.
87 87
88 The use of an array allows this control to 88 The use of an array allows this control to be extended to sensors
89 with, for example, non-Bayer CFAs (colour 89 with, for example, non-Bayer CFAs (colour filter arrays).
90 90
91 The units for the gain values are linear, 91 The units for the gain values are linear, with the default value
92 representing a gain of exactly 1.0. For ex 92 representing a gain of exactly 1.0. For example, if this default value
93 is reported as being (say) 128, then a val 93 is reported as being (say) 128, then a value of 192 would represent
94 a gain of exactly 1.5. 94 a gain of exactly 1.5.
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