From patchwork Wed Nov 11 11:55:55 2026 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= X-Patchwork-Id: 28855 Return-Path: X-Original-To: parsemail@patchwork.libcamera.org Delivered-To: parsemail@patchwork.libcamera.org Received: from lancelot.ideasonboard.com (lancelot.ideasonboard.com [92.243.16.209]) by patchwork.libcamera.org (Postfix) with ESMTPS id 747E1C335E for ; Wed, 11 Nov 2026 11:56:28 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id 39D4D6A7D3; Wed, 11 Nov 2026 12:56:24 +0100 (CET) Authentication-Results: lancelot.ideasonboard.com; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="lFS/gOjF"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id CB4EE6910E for ; Wed, 11 Nov 2026 12:56:07 +0100 (CET) Received: from pb-laptop.local (185.221.143.99.nat.pool.zt.hu [185.221.143.99]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id AA87E1D14; Wed, 11 Nov 2026 12:53:44 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1794398024; bh=GlvVp38LnDr2AsJMeGOKplOSDvQ4ask5h86TgEfUshc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lFS/gOjFiQUd2nH4V4C0fiTtdF0y7KcN4Mtwerb0DJLwSW4qYup344+ZS6t30l9jB 456YUMMnyIoH+GByJ823NiaDrQ39wXFtLVpL1axL5wb8KSzG/mN9BwaaVyxMpLiBJ5 70P5OenG/iI+VLZl7w6KO+r4heh/LGWYsP7zqDp4= From: =?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= To: libcamera-devel@lists.libcamera.org Cc: Jacopo Mondi , Kieran Bingham , Stefan Klug Subject: [PATCH v9 14/18] ipa: camera_sensor_helper: Introduce exposure margin Date: Wed, 11 Nov 2026 12:55:55 +0100 Message-ID: <20261111115600.1097488-15-barnabas.pocze@ideasonboard.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261111115600.1097488-1-barnabas.pocze@ideasonboard.com> References: <20261111115600.1097488-1-barnabas.pocze@ideasonboard.com> MIME-Version: 1.0 X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" From: Jacopo Mondi There is a margin between the maximum achievable shutter time and the frame length. The value is sensor-dependent and should be used to adjust the maximum achievable exposure time whenever the frame length changes. Introduce in the CameraSensorHelper the notion of exposureMargin_ as the minimum difference in number of lines between the current frame length and the maximum exposure time. This feature is already implemented in the RPi CamHelper class hierarchy with the name of frameIntegrationDiff. Populate the CameraSensorHelper instances with an exposureMargin_. The value of the exposure margin comes from the mainline driver version of each sensor, and it has been compared with the frameIntegrationDiff_ value in the rpi camera helpers. Signed-off-by: Jacopo Mondi Signed-off-by: Barnabás Pőcze Reviewed-by: Kieran Bingham Reviewed-by: Stefan Klug --- src/ipa/libipa/camera_sensor_helper.cpp | 68 +++++++++++++++++++++++++ src/ipa/libipa/camera_sensor_helper.h | 2 + 2 files changed, 70 insertions(+) diff --git a/src/ipa/libipa/camera_sensor_helper.cpp b/src/ipa/libipa/camera_sensor_helper.cpp index 359040ec74..608937d45e 100644 --- a/src/ipa/libipa/camera_sensor_helper.cpp +++ b/src/ipa/libipa/camera_sensor_helper.cpp @@ -76,6 +76,16 @@ namespace ipa { * \return The black level of the sensor, or std::nullopt if not known */ +/** + * \fn CameraSensorHelper::exposureMargin() + * \brief Fetch the exposure margin of the sensor + * + * This function returns the exposure margin of the sensor, in lines, which + * is the minimum difference between the integration time and frame length. + * + * \return The exposure margin of the sensor, or std::nullopt if not known + */ + /** * \brief Compute gain code from the analogue gain absolute value * \param[in] gain The real gain to pass @@ -229,6 +239,12 @@ double CameraSensorHelper::quantizeGain(double _gain, double *quantizationGain) * sensor specific. Use this variable to store the values at init time. */ +/** + * \var CameraSensorHelper::exposureMargin_ + * \brief The smallest margin between the integration time and the frame length + * in lines + */ + /** * \class CameraSensorHelperFactoryBase * \brief Base class for camera sensor helper factories @@ -387,6 +403,7 @@ public: { /* Power-on default value: 168 at 12bits. */ blackLevel_ = 2688; + exposureMargin_ = 4; } uint32_t gainCode(double gain) const override @@ -473,6 +490,11 @@ REGISTER_CAMERA_SENSOR_HELPER("ar0144", CameraSensorHelperAr0144) class CameraSensorHelperAr0521 : public CameraSensorHelper { public: + CameraSensorHelperAr0521() + { + exposureMargin_ = 4; + } + uint32_t gainCode(double gain) const override { gain = std::clamp(gain, 1.0, 15.5); @@ -503,6 +525,7 @@ public: /* From datasheet: 64 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 100, 0, 0, 1024 }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("gc05a2", CameraSensorHelperGc05a2) @@ -515,6 +538,7 @@ public: /* From datasheet: 64 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 100, 0, 0, 1024 }; + exposureMargin_ = 16; } }; REGISTER_CAMERA_SENSOR_HELPER("gc08a3", CameraSensorHelperGc08a3) @@ -525,6 +549,7 @@ public: CameraSensorHelperHm1246() { gain_ = AnalogueGainLinear{ 1, 16, 0, 16 }; + exposureMargin_ = 2; } }; REGISTER_CAMERA_SENSOR_HELPER("hm1246", CameraSensorHelperHm1246) @@ -537,6 +562,7 @@ public: /* From datasheet: 64 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 0, 512, -1, 512 }; + exposureMargin_ = 10; } }; REGISTER_CAMERA_SENSOR_HELPER("imx214", CameraSensorHelperImx214) @@ -549,6 +575,7 @@ public: /* From datasheet: 64 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 0, 256, -1, 256 }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("imx219", CameraSensorHelperImx219) @@ -561,6 +588,7 @@ public: /* From datasheet: 0x40 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 0, 512, -1, 512 }; + exposureMargin_ = 10; } }; REGISTER_CAMERA_SENSOR_HELPER("imx258", CameraSensorHelperImx258) @@ -573,6 +601,7 @@ public: /* From datasheet: 0x32 at 10bits. */ blackLevel_ = 3200; gain_ = AnalogueGainLinear{ 0, 2048, -1, 2048 }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("imx283", CameraSensorHelperImx283) @@ -585,6 +614,7 @@ public: /* From datasheet: 0xf0 at 12bits. */ blackLevel_ = 3840; gain_ = AnalogueGainExp{ 1.0, expGainDb(0.3) }; + exposureMargin_ = 2; } }; REGISTER_CAMERA_SENSOR_HELPER("imx290", CameraSensorHelperImx290) @@ -595,6 +625,11 @@ public: CameraSensorHelperImx296() { gain_ = AnalogueGainExp{ 1.0, expGainDb(0.1) }; + /* + * The driver doesn't apply any margin. Use the value + * in RPi's CamHelper. + */ + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("imx296", CameraSensorHelperImx296) @@ -612,6 +647,7 @@ public: /* From datasheet: 0x32 at 10bits. */ blackLevel_ = 3200; gain_ = AnalogueGainExp{ 1.0, expGainDb(0.3) }; + exposureMargin_ = 10; } }; REGISTER_CAMERA_SENSOR_HELPER("imx335", CameraSensorHelperImx335) @@ -624,6 +660,7 @@ public: /* From datasheet: 64 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 0, 1024, -1, 1024 }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("imx355", CameraSensorHelperImx355) @@ -634,6 +671,7 @@ public: CameraSensorHelperImx415() { gain_ = AnalogueGainExp{ 1.0, expGainDb(0.3) }; + exposureMargin_ = 8; } }; REGISTER_CAMERA_SENSOR_HELPER("imx415", CameraSensorHelperImx415) @@ -652,6 +690,7 @@ public: blackLevel_ = 4096; /* gain = 1024/(1024 - code); code = [0, 800]; max gain = x4.57 */ gain_ = AnalogueGainLinear{ 0, 1024, -1, 1024 }; + exposureMargin_ = 18; } }; REGISTER_CAMERA_SENSOR_HELPER("imx471", CameraSensorHelperImx471) @@ -662,6 +701,7 @@ public: CameraSensorHelperImx477() { gain_ = AnalogueGainLinear{ 0, 1024, -1, 1024 }; + exposureMargin_ = 22; } }; REGISTER_CAMERA_SENSOR_HELPER("imx477", CameraSensorHelperImx477) @@ -674,6 +714,7 @@ public: /* From datasheet: 0xc8 at 12bits. */ blackLevel_ = 3200; gain_ = AnalogueGainExp{ 1.0, expGainDb(0.3) }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("imx662", CameraSensorHelperImx662) @@ -686,6 +727,7 @@ public: /* From datasheet: 0x32 at 10bits. */ blackLevel_ = 3200; gain_ = AnalogueGainExp{ 1.0, expGainDb(0.3) }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("imx678", CameraSensorHelperImx678) @@ -697,6 +739,7 @@ public: { blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 0, 1024, -1, 1024 }; + exposureMargin_ = 48; } }; REGISTER_CAMERA_SENSOR_HELPER("imx708", CameraSensorHelperImx708) @@ -709,6 +752,7 @@ public: /* From dark frame measurement: 0x40 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 1, 0, 0, 256 }; + exposureMargin_ = 8; } }; REGISTER_CAMERA_SENSOR_HELPER("ov01a10", CameraSensorHelperOv01a10) @@ -721,6 +765,7 @@ public: /* From Linux kernel driver: 0x40 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 6; } }; REGISTER_CAMERA_SENSOR_HELPER("ov08d10", CameraSensorHelperOv08d10) @@ -732,6 +777,7 @@ public: { blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 8; } }; REGISTER_CAMERA_SENSOR_HELPER("ov08x40", CameraSensorHelperOv08x40) @@ -744,6 +790,7 @@ public: blackLevel_ = 3600; /* gain is fixed to 1x, this is just a place holder. */ gain_ = AnalogueGainLinear{ 0, 2048, -1, 2048 }; + exposureMargin_ = 6; } }; REGISTER_CAMERA_SENSOR_HELPER("mira220", CameraSensorHelperMira220) @@ -758,6 +805,7 @@ public: * This has been validated with some empirical testing only. */ gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("ov2685", CameraSensorHelperOv2685) @@ -770,6 +818,7 @@ public: /* From Linux kernel driver: 0x40 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 8; } }; REGISTER_CAMERA_SENSOR_HELPER("ov2740", CameraSensorHelperOv2740) @@ -782,6 +831,7 @@ public: /* From datasheet: 0x40 at 12bits. */ blackLevel_ = 1024; gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("ov4689", CameraSensorHelperOv4689) @@ -794,6 +844,14 @@ public: /* From datasheet: 0x10 at 10bits. */ blackLevel_ = 1024; gain_ = AnalogueGainLinear{ 1, 0, 0, 16 }; + /* + * Very convoluted in the driver that however applies a margin + * of 4 lines when setting vts. + * + * cap_vts = cap_shutter + 4; + * ret = ov5640_set_vts(sensor, cap_vts); + */ + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5640", CameraSensorHelperOv5640) @@ -804,6 +862,7 @@ public: CameraSensorHelperOv5647() { gain_ = AnalogueGainLinear{ 1, 0, 0, 16 }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5647", CameraSensorHelperOv5647) @@ -814,6 +873,7 @@ public: CameraSensorHelperOv5670() { gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 8; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5670", CameraSensorHelperOv5670) @@ -826,6 +886,7 @@ public: /* From Linux kernel driver: 0x40 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5675", CameraSensorHelperOv5675) @@ -837,6 +898,7 @@ public: { blackLevel_ = 1024; gain_ = AnalogueGainLinear{ 1, 0, 0, 16 }; + exposureMargin_ = 8; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5693", CameraSensorHelperOv5693) @@ -847,6 +909,7 @@ public: CameraSensorHelperOv64a40() { gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 32; } }; REGISTER_CAMERA_SENSOR_HELPER("ov64a40", CameraSensorHelperOv64a40) @@ -863,6 +926,7 @@ public: * See: https://patchwork.linuxtv.org/project/linux-media/patch/20221106171129.166892-2-nicholas@rothemail.net/#142267 */ gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 4; } }; REGISTER_CAMERA_SENSOR_HELPER("ov8858", CameraSensorHelperOv8858) @@ -873,6 +937,7 @@ public: CameraSensorHelperOv8865() { gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 8; } }; REGISTER_CAMERA_SENSOR_HELPER("ov8865", CameraSensorHelperOv8865) @@ -883,6 +948,7 @@ public: CameraSensorHelperOv13858() { gain_ = AnalogueGainLinear{ 1, 0, 0, 128 }; + exposureMargin_ = 8; } }; REGISTER_CAMERA_SENSOR_HELPER("ov13858", CameraSensorHelperOv13858) @@ -895,6 +961,7 @@ public: /* From datasheet: 0x40 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 0, 32, -1, 32 }; + exposureMargin_ = 64; } }; REGISTER_CAMERA_SENSOR_HELPER("vd55g1", CameraSensorHelperVd55g1) @@ -907,6 +974,7 @@ public: /* From datasheet: 0x40 at 10bits. */ blackLevel_ = 4096; gain_ = AnalogueGainLinear{ 0, 32, -1, 32 }; + exposureMargin_ = 75; } }; REGISTER_CAMERA_SENSOR_HELPER("vd56g3", CameraSensorHelperVd56g3) diff --git a/src/ipa/libipa/camera_sensor_helper.h b/src/ipa/libipa/camera_sensor_helper.h index bd3d0beec7..a9e55c832d 100644 --- a/src/ipa/libipa/camera_sensor_helper.h +++ b/src/ipa/libipa/camera_sensor_helper.h @@ -27,6 +27,7 @@ public: virtual ~CameraSensorHelper() = default; std::optional blackLevel() const { return blackLevel_; } + std::optional exposureMargin() const { return exposureMargin_; } virtual uint32_t gainCode(double gain) const; virtual double gain(uint32_t gainCode) const; double quantizeGain(double gain, double *quantizationGain) const; @@ -46,6 +47,7 @@ protected: std::optional blackLevel_; std::variant gain_; + std::optional exposureMargin_; private: LIBCAMERA_DISABLE_COPY_AND_MOVE(CameraSensorHelper)