From patchwork Sat May 9 09:04:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jacopo Mondi X-Patchwork-Id: 200848 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E9FCC47254 for ; Sat, 9 May 2020 09:02:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1589124957 for ; Sat, 9 May 2020 09:02:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726885AbgEIJCC (ORCPT ); Sat, 9 May 2020 05:02:02 -0400 Received: from relay5-d.mail.gandi.net ([217.70.183.197]:53675 "EHLO relay5-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725930AbgEIJCC (ORCPT ); Sat, 9 May 2020 05:02:02 -0400 X-Originating-IP: 212.216.150.148 Received: from uno.homenet.telecomitalia.it (a-ur1-85.tin.it [212.216.150.148]) (Authenticated sender: jacopo@jmondi.org) by relay5-d.mail.gandi.net (Postfix) with ESMTPSA id F22AF1C0007; Sat, 9 May 2020 09:01:56 +0000 (UTC) From: Jacopo Mondi To: linux-media@vger.kernel.org (open list:MEDIA INPUT INFRASTRUCTURE (V4L/DVB)), libcamera-devel@lists.libcamera.org, Mauro Carvalho Chehab , Hans Verkuil , Sakari Ailus , Laurent Pinchart , Rob Herring Cc: Jacopo Mondi , tfiga@google.com, pavel@ucw.cz, devicetree@vger.kernel.org Subject: [PATCH v11 02/13] dt-bindings: video-interface: Replace 'rotation' description Date: Sat, 9 May 2020 11:04:45 +0200 Message-Id: <20200509090456.3496481-3-jacopo@jmondi.org> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200509090456.3496481-1-jacopo@jmondi.org> References: <20200509090456.3496481-1-jacopo@jmondi.org> MIME-Version: 1.0 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Replace the 'rotation' property description by providing a definition relative to the camera sensor pixel array coordinate system and the captured scene. Acked-by: Rob Herring Signed-off-by: Jacopo Mondi --- .../bindings/media/video-interfaces.txt | 359 +++++++++++++++++- 1 file changed, 356 insertions(+), 3 deletions(-) -- 2.26.1 diff --git a/Documentation/devicetree/bindings/media/video-interfaces.txt b/Documentation/devicetree/bindings/media/video-interfaces.txt index b1ff492c7da7a..3920f25a91235 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: + + 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 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: + + + 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: + + +--------------------+ + | | + | | + | | + | | + | | + | | + | |\____)\___ | + | ) _____ __`< | + | |/ )/ | + | | + | | + | | + | | + | | + +--------------------+ - orientation: The orientation of a device (typically an image sensor or a flash LED) describing its mounting position relative to the usage orientation of the