{"id":14456,"url":"https://patchwork.libcamera.org/api/1.1/patches/14456/?format=json","web_url":"https://patchwork.libcamera.org/patch/14456/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/1.1/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20211104113621.60730-1-jeanmichel.hautbois@ideasonboard.com>","date":"2021-11-04T11:36:21","name":"[libcamera-devel,v2] ipa: ipu3: agc: Limit the number of saturated cells","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"6ea8714a0c33c48552753ac47b93735052f05279","submitter":{"id":75,"url":"https://patchwork.libcamera.org/api/1.1/people/75/?format=json","name":"Jean-Michel Hautbois","email":"jeanmichel.hautbois@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/14456/mbox/","series":[{"id":2690,"url":"https://patchwork.libcamera.org/api/1.1/series/2690/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=2690","date":"2021-11-04T11:36:21","name":"[libcamera-devel,v2] ipa: ipu3: agc: Limit the number of saturated cells","version":2,"mbox":"https://patchwork.libcamera.org/series/2690/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/14456/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/14456/checks/","tags":{},"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 1AC1DBF415\n\tfor ;\n\tThu, 4 Nov 2021 11:36:27 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 69E5E6032F;\n\tThu, 4 Nov 2021 12:36:26 +0100 (CET)","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 362126032C\n\tfor ;\n\tThu, 4 Nov 2021 12:36:25 +0100 (CET)","from tatooine.ideasonboard.com (unknown\n\t[IPv6:2a01:e0a:169:7140:3875:cc64:ce12:aabc])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id BC4D3E52;\n\tThu, 4 Nov 2021 12:36:24 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"kpk14I+s\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1636025784;\n\tbh=hN9HJZvk6P5YS4KN6dKSRegMF8+zEFkQAJWYDuvreGw=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=kpk14I+shW62C+mZ9ZRZsYTlam9bRWjZqZ5wcyw35NtVvMXLzjvtjUWzkMVKgGkCn\n\txyCryZuOAGc7esnX6HLN+yIoUyGNmgJEBWUi+48fFxe+jnDSUZtvTpQzTqawog9V0O\n\tcxWfyCNyse9fkISiS5VK0mZ8FVbBMSc52SsJ6K7c=","From":"Jean-Michel Hautbois ","To":"libcamera-devel@lists.libcamera.org","Date":"Thu, 4 Nov 2021 12:36:21 +0100","Message-Id":"<20211104113621.60730-1-jeanmichel.hautbois@ideasonboard.com>","X-Mailer":"git-send-email 2.32.0","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","Subject":"[libcamera-devel] [PATCH v2] ipa: ipu3: agc: Limit the number of\n\tsaturated cells","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\" "},"content":"When the histogram is calculated, we check if a cell is saturated or not\nbefore cumulating its green value. This is wrong, and it can lead to an\nempty histogram in case of a fully saturated frame.\n\nUse a constant to limit the amount of pixels within a cell before\nconsidering it saturated. If at the end of the loop we still have an\nempty histogram, then make it a fully saturated one.\n\nBug: https://bugs.libcamera.org/show_bug.cgi?id=84\nSigned-off-by: Jean-Michel Hautbois \n---\n src/ipa/ipu3/algorithms/agc.cpp | 16 ++++++++++++++--\n 1 file changed, 14 insertions(+), 2 deletions(-)","diff":"diff --git a/src/ipa/ipu3/algorithms/agc.cpp b/src/ipa/ipu3/algorithms/agc.cpp\nindex b5d736c1..dcdfb95c 100644\n--- a/src/ipa/ipu3/algorithms/agc.cpp\n+++ b/src/ipa/ipu3/algorithms/agc.cpp\n@@ -63,6 +63,12 @@ static constexpr uint32_t knumHistogramBins = 256;\n /* Target value to reach for the top 2% of the histogram */\n static constexpr double kEvGainTarget = 0.5;\n \n+/*\n+ * Maximum ratio of saturated pixels in a cell for the cell to be considered\n+ * non-saturated and counted by the AGC algorithm.\n+ */\n+static constexpr uint32_t kMinCellsPerZoneRatio = 255 * 50 / 100;\n+\n Agc::Agc()\n \t: frameCount_(0), lastFrame_(0), iqMean_(0.0), lineDuration_(0s),\n \t minExposureLines_(0), maxExposureLines_(0), filteredExposure_(0s),\n@@ -124,7 +130,7 @@ void Agc::measureBrightness(const ipu3_uapi_stats_3a *stats,\n \t\t\t\t\t&stats->awb_raw_buffer.meta_data[cellPosition]\n \t\t\t\t);\n \n-\t\t\tif (cell->sat_ratio == 0) {\n+\t\t\tif (cell->sat_ratio <= kMinCellsPerZoneRatio) {\n \t\t\t\tuint8_t gr = cell->Gr_avg;\n \t\t\t\tuint8_t gb = cell->Gb_avg;\n \t\t\t\t/*\n@@ -137,8 +143,14 @@ void Agc::measureBrightness(const ipu3_uapi_stats_3a *stats,\n \t\t}\n \t}\n \n+\tHistogram cumulativeHist = Histogram(Span(hist));\n \t/* Estimate the quantile mean of the top 2% of the histogram */\n-\tiqMean_ = Histogram(Span(hist)).interQuantileMean(0.98, 1.0);\n+\tif (cumulativeHist.total() == 0) {\n+\t\t/* Force the value as histogram is empty */\n+\t\tiqMean_ = knumHistogramBins - 0.5;\n+\t} else {\n+\t\tiqMean_ = cumulativeHist.interQuantileMean(0.98, 1.0);\n+\t}\n }\n \n /**\n","prefixes":["libcamera-devel","v2"]}