1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2 3.. _camera-controls: 4 5************************ 6Camera Control Reference 7************************ 8 9The Camera class includes controls for mechanical (or equivalent 10digital) features of a device such as controllable lenses or sensors. 11 12 13.. _camera-control-id: 14 15Camera 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 28enum 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 35 36.. flat-table:: 37 :header-rows: 0 38 :stub-columns: 0 39 40 * - ``V4L2_EXPOSURE_AUTO`` 41 - Automatic exposure time, automatic iris aperture. 42 * - ``V4L2_EXPOSURE_MANUAL`` 43 - Manual exposure time, manual iris. 44 * - ``V4L2_EXPOSURE_SHUTTER_PRIORITY`` 45 - Manual exposure time, auto iris. 46 * - ``V4L2_EXPOSURE_APERTURE_PRIORITY`` 47 - Auto exposure time, manual iris. 48 49 50 51``V4L2_CID_EXPOSURE_ABSOLUTE (integer)`` 52 Determines the exposure time of the camera sensor. The exposure time 53 is limited by the frame interval. Drivers should interpret the 54 values as 100 µs units, where the value 1 stands for 1/10000th of a 55 second, 10000 for 1 second and 100000 for 10 seconds. 56 57``V4L2_CID_EXPOSURE_AUTO_PRIORITY (boolean)`` 58 When ``V4L2_CID_EXPOSURE_AUTO`` is set to ``AUTO`` or 59 ``APERTURE_PRIORITY``, this control determines if the device may 60 dynamically vary the frame rate. By default this feature is disabled 61 (0) and the frame rate must remain constant. 62 63``V4L2_CID_AUTO_EXPOSURE_BIAS (integer menu)`` 64 Determines the automatic exposure compensation, it is effective only 65 when ``V4L2_CID_EXPOSURE_AUTO`` control is set to ``AUTO``, 66 ``SHUTTER_PRIORITY`` or ``APERTURE_PRIORITY``. It is expressed in 67 terms of EV, drivers should interpret the values as 0.001 EV units, 68 where the value 1000 stands for +1 EV. 69 70 Increasing the exposure compensation value is equivalent to 71 decreasing the exposure value (EV) and will increase the amount of 72 light at the image sensor. The camera performs the exposure 73 compensation by adjusting absolute exposure time and/or aperture. 74 75.. _v4l2-exposure-metering: 76 77``V4L2_CID_EXPOSURE_METERING`` 78 (enum) 79 80enum v4l2_exposure_metering - 81 Determines how the camera measures the amount of light available for 82 the frame exposure. Possible values are: 83 84.. tabularcolumns:: |p{8.7cm}|p{8.8cm}| 85 86.. flat-table:: 87 :header-rows: 0 88 :stub-columns: 0 89 90 * - ``V4L2_EXPOSURE_METERING_AVERAGE`` 91 - Use the light information coming from the entire frame and average 92 giving no weighting to any particular portion of the metered area. 93 * - ``V4L2_EXPOSURE_METERING_CENTER_WEIGHTED`` 94 - Average the light information coming from the entire frame giving 95 priority to the center of the metered area. 96 * - ``V4L2_EXPOSURE_METERING_SPOT`` 97 - Measure only very small area at the center of the frame. 98 * - ``V4L2_EXPOSURE_METERING_MATRIX`` 99 - A multi-zone metering. The light intensity is measured in several 100 points of the frame and the results are combined. The algorithm of 101 the zones selection and their significance in calculating the 102 final value is device dependent. 103 104 105 106``V4L2_CID_PAN_RELATIVE (integer)`` 107 This control turns the camera horizontally by the specified amount. 108 The unit is undefined. A positive value moves the camera to the 109 right (clockwise when viewed from above), a negative value to the 110 left. A value of zero does not cause motion. This is a write-only 111 control. 112 113``V4L2_CID_TILT_RELATIVE (integer)`` 114 This control turns the camera vertically by the specified amount. 115 The unit is undefined. A positive value moves the camera up, a 116 negative value down. A value of zero does not cause motion. This is 117 a write-only control. 118 119``V4L2_CID_PAN_RESET (button)`` 120 When this control is set, the camera moves horizontally to the 121 default position. 122 123``V4L2_CID_TILT_RESET (button)`` 124 When this control is set, the camera moves vertically to the default 125 position. 126 127``V4L2_CID_PAN_ABSOLUTE (integer)`` 128 This control turns the camera horizontally to the specified 129 position. Positive values move the camera to the right (clockwise 130 when viewed from above), negative values to the left. Drivers should 131 interpret the values as arc seconds, with valid values between -180 132 * 3600 and +180 * 3600 inclusive. 133 134``V4L2_CID_TILT_ABSOLUTE (integer)`` 135 This control turns the camera vertically to the specified position. 136 Positive values move the camera up, negative values down. Drivers 137 should interpret the values as arc seconds, with valid values 138 between -180 * 3600 and +180 * 3600 inclusive. 139 140``V4L2_CID_FOCUS_ABSOLUTE (integer)`` 141 This control sets the focal point of the camera to the specified 142 position. The unit is undefined. Positive values set the focus 143 closer to the camera, negative values towards infinity. 144 145``V4L2_CID_FOCUS_RELATIVE (integer)`` 146 This control moves the focal point of the camera by the specified 147 amount. The unit is undefined. Positive values move the focus closer 148 to the camera, negative values towards infinity. This is a 149 write-only control. 150 151``V4L2_CID_FOCUS_AUTO (boolean)`` 152 Enables continuous automatic focus adjustments. The effect of manual 153 focus adjustments while this feature is enabled is undefined, 154 drivers should ignore such requests. 155 156``V4L2_CID_AUTO_FOCUS_START (button)`` 157 Starts single auto focus process. The effect of setting this control 158 when ``V4L2_CID_FOCUS_AUTO`` is set to ``TRUE`` (1) is undefined, 159 drivers should ignore such requests. 160 161``V4L2_CID_AUTO_FOCUS_STOP (button)`` 162 Aborts automatic focusing started with ``V4L2_CID_AUTO_FOCUS_START`` 163 control. It is effective only when the continuous autofocus is 164 disabled, that is when ``V4L2_CID_FOCUS_AUTO`` control is set to 165 ``FALSE`` (0). 166 167.. _v4l2-auto-focus-status: 168 169``V4L2_CID_AUTO_FOCUS_STATUS (bitmask)`` 170 The automatic focus status. This is a read-only control. 171 172 Setting ``V4L2_LOCK_FOCUS`` lock bit of the ``V4L2_CID_3A_LOCK`` 173 control may stop updates of the ``V4L2_CID_AUTO_FOCUS_STATUS`` 174 control value. 175 176.. tabularcolumns:: |p{6.7cm}|p{10.8cm}| 177 178.. flat-table:: 179 :header-rows: 0 180 :stub-columns: 0 181 182 * - ``V4L2_AUTO_FOCUS_STATUS_IDLE`` 183 - Automatic focus is not active. 184 * - ``V4L2_AUTO_FOCUS_STATUS_BUSY`` 185 - Automatic focusing is in progress. 186 * - ``V4L2_AUTO_FOCUS_STATUS_REACHED`` 187 - Focus has been reached. 188 * - ``V4L2_AUTO_FOCUS_STATUS_FAILED`` 189 - Automatic focus has failed, the driver will not transition from 190 this state until another action is performed by an application. 191 192 193 194.. _v4l2-auto-focus-range: 195 196``V4L2_CID_AUTO_FOCUS_RANGE`` 197 (enum) 198 199enum v4l2_auto_focus_range - 200 Determines auto focus distance range for which lens may be adjusted. 201 202.. tabularcolumns:: |p{6.8cm}|p{10.7cm}| 203 204.. flat-table:: 205 :header-rows: 0 206 :stub-columns: 0 207 208 * - ``V4L2_AUTO_FOCUS_RANGE_AUTO`` 209 - The camera automatically selects the focus range. 210 * - ``V4L2_AUTO_FOCUS_RANGE_NORMAL`` 211 - Normal distance range, limited for best automatic focus 212 performance. 213 * - ``V4L2_AUTO_FOCUS_RANGE_MACRO`` 214 - Macro (close-up) auto focus. The camera will use its minimum 215 possible distance for auto focus. 216 * - ``V4L2_AUTO_FOCUS_RANGE_INFINITY`` 217 - The lens is set to focus on an object at infinite distance. 218 219 220 221``V4L2_CID_ZOOM_ABSOLUTE (integer)`` 222 Specify the objective lens focal length as an absolute value. The 223 zoom unit is driver-specific and its value should be a positive 224 integer. 225 226``V4L2_CID_ZOOM_RELATIVE (integer)`` 227 Specify the objective lens focal length relatively to the current 228 value. Positive values move the zoom lens group towards the 229 telephoto direction, negative values towards the wide-angle 230 direction. The zoom unit is driver-specific. This is a write-only 231 control. 232 233``V4L2_CID_ZOOM_CONTINUOUS (integer)`` 234 Move the objective lens group at the specified speed until it 235 reaches physical device limits or until an explicit request to stop 236 the movement. A positive value moves the zoom lens group towards the 237 telephoto direction. A value of zero stops the zoom lens group 238 movement. A negative value moves the zoom lens group towards the 239 wide-angle direction. The zoom speed unit is driver-specific. 240 241``V4L2_CID_IRIS_ABSOLUTE (integer)`` 242 This control sets the camera's aperture to the specified value. The 243 unit is undefined. Larger values open the iris wider, smaller values 244 close it. 245 246``V4L2_CID_IRIS_RELATIVE (integer)`` 247 This control modifies the camera's aperture by the specified amount. 248 The unit is undefined. Positive values open the iris one step 249 further, negative values close it one step further. This is a 250 write-only control. 251 252``V4L2_CID_PRIVACY (boolean)`` 253 Prevent video from being acquired by the camera. When this control 254 is set to ``TRUE`` (1), no image can be captured by the camera. 255 Common means to enforce privacy are mechanical obturation of the 256 sensor and firmware image processing, but the device is not 257 restricted to these methods. Devices that implement the privacy 258 control must support read access and may support write access. 259 260``V4L2_CID_BAND_STOP_FILTER (integer)`` 261 Switch the band-stop filter of a camera sensor on or off, or specify 262 its strength. Such band-stop filters can be used, for example, to 263 filter out the fluorescent light component. 264 265.. _v4l2-auto-n-preset-white-balance: 266 267``V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE`` 268 (enum) 269 270enum v4l2_auto_n_preset_white_balance - 271 Sets white balance to automatic, manual or a preset. The presets 272 determine color temperature of the light as a hint to the camera for 273 white balance adjustments resulting in most accurate color 274 representation. The following white balance presets are listed in 275 order of increasing color temperature. 276 277.. tabularcolumns:: |p{7.2 cm}|p{10.3cm}| 278 279.. flat-table:: 280 :header-rows: 0 281 :stub-columns: 0 282 283 * - ``V4L2_WHITE_BALANCE_MANUAL`` 284 - Manual white balance. 285 * - ``V4L2_WHITE_BALANCE_AUTO`` 286 - Automatic white balance adjustments. 287 * - ``V4L2_WHITE_BALANCE_INCANDESCENT`` 288 - White balance setting for incandescent (tungsten) lighting. It 289 generally cools down the colors and corresponds approximately to 290 2500...3500 K color temperature range. 291 * - ``V4L2_WHITE_BALANCE_FLUORESCENT`` 292 - White balance preset for fluorescent lighting. It corresponds 293 approximately to 4000...5000 K color temperature. 294 * - ``V4L2_WHITE_BALANCE_FLUORESCENT_H`` 295 - With this setting the camera will compensate for fluorescent H 296 lighting. 297 * - ``V4L2_WHITE_BALANCE_HORIZON`` 298 - White balance setting for horizon daylight. It corresponds 299 approximately to 5000 K color temperature. 300 * - ``V4L2_WHITE_BALANCE_DAYLIGHT`` 301 - White balance preset for daylight (with clear sky). It corresponds 302 approximately to 5000...6500 K color temperature. 303 * - ``V4L2_WHITE_BALANCE_FLASH`` 304 - With this setting the camera will compensate for the flash light. 305 It slightly warms up the colors and corresponds roughly to 306 5000...5500 K color temperature. 307 * - ``V4L2_WHITE_BALANCE_CLOUDY`` 308 - White balance preset for moderately overcast sky. This option 309 corresponds approximately to 6500...8000 K color temperature 310 range. 311 * - ``V4L2_WHITE_BALANCE_SHADE`` 312 - White balance preset for shade or heavily overcast sky. It 313 corresponds approximately to 9000...10000 K color temperature. 314 315 316 317.. _v4l2-wide-dynamic-range: 318 319``V4L2_CID_WIDE_DYNAMIC_RANGE (boolean)`` 320 Enables or disables the camera's wide dynamic range feature. This 321 feature allows to obtain clear images in situations where intensity 322 of the illumination varies significantly throughout the scene, i.e. 323 there are simultaneously very dark and very bright areas. It is most 324 commonly realized in cameras by combining two subsequent frames with 325 different exposure times. [#f1]_ 326 327.. _v4l2-image-stabilization: 328 329``V4L2_CID_IMAGE_STABILIZATION (boolean)`` 330 Enables or disables image stabilization. 331 332``V4L2_CID_ISO_SENSITIVITY (integer menu)`` 333 Determines ISO equivalent of an image sensor indicating the sensor's 334 sensitivity to light. The numbers are expressed in arithmetic scale, 335 as per :ref:`iso12232` standard, where doubling the sensor 336 sensitivity is represented by doubling the numerical ISO value. 337 Applications should interpret the values as standard ISO values 338 multiplied by 1000, e.g. control value 800 stands for ISO 0.8. 339 Drivers will usually support only a subset of standard ISO values. 340 The effect of setting this control while the 341 ``V4L2_CID_ISO_SENSITIVITY_AUTO`` control is set to a value other 342 than ``V4L2_CID_ISO_SENSITIVITY_MANUAL`` is undefined, drivers 343 should ignore such requests. 344 345.. _v4l2-iso-sensitivity-auto-type: 346 347``V4L2_CID_ISO_SENSITIVITY_AUTO`` 348 (enum) 349 350enum v4l2_iso_sensitivity_type - 351 Enables or disables automatic ISO sensitivity adjustments. 352 353 354 355.. flat-table:: 356 :header-rows: 0 357 :stub-columns: 0 358 359 * - ``V4L2_CID_ISO_SENSITIVITY_MANUAL`` 360 - Manual ISO sensitivity. 361 * - ``V4L2_CID_ISO_SENSITIVITY_AUTO`` 362 - Automatic ISO sensitivity adjustments. 363 364 365 366.. _v4l2-scene-mode: 367 368``V4L2_CID_SCENE_MODE`` 369 (enum) 370 371enum v4l2_scene_mode - 372 This control allows to select scene programs as the camera automatic 373 modes optimized for common shooting scenes. Within these modes the 374 camera determines best exposure, aperture, focusing, light metering, 375 white balance and equivalent sensitivity. The controls of those 376 parameters are influenced by the scene mode control. An exact 377 behavior in each mode is subject to the camera specification. 378 379 When the scene mode feature is not used, this control should be set 380 to ``V4L2_SCENE_MODE_NONE`` to make sure the other possibly related 381 controls are accessible. The following scene programs are defined: 382 383.. raw:: latex 384 385 \small 386 387.. tabularcolumns:: |p{5.9cm}|p{11.5cm}| 388 389.. flat-table:: 390 :header-rows: 0 391 :stub-columns: 0 392 393 * - ``V4L2_SCENE_MODE_NONE`` 394 - The scene mode feature is disabled. 395 * - ``V4L2_SCENE_MODE_BACKLIGHT`` 396 - Backlight. Compensates for dark shadows when light is coming from 397 behind a subject, also by automatically turning on the flash. 398 * - ``V4L2_SCENE_MODE_BEACH_SNOW`` 399 - Beach and snow. This mode compensates for all-white or bright 400 scenes, which tend to look gray and low contrast, when camera's 401 automatic exposure is based on an average scene brightness. To 402 compensate, this mode automatically slightly overexposes the 403 frames. The white balance may also be adjusted to compensate for 404 the fact that reflected snow looks bluish rather than white. 405 * - ``V4L2_SCENE_MODE_CANDLELIGHT`` 406 - Candle light. The camera generally raises the ISO sensitivity and 407 lowers the shutter speed. This mode compensates for relatively 408 close subject in the scene. The flash is disabled in order to 409 preserve the ambiance of the light. 410 * - ``V4L2_SCENE_MODE_DAWN_DUSK`` 411 - Dawn and dusk. Preserves the colors seen in low natural light 412 before dusk and after down. The camera may turn off the flash, and 413 automatically focus at infinity. It will usually boost saturation 414 and lower the shutter speed. 415 * - ``V4L2_SCENE_MODE_FALL_COLORS`` 416 - Fall colors. Increases saturation and adjusts white balance for 417 color enhancement. Pictures of autumn leaves get saturated reds 418 and yellows. 419 * - ``V4L2_SCENE_MODE_FIREWORKS`` 420 - Fireworks. Long exposure times are used to capture the expanding 421 burst of light from a firework. The camera may invoke image 422 stabilization. 423 * - ``V4L2_SCENE_MODE_LANDSCAPE`` 424 - Landscape. The camera may choose a small aperture to provide deep 425 depth of field and long exposure duration to help capture detail 426 in dim light conditions. The focus is fixed at infinity. Suitable 427 for distant and wide scenery. 428 * - ``V4L2_SCENE_MODE_NIGHT`` 429 - Night, also known as Night Landscape. Designed for low light 430 conditions, it preserves detail in the dark areas without blowing 431 out bright objects. The camera generally sets itself to a 432 medium-to-high ISO sensitivity, with a relatively long exposure 433 time, and turns flash off. As such, there will be increased image 434 noise and the possibility of blurred image. 435 * - ``V4L2_SCENE_MODE_PARTY_INDOOR`` 436 - Party and indoor. Designed to capture indoor scenes that are lit 437 by indoor background lighting as well as the flash. The camera 438 usually increases ISO sensitivity, and adjusts exposure for the 439 low light conditions. 440 * - ``V4L2_SCENE_MODE_PORTRAIT`` 441 - Portrait. The camera adjusts the aperture so that the depth of 442 field is reduced, which helps to isolate the subject against a 443 smooth background. Most cameras recognize the presence of faces in 444 the scene and focus on them. The color hue is adjusted to enhance 445 skin tones. The intensity of the flash is often reduced. 446 * - ``V4L2_SCENE_MODE_SPORTS`` 447 - Sports. Significantly increases ISO and uses a fast shutter speed 448 to freeze motion of rapidly-moving subjects. Increased image noise 449 may be seen in this mode. 450 * - ``V4L2_SCENE_MODE_SUNSET`` 451 - Sunset. Preserves deep hues seen in sunsets and sunrises. It bumps 452 up the saturation. 453 * - ``V4L2_SCENE_MODE_TEXT`` 454 - Text. It applies extra contrast and sharpness, it is typically a 455 black-and-white mode optimized for readability. Automatic focus 456 may be switched to close-up mode and this setting may also involve 457 some lens-distortion correction. 458 459.. raw:: latex 460 461 \normalsize 462 463 464``V4L2_CID_3A_LOCK (bitmask)`` 465 This control locks or unlocks the automatic focus, exposure and 466 white balance. The automatic adjustments can be paused independently 467 by setting the corresponding lock bit to 1. The camera then retains 468 the settings until the lock bit is cleared. The following lock bits 469 are defined: 470 471 When a given algorithm is not enabled, drivers should ignore 472 requests to lock it and should return no error. An example might be 473 an application setting bit ``V4L2_LOCK_WHITE_BALANCE`` when the 474 ``V4L2_CID_AUTO_WHITE_BALANCE`` control is set to ``FALSE``. The 475 value of this control may be changed by exposure, white balance or 476 focus controls. 477 478 479 480.. flat-table:: 481 :header-rows: 0 482 :stub-columns: 0 483 484 * - ``V4L2_LOCK_EXPOSURE`` 485 - Automatic exposure adjustments lock. 486 * - ``V4L2_LOCK_WHITE_BALANCE`` 487 - Automatic white balance adjustments lock. 488 * - ``V4L2_LOCK_FOCUS`` 489 - Automatic focus lock. 490 491 492 493``V4L2_CID_PAN_SPEED (integer)`` 494 This control turns the camera horizontally at the specific speed. 495 The unit is undefined. A positive value moves the camera to the 496 right (clockwise when viewed from above), a negative value to the 497 left. A value of zero stops the motion if one is in progress and has 498 no effect otherwise. 499 500``V4L2_CID_TILT_SPEED (integer)`` 501 This control turns the camera vertically at the specified speed. The 502 unit is undefined. A positive value moves the camera up, a negative 503 value down. A value of zero stops the motion if one is in progress 504 and has no effect otherwise. 505 506``V4L2_CID_CAMERA_ORIENTATION (menu)`` 507 This read-only control describes the camera orientation by reporting its 508 mounting position on the device where the camera is installed. The control 509 value is constant and not modifiable by software. This control is 510 particularly meaningful for devices which have a well defined orientation, 511 such as phones, laptops and portable devices since the control is expressed 512 as a position relative to the device's intended usage orientation. For 513 example, a camera installed on the user-facing side of a phone, a tablet or 514 a laptop device is said to be have ``V4L2_CAMERA_ORIENTATION_FRONT`` 515 orientation, while a camera installed on the opposite side of the front one 516 is said to be have ``V4L2_CAMERA_ORIENTATION_BACK`` orientation. Camera 517 sensors not directly attached to the device, or attached in a way that 518 allows them to move freely, such as webcams and digital cameras, are said to 519 have the ``V4L2_CAMERA_ORIENTATION_EXTERNAL`` orientation. 520 521 522 523.. flat-table:: 524 :header-rows: 0 525 :stub-columns: 0 526 527 * - ``V4L2_CAMERA_ORIENTATION_FRONT`` 528 - The camera is oriented towards the user facing side of the device. 529 * - ``V4L2_CAMERA_ORIENTATION_BACK`` 530 - The camera is oriented towards the back facing side of the device. 531 * - ``V4L2_CAMERA_ORIENTATION_EXTERNAL`` 532 - The camera is not directly attached to the device and is freely movable. 533 534 535 536``V4L2_CID_CAMERA_SENSOR_ROTATION (integer)`` 537 This read-only control describes the rotation correction in degrees in the 538 counter-clockwise direction to be applied to the captured images once 539 captured to memory to compensate for the camera sensor mounting rotation. 540 541 For a precise definition of the sensor mounting rotation refer to the 542 extensive description of the 'rotation' properties in the device tree 543 bindings file 'video-interfaces.txt'. 544 545 A few examples are below reported, using a shark swimming from left to 546 right in front of the user as the example scene to capture. :: 547 548 0 X-axis 549 0 +-------------------------------------> 550 ! 551 ! 552 ! 553 ! |\____)\___ 554 ! ) _____ __`< 555 ! |/ )/ 556 ! 557 ! 558 ! 559 V 560 Y-axis 561 562 Example one - Webcam 563 564 Assuming you can bring your laptop with you while swimming with sharks, 565 the camera module of the laptop is installed on the user facing part of a 566 laptop screen casing, and is typically used for video calls. The captured 567 images are meant to be displayed in landscape mode (width > height) on the 568 laptop screen. 569 570 The camera is typically mounted upside-down to compensate the lens optical 571 inversion effect. In this case the value of the 572 V4L2_CID_CAMERA_SENSOR_ROTATION control is 0, no rotation is required to 573 display images correctly to the user. 574 575 If the camera sensor is not mounted upside-down it is required to compensate 576 the lens optical inversion effect and the value of the 577 V4L2_CID_CAMERA_SENSOR_ROTATION control is 180 degrees, as images will 578 result rotated when captured to memory. :: 579 580 +--------------------------------------+ 581 ! ! 582 ! ! 583 ! ! 584 ! __/(_____/| ! 585 ! >.___ ____ ( ! 586 ! \( \| ! 587 ! ! 588 ! ! 589 ! ! 590 +--------------------------------------+ 591 592 A software rotation correction of 180 degrees has to be applied to correctly 593 display the image on the user screen. :: 594 595 +--------------------------------------+ 596 ! ! 597 ! ! 598 ! ! 599 ! |\____)\___ ! 600 ! ) _____ __`< ! 601 ! |/ )/ ! 602 ! ! 603 ! ! 604 ! ! 605 +--------------------------------------+ 606 607 Example two - Phone camera 608 609 It is more handy to go and swim with sharks with only your mobile phone 610 with you and take pictures with the camera that is installed on the back 611 side of the device, facing away from the user. The captured images are meant 612 to be displayed in portrait mode (height > width) to match the device screen 613 orientation and the device usage orientation used when taking the picture. 614 615 The camera sensor is typically mounted with its pixel array longer side 616 aligned to the device longer side, upside-down mounted to compensate for 617 the lens optical inversion effect. 618 619 The images once captured to memory will be rotated and the value of the 620 V4L2_CID_CAMERA_SENSOR_ROTATION will report a 90 degree rotation. :: 621 622 623 +-------------------------------------+ 624 | _ _ | 625 | \ / | 626 | | | | 627 | | | | 628 | | > | 629 | < | | 630 | | | | 631 | . | 632 | V | 633 +-------------------------------------+ 634 635 A correction of 90 degrees in counter-clockwise direction has to be 636 applied to correctly display the image in portrait mode on the device 637 screen. :: 638 639 +--------------------+ 640 | | 641 | | 642 | | 643 | | 644 | | 645 | | 646 | |\____)\___ | 647 | ) _____ __`< | 648 | |/ )/ | 649 | | 650 | | 651 | | 652 | | 653 | | 654 +--------------------+ 655 656 657.. [#f1] 658 This control may be changed to a menu control in the future, if more 659 options are required. 660