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.. tabularcolumns:: |p{7.1cm}|p{10.4cm}| 36 37.. flat-table:: 38 :header-rows: 0 39 :stub-columns: 0 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 81enum v4l2_exposure_metering - 82 Determines how the camera measures the amount of light available for 83 the frame exposure. Possible values are: 84 85.. tabularcolumns:: |p{8.7cm}|p{8.7cm}| 86 87.. flat-table:: 88 :header-rows: 0 89 :stub-columns: 0 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. 176 177.. tabularcolumns:: |p{6.8cm}|p{10.7cm}| 178 179.. flat-table:: 180 :header-rows: 0 181 :stub-columns: 0 182 183 * - ``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 200enum v4l2_auto_focus_range - 201 Determines auto focus distance range for which lens may be adjusted. 202 203.. tabularcolumns:: |p{6.9cm}|p{10.6cm}| 204 205.. flat-table:: 206 :header-rows: 0 207 :stub-columns: 0 208 209 * - ``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 271enum 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. 277 278.. tabularcolumns:: |p{7.4cm}|p{10.1cm}| 279 280.. flat-table:: 281 :header-rows: 0 282 :stub-columns: 0 283 284 * - ``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 351enum v4l2_iso_sensitivity_type - 352 Enables or disables automatic ISO sensitivity adjustments. 353 354 355 356.. flat-table:: 357 :header-rows: 0 358 :stub-columns: 0 359 360 * - ``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 372enum 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 387 388.. tabularcolumns:: |p{5.9cm}|p{11.6cm}| 389 390.. cssclass:: longtable 391 392.. flat-table:: 393 :header-rows: 0 394 :stub-columns: 0 395 396 * - ``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:: 484 :header-rows: 0 485 :stub-columns: 0 486 487 * - ``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_CID_CAMERA_ORIENTATION (menu)`` 510 This read-only control describes the camera orientation by reporting its 511 mounting position on the device where the camera is installed. The control 512 value is constant and not modifiable by software. This control is 513 particularly meaningful for devices which have a well defined orientation, 514 such as phones, laptops and portable devices since the control is expressed 515 as a position relative to the device's intended usage orientation. For 516 example, a camera installed on the user-facing side of a phone, a tablet or 517 a laptop device is said to be have ``V4L2_CAMERA_ORIENTATION_FRONT`` 518 orientation, while a camera installed on the opposite side of the front one 519 is said to be have ``V4L2_CAMERA_ORIENTATION_BACK`` orientation. Camera 520 sensors not directly attached to the device, or attached in a way that 521 allows them to move freely, such as webcams and digital cameras, are said to 522 have the ``V4L2_CAMERA_ORIENTATION_EXTERNAL`` orientation. 523 524 525.. tabularcolumns:: |p{7.7cm}|p{9.8cm}| 526 527.. flat-table:: 528 :header-rows: 0 529 :stub-columns: 0 530 531 * - ``V4L2_CAMERA_ORIENTATION_FRONT`` 532 - The camera is oriented towards the user facing side of the device. 533 * - ``V4L2_CAMERA_ORIENTATION_BACK`` 534 - The camera is oriented towards the back facing side of the device. 535 * - ``V4L2_CAMERA_ORIENTATION_EXTERNAL`` 536 - The camera is not directly attached to the device and is freely movable. 537 538 539 540``V4L2_CID_CAMERA_SENSOR_ROTATION (integer)`` 541 This read-only control describes the rotation correction in degrees in the 542 counter-clockwise direction to be applied to the captured images once 543 captured to memory to compensate for the camera sensor mounting rotation. 544 545 For a precise definition of the sensor mounting rotation refer to the 546 extensive description of the 'rotation' properties in the device tree 547 bindings file 'video-interfaces.txt'. 548 549 A few examples are below reported, using a shark swimming from left to 550 right in front of the user as the example scene to capture. :: 551 552 0 X-axis 553 0 +-------------------------------------> 554 ! 555 ! 556 ! 557 ! |\____)\___ 558 ! ) _____ __`< 559 ! |/ )/ 560 ! 561 ! 562 ! 563 V 564 Y-axis 565 566 Example one - Webcam 567 568 Assuming you can bring your laptop with you while swimming with sharks, 569 the camera module of the laptop is installed on the user facing part of a 570 laptop screen casing, and is typically used for video calls. The captured 571 images are meant to be displayed in landscape mode (width > height) on the 572 laptop screen. 573 574 The camera is typically mounted upside-down to compensate the lens optical 575 inversion effect. In this case the value of the 576 V4L2_CID_CAMERA_SENSOR_ROTATION control is 0, no rotation is required to 577 display images correctly to the user. 578 579 If the camera sensor is not mounted upside-down it is required to compensate 580 the lens optical inversion effect and the value of the 581 V4L2_CID_CAMERA_SENSOR_ROTATION control is 180 degrees, as images will 582 result rotated when captured to memory. :: 583 584 +--------------------------------------+ 585 ! ! 586 ! ! 587 ! ! 588 ! __/(_____/| ! 589 ! >.___ ____ ( ! 590 ! \( \| ! 591 ! ! 592 ! ! 593 ! ! 594 +--------------------------------------+ 595 596 A software rotation correction of 180 degrees has to be applied to correctly 597 display the image on the user screen. :: 598 599 +--------------------------------------+ 600 ! ! 601 ! ! 602 ! ! 603 ! |\____)\___ ! 604 ! ) _____ __`< ! 605 ! |/ )/ ! 606 ! ! 607 ! ! 608 ! ! 609 +--------------------------------------+ 610 611 Example two - Phone camera 612 613 It is more handy to go and swim with sharks with only your mobile phone 614 with you and take pictures with the camera that is installed on the back 615 side of the device, facing away from the user. The captured images are meant 616 to be displayed in portrait mode (height > width) to match the device screen 617 orientation and the device usage orientation used when taking the picture. 618 619 The camera sensor is typically mounted with its pixel array longer side 620 aligned to the device longer side, upside-down mounted to compensate for 621 the lens optical inversion effect. 622 623 The images once captured to memory will be rotated and the value of the 624 V4L2_CID_CAMERA_SENSOR_ROTATION will report a 90 degree rotation. :: 625 626 627 +-------------------------------------+ 628 | _ _ | 629 | \ / | 630 | | | | 631 | | | | 632 | | > | 633 | < | | 634 | | | | 635 | . | 636 | V | 637 +-------------------------------------+ 638 639 A correction of 90 degrees in counter-clockwise direction has to be 640 applied to correctly display the image in portrait mode on the device 641 screen. :: 642 643 +--------------------+ 644 | | 645 | | 646 | | 647 | | 648 | | 649 | | 650 | |\____)\___ | 651 | ) _____ __`< | 652 | |/ )/ | 653 | | 654 | | 655 | | 656 | | 657 | | 658 +--------------------+ 659 660 661.. [#f1] 662 This control may be changed to a menu control in the future, if more 663 options are required. 664