[{"id":35712,"web_url":"https://patchwork.libcamera.org/comment/35712/","msgid":"<175706898237.1787083.17916175835267118388@neptunite.rasen.tech>","date":"2025-09-05T10:43:02","subject":"Re: [PATCH v3 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":"Quoting Stefan Klug (2025-08-15 19:29:23)\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> \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..a490161faf4c 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 sensors gain\n\ns/sensors/sensor's/\n\n> + * is set to gainCode(gain).\n\ns/(gain)/(_gain)/ I think might be clearer?\n\n> + *\n> + * It shall be guaranteed that gainCode(gain) == gainCode(quantizeGain(gain)).\n\nSame here.\n\n> + *\n> + * If \\a quantizationGain is provided it is filled with the gain that must be\n\nPersonally I'd prefer s/filled/populated/, since filling feels like there could\nbe an initial value that you \"fill\" until you reach the target value. It's just\na feeling though :)\n\n> + * applied to correct the losses due to quantization.\n\ns/applied to/applied to \\a _gain/ and s/the/for the/ I think is slightly clearer.\n\nReviewed-by: Paul Elder \n\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 D83D0C332D\n\tfor ;\n\tFri, 5 Sep 2025 10:43:25 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 0D42469369;\n\tFri, 5 Sep 2025 12:43:25 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 00F4769345\n\tfor ;\n\tFri, 5 Sep 2025 12:43:09 +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 403D01666; \n\tFri, 5 Sep 2025 12:41:58 +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=\"Airn+BtF\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1757068919;\n\tbh=t3LvGQAZb+g3xR9DVopKaTX+H/gP8SMziga91Jjik2M=;\n\th=In-Reply-To:References:Subject:From:Cc:To:Date:From;\n\tb=Airn+BtFttQz4aDcOlWnqQU9og8FLHwp8f1AfV3mi1DuFIH1zYfBWC2g2mnzG1p0o\n\tF2ZdI8BnYf4k2cd2p1ZrP9a7kHvKXTIcedAi0KUoZpBxRlnuYsjTjdoZ1pK6IeS7C+\n\tarrhkVEjlv4b0cQtjpaPme+f7+VJIYYoQNsOoEzE=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<20250815102945.1602071-4-stefan.klug@ideasonboard.com>","References":"<20250815102945.1602071-1-stefan.klug@ideasonboard.com>\n\t<20250815102945.1602071-4-stefan.klug@ideasonboard.com>","Subject":"Re: [PATCH v3 03/19] libipa: camera_sensor_helper: Add\n\tquantizeGain() function","From":"Paul Elder ","Cc":"Stefan Klug ,\n\tIsaac Scott ,\n\tDaniel Scally ","To":"Stefan Klug ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Fri, 05 Sep 2025 19:43:02 +0900","Message-ID":"<175706898237.1787083.17916175835267118388@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\" "}},{"id":35896,"web_url":"https://patchwork.libcamera.org/comment/35896/","msgid":"<175820138833.17312.18397619129142504274@localhost>","date":"2025-09-18T13:16:28","subject":"Re: [PATCH v3 03/19] libipa: camera_sensor_helper: Add\n\tquantizeGain() function","submitter":{"id":184,"url":"https://patchwork.libcamera.org/api/people/184/","name":"Stefan Klug","email":"stefan.klug@ideasonboard.com"},"content":"Hi Paul,\n\nThank you for the review.\n\nQuoting Paul Elder (2025-09-05 12:43:02)\n> Quoting Stefan Klug (2025-08-15 19:29:23)\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> > \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..a490161faf4c 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 sensors gain\n> \n> s/sensors/sensor's/\n> \n> > + * is set to gainCode(gain).\n> \n> s/(gain)/(_gain)/ I think might be clearer?\n> \n> > + *\n> > + * It shall be guaranteed that gainCode(gain) == gainCode(quantizeGain(gain)).\n> \n> Same here.\n> \n> > + *\n> > + * If \\a quantizationGain is provided it is filled with the gain that must be\n> \n> Personally I'd prefer s/filled/populated/, since filling feels like there could\n> be an initial value that you \"fill\" until you reach the target value. It's just\n> a feeling though :)\n> \n> > + * applied to correct the losses due to quantization.\n> \n> s/applied to/applied to \\a _gain/ and s/the/for the/ I think is slightly clearer.\n\nI applied the previous fixes. Here I think it is not exactly right as\nquantizationGain is not applied to _gain but to the result of this\nfunction. I went for \"... the gain that must be applied on top to\ncorrect for the losses...\". This is also not ideal, but I already have\nthe next rewrite of this function in the pipeline so I guess it's ok for\nnow.\n\n> \n> Reviewed-by: Paul Elder \n\nThanks,\nStefan\n\n> \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 56859C328C\n\tfor ;\n\tThu, 18 Sep 2025 13:16:34 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 63E796936F;\n\tThu, 18 Sep 2025 15:16:33 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 808FA62C3B\n\tfor ;\n\tThu, 18 Sep 2025 15:16:31 +0200 (CEST)","from ideasonboard.com (unknown\n\t[IPv6:2a00:6020:448c:6c00:ace3:d2c2:5eff:9cc5])\n\tby perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id CECE9558;\n\tThu, 18 Sep 2025 15:15:11 +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=\"rmMH2PW6\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1758201311;\n\tbh=+SNS9bIlv9VXFM7hIPH6/d60UDj3ErL4nih85Nt4Fa0=;\n\th=In-Reply-To:References:Subject:From:Cc:To:Date:From;\n\tb=rmMH2PW6+A659mZeSQcN+ldjcXmr6OxYhnmyNHkeSnQrZC076gZlzA4qRjenwD9qx\n\tfRXlwWieUnwMIOaLSz1JPZOveZ3333Cud3jQhT9QgfuVTy/zSZ0Eroo6ZC59g58rGk\n\te5/3w5M0J/gzzJcODthEGkLjKnZ4/1sheIALVm/c=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<175706898237.1787083.17916175835267118388@neptunite.rasen.tech>","References":"<20250815102945.1602071-1-stefan.klug@ideasonboard.com>\n\t<20250815102945.1602071-4-stefan.klug@ideasonboard.com>\n\t<175706898237.1787083.17916175835267118388@neptunite.rasen.tech>","Subject":"Re: [PATCH v3 03/19] libipa: camera_sensor_helper: Add\n\tquantizeGain() function","From":"Stefan Klug ","Cc":"Isaac Scott ,\n\tDaniel Scally ","To":"Paul Elder ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Thu, 18 Sep 2025 15:16:28 +0200","Message-ID":"<175820138833.17312.18397619129142504274@localhost>","User-Agent":"alot/0.12.dev8+g2c003385c862.d20250602","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\" "}},{"id":35909,"web_url":"https://patchwork.libcamera.org/comment/35909/","msgid":"<175822146746.2724359.2511869900989079706@neptunite.rasen.tech>","date":"2025-09-18T18:51:07","subject":"Re: [PATCH v3 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":"Quoting Stefan Klug (2025-09-18 22:16:28)\n> Hi Paul,\n> \n> Thank you for the review.\n> \n> Quoting Paul Elder (2025-09-05 12:43:02)\n> > Quoting Stefan Klug (2025-08-15 19:29:23)\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> > > \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..a490161faf4c 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 sensors gain\n> > \n> > s/sensors/sensor's/\n> > \n> > > + * is set to gainCode(gain).\n> > \n> > s/(gain)/(_gain)/ I think might be clearer?\n> > \n> > > + *\n> > > + * It shall be guaranteed that gainCode(gain) == gainCode(quantizeGain(gain)).\n> > \n> > Same here.\n> > \n> > > + *\n> > > + * If \\a quantizationGain is provided it is filled with the gain that must be\n> > \n> > Personally I'd prefer s/filled/populated/, since filling feels like there could\n> > be an initial value that you \"fill\" until you reach the target value. It's just\n> > a feeling though :)\n> > \n> > > + * applied to correct the losses due to quantization.\n> > \n> > s/applied to/applied to \\a _gain/ and s/the/for the/ I think is slightly clearer.\n> \n> I applied the previous fixes. Here I think it is not exactly right as\n> quantizationGain is not applied to _gain but to the result of this\n> function. I went for \"... the gain that must be applied on top to\n> correct for the losses...\". This is also not ideal, but I already have\n\nOk, that's good too, I'll take that.\n\nPaul\n\n> the next rewrite of this function in the pipeline so I guess it's ok for\n> now.\n> \n> > \n> > Reviewed-by: Paul Elder \n> \n> Thanks,\n> Stefan\n> \n> > \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 5E73CBE173\n\tfor ;\n\tThu, 18 Sep 2025 18:51:17 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 68ED069371;\n\tThu, 18 Sep 2025 20:51:16 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id AEFD462C3A\n\tfor ;\n\tThu, 18 Sep 2025 20:51:14 +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 1186C3A4;\n\tThu, 18 Sep 2025 20:49:53 +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=\"rRmJ84g3\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1758221394;\n\tbh=a+tqWUtMIOVEFWUpn5ulgqP13vxIlDkhWqi/ZgRL9FE=;\n\th=In-Reply-To:References:Subject:From:Cc:To:Date:From;\n\tb=rRmJ84g3G9Z5NILu/l1wsDDwKbiJXaseWPptE0ovZSNFP7aqOsOA0PPTjY9ATV6/g\n\tqI4bMCG+yolCcdF/r6e6x7HFi7IWZJkFChUgfxm4/IrY8j674zKrate0ch/2zE0bnw\n\tukhbbx9Mzce8BQWeuKKYXu51+RZr5Ki2uhB7IwGY=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<175820138833.17312.18397619129142504274@localhost>","References":"<20250815102945.1602071-1-stefan.klug@ideasonboard.com>\n\t<20250815102945.1602071-4-stefan.klug@ideasonboard.com>\n\t<175706898237.1787083.17916175835267118388@neptunite.rasen.tech>\n\t<175820138833.17312.18397619129142504274@localhost>","Subject":"Re: [PATCH v3 03/19] libipa: camera_sensor_helper: Add\n\tquantizeGain() function","From":"Paul Elder ","Cc":"Isaac Scott ,\n\tDaniel Scally ","To":"Stefan Klug ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Fri, 19 Sep 2025 03:51:07 +0900","Message-ID":"<175822146746.2724359.2511869900989079706@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\" "}}]