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{ "id": 26268, "url": "https://patchwork.libcamera.org/api/1.1/patches/26268/?format=api", "web_url": "https://patchwork.libcamera.org/patch/26268/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/1.1/projects/1/?format=api", "name": "libcamera", "link_name": "libcamera", "list_id": "libcamera_core", "list_email": "libcamera-devel@lists.libcamera.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20260306-agc-proportional-v4-2-e87c7e0d837a@jetm.me>", "date": "2026-03-06T18:46:41", "name": "[v4,2/3] libcamera: software_isp: Normalize statistics sums to 8-bit", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "15d3a93126e966d30f221d659254a61949de44c9", "submitter": { "id": 261, "url": "https://patchwork.libcamera.org/api/1.1/people/261/?format=api", "name": "Javier Tia", "email": "floss@jetm.me" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/26268/mbox/", "series": [ { "id": 5824, "url": "https://patchwork.libcamera.org/api/1.1/series/5824/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=5824", "date": "2026-03-06T18:46:39", "name": "Simple pipeline: proportional AGC, AWB stats fix, OV2740 black level", "version": 4, "mbox": "https://patchwork.libcamera.org/series/5824/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/26268/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/26268/checks/", "tags": {}, "headers": { "Return-Path": "<libcamera-devel-bounces@lists.libcamera.org>", "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 C9E49BE086\n\tfor <parsemail@patchwork.libcamera.org>;\n\tFri, 6 Mar 2026 18:47:26 +0000 (UTC)", "from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 7ED6162633;\n\tFri, 6 Mar 2026 19:47:26 +0100 (CET)", "from fout-b3-smtp.messagingengine.com\n\t(fout-b3-smtp.messagingengine.com [202.12.124.146])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 815686261B\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tFri, 6 Mar 2026 19:47:25 +0100 (CET)", "from phl-compute-02.internal (phl-compute-02.internal\n\t[10.202.2.42])\n\tby mailfout.stl.internal (Postfix) with ESMTP id 8EC401D00128;\n\tFri, 6 Mar 2026 13:47:24 -0500 (EST)", "from phl-imap-07 ([10.202.2.97])\n\tby phl-compute-02.internal (MEProxy); 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charset=\"utf-8\"", "Content-Transfer-Encoding": "8bit", "Message-Id": "<20260306-agc-proportional-v4-2-e87c7e0d837a@jetm.me>", "To": "libcamera-devel@lists.libcamera.org", "Cc": "Javier Tia <floss@jetm.me>, Milan Zamazal <mzamazal@redhat.com>,\n\t=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= <barnabas.pocze@ideasonboard.com>", "X-Developer-Signature": "v=1; a=openpgp-sha256; l=3262; i=floss@jetm.me;\n\th=from:subject:message-id;\n\tbh=LPdCiSDd3MA8NAdHMsUrfV6hJzO9wW24ssL+LcTrfSg=; \n\tb=owEB7QES/pANAwAKAbXuwwuoZ3cfAcsmYgBpqyEPM0DYOvoMGOjeah2y0sdaHWmcMOG/wzKEq\n\tOmSLOmMOZyJAbMEAAEKAB0WIQSbE7ILzw7eI0VKk8m17sMLqGd3HwUCaashDwAKCRC17sMLqGd3\n\tHyFDDACbwlLXhgrHH3oYsJfyvDmsJhZH9uK8XpvVjFAK7LDYGWHy+2v9Or3k574Cut7XRAmIV3L\n\tdvE8W1DH2nQmIUlFL9xdGzaGbyjtXss2xcpZvw1DL4mT4QYyZxhXVCHWXGfTv98AsgfFIWgLAT3\n\t1m0yd5Y+DDzsvVGafZl2JOMm1Kjzd/RGCN1OTSPdSTUGLLoAg++SfBIpQ6ogMeIfSKcA5kX3nGy\n\tv3sg31YLf5kEZHPPwLHGqFG5fCx//x6qyM9/JrLXDmg0qruRaEm95wAFefMTvgGzU0JFC78HEVZ\n\tsfJl+i6cQpVH8VCY0YTTatqLQ1tJxjjyCTBNMRnX5QSGa/UA4sM6OvBwwl1goolYdJAlpS65331\n\tITMcTliQJJtSxVY5VyAPZH7g5xTV0RldRgCnjYwCOQVIDx20eB7M2Ml3C6Q3YZ5P8Me4z1Dx7No\n\tGZ5wWqvDi2jt0M+Ph1ybCZZxcfSZlCxcw4+13OSm944/EIgq0GXlrxanOuy5rQmKOYjng=", "X-Developer-Key": "i=floss@jetm.me; a=openpgp;\n\tfpr=9B13B20BCF0EDE23454A93C9B5EEC30BA867771F", "In-Reply-To": "<20260306-agc-proportional-v4-0-e87c7e0d837a@jetm.me>", "References": "<20260306-agc-proportional-v4-0-e87c7e0d837a@jetm.me>", "X-BeenThere": "libcamera-devel@lists.libcamera.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "<libcamera-devel.lists.libcamera.org>", "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>", "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>", "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>", "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>", "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>", "Errors-To": "libcamera-devel-bounces@lists.libcamera.org", "Sender": "\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>" }, "content": "The SWSTATS_ACCUMULATE_LINE_STATS() macro divides the luminance value\nfor the histogram to normalize it to 8-bit range, but does not apply\nthe same normalization to the RGB sums. For 10-bit and 12-bit unpacked\nBayer formats this means the sums are accumulated at native bit depth\n(0-1023 or 0-4095 per pixel) while the AWB algorithm subtracts an\n8-bit black level from them, under-correcting by 4x or 16x\nrespectively.\n\nThis mismatch between the AWB's gain calculation (using incorrectly\nBLC-subtracted sums) and the debayer's correct normalized BLC\nsubtraction produces a visible color cast. For example, with the\nOV2740 sensor (10-bit, BLC=16), the under-subtraction skews R/G gain\nby ~9%.\n\nFix this by right-shifting the RGB sums in finishFrame() to normalize\nthem to 8-bit scale, matching the histogram and the 8-bit black level\nused by AWB. A per-format sumShift_ value is set in configure():\n0 for 8-bit and CSI-2 packed formats (already 8-bit), 2 for 10-bit,\nand 4 for 12-bit unpacked formats.\n\nSigned-off-by: Javier Tia <floss@jetm.me>\nReviewed-by: Milan Zamazal <mzamazal@redhat.com>\nTested-by: Milan Zamazal <mzamazal@redhat.com>\nReviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>\nTested-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>\n---\n include/libcamera/internal/software_isp/swstats_cpu.h | 1 +\n src/libcamera/software_isp/swstats_cpu.cpp | 7 +++++++\n 2 files changed, 8 insertions(+)", "diff": "diff --git a/include/libcamera/internal/software_isp/swstats_cpu.h b/include/libcamera/internal/software_isp/swstats_cpu.h\nindex 64b3e23f..37bfde53 100644\n--- a/include/libcamera/internal/software_isp/swstats_cpu.h\n+++ b/include/libcamera/internal/software_isp/swstats_cpu.h\n@@ -115,6 +115,7 @@ private:\n \n \tunsigned int xShift_;\n \tunsigned int stride_;\n+\tunsigned int sumShift_;\n \n \tSharedMemObject<SwIspStats> sharedStats_;\n \tSwIspStats stats_;\ndiff --git a/src/libcamera/software_isp/swstats_cpu.cpp b/src/libcamera/software_isp/swstats_cpu.cpp\nindex 1cedcfbc..744a7560 100644\n--- a/src/libcamera/software_isp/swstats_cpu.cpp\n+++ b/src/libcamera/software_isp/swstats_cpu.cpp\n@@ -346,6 +346,11 @@ void SwStatsCpu::startFrame(uint32_t frame)\n void SwStatsCpu::finishFrame(uint32_t frame, uint32_t bufferId)\n {\n \tstats_.valid = frame % kStatPerNumFrames == 0;\n+\tif (stats_.valid && sumShift_) {\n+\t\tstats_.sum_.r() >>= sumShift_;\n+\t\tstats_.sum_.g() >>= sumShift_;\n+\t\tstats_.sum_.b() >>= sumShift_;\n+\t}\n \t*sharedStats_ = stats_;\n \tstatsReady.emit(frame, bufferId);\n }\n@@ -402,6 +407,7 @@ int SwStatsCpu::configure(const StreamConfiguration &inputCfg)\n \tif (bayerFormat.packing == BayerFormat::Packing::None &&\n \t setupStandardBayerOrder(bayerFormat.order) == 0) {\n \t\tprocessFrame_ = &SwStatsCpu::processBayerFrame2;\n+\t\tsumShift_ = bayerFormat.bitDepth - 8;\n \t\tswitch (bayerFormat.bitDepth) {\n \t\tcase 8:\n \t\t\tstats0_ = &SwStatsCpu::statsBGGR8Line0;\n@@ -422,6 +428,7 @@ int SwStatsCpu::configure(const StreamConfiguration &inputCfg)\n \t\t/* Skip every 3th and 4th line, sample every other 2x2 block */\n \t\tySkipMask_ = 0x02;\n \t\txShift_ = 0;\n+\t\tsumShift_ = 0;\n \t\tprocessFrame_ = &SwStatsCpu::processBayerFrame2;\n \n \t\tswitch (bayerFormat.order) {\n", "prefixes": [ "v4", "2/3" ] }