[{"id":35703,"web_url":"https://patchwork.libcamera.org/comment/35703/","msgid":"<175706897640.1787083.9189914118137381397@neptunite.rasen.tech>","date":"2025-09-05T10:42:56","subject":"Re: [PATCH v3 10/19] ipa: rkisp1: agc: Add correction for exposure\n\tquantization","submitter":{"id":17,"url":"https://patchwork.libcamera.org/api/people/17/","name":"Paul Elder","email":"paul.elder@ideasonboard.com"},"content":"Quoting Stefan Klug (2025-08-15 19:29:30)\n> There are several occations where quantization can lead to visible\n> effects.\n> \n> In WDR mode it can happen that exposure times get set to very low values\n> (Sometimes 2-3 lines). This intentionally introduced underexposure is\n> corrected by the GWDR module. As exposure time is quantized by lines,\n> the smallest possible change in exposure time now results in a quite\n> visible change in perceived brightness.\n> \n> Sometimes the possible gain steps are also quite large leading to\n> visible jumps if e.g. if the exposure time is fixed.\n> \n> Mitigate that by applying a global gain to account for the error\n> introduced by the exposure quantization.\n> \n> ToDo: This needs perfect frame synchronous control of the sensor to work\n> properly which is not guaranteed in all cases. It still improves the\n> behavior with the current regulation and can easily be skipped, when\n> there is no compress algorithm.\n> \n> Signed-off-by: Stefan Klug \n> Reviewed-by: Kieran Bingham \n> Reviewed-by: Daniel Scally \n\nReviewed-by: Paul Elder \n\n> \n> ---\n> \n> Changes in v3:\n> - Collected tags\n> ---\n> src/ipa/rkisp1/algorithms/agc.cpp | 24 +++++++++++++++++++++---\n> src/ipa/rkisp1/ipa_context.h | 2 ++\n> 2 files changed, 23 insertions(+), 3 deletions(-)\n> \n> diff --git a/src/ipa/rkisp1/algorithms/agc.cpp b/src/ipa/rkisp1/algorithms/agc.cpp\n> index 0a29326841fb..d34c041f9fe1 100644\n> --- a/src/ipa/rkisp1/algorithms/agc.cpp\n> +++ b/src/ipa/rkisp1/algorithms/agc.cpp\n> @@ -199,6 +199,9 @@ int Agc::configure(IPAContext &context, const IPACameraSensorInfo &configInfo)\n> context.configuration.agc.measureWindow.h_size = configInfo.outputSize.width;\n> context.configuration.agc.measureWindow.v_size = configInfo.outputSize.height;\n> \n> + AgcMeanLuminance::configure(context.configuration.sensor.lineDuration,\n> + context.camHelper.get());\n> +\n> setLimits(context.configuration.sensor.minExposureTime,\n> context.configuration.sensor.maxExposureTime,\n> context.configuration.sensor.minAnalogueGain,\n> @@ -283,6 +286,10 @@ void Agc::queueRequest(IPAContext &context,\n> if (!frameContext.agc.autoGainEnabled)\n> frameContext.agc.gain = agc.manual.gain;\n> \n> + if (!frameContext.agc.autoExposureEnabled &&\n> + !frameContext.agc.autoGainEnabled)\n> + frameContext.agc.quantizationGain = 1.0;\n> +\n> const auto &meteringMode = controls.get(controls::AeMeteringMode);\n> if (meteringMode) {\n> frameContext.agc.updateMetering = agc.meteringMode != *meteringMode;\n> @@ -336,12 +343,17 @@ void Agc::prepare(IPAContext &context, const uint32_t frame,\n> {\n> uint32_t activeAutoExposure = context.activeState.agc.automatic.exposure;\n> double activeAutoGain = context.activeState.agc.automatic.gain;\n> + double activeAutoQGain = context.activeState.agc.automatic.quantizationGain;\n> \n> /* Populate exposure and gain in auto mode */\n> - if (frameContext.agc.autoExposureEnabled)\n> + if (frameContext.agc.autoExposureEnabled) {\n> frameContext.agc.exposure = activeAutoExposure;\n> - if (frameContext.agc.autoGainEnabled)\n> + frameContext.agc.quantizationGain = activeAutoQGain;\n> + }\n> + if (frameContext.agc.autoGainEnabled) {\n> frameContext.agc.gain = activeAutoGain;\n> + frameContext.agc.quantizationGain = activeAutoQGain;\n> + }\n> \n> /*\n> * Populate manual exposure and gain from the active auto values when\n> @@ -354,6 +366,12 @@ void Agc::prepare(IPAContext &context, const uint32_t frame,\n> if (!frameContext.agc.autoGainEnabled && frameContext.agc.autoGainModeChange) {\n> context.activeState.agc.manual.gain = activeAutoGain;\n> frameContext.agc.gain = activeAutoGain;\n> + frameContext.agc.quantizationGain = activeAutoQGain;\n> + }\n> +\n> + if (context.activeState.compress.supported) {\n> + frameContext.compress.enable = true;\n> + frameContext.compress.gain = frameContext.agc.quantizationGain;\n> }\n> \n> if (frame > 0 && !frameContext.agc.updateMetering)\n> @@ -582,7 +600,7 @@ void Agc::process(IPAContext &context, [[maybe_unused]] const uint32_t frame,\n> /* Update the estimated exposure and gain. */\n> activeState.agc.automatic.exposure = newExposureTime / lineDuration;\n> activeState.agc.automatic.gain = aGain;\n> -\n> + activeState.agc.automatic.quantizationGain = qGain;\n> /*\n> * Expand the target frame duration so that we do not run faster than\n> * the minimum frame duration when we have short exposures.\n> diff --git a/src/ipa/rkisp1/ipa_context.h b/src/ipa/rkisp1/ipa_context.h\n> index 37a74215ce19..362ab2fda5fe 100644\n> --- a/src/ipa/rkisp1/ipa_context.h\n> +++ b/src/ipa/rkisp1/ipa_context.h\n> @@ -77,6 +77,7 @@ struct IPAActiveState {\n> struct {\n> uint32_t exposure;\n> double gain;\n> + double quantizationGain;\n> } automatic;\n> \n> bool autoExposureEnabled;\n> @@ -135,6 +136,7 @@ struct IPAFrameContext : public FrameContext {\n> uint32_t exposure;\n> double gain;\n> double exposureValue;\n> + double quantizationGain;\n> uint32_t vblank;\n> bool autoExposureEnabled;\n> bool autoGainEnabled;\n> -- \n> 2.48.1\n>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 17F1FC328C\n\tfor ;\n\tFri, 5 Sep 2025 10:43:03 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 5A19769357;\n\tFri, 5 Sep 2025 12:43:03 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 6D3A569337\n\tfor ;\n\tFri, 5 Sep 2025 12:43:02 +0200 (CEST)","from neptunite.rasen.tech (unknown\n\t[IPv6:2404:7a81:160:2100:dbfb:387c:7405:52bc])\n\tby perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id D722A1129; \n\tFri, 5 Sep 2025 12:41:51 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"PEPacOBN\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1757068912;\n\tbh=aQIVDJjS7h6pLG53QgzroOX2BHyL64b1onrIe+4PXRU=;\n\th=In-Reply-To:References:Subject:From:Cc:To:Date:From;\n\tb=PEPacOBNGAGC9Nv2J6e2umhyYL3JXXWEWIDxNaPU4cI7qpAjGQDHgH2j43T7/YNom\n\tg6Es51fG7o0mEDT4ktprw5hhvXEovuO/SExPsRq+uyoz6dU2sbIjwxspjoA2JPDwG+\n\tCREUYpVCVPFWLJpC2/XPdVtwjppAsh33lCOtERRY=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<20250815102945.1602071-11-stefan.klug@ideasonboard.com>","References":"<20250815102945.1602071-1-stefan.klug@ideasonboard.com>\n\t<20250815102945.1602071-11-stefan.klug@ideasonboard.com>","Subject":"Re: [PATCH v3 10/19] ipa: rkisp1: agc: Add correction for exposure\n\tquantization","From":"Paul Elder ","Cc":"Stefan Klug ,\n\tKieran Bingham ,\n\tDaniel Scally ","To":"Stefan Klug ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Fri, 05 Sep 2025 19:42:56 +0900","Message-ID":"<175706897640.1787083.9189914118137381397@neptunite.rasen.tech>","User-Agent":"alot/0.0.0","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}}]