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{ "id": 27589, "url": "https://patchwork.libcamera.org/api/patches/27589/?format=api", "web_url": "https://patchwork.libcamera.org/patch/27589/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/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": "<20260803131435.153927-41-barnabas.pocze@ideasonboard.com>", "date": "2026-08-03T13:14:25", "name": "[RFC,v3,40/50] ipa: simple: agc: Adjust histogram for black level", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "bd6fefde1c60c98097f7ae9d04df34b2ca631032", "submitter": { "id": 216, "url": "https://patchwork.libcamera.org/api/people/216/?format=api", "name": "Barnabás Pőcze", "email": "barnabas.pocze@ideasonboard.com" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/27589/mbox/", "series": [ { "id": 6103, "url": "https://patchwork.libcamera.org/api/series/6103/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=6103", "date": "2026-08-03T13:13:45", "name": "ipa: libipa: agc rework", "version": 3, "mbox": "https://patchwork.libcamera.org/series/6103/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/27589/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/27589/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 44272C3348\n\tfor <parsemail@patchwork.libcamera.org>;\n\tMon, 3 Aug 2026 13:15:23 +0000 (UTC)", "from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 49AF6680FC;\n\tMon, 3 Aug 2026 15:15:20 +0200 (CEST)", "from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id DBB5E680B4\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tMon, 3 Aug 2026 15:14:47 +0200 (CEST)", "from pb-laptop.local (185.221.141.208.nat.pool.zt.hu\n\t[185.221.141.208])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 06E085B3\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tMon, 3 Aug 2026 15:13:39 +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=\"M/5lBKz6\"; dkim-atps=neutral", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1785762819;\n\tbh=Ch7Eiq1lpvW3U4J8QDDus2uEA7uHeblo7NL8vJMXO1U=;\n\th=From:To:Subject:Date:In-Reply-To:References:From;\n\tb=M/5lBKz6U37LiY7zSnbA3c6NrOfaPBd8HysWWwmhHcw7Usj7wcUzm9tnh8c/9Mo6N\n\tVao76eea+reNTgbNZ8Py20aY1MLpcR/uwBAhGd+kzMAr2pat+Mx7XpvkQmt0Hg+X2h\n\tprS/b3Pv2t8lp9gdJS3qlvN9Dju/mYuGZefepiyw=", "From": "=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= <barnabas.pocze@ideasonboard.com>", "To": "libcamera-devel@lists.libcamera.org", "Subject": "[RFC PATCH v3 40/50] ipa: simple: agc: Adjust histogram for black\n\tlevel", "Date": "Mon, 3 Aug 2026 15:14:25 +0200", "Message-ID": "<20260803131435.153927-41-barnabas.pocze@ideasonboard.com>", "X-Mailer": "git-send-email 2.55.0", "In-Reply-To": "<20260803131435.153927-1-barnabas.pocze@ideasonboard.com>", "References": "<20260803131435.153927-1-barnabas.pocze@ideasonboard.com>", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=UTF-8", "Content-Transfer-Encoding": "8bit", "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": "Instead of providing the black separately, adjust the luminance histogram\naccording to the current black level. This changes the behaviour slightly\nas previously everything under the black level was ignored, and only the\nremaining part was split into the 5 bins, but now the full histogram is\nsplit into the 5 bins.\n\nTODO: or should the previous behaviour be preserved and a smaller histogram be used without adjustments?\nTODO: is it `i < blackLevelHistIdx` or `i <= blackLevelHistIdx` ???\n\nSigned-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>\n---\n src/ipa/simple/algorithms/agc.cpp | 24 ++++++++++++++----------\n 1 file changed, 14 insertions(+), 10 deletions(-)", "diff": "diff --git a/src/ipa/simple/algorithms/agc.cpp b/src/ipa/simple/algorithms/agc.cpp\nindex cc33b269bf..199b444f5a 100644\n--- a/src/ipa/simple/algorithms/agc.cpp\n+++ b/src/ipa/simple/algorithms/agc.cpp\n@@ -11,6 +11,7 @@\n #include <cmath>\n #include <optional>\n #include <stdint.h>\n+#include <utility>\n \n #include <libcamera/base/log.h>\n \n@@ -66,19 +67,15 @@ static constexpr float kExpMaxStep = 0.15;\n \n namespace {\n \n-std::optional<float> calculateMSV(const Histogram &histogram, uint8_t blackLevel)\n+std::optional<float> calculateMSV(const Histogram &histogram)\n {\n \t/*\n \t * Calculate Mean Sample Value (MSV) according to formula from:\n \t * https://www.araa.asn.au/acra/acra2007/papers/paper84final.pdf\n \t */\n-\tconst unsigned int blackLevelHistIdx =\n-\t\tblackLevel * histogram.bins() / 256;\n-\tconst unsigned int histogramSize =\n-\t\thistogram.bins() - blackLevelHistIdx;\n-\tconst unsigned int yHistValsPerBin = histogramSize / kExposureBinsCount;\n+\tconst unsigned int yHistValsPerBin = histogram.bins() / kExposureBinsCount;\n \tconst unsigned int yHistValsPerBinMod =\n-\t\thistogramSize / (histogramSize % kExposureBinsCount + 1);\n+\t\thistogram.bins() / (histogram.bins() % kExposureBinsCount + 1);\n \tint exposureBins[kExposureBinsCount] = {};\n \tunsigned int denom = 0;\n \tunsigned int num = 0;\n@@ -86,9 +83,9 @@ std::optional<float> calculateMSV(const Histogram &histogram, uint8_t blackLevel\n \tif (yHistValsPerBin == 0)\n \t\treturn {};\n \n-\tfor (unsigned int i = 0; i < histogramSize; i++) {\n+\tfor (unsigned int i = 0; i < histogram.bins(); i++) {\n \t\tunsigned int idx = (i - (i / yHistValsPerBinMod)) / yHistValsPerBin;\n-\t\texposureBins[idx] += histogram[blackLevelHistIdx + i];\n+\t\texposureBins[idx] += histogram[i];\n \t}\n \n \tfor (unsigned int i = 0; i < kExposureBinsCount; i++) {\n@@ -193,7 +190,14 @@ void Agc::process(IPAContext &context,\n \t\treturn;\n \t}\n \n-\tauto exposureMSV = calculateMSV({ stats->yHistogram }, context.activeState.blc.level);\n+\tauto histogram = stats->yHistogram;\n+\tconst unsigned int blackLevelHistIdx =\n+\t\tcontext.activeState.blc.level * std::size(histogram) / 256;\n+\n+\tfor (unsigned int i = 1; i < blackLevelHistIdx; i++)\n+\t\thistogram[0] += std::exchange(histogram[i], 0);\n+\n+\tauto exposureMSV = calculateMSV({ histogram });\n \tif (!exposureMSV) {\n \t\tLOG(IPASoftExposure, Debug)\n \t\t\t<< \"Not adjusting exposure due to insufficient histogram data\";\n", "prefixes": [ "RFC", "v3", "40/50" ] }