path: root/src/libcamera/property_ids.yaml

# SPDX-License-Identifier: LGPL-2.1-or-later
#
# Copyright (C) 2019, Google Inc.
#
%YAML 1.2
---
controls:
  - Location:
      type: int32_t
      description: |
        Camera mounting location
      enum:
        - name: CameraLocationFront
          value: 0
          description: |
            The camera is mounted on the front side of the device, facing the
            user
        - name: CameraLocationBack
          value: 1
          description: |
            The camera is mounted on the back side of the device, facing away
            from the user
        - name: CameraLocationExternal
          value: 2
          description: |
            The camera is attached to the device in a way that allows it to
            be moved freely

  - Rotation:
      type: int32_t
      description: |
        The camera rotation is expressed as the angular difference in degrees
        between two reference systems, one relative to the camera module, and
        one defined on the external world scene to be captured when projected
        on the image sensor pixel array.

        A camera sensor has a 2-dimensional reference system 'Rc' defined by
        its pixel array read-out order. The origin is set to the first pixel
        being read out, the X-axis points along the column read-out direction
        towards the last columns, and the Y-axis along the row read-out
        direction towards the last row.

        A typical example for a sensor with a 2592x1944 pixel array matrix
        observed from the front is

                    2591       X-axis          0
                      <------------------------+ 0
                      .......... ... ..........!
                      .......... ... ..........! Y-axis
                                 ...           !
                      .......... ... ..........!
                      .......... ... ..........! 1943
                                               V


        The external world scene reference system 'Rs' is a 2-dimensional
        reference system on the focal plane of the camera module. The origin is
        placed on the top-left corner of the visible scene, the X-axis points
        towards the right, and the Y-axis points towards the bottom of the
        scene. The top, bottom, left and right directions are intentionally not
        defined and depend on the environment in which the camera is used.

        A typical example of a (very common) picture of a shark swimming from
        left to right, as seen from the camera, is

                     0               X-axis
                   0 +------------------------------------->
                     !
                     !
                     !
                     !           |\____)\___
                     !           ) _____  __`<
                     !           |/     )/
                     !
                     !
                     !
                     V
                   Y-axis

        With the reference system 'Rs' placed on the camera focal plane.

                                        ¸.·˙!
                                    ¸.·˙    !
                        _       ¸.·˙        !
                     +-/ \-+¸.·˙            !
                     | (o) |                ! Camera focal plane
                     +-----+˙·.¸            !
                                ˙·.¸        !
                                    ˙·.¸    !
                                        ˙·.¸!

        When projected on the sensor's pixel array, the image and the associated
        reference system 'Rs' are typically (but not always) inverted, due to
        the camera module's lens optical inversion effect.

        Assuming the above represented scene of the swimming shark, the lens
        inversion projects the scene and its reference system onto the sensor
        pixel array, seen from the front of the camera sensor, as follow

                  Y-axis
                     ^
                     !
                     !
                     !
                     !            |\_____)\__
                     !            ) ____  ___.<
                     !            |/    )/
                     !
                     !
                     !
                   0 +------------------------------------->
                     0               X-axis

        Note the shark being upside-down.

        The resulting projected reference system is named 'Rp'.

        The camera rotation property is then defined as the angular difference
        in the counter-clockwise direction between the camera reference system
        'Rc' and the projected scene reference system 'Rp'. It is expressed in
        degrees as a number in the range [0, 360[.

        Examples

        0 degrees camera rotation


                          Y-Rp
                           ^
                    Y-Rc   !
                     ^     !
                     !     !
                     !     !
                     !     !
                     !     !
                     !     !
                     !     !
                     !     !
                     !   0 +------------------------------------->
                     !     0               X-Rp
                   0 +------------------------------------->
                     0               X-Rc


                                      X-Rc                0
                     <------------------------------------+ 0
                                 X-Rp                 0   !
                 <------------------------------------+ 0 !
                                                      !   !
                                                      !   !
                                                      !   !
                                                      !   !
                                                      !   !
                                                      !   !
                                                      !   !
                                                      !   V
                                                      !  Y-Rc
                                                      V
                                                     Y-Rp

        90 degrees camera rotation

                     0        Y-Rc
                   0 +-------------------->
                     !   Y-Rp
                     !    ^
                     !    !
                     !    !
                     !    !
                     !    !
                     !    !
                     !    !
                     !    !
                     !    !
                     !    !
                     !  0 +------------------------------------->
                     !    0              X-Rp
                     !
                     !
                     !
                     !
                     V
                    X-Rc

        180 degrees camera rotation

                                                  0
             <------------------------------------+ 0
                              X-Rc                !
                    Y-Rp                          !
                     ^                            !
                     !                            !
                     !                            !
                     !                            !
                     !                            !
                     !                            !
                     !                            !
                     !                            V
                     !                           Y-Rc
                   0 +------------------------------------->
                     0              X-Rp

        270 degrees camera rotation

                     0        Y-Rc
                   0 +-------------------->
                     !                                        0
                     !    <-----------------------------------+ 0
                     !                    X-Rp                !
                     !                                        !
                     !                                        !
                     !                                        !
                     !                                        !
                     !                                        !
                     !                                        !
                     !                                        !
                     !                                        !
                     !                                        V
                     !                                       Y-Rp
                     !
                     !
                     !
                     !
                     V
                    X-Rc


        Example one - Webcam

        A camera module installed on the user facing part of a laptop screen
        casing used for video calls. The captured images are meant to be
        displayed in landscape mode (width > height) on the laptop screen.

        The camera is typically mounted upside-down to compensate the lens
        optical inversion effect.

                          Y-Rp
                    Y-Rc   ^
                     ^     !
                     !     !
                     !     !       |\_____)\__
                     !     !       ) ____  ___.<
                     !     !       |/    )/
                     !     !
                     !     !
                     !     !
                     !   0 +------------------------------------->
                     !     0           X-Rp
                   0 +------------------------------------->
                     0            X-Rc

        The two reference systems are aligned, the resulting camera rotation is
        0 degrees, no rotation correction needs to be applied to the resulting
        image once captured to memory buffers to correctly display it to users.

                     +--------------------------------------+
                     !                                      !
                     !                                      !
                     !                                      !
                     !             |\____)\___              !
                     !             ) _____  __`<            !
                     !             |/     )/                !
                     !                                      !
                     !                                      !
                     !                                      !
                     +--------------------------------------+

        If the camera sensor is not mounted upside-down to compensate for the
        lens optical inversion, the two reference systems will not be aligned,
        with 'Rp' being rotated 180 degrees relatively to 'Rc'.


                              X-Rc                0
             <------------------------------------+ 0
                                                  !
                    Y-Rp                          !
                     ^                            !
                     !                            !
                     !       |\_____)\__          !
                     !       ) ____  ___.<        !
                     !       |/    )/             !
                     !                            !
                     !                            !
                     !                            V
                     !                           Y-Rc
                   0 +------------------------------------->
                     0            X-Rp

        The image once captured to memory will then be rotated by 180 degrees

                     +--------------------------------------+
                     !                                      !
                     !                                      !
                     !                                      !
                     !              __/(_____/|             !
                     !            >.___  ____ (             !
                     !                 \(    \|             !
                     !                                      !
                     !                                      !
                     !                                      !
                     +--------------------------------------+

        A software rotation correction of 180 degrees should be applied to
        correctly display the image.

                     +--------------------------------------+
                     !                                      !
                     !                                      !
                     !                                      !
                     !             |\____)\___              !
                     !             ) _____  __`<            !
                     !             |/     )/                !
                     !                                      !
                     !                                      !
                     !                                      !
                     +--------------------------------------+

        Example two - Phone camera

        A camera installed on the back side of a mobile device facing away from
        the user. The captured images are meant to be displayed in portrait mode
        (height > width) to match the device screen orientation and the device
        usage orientation used when taking the picture.

        The camera sensor is typically mounted with its pixel array longer side
        aligned to the device longer side, upside-down mounted to compensate for
        the lens optical inversion effect.

                     0        Y-Rc
                   0 +-------------------->
                     !   Y-Rp
                     !    ^
                     !    !
                     !    !
                     !    !
                     !    !            |\_____)\__
                     !    !            ) ____  ___.<
                     !    !            |/    )/
                     !    !
                     !    !
                     !    !
                     !  0 +------------------------------------->
                     !    0                X-Rp
                     !
                     !
                     !
                     !
                     V
                    X-Rc

        The two reference systems are not aligned and the 'Rp' reference
        system is rotated by 90 degrees in the counter-clockwise direction
        relatively to the 'Rc' reference system.

        The image once captured to memory will be rotated.

                     +-------------------------------------+
                     |                 _ _                 |
                     |                \   /                |
                     |                 | |                 |
                     |                 | |                 |
                     |                 |  >                |
                     |                <  |                 |
                     |                 | |                 |
                     |                   .                 |
                     |                  V                  |
                     +-------------------------------------+

        A correction of 90 degrees in counter-clockwise direction has to be
        applied to correctly display the image in portrait mode on the device
        screen.

                              +--------------------+
                              |                    |
                              |                    |
                              |                    |
                              |                    |
                              |                    |
                              |                    |
                              |   |\____)\___      |
                              |   ) _____  __`<    |
                              |   |/     )/        |
                              |                    |
                              |                    |
                              |                    |
                              |                    |
                              |                    |
                              +--------------------+
...