1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2
3 .. _camera-controls:
4
5 ************************
6 Camera Control Reference
7 ************************
8
9 The Camera class includes controls for mechanical (or equivalent
10 digital) features of a device such as controllable lenses or sensors.
11
12
13 .. _camera-control-id:
14
15 Camera Control IDs
16 ==================
17
18 ``V4L2_CID_CAMERA_CLASS (class)``
19 The Camera class descriptor. Calling
20 :ref:`VIDIOC_QUERYCTRL` for this control will
21 return a description of this control class.
22
23 .. _v4l2-exposure-auto-type:
24
25 ``V4L2_CID_EXPOSURE_AUTO``
26 (enum)
27
28 enum v4l2_exposure_auto_type -
29 Enables automatic adjustments of the exposure time and/or iris
30 aperture. The effect of manual changes of the exposure time or iris
31 aperture while these features are enabled is undefined, drivers
32 should ignore such requests. Possible values are:
33
34
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36
37 .. flat-table::
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40
41 * - ``V4L2_EXPOSURE_AUTO``
42 - Automatic exposure time, automatic iris aperture.
43 * - ``V4L2_EXPOSURE_MANUAL``
44 - Manual exposure time, manual iris.
45 * - ``V4L2_EXPOSURE_SHUTTER_PRIORITY``
46 - Manual exposure time, auto iris.
47 * - ``V4L2_EXPOSURE_APERTURE_PRIORITY``
48 - Auto exposure time, manual iris.
49
50
51
52 ``V4L2_CID_EXPOSURE_ABSOLUTE (integer)``
53 Determines the exposure time of the camera sensor. The exposure time
54 is limited by the frame interval. Drivers should interpret the
55 values as 100 µs units, where the value 1 stands for 1/10000th of a
56 second, 10000 for 1 second and 100000 for 10 seconds.
57
58 ``V4L2_CID_EXPOSURE_AUTO_PRIORITY (boolean)``
59 When ``V4L2_CID_EXPOSURE_AUTO`` is set to ``AUTO`` or
60 ``APERTURE_PRIORITY``, this control determines if the device may
61 dynamically vary the frame rate. By default this feature is disabled
62 (0) and the frame rate must remain constant.
63
64 ``V4L2_CID_AUTO_EXPOSURE_BIAS (integer menu)``
65 Determines the automatic exposure compensation, it is effective only
66 when ``V4L2_CID_EXPOSURE_AUTO`` control is set to ``AUTO``,
67 ``SHUTTER_PRIORITY`` or ``APERTURE_PRIORITY``. It is expressed in
68 terms of EV, drivers should interpret the values as 0.001 EV units,
69 where the value 1000 stands for +1 EV.
70
71 Increasing the exposure compensation value is equivalent to
72 decreasing the exposure value (EV) and will increase the amount of
73 light at the image sensor. The camera performs the exposure
74 compensation by adjusting absolute exposure time and/or aperture.
75
76 .. _v4l2-exposure-metering:
77
78 ``V4L2_CID_EXPOSURE_METERING``
79 (enum)
80
81 enum v4l2_exposure_metering -
82 Determines how the camera measures the amount of light available for
83 the frame exposure. Possible values are:
84
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90
91 * - ``V4L2_EXPOSURE_METERING_AVERAGE``
92 - Use the light information coming from the entire frame and average
93 giving no weighting to any particular portion of the metered area.
94 * - ``V4L2_EXPOSURE_METERING_CENTER_WEIGHTED``
95 - Average the light information coming from the entire frame giving
96 priority to the center of the metered area.
97 * - ``V4L2_EXPOSURE_METERING_SPOT``
98 - Measure only very small area at the center of the frame.
99 * - ``V4L2_EXPOSURE_METERING_MATRIX``
100 - A multi-zone metering. The light intensity is measured in several
101 points of the frame and the results are combined. The algorithm of
102 the zones selection and their significance in calculating the
103 final value is device dependent.
104
105
106
107 ``V4L2_CID_PAN_RELATIVE (integer)``
108 This control turns the camera horizontally by the specified amount.
109 The unit is undefined. A positive value moves the camera to the
110 right (clockwise when viewed from above), a negative value to the
111 left. A value of zero does not cause motion. This is a write-only
112 control.
113
114 ``V4L2_CID_TILT_RELATIVE (integer)``
115 This control turns the camera vertically by the specified amount.
116 The unit is undefined. A positive value moves the camera up, a
117 negative value down. A value of zero does not cause motion. This is
118 a write-only control.
119
120 ``V4L2_CID_PAN_RESET (button)``
121 When this control is set, the camera moves horizontally to the
122 default position.
123
124 ``V4L2_CID_TILT_RESET (button)``
125 When this control is set, the camera moves vertically to the default
126 position.
127
128 ``V4L2_CID_PAN_ABSOLUTE (integer)``
129 This control turns the camera horizontally to the specified
130 position. Positive values move the camera to the right (clockwise
131 when viewed from above), negative values to the left. Drivers should
132 interpret the values as arc seconds, with valid values between -180
133 * 3600 and +180 * 3600 inclusive.
134
135 ``V4L2_CID_TILT_ABSOLUTE (integer)``
136 This control turns the camera vertically to the specified position.
137 Positive values move the camera up, negative values down. Drivers
138 should interpret the values as arc seconds, with valid values
139 between -180 * 3600 and +180 * 3600 inclusive.
140
141 ``V4L2_CID_FOCUS_ABSOLUTE (integer)``
142 This control sets the focal point of the camera to the specified
143 position. The unit is undefined. Positive values set the focus
144 closer to the camera, negative values towards infinity.
145
146 ``V4L2_CID_FOCUS_RELATIVE (integer)``
147 This control moves the focal point of the camera by the specified
148 amount. The unit is undefined. Positive values move the focus closer
149 to the camera, negative values towards infinity. This is a
150 write-only control.
151
152 ``V4L2_CID_FOCUS_AUTO (boolean)``
153 Enables continuous automatic focus adjustments. The effect of manual
154 focus adjustments while this feature is enabled is undefined,
155 drivers should ignore such requests.
156
157 ``V4L2_CID_AUTO_FOCUS_START (button)``
158 Starts single auto focus process. The effect of setting this control
159 when ``V4L2_CID_FOCUS_AUTO`` is set to ``TRUE`` (1) is undefined,
160 drivers should ignore such requests.
161
162 ``V4L2_CID_AUTO_FOCUS_STOP (button)``
163 Aborts automatic focusing started with ``V4L2_CID_AUTO_FOCUS_START``
164 control. It is effective only when the continuous autofocus is
165 disabled, that is when ``V4L2_CID_FOCUS_AUTO`` control is set to
166 ``FALSE`` (0).
167
168 .. _v4l2-auto-focus-status:
169
170 ``V4L2_CID_AUTO_FOCUS_STATUS (bitmask)``
171 The automatic focus status. This is a read-only control.
172
173 Setting ``V4L2_LOCK_FOCUS`` lock bit of the ``V4L2_CID_3A_LOCK``
174 control may stop updates of the ``V4L2_CID_AUTO_FOCUS_STATUS``
175 control value.
176
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182
183 * - ``V4L2_AUTO_FOCUS_STATUS_IDLE``
184 - Automatic focus is not active.
185 * - ``V4L2_AUTO_FOCUS_STATUS_BUSY``
186 - Automatic focusing is in progress.
187 * - ``V4L2_AUTO_FOCUS_STATUS_REACHED``
188 - Focus has been reached.
189 * - ``V4L2_AUTO_FOCUS_STATUS_FAILED``
190 - Automatic focus has failed, the driver will not transition from
191 this state until another action is performed by an application.
192
193
194
195 .. _v4l2-auto-focus-range:
196
197 ``V4L2_CID_AUTO_FOCUS_RANGE``
198 (enum)
199
200 enum v4l2_auto_focus_range -
201 Determines auto focus distance range for which lens may be adjusted.
202
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208
209 * - ``V4L2_AUTO_FOCUS_RANGE_AUTO``
210 - The camera automatically selects the focus range.
211 * - ``V4L2_AUTO_FOCUS_RANGE_NORMAL``
212 - Normal distance range, limited for best automatic focus
213 performance.
214 * - ``V4L2_AUTO_FOCUS_RANGE_MACRO``
215 - Macro (close-up) auto focus. The camera will use its minimum
216 possible distance for auto focus.
217 * - ``V4L2_AUTO_FOCUS_RANGE_INFINITY``
218 - The lens is set to focus on an object at infinite distance.
219
220
221
222 ``V4L2_CID_ZOOM_ABSOLUTE (integer)``
223 Specify the objective lens focal length as an absolute value. The
224 zoom unit is driver-specific and its value should be a positive
225 integer.
226
227 ``V4L2_CID_ZOOM_RELATIVE (integer)``
228 Specify the objective lens focal length relatively to the current
229 value. Positive values move the zoom lens group towards the
230 telephoto direction, negative values towards the wide-angle
231 direction. The zoom unit is driver-specific. This is a write-only
232 control.
233
234 ``V4L2_CID_ZOOM_CONTINUOUS (integer)``
235 Move the objective lens group at the specified speed until it
236 reaches physical device limits or until an explicit request to stop
237 the movement. A positive value moves the zoom lens group towards the
238 telephoto direction. A value of zero stops the zoom lens group
239 movement. A negative value moves the zoom lens group towards the
240 wide-angle direction. The zoom speed unit is driver-specific.
241
242 ``V4L2_CID_IRIS_ABSOLUTE (integer)``
243 This control sets the camera's aperture to the specified value. The
244 unit is undefined. Larger values open the iris wider, smaller values
245 close it.
246
247 ``V4L2_CID_IRIS_RELATIVE (integer)``
248 This control modifies the camera's aperture by the specified amount.
249 The unit is undefined. Positive values open the iris one step
250 further, negative values close it one step further. This is a
251 write-only control.
252
253 ``V4L2_CID_PRIVACY (boolean)``
254 Prevent video from being acquired by the camera. When this control
255 is set to ``TRUE`` (1), no image can be captured by the camera.
256 Common means to enforce privacy are mechanical obturation of the
257 sensor and firmware image processing, but the device is not
258 restricted to these methods. Devices that implement the privacy
259 control must support read access and may support write access.
260
261 ``V4L2_CID_BAND_STOP_FILTER (integer)``
262 Switch the band-stop filter of a camera sensor on or off, or specify
263 its strength. Such band-stop filters can be used, for example, to
264 filter out the fluorescent light component.
265
266 .. _v4l2-auto-n-preset-white-balance:
267
268 ``V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE``
269 (enum)
270
271 enum v4l2_auto_n_preset_white_balance -
272 Sets white balance to automatic, manual or a preset. The presets
273 determine color temperature of the light as a hint to the camera for
274 white balance adjustments resulting in most accurate color
275 representation. The following white balance presets are listed in
276 order of increasing color temperature.
277
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283
284 * - ``V4L2_WHITE_BALANCE_MANUAL``
285 - Manual white balance.
286 * - ``V4L2_WHITE_BALANCE_AUTO``
287 - Automatic white balance adjustments.
288 * - ``V4L2_WHITE_BALANCE_INCANDESCENT``
289 - White balance setting for incandescent (tungsten) lighting. It
290 generally cools down the colors and corresponds approximately to
291 2500...3500 K color temperature range.
292 * - ``V4L2_WHITE_BALANCE_FLUORESCENT``
293 - White balance preset for fluorescent lighting. It corresponds
294 approximately to 4000...5000 K color temperature.
295 * - ``V4L2_WHITE_BALANCE_FLUORESCENT_H``
296 - With this setting the camera will compensate for fluorescent H
297 lighting.
298 * - ``V4L2_WHITE_BALANCE_HORIZON``
299 - White balance setting for horizon daylight. It corresponds
300 approximately to 5000 K color temperature.
301 * - ``V4L2_WHITE_BALANCE_DAYLIGHT``
302 - White balance preset for daylight (with clear sky). It corresponds
303 approximately to 5000...6500 K color temperature.
304 * - ``V4L2_WHITE_BALANCE_FLASH``
305 - With this setting the camera will compensate for the flash light.
306 It slightly warms up the colors and corresponds roughly to
307 5000...5500 K color temperature.
308 * - ``V4L2_WHITE_BALANCE_CLOUDY``
309 - White balance preset for moderately overcast sky. This option
310 corresponds approximately to 6500...8000 K color temperature
311 range.
312 * - ``V4L2_WHITE_BALANCE_SHADE``
313 - White balance preset for shade or heavily overcast sky. It
314 corresponds approximately to 9000...10000 K color temperature.
315
316
317
318 .. _v4l2-wide-dynamic-range:
319
320 ``V4L2_CID_WIDE_DYNAMIC_RANGE (boolean)``
321 Enables or disables the camera's wide dynamic range feature. This
322 feature allows to obtain clear images in situations where intensity
323 of the illumination varies significantly throughout the scene, i.e.
324 there are simultaneously very dark and very bright areas. It is most
325 commonly realized in cameras by combining two subsequent frames with
326 different exposure times. [#f1]_
327
328 .. _v4l2-image-stabilization:
329
330 ``V4L2_CID_IMAGE_STABILIZATION (boolean)``
331 Enables or disables image stabilization.
332
333 ``V4L2_CID_ISO_SENSITIVITY (integer menu)``
334 Determines ISO equivalent of an image sensor indicating the sensor's
335 sensitivity to light. The numbers are expressed in arithmetic scale,
336 as per :ref:`iso12232` standard, where doubling the sensor
337 sensitivity is represented by doubling the numerical ISO value.
338 Applications should interpret the values as standard ISO values
339 multiplied by 1000, e.g. control value 800 stands for ISO 0.8.
340 Drivers will usually support only a subset of standard ISO values.
341 The effect of setting this control while the
342 ``V4L2_CID_ISO_SENSITIVITY_AUTO`` control is set to a value other
343 than ``V4L2_CID_ISO_SENSITIVITY_MANUAL`` is undefined, drivers
344 should ignore such requests.
345
346 .. _v4l2-iso-sensitivity-auto-type:
347
348 ``V4L2_CID_ISO_SENSITIVITY_AUTO``
349 (enum)
350
351 enum v4l2_iso_sensitivity_type -
352 Enables or disables automatic ISO sensitivity adjustments.
353
354
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359
360 * - ``V4L2_CID_ISO_SENSITIVITY_MANUAL``
361 - Manual ISO sensitivity.
362 * - ``V4L2_CID_ISO_SENSITIVITY_AUTO``
363 - Automatic ISO sensitivity adjustments.
364
365
366
367 .. _v4l2-scene-mode:
368
369 ``V4L2_CID_SCENE_MODE``
370 (enum)
371
372 enum v4l2_scene_mode -
373 This control allows to select scene programs as the camera automatic
374 modes optimized for common shooting scenes. Within these modes the
375 camera determines best exposure, aperture, focusing, light metering,
376 white balance and equivalent sensitivity. The controls of those
377 parameters are influenced by the scene mode control. An exact
378 behavior in each mode is subject to the camera specification.
379
380 When the scene mode feature is not used, this control should be set
381 to ``V4L2_SCENE_MODE_NONE`` to make sure the other possibly related
382 controls are accessible. The following scene programs are defined:
383
384 .. raw:: latex
385
386 \small
387
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390 .. cssclass:: longtable
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395
396 * - ``V4L2_SCENE_MODE_NONE``
397 - The scene mode feature is disabled.
398 * - ``V4L2_SCENE_MODE_BACKLIGHT``
399 - Backlight. Compensates for dark shadows when light is coming from
400 behind a subject, also by automatically turning on the flash.
401 * - ``V4L2_SCENE_MODE_BEACH_SNOW``
402 - Beach and snow. This mode compensates for all-white or bright
403 scenes, which tend to look gray and low contrast, when camera's
404 automatic exposure is based on an average scene brightness. To
405 compensate, this mode automatically slightly overexposes the
406 frames. The white balance may also be adjusted to compensate for
407 the fact that reflected snow looks bluish rather than white.
408 * - ``V4L2_SCENE_MODE_CANDLELIGHT``
409 - Candle light. The camera generally raises the ISO sensitivity and
410 lowers the shutter speed. This mode compensates for relatively
411 close subject in the scene. The flash is disabled in order to
412 preserve the ambiance of the light.
413 * - ``V4L2_SCENE_MODE_DAWN_DUSK``
414 - Dawn and dusk. Preserves the colors seen in low natural light
415 before dusk and after down. The camera may turn off the flash, and
416 automatically focus at infinity. It will usually boost saturation
417 and lower the shutter speed.
418 * - ``V4L2_SCENE_MODE_FALL_COLORS``
419 - Fall colors. Increases saturation and adjusts white balance for
420 color enhancement. Pictures of autumn leaves get saturated reds
421 and yellows.
422 * - ``V4L2_SCENE_MODE_FIREWORKS``
423 - Fireworks. Long exposure times are used to capture the expanding
424 burst of light from a firework. The camera may invoke image
425 stabilization.
426 * - ``V4L2_SCENE_MODE_LANDSCAPE``
427 - Landscape. The camera may choose a small aperture to provide deep
428 depth of field and long exposure duration to help capture detail
429 in dim light conditions. The focus is fixed at infinity. Suitable
430 for distant and wide scenery.
431 * - ``V4L2_SCENE_MODE_NIGHT``
432 - Night, also known as Night Landscape. Designed for low light
433 conditions, it preserves detail in the dark areas without blowing
434 out bright objects. The camera generally sets itself to a
435 medium-to-high ISO sensitivity, with a relatively long exposure
436 time, and turns flash off. As such, there will be increased image
437 noise and the possibility of blurred image.
438 * - ``V4L2_SCENE_MODE_PARTY_INDOOR``
439 - Party and indoor. Designed to capture indoor scenes that are lit
440 by indoor background lighting as well as the flash. The camera
441 usually increases ISO sensitivity, and adjusts exposure for the
442 low light conditions.
443 * - ``V4L2_SCENE_MODE_PORTRAIT``
444 - Portrait. The camera adjusts the aperture so that the depth of
445 field is reduced, which helps to isolate the subject against a
446 smooth background. Most cameras recognize the presence of faces in
447 the scene and focus on them. The color hue is adjusted to enhance
448 skin tones. The intensity of the flash is often reduced.
449 * - ``V4L2_SCENE_MODE_SPORTS``
450 - Sports. Significantly increases ISO and uses a fast shutter speed
451 to freeze motion of rapidly-moving subjects. Increased image noise
452 may be seen in this mode.
453 * - ``V4L2_SCENE_MODE_SUNSET``
454 - Sunset. Preserves deep hues seen in sunsets and sunrises. It bumps
455 up the saturation.
456 * - ``V4L2_SCENE_MODE_TEXT``
457 - Text. It applies extra contrast and sharpness, it is typically a
458 black-and-white mode optimized for readability. Automatic focus
459 may be switched to close-up mode and this setting may also involve
460 some lens-distortion correction.
461
462 .. raw:: latex
463
464 \normalsize
465
466
467 ``V4L2_CID_3A_LOCK (bitmask)``
468 This control locks or unlocks the automatic focus, exposure and
469 white balance. The automatic adjustments can be paused independently
470 by setting the corresponding lock bit to 1. The camera then retains
471 the settings until the lock bit is cleared. The following lock bits
472 are defined:
473
474 When a given algorithm is not enabled, drivers should ignore
475 requests to lock it and should return no error. An example might be
476 an application setting bit ``V4L2_LOCK_WHITE_BALANCE`` when the
477 ``V4L2_CID_AUTO_WHITE_BALANCE`` control is set to ``FALSE``. The
478 value of this control may be changed by exposure, white balance or
479 focus controls.
480
481
482
483 .. flat-table::
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486
487 * - ``V4L2_LOCK_EXPOSURE``
488 - Automatic exposure adjustments lock.
489 * - ``V4L2_LOCK_WHITE_BALANCE``
490 - Automatic white balance adjustments lock.
491 * - ``V4L2_LOCK_FOCUS``
492 - Automatic focus lock.
493
494
495
496 ``V4L2_CID_PAN_SPEED (integer)``
497 This control turns the camera horizontally at the specific speed.
498 The unit is undefined. A positive value moves the camera to the
499 right (clockwise when viewed from above), a negative value to the
500 left. A value of zero stops the motion if one is in progress and has
501 no effect otherwise.
502
503 ``V4L2_CID_TILT_SPEED (integer)``
504 This control turns the camera vertically at the specified speed. The
505 unit is undefined. A positive value moves the camera up, a negative
506 value down. A value of zero stops the motion if one is in progress
507 and has no effect otherwise.
508
509 .. _v4l2-camera-sensor-orientation:
510
511 ``V4L2_CID_CAMERA_ORIENTATION (menu)``
512 This read-only control describes the camera orientation by reporting its
513 mounting position on the device where the camera is installed. The control
514 value is constant and not modifiable by software. This control is
515 particularly meaningful for devices which have a well defined orientation,
516 such as phones, laptops and portable devices since the control is expressed
517 as a position relative to the device's intended usage orientation. For
518 example, a camera installed on the user-facing side of a phone, a tablet or
519 a laptop device is said to be have ``V4L2_CAMERA_ORIENTATION_FRONT``
520 orientation, while a camera installed on the opposite side of the front one
521 is said to be have ``V4L2_CAMERA_ORIENTATION_BACK`` orientation. Camera
522 sensors not directly attached to the device, or attached in a way that
523 allows them to move freely, such as webcams and digital cameras, are said to
524 have the ``V4L2_CAMERA_ORIENTATION_EXTERNAL`` orientation.
525
526
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532
533 * - ``V4L2_CAMERA_ORIENTATION_FRONT``
534 - The camera is oriented towards the user facing side of the device.
535 * - ``V4L2_CAMERA_ORIENTATION_BACK``
536 - The camera is oriented towards the back facing side of the device.
537 * - ``V4L2_CAMERA_ORIENTATION_EXTERNAL``
538 - The camera is not directly attached to the device and is freely movable.
539
540
541 .. _v4l2-camera-sensor-rotation:
542
543 ``V4L2_CID_CAMERA_SENSOR_ROTATION (integer)``
544 This read-only control describes the rotation correction in degrees in the
545 counter-clockwise direction to be applied to the captured images once
546 captured to memory to compensate for the camera sensor mounting rotation.
547
548 For a precise definition of the sensor mounting rotation refer to the
549 extensive description of the 'rotation' properties in the device tree
550 bindings file 'video-interfaces.txt'.
551
552 A few examples are below reported, using a shark swimming from left to
553 right in front of the user as the example scene to capture. ::
554
555 0 X-axis
556 0 +------------------------------------->
557 !
558 !
559 !
560 ! |\____)\___
561 ! ) _____ __`<
562 ! |/ )/
563 !
564 !
565 !
566 V
567 Y-axis
568
569 Example one - Webcam
570
571 Assuming you can bring your laptop with you while swimming with sharks,
572 the camera module of the laptop is installed on the user facing part of a
573 laptop screen casing, and is typically used for video calls. The captured
574 images are meant to be displayed in landscape mode (width > height) on the
575 laptop screen.
576
577 The camera is typically mounted upside-down to compensate the lens optical
578 inversion effect. In this case the value of the
579 V4L2_CID_CAMERA_SENSOR_ROTATION control is 0, no rotation is required to
580 display images correctly to the user.
581
582 If the camera sensor is not mounted upside-down it is required to compensate
583 the lens optical inversion effect and the value of the
584 V4L2_CID_CAMERA_SENSOR_ROTATION control is 180 degrees, as images will
585 result rotated when captured to memory. ::
586
587 +--------------------------------------+
588 ! !
589 ! !
590 ! !
591 ! __/(_____/| !
592 ! >.___ ____ ( !
593 ! \( \| !
594 ! !
595 ! !
596 ! !
597 +--------------------------------------+
598
599 A software rotation correction of 180 degrees has to be applied to correctly
600 display the image on the user screen. ::
601
602 +--------------------------------------+
603 ! !
604 ! !
605 ! !
606 ! |\____)\___ !
607 ! ) _____ __`< !
608 ! |/ )/ !
609 ! !
610 ! !
611 ! !
612 +--------------------------------------+
613
614 Example two - Phone camera
615
616 It is more handy to go and swim with sharks with only your mobile phone
617 with you and take pictures with the camera that is installed on the back
618 side of the device, facing away from the user. The captured images are meant
619 to be displayed in portrait mode (height > width) to match the device screen
620 orientation and the device usage orientation used when taking the picture.
621
622 The camera sensor is typically mounted with its pixel array longer side
623 aligned to the device longer side, upside-down mounted to compensate for
624 the lens optical inversion effect.
625
626 The images once captured to memory will be rotated and the value of the
627 V4L2_CID_CAMERA_SENSOR_ROTATION will report a 90 degree rotation. ::
628
629
630 +-------------------------------------+
631 | _ _ |
632 | \ / |
633 | | | |
634 | | | |
635 | | > |
636 | < | |
637 | | | |
638 | . |
639 | V |
640 +-------------------------------------+
641
642 A correction of 90 degrees in counter-clockwise direction has to be
643 applied to correctly display the image in portrait mode on the device
644 screen. ::
645
646 +--------------------+
647 | |
648 | |
649 | |
650 | |
651 | |
652 | |
653 | |\____)\___ |
654 | ) _____ __`< |
655 | |/ )/ |
656 | |
657 | |
658 | |
659 | |
660 | |
661 +--------------------+
662
663
664 .. [#f1]
665 This control may be changed to a menu control in the future, if more
666 options are required.
667
668 ``V4L2_CID_HDR_SENSOR_MODE (menu)``
669 Change the sensor HDR mode. A HDR picture is obtained by merging two
670 captures of the same scene using two different exposure periods. HDR mode
671 describes the way these two captures are merged in the sensor.
672
673 As modes differ for each sensor, menu items are not standardized by this
674 control and are left to the programmer.
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