From patchwork Tue Jan 27 20:47:11 2026 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Milan Zamazal X-Patchwork-Id: 25983 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 0931AC3200 for ; Tue, 27 Jan 2026 20:47:26 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id DA6BF61FC4; Tue, 27 Jan 2026 21:47:24 +0100 (CET) Authentication-Results: lancelot.ideasonboard.com; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.b="UTXM3/6p"; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id C131261FBF for ; Tue, 27 Jan 2026 21:47:22 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1769546841; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=4cizD0pj70LtvMk1qgwfB9ooskLrQbDHP7ywqomQDuI=; b=UTXM3/6peWdl/OGDCPfPMmtW/sBNnRffb2SX3AwZE+CXbO22gY8HkpL5L3QAe6MM8TtL58 5UKCbKogkreBd6UmtmvC1cQFNouBpxH1daJpul5RWXKKZLVMc+XKlE/HrkuHDwenyMX6Vb b7496C324vmojjN/WLyVuuRRgWrWacI= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-125-82kLxG6GNEizqv6Xyf-YRg-1; Tue, 27 Jan 2026 15:47:18 -0500 X-MC-Unique: 82kLxG6GNEizqv6Xyf-YRg-1 X-Mimecast-MFC-AGG-ID: 82kLxG6GNEizqv6Xyf-YRg_1769546837 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 96B7419775A3; Tue, 27 Jan 2026 20:47:16 +0000 (UTC) Received: from mzamazal-thinkpadp1gen7.tpbc.com (unknown [10.44.34.174]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 142C719560B2; Tue, 27 Jan 2026 20:47:13 +0000 (UTC) From: Milan Zamazal To: libcamera-devel@lists.libcamera.org Cc: Milan Zamazal , Laurent Pinchart , Robert Mader , =?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= Subject: [PATCH v3] libcamera: simple: Fix black level offsets in AWB Date: Tue, 27 Jan 2026 21:47:11 +0100 Message-ID: <20260127204711.155002-1-mzamazal@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: DUvzBjuGvDUS4M86_6dB4cB7FUy_eWgJrUl7TNS9g00_1769546837 X-Mimecast-Originator: redhat.com content-type: text/plain; charset="US-ASCII"; x-default=true 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" The black level offset subtracted in AWB is wrong. It assumes that the stats contain sums of the individual colour pixels. But they actually contain sums of the colour channels of larger "superpixels" consisting of the individual colour pixels. Each of the RGB colour values and the computed luminosity (a histogram entry) are added once to the stats per such a superpixel. This means the offset computed from the black level and the number of pixels should be used as it is, not divided. The patch fixes the subtracted offset. Since the evaluation is the same for all the three colours now, the individual class variables are replaced with a single RGB variable. Fixes: 4e13c6f55bd667 ("Honor black level in AWB") Reviewed-by: Laurent Pinchart Reviewed-by: Robert Mader Tested-by: Robert Mader Signed-off-by: Milan Zamazal --- .../internal/software_isp/swisp_stats.h | 16 +++++----------- src/ipa/simple/algorithms/awb.cpp | 14 ++++++++------ src/libcamera/software_isp/swstats_cpu.cpp | 10 ++++------ 3 files changed, 17 insertions(+), 23 deletions(-) diff --git a/include/libcamera/internal/software_isp/swisp_stats.h b/include/libcamera/internal/software_isp/swisp_stats.h index 3c9860185..d9d0d9be8 100644 --- a/include/libcamera/internal/software_isp/swisp_stats.h +++ b/include/libcamera/internal/software_isp/swisp_stats.h @@ -10,6 +10,8 @@ #include #include +#include "libcamera/internal/vector.h" + namespace libcamera { /** @@ -26,17 +28,9 @@ struct SwIspStats { */ bool valid; /** - * \brief Holds the sum of all sampled red pixels - */ - uint64_t sumR_; - /** - * \brief Holds the sum of all sampled green pixels - */ - uint64_t sumG_; - /** - * \brief Holds the sum of all sampled blue pixels + * \brief Sums of colour channels of all the sampled pixels */ - uint64_t sumB_; + RGB sum_; /** * \brief Number of bins in the yHistogram */ @@ -46,7 +40,7 @@ struct SwIspStats { */ using Histogram = std::array; /** - * \brief A histogram of luminance values + * \brief A histogram of luminance values of all the sampled pixels */ Histogram yHistogram; }; diff --git a/src/ipa/simple/algorithms/awb.cpp b/src/ipa/simple/algorithms/awb.cpp index 0080865aa..50565fe8a 100644 --- a/src/ipa/simple/algorithms/awb.cpp +++ b/src/ipa/simple/algorithms/awb.cpp @@ -1,6 +1,6 @@ /* SPDX-License-Identifier: LGPL-2.1-or-later */ /* - * Copyright (C) 2024, Red Hat Inc. + * Copyright (C) 2024-2026 Red Hat Inc. * * Auto white balance */ @@ -73,9 +73,11 @@ void Awb::process(IPAContext &context, histogram.begin(), histogram.end(), uint64_t(0)); const uint64_t offset = blackLevel * nPixels; const uint64_t minValid = 1; - const uint64_t sumR = stats->sumR_ > offset / 4 ? stats->sumR_ - offset / 4 : minValid; - const uint64_t sumG = stats->sumG_ > offset / 2 ? stats->sumG_ - offset / 2 : minValid; - const uint64_t sumB = stats->sumB_ > offset / 4 ? stats->sumB_ - offset / 4 : minValid; + /* + * Make sure the sums are at least minValid, while preventing unsigned + * integer underflow. + */ + const RGB sum = stats->sum_.max(offset + minValid) - offset; /* * Calculate red and blue gains for AWB. @@ -83,9 +85,9 @@ void Awb::process(IPAContext &context, */ auto &gains = context.activeState.awb.gains; gains = { { - sumR <= sumG / 4 ? 4.0f : static_cast(sumG) / sumR, + sum.r() <= sum.g() / 4 ? 4.0f : static_cast(sum.g()) / sum.r(), 1.0, - sumB <= sumG / 4 ? 4.0f : static_cast(sumG) / sumB, + sum.b() <= sum.g() / 4 ? 4.0f : static_cast(sum.g()) / sum.b(), } }; RGB rgbGains{ { 1 / gains.r(), 1 / gains.g(), 1 / gains.b() } }; diff --git a/src/libcamera/software_isp/swstats_cpu.cpp b/src/libcamera/software_isp/swstats_cpu.cpp index c931edb41..5c3011a7f 100644 --- a/src/libcamera/software_isp/swstats_cpu.cpp +++ b/src/libcamera/software_isp/swstats_cpu.cpp @@ -185,9 +185,9 @@ static constexpr unsigned int kBlueYMul = 29; /* 0.114 * 256 */ stats_.yHistogram[yVal * SwIspStats::kYHistogramSize / (256 * 256 * (div))]++; #define SWSTATS_FINISH_LINE_STATS() \ - stats_.sumR_ += sumR; \ - stats_.sumG_ += sumG; \ - stats_.sumB_ += sumB; + stats_.sum_.r() += sumR; \ + stats_.sum_.g() += sumG; \ + stats_.sum_.b() += sumB; void SwStatsCpu::statsBGGR8Line0(const uint8_t *src[]) { @@ -332,9 +332,7 @@ void SwStatsCpu::startFrame(uint32_t frame) if (window_.width == 0) LOG(SwStatsCpu, Error) << "Calling startFrame() without setWindow()"; - stats_.sumR_ = 0; - stats_.sumB_ = 0; - stats_.sumG_ = 0; + stats_.sum_ = RGB({ 0, 0, 0 }); stats_.yHistogram.fill(0); }