[{"id":20932,"web_url":"https://patchwork.libcamera.org/comment/20932/","msgid":"<20211112225832.GB8453@jade.amanokami.net>","date":"2021-11-12T22:58:32","subject":"Re: [libcamera-devel] [PATCH v4 04/14] ipa: ipu3: agc: Limit the\n\tnumber of saturated cells","submitter":{"id":17,"url":"https://patchwork.libcamera.org/api/people/17/","name":"Paul Elder","email":"paul.elder@ideasonboard.com"},"content":"Hi Jean-Michel,\n\nOn Thu, Nov 11, 2021 at 03:09:18PM +0100, Jean-Michel Hautbois wrote:\n> When the histogram is calculated, we check if a cell is saturated or not\n> before cumulating its green value. This is wrong, and it can lead to an\n> empty histogram in case of a fully saturated frame.\n> \n> Use a constant to limit the amount of pixels within a cell before\n> considering it saturated. If at the end of the loop we still have an\n> empty histogram, then make it a fully saturated one.\n> \n> Bug: https://bugs.libcamera.org/show_bug.cgi?id=84\n> Signed-off-by: Jean-Michel Hautbois \n> Reviewed-by: Kieran Bingham \n\nReviewed-by: Paul Elder \n\n> ---\n> src/ipa/ipu3/algorithms/agc.cpp | 16 ++++++++++++++--\n> 1 file changed, 14 insertions(+), 2 deletions(-)\n> \n> diff --git a/src/ipa/ipu3/algorithms/agc.cpp b/src/ipa/ipu3/algorithms/agc.cpp\n> index 5723f6f3..83aa3676 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 * 20 / 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> -- \n> 2.32.0\n>","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 4E9FABF415\n\tfor ;\n\tFri, 12 Nov 2021 22:58:43 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 7B6EC6036B;\n\tFri, 12 Nov 2021 23:58:42 +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 86AF16032C\n\tfor ;\n\tFri, 12 Nov 2021 23:58:40 +0100 (CET)","from jade.amanokami.net (KD027085206038.au-net.ne.jp\n\t[27.85.206.38])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id B1C3D74C;\n\tFri, 12 Nov 2021 23:58:38 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"ajDMXTQT\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1636757920;\n\tbh=HdnnR64KxWVOJwOFr5POK3oa/8DXxrFJ5vTGPKtk48g=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=ajDMXTQTZe3BNWi60s/gGp3vSlS2mMLTW/W8shwiNUzQuTQ7gsRMzwxtMLF4cDyBo\n\tQsCimYcvJIAwD8i1Yqm2AM1e0ccVzPrECUsGR+S4J4lHDJpVhiOmIOWJP6dmI6iiyR\n\tLoh4VLaeyEDc4y9b791Dzebq1yc+UW8KsSG2vNQ0=","Date":"Sat, 13 Nov 2021 07:58:32 +0900","From":"Paul Elder ","To":"Jean-Michel Hautbois ","Message-ID":"<20211112225832.GB8453@jade.amanokami.net>","References":"<20211111140928.136111-1-jeanmichel.hautbois@ideasonboard.com>\n\t<20211111140928.136111-5-jeanmichel.hautbois@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<20211111140928.136111-5-jeanmichel.hautbois@ideasonboard.com>","Subject":"Re: [libcamera-devel] [PATCH v4 04/14] ipa: ipu3: agc: Limit the\n\tnumber of saturated 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","Cc":"libcamera-devel@lists.libcamera.org","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}}]