From: Hans Verkuil <hverkuil-cisco@xs4all.nl>
To: Jacopo Mondi <jacopo@jmondi.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
tfiga@google.com, pavel@ucw.cz
Cc: "open list:MEDIA INPUT INFRASTRUCTURE (V4L/DVB)"
<linux-media@vger.kernel.org>,
libcamera-devel@lists.libcamera.org, robh@kernel.org,
devicetree@vger.kernel.org,
Niklas Soderlund <niklas.soderlund@ragnatech.se>
Subject: Re: [PATCH v7 03/11] dt-bindings: video-interface: Replace 'rotation' description
Date: Tue, 31 Mar 2020 12:21:07 +0200 [thread overview]
Message-ID: <9837f79e-4a5f-5a74-33eb-ed35b59a94a5@xs4all.nl> (raw)
In-Reply-To: <20200318205034.949531-4-jacopo@jmondi.org>
On 3/18/20 9:50 PM, Jacopo Mondi wrote:
> Replace the 'rotation' property description by providing a definition
> relative to the camera sensor pixel array coordinate system and the
> captured scene.
>
> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> Co-developed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Co-developed-by: Niklas Soderlund <niklas.soderlund@ragnatech.se>
>
> ---
> .../bindings/media/video-interfaces.txt | 359 +++++++++++++++++-
> 1 file changed, 356 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/media/video-interfaces.txt b/Documentation/devicetree/bindings/media/video-interfaces.txt
> index 1211bdf80722..36e61d599f34 100644
> --- a/Documentation/devicetree/bindings/media/video-interfaces.txt
> +++ b/Documentation/devicetree/bindings/media/video-interfaces.txt
> @@ -85,9 +85,362 @@ Optional properties
>
> - lens-focus: A phandle to the node of the focus lens controller.
>
> -- rotation: The device, typically an image sensor, is not mounted upright,
> - but a number of degrees counter clockwise. Typical values are 0 and 180
> - (upside down).
> +- rotation: 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
is -> 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
is -> is:
> +
> + 0 X-axis
> + 0 +------------------------------------->
> + !
> + !
> + !
> + ! |\____)\___
> + ! ) _____ __`<
> + ! |/ )/
> + !
> + !
> + !
> + V
> + Y-axis
> +
> + With the reference system 'Rs' placed on the camera focal plane.
I think here 'With' can be 'with' (since you continue the previous sentence)
and 'plane.' should be 'plane:' since it refers to the picture below that explains
the 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
follow -> follows:
> +
> + 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
rotation -> 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
Ditto here and for the 180 and 270 examples below.
> +
> + 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.
effect. -> effect:
The : links the sentence with the following picture. I think this should be
done in the remainder of this section, so I won't repeat myself.
> +
> + 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.
> +
> + +--------------------+
> + | |
> + | |
> + | |
> + | |
> + | |
> + | |
> + | |\____)\___ |
> + | ) _____ __`< |
> + | |/ )/ |
> + | |
> + | |
> + | |
> + | |
> + | |
> + +--------------------+
>
> - location: The mount location of a device (typically an image sensor or a flash
> LED) expressed as a position relative to the usage orientation of the system
> --
> 2.25.1
>
Regards,
Hans
next prev parent reply other threads:[~2020-03-31 10:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-18 20:50 [PATCH v7 00/11] media: Report camera sensor properties Jacopo Mondi
2020-03-18 20:50 ` [PATCH v7 01/11] dt-bindings: video-interfaces: Document 'location' property Jacopo Mondi
2020-03-18 20:50 ` [PATCH v7 02/11] media: v4l2-ctrl: Document V4L2_CID_CAMERA_SENSOR_LOCATION Jacopo Mondi
2020-03-18 20:50 ` [PATCH v7 03/11] dt-bindings: video-interface: Replace 'rotation' description Jacopo Mondi
2020-03-20 1:03 ` Rob Herring
2020-03-31 10:21 ` Hans Verkuil [this message]
2020-06-08 10:09 ` Sakari Ailus
2020-06-08 21:41 ` Laurent Pinchart
2020-03-18 20:50 ` [PATCH v7 04/11] media: v4l2-ctrl: Document V4L2_CID_CAMERA_SENSOR_ROTATION Jacopo Mondi
2020-03-18 20:50 ` [PATCH v7 05/11] media: v4l2-ctrls: Add camera location and rotation Jacopo Mondi
2020-03-18 20:50 ` [PATCH v7 06/11] media: v4l2-fwnode: Add helper to parse device properties Jacopo Mondi
2020-03-18 20:50 ` [PATCH v7 07/11] include: v4l2-ctrl: Sort forward declarations Jacopo Mondi
2020-03-18 20:50 ` [PATCH v7 08/11] media: v4l2-ctrls: Sort includes alphabetically Jacopo Mondi
2020-03-18 20:50 ` [PATCH v7 09/11] media: v4l2-ctrls: Add helper to register properties Jacopo Mondi
2020-03-18 20:50 ` [PATCH v7 10/11] media: i2c: ov5670: Parse and " Jacopo Mondi
2020-03-18 20:50 ` [PATCH v7 11/11] media: i2c: ov13858: " Jacopo Mondi
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