[{"id":35924,"web_url":"https://patchwork.libcamera.org/comment/35924/","msgid":"<175828115252.3174118.9258083567087125918@neptunite.rasen.tech>","date":"2025-09-19T11:25:52","subject":"Re: [PATCH v5 03/19] libipa: camera_sensor_helper: Add\n\tquantizeGain() function","submitter":{"id":17,"url":"https://patchwork.libcamera.org/api/people/17/","name":"Paul Elder","email":"paul.elder@ideasonboard.com"},"content":"Hi Stefan,\n\nThanks for the patch.\n\nQuoting Stefan Klug (2025-09-19 18:40:18)\n> Add a small utility function that calculates the quantized gain that\n> gets applied by a sensor when the gain code is set to gainCode(gain).\n> This is needed by algorithms to calculate a digital correction gain that\n> gets applied to mitigate the error introduce by quantization.\n> \n> Signed-off-by: Stefan Klug \n> Reviewed-by: Isaac Scott \n> Reviewed-by: Daniel Scally \n\nLooks good to me!\n\nReviewed-by: Paul Elder \n\n> \n> ---\n> \n> Changes in v3:\n> - Remove virtual from quantizeGain()\n> - Improved documentation\n> - Collected tags\n> ---\n> src/ipa/libipa/camera_sensor_helper.cpp | 23 +++++++++++++++++++++++\n> src/ipa/libipa/camera_sensor_helper.h | 1 +\n> 2 files changed, 24 insertions(+)\n> \n> diff --git a/src/ipa/libipa/camera_sensor_helper.cpp b/src/ipa/libipa/camera_sensor_helper.cpp\n> index dcd69d9f2bbb..01f6470a196f 100644\n> --- a/src/ipa/libipa/camera_sensor_helper.cpp\n> +++ b/src/ipa/libipa/camera_sensor_helper.cpp\n> @@ -131,6 +131,29 @@ double CameraSensorHelper::gain(uint32_t gainCode) const\n> }\n> }\n> \n> +/**\n> + * \\brief Quantize the given gain value\n> + * \\param[in] _gain The real gain\n> + * \\param[out] quantizationGain The gain that is lost due to quantization\n> + *\n> + * This function returns the actual gain that is applied when the sensor's gain\n> + * is set to gainCode(_gain).\n> + *\n> + * It shall be guaranteed that gainCode(_gain) == gainCode(quantizeGain(_gain)).\n> + *\n> + * If \\a quantizationGain is provided it is populated with the gain that must be\n> + * applied on top to correct for the losses due to quantization.\n> + *\n> + * \\return The quantized real gain\n> + */\n> +double CameraSensorHelper::quantizeGain(double _gain, double *quantizationGain) const\n> +{\n> + double g = gain(gainCode(_gain));\n> + if (quantizationGain)\n> + *quantizationGain = _gain / g;\n> + return g;\n> +}\n> +\n> /**\n> * \\struct CameraSensorHelper::AnalogueGainLinear\n> * \\brief Analogue gain constants for the linear gain model\n> diff --git a/src/ipa/libipa/camera_sensor_helper.h b/src/ipa/libipa/camera_sensor_helper.h\n> index a9300a64f1e7..bd3d0beec77f 100644\n> --- a/src/ipa/libipa/camera_sensor_helper.h\n> +++ b/src/ipa/libipa/camera_sensor_helper.h\n> @@ -29,6 +29,7 @@ public:\n> std::optional blackLevel() const { return blackLevel_; }\n> virtual uint32_t gainCode(double gain) const;\n> virtual double gain(uint32_t gainCode) const;\n> + double quantizeGain(double gain, double *quantizationGain) const;\n> \n> protected:\n> struct AnalogueGainLinear {\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 0ADBBC328C\n\tfor ;\n\tFri, 19 Sep 2025 11:26:03 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id F1E3F62C35;\n\tFri, 19 Sep 2025 13:26:01 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id F2EEE62C35\n\tfor ;\n\tFri, 19 Sep 2025 13:25:59 +0200 (CEST)","from neptunite.rasen.tech (unknown\n\t[IPv6:2404:7a81:160:2100:ae7e:60b0:e249:fbe5])\n\tby perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id EBCE850A;\n\tFri, 19 Sep 2025 13:24:38 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; 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