From patchwork Thu Jan 23 14:07:26 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Scally X-Patchwork-Id: 22636 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 62AA9C3226 for ; Thu, 23 Jan 2025 14:07:54 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id 8D6046855C; Thu, 23 Jan 2025 15:07:51 +0100 (CET) Authentication-Results: lancelot.ideasonboard.com; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="ceGjsVlZ"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 0564E61878 for ; Thu, 23 Jan 2025 15:07:46 +0100 (CET) Received: from mail.ideasonboard.com (cpc141996-chfd3-2-0-cust928.12-3.cable.virginm.net [86.13.91.161]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 697AD1081; Thu, 23 Jan 2025 15:06:42 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1737641202; bh=TOMu82SphVk7MFOmJTgjlewOu9jdsrMrgssQKtJznRM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ceGjsVlZnURtY0jnM50PotDi5sPWzwLKR2k689xHU2lIvZL17OT91p+z7s3f56iC+ CylibrHvXl54HQf6J3mUh3qpCVPT4up/JeBFfNbZp9IReTP+7HrkuJ+g6TxT9vHm0z kczBmY1ZItB+ZSdItkSLUDcli3pZyZFz7DME4ROA= From: Daniel Scally To: libcamera-devel@lists.libcamera.org Cc: Daniel Scally Subject: [PATCH v2 2/3] ipa: libipa: Adjust for flicker in ExposureModeHelper Date: Thu, 23 Jan 2025 14:07:26 +0000 Message-Id: <20250123140727.458567-3-dan.scally@ideasonboard.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250123140727.458567-1-dan.scally@ideasonboard.com> References: <20250123140727.458567-1-dan.scally@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" Update the ExposureModeHelper class to compensate for flickering light sources in the ExposureModeHelper::splitExposure() function. The adjustment simply caps exposure time at a multiple of the given flicker period and compensates for any loss in the effective exposure value by increasing analogue and then digital gain. Initially in the one call-site for this function, a std::nullopt is passed to make this a no-op. Signed-off-by: Daniel Scally --- Changes in v2: - Added a function to perform all the exposure time functionality in a single place so we're not repeating ourselves - Called that function in all the return sites rather than just one so the flicker mitigation takes effect using exposure from the stages list - Switched the flickerPeriod input to a std::optional - Clamped the calculated exposure time to guarantee it can't go beneath the configured minima src/ipa/libipa/agc_mean_luminance.cpp | 3 +- src/ipa/libipa/exposure_mode_helper.cpp | 37 ++++++++++++++++++++++--- src/ipa/libipa/exposure_mode_helper.h | 6 +++- 3 files changed, 40 insertions(+), 6 deletions(-) diff --git a/src/ipa/libipa/agc_mean_luminance.cpp b/src/ipa/libipa/agc_mean_luminance.cpp index 02555a44..273ec4e5 100644 --- a/src/ipa/libipa/agc_mean_luminance.cpp +++ b/src/ipa/libipa/agc_mean_luminance.cpp @@ -8,6 +8,7 @@ #include "agc_mean_luminance.h" #include +#include #include #include @@ -560,7 +561,7 @@ AgcMeanLuminance::calculateNewEv(uint32_t constraintModeIndex, newExposureValue = filterExposure(newExposureValue); frameCount_++; - return exposureModeHelper->splitExposure(newExposureValue); + return exposureModeHelper->splitExposure(newExposureValue, std::nullopt); } /** diff --git a/src/ipa/libipa/exposure_mode_helper.cpp b/src/ipa/libipa/exposure_mode_helper.cpp index f235316d..4e1ba943 100644 --- a/src/ipa/libipa/exposure_mode_helper.cpp +++ b/src/ipa/libipa/exposure_mode_helper.cpp @@ -7,6 +7,7 @@ #include "exposure_mode_helper.h" #include +#include #include @@ -118,9 +119,31 @@ double ExposureModeHelper::clampGain(double gain) const return std::clamp(gain, minGain_, maxGain_); } +utils::Duration +ExposureModeHelper::calculateExposureTime(utils::Duration exposure, double stageGain, + std::optional flickerPeriod) const +{ + utils::Duration exposureTime; + + exposureTime = clampExposureTime(exposure / stageGain); + + /* + * If we haven't been given a flicker period to adjust for or if it's + * longer than the exposure time that we need to set then there's not + * much we can do to compensate. + */ + if (!flickerPeriod.has_value() || flickerPeriod.value() >= exposureTime) + return exposureTime; + + unsigned int flickerPeriods = exposureTime / flickerPeriod.value(); + + return clampExposureTime(flickerPeriods * flickerPeriod.value()); +} + /** * \brief Split exposure into exposure time and gain * \param[in] exposure Exposure value + * \param[in] flickerPeriod The period of a flickering light source * * This function divides a given exposure into exposure time, analogue and * digital gain by iterating through stages of exposure time and gain limits. @@ -147,10 +170,15 @@ double ExposureModeHelper::clampGain(double gain) const * required exposure, the helper falls-back to simply maximising the exposure * time first, followed by analogue gain, followed by digital gain. * + * Once the exposure time has been determined from the modes, an adjustment is + * made to compensate for a flickering light source by fixing the exposure time + * to an exact multiple of the flicker period. Any effective exposure value that + * is lost is added back via analogue and digital gain. + * * \return Tuple of exposure time, analogue gain, and digital gain */ std::tuple -ExposureModeHelper::splitExposure(utils::Duration exposure) const +ExposureModeHelper::splitExposure(utils::Duration exposure, std::optional flickerPeriod) const { ASSERT(maxExposureTime_); ASSERT(maxGain_); @@ -183,14 +211,14 @@ ExposureModeHelper::splitExposure(utils::Duration exposure) const */ if (stageExposureTime * lastStageGain >= exposure) { - exposureTime = clampExposureTime(exposure / clampGain(lastStageGain)); + exposureTime = calculateExposureTime(exposure, clampGain(lastStageGain), flickerPeriod); gain = clampGain(exposure / exposureTime); return { exposureTime, gain, exposure / (exposureTime * gain) }; } if (stageExposureTime * stageGain >= exposure) { - exposureTime = clampExposureTime(exposure / clampGain(stageGain)); + exposureTime = calculateExposureTime(exposure, clampGain(stageGain), flickerPeriod); gain = clampGain(exposure / exposureTime); return { exposureTime, gain, exposure / (exposureTime * gain) }; @@ -204,7 +232,8 @@ ExposureModeHelper::splitExposure(utils::Duration exposure) const * stages to use then the default stageGain of 1.0 is used so that * exposure time is maxed before gain is touched at all. */ - exposureTime = clampExposureTime(exposure / clampGain(stageGain)); + exposureTime = calculateExposureTime(exposure, clampGain(stageGain), flickerPeriod); + gain = clampGain(exposure / exposureTime); return { exposureTime, gain, exposure / (exposureTime * gain) }; diff --git a/src/ipa/libipa/exposure_mode_helper.h b/src/ipa/libipa/exposure_mode_helper.h index c5be1b67..a1d8c6bf 100644 --- a/src/ipa/libipa/exposure_mode_helper.h +++ b/src/ipa/libipa/exposure_mode_helper.h @@ -7,6 +7,7 @@ #pragma once +#include #include #include #include @@ -28,7 +29,7 @@ public: double minGain, double maxGain); std::tuple - splitExposure(utils::Duration exposure) const; + splitExposure(utils::Duration exposure, std::optional flickerPeriod) const; utils::Duration minExposureTime() const { return minExposureTime_; } utils::Duration maxExposureTime() const { return maxExposureTime_; } @@ -38,6 +39,9 @@ public: private: utils::Duration clampExposureTime(utils::Duration exposureTime) const; double clampGain(double gain) const; + utils::Duration + calculateExposureTime(utils::Duration exposureTime, double stageGain, + std::optional flickerPeriod) const; std::vector exposureTimes_; std::vector gains_;