[{"id":38850,"web_url":"https://patchwork.libcamera.org/comment/38850/","msgid":"<85pl32thxv.fsf@mzamazal-thinkpadp1gen7.tpbc.csb>","date":"2026-05-11T09:27:08","subject":"Re: [PATCH v2 02/10] ipa: simple: awb: Add temporal smoothing and\n\tper-channel gain limits","submitter":{"id":177,"url":"https://patchwork.libcamera.org/api/people/177/","name":"Milan Zamazal","email":"mzamazal@redhat.com"},"content":"d3vv3 writes:\n\n> Add configurable YAML parameters maxGainR, maxGainB, and speed to AWB.\n> Replace the single hardcoded max gain (4.0x) with per-channel limits,\n> and apply exponential moving average smoothing to reduce colour\n> temperature oscillation between frames.\n>\n> Signed-off-by: d3vv3 \n\nReviewed-by: Milan Zamazal \n\n> ---\n> src/ipa/simple/algorithms/awb.cpp | 34 ++++++++++++++++++++++++++-----\n> src/ipa/simple/algorithms/awb.h | 6 ++++++\n> 2 files changed, 35 insertions(+), 5 deletions(-)\n>\n> diff --git a/src/ipa/simple/algorithms/awb.cpp b/src/ipa/simple/algorithms/awb.cpp\n> index f5c88ea6..937aabc8 100644\n> --- a/src/ipa/simple/algorithms/awb.cpp\n> +++ b/src/ipa/simple/algorithms/awb.cpp\n> @@ -14,6 +14,8 @@\n> \n> #include \n> \n> +#include \"libcamera/internal/yaml_parser.h\"\n> +\n> #include \"libipa/colours.h\"\n> #include \"simple/ipa_context.h\"\n> \n> @@ -23,6 +25,21 @@ LOG_DEFINE_CATEGORY(IPASoftAwb)\n> \n> namespace ipa::soft::algorithms {\n> \n> +int Awb::init([[maybe_unused]] IPAContext &context,\n> +\t const ValueNode &tuningData)\n> +{\n> +\tmaxGainR_ = tuningData[\"maxGainR\"].get().value_or(4.0f);\n> +\tmaxGainB_ = tuningData[\"maxGainB\"].get().value_or(4.0f);\n> +\tspeed_ = tuningData[\"speed\"].get().value_or(1.0f);\n> +\n> +\tLOG(IPASoftAwb, Debug)\n> +\t\t<< \"AWB: maxGainR \" << maxGainR_\n> +\t\t<< \", maxGainB \" << maxGainB_\n> +\t\t<< \", speed \" << speed_;\n> +\n> +\treturn 0;\n> +}\n> +\n> int Awb::configure(IPAContext &context,\n> \t\t [[maybe_unused]] const IPAConfigInfo &configInfo)\n> {\n> @@ -84,14 +101,21 @@ void Awb::process(IPAContext &context,\n> \tconst RGB sum = stats->sum_.max(offset + minValid) - offset;\n> \n> \t/*\n> -\t * Calculate red and blue gains for AWB.\n> -\t * Clamp max gain at 4.0, this also avoids 0 division.\n> +\t * Calculate red and blue gains for AWB. Clamp max gain to avoid\n> +\t * division by zero and extreme color casts.\n> \t */\n> \tauto &gains = context.activeState.awb.gains;\n> +\tfloat rawRGain = sum.r() <= sum.g() / maxGainR_ ? maxGainR_ :\n> +\t\t\t\tstatic_cast(sum.g()) / sum.r();\n> +\tfloat rawBGain = sum.b() <= sum.g() / maxGainB_ ? maxGainB_ :\n> +\t\t\t\tstatic_cast(sum.g()) / sum.b();\n> +\n> +\t/* Apply temporal smoothing to avoid rapid white balance changes. */\n> +\tfloat alpha = std::clamp(speed_, 0.01f, 1.0f);\n> \tgains = { {\n> -\t\tsum.r() <= sum.g() / 4 ? 4.0f : static_cast(sum.g()) / sum.r(),\n> -\t\t1.0,\n> -\t\tsum.b() <= sum.g() / 4 ? 4.0f : static_cast(sum.g()) / sum.b(),\n> +\t\tgains.r() * (1.0f - alpha) + rawRGain * alpha,\n> +\t\t1.0f,\n> +\t\tgains.b() * (1.0f - alpha) + rawBGain * alpha,\n> \t} };\n> \n> \tRGB rgbGains{ { 1 / gains.r(), 1 / gains.g(), 1 / gains.b() } };\n> diff --git a/src/ipa/simple/algorithms/awb.h b/src/ipa/simple/algorithms/awb.h\n> index ad993f39..0aedc1d1 100644\n> --- a/src/ipa/simple/algorithms/awb.h\n> +++ b/src/ipa/simple/algorithms/awb.h\n> @@ -19,6 +19,7 @@ public:\n> \tAwb() = default;\n> \t~Awb() = default;\n> \n> +\tint init(IPAContext &context, const ValueNode &tuningData) override;\n> \tint configure(IPAContext &context, const IPAConfigInfo &configInfo) override;\n> \tvoid prepare(IPAContext &context,\n> \t\t const uint32_t frame,\n> @@ -29,6 +30,11 @@ public:\n> \t\t IPAFrameContext &frameContext,\n> \t\t const SwIspStats *stats,\n> \t\t ControlList &metadata) override;\n> +\n> +private:\n> +\tfloat maxGainR_;\n> +\tfloat maxGainB_;\n> +\tfloat speed_;\n> };\n> \n> } /* namespace ipa::soft::algorithms */","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 BF08BBDCBD\n\tfor ;\n\tMon, 11 May 2026 09:27:16 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 506E16301E;\n\tMon, 11 May 2026 11:27:15 +0200 (CEST)","from us-smtp-delivery-124.mimecast.com\n\t(us-smtp-delivery-124.mimecast.com [170.10.133.124])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 4811E62010\n\tfor ;\n\tMon, 11 May 2026 11:27:14 +0200 (CEST)","from mail-wr1-f70.google.com (mail-wr1-f70.google.com\n\t[209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS\n\t(version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id\n\tus-mta-582-JjiG7OfoNpiUY3xuMdDi4w-1; Mon, 11 May 2026 05:27:11 -0400","by mail-wr1-f70.google.com with SMTP id\n\tffacd0b85a97d-44f56d5523eso3469334f8f.1\n\tfor ;\n\tMon, 11 May 2026 02:27:11 -0700 (PDT)","from mzamazal-thinkpadp1gen7.tpbc.csb\n\t(ip-77-48-47-4.net.vodafone.cz. 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