{"id":11959,"url":"https://patchwork.libcamera.org/api/1.1/patches/11959/?format=json","web_url":"https://patchwork.libcamera.org/patch/11959/","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":"<20210416074909.24218-3-jeanmichel.hautbois@ideasonboard.com>","date":"2021-04-16T07:49:07","name":"[libcamera-devel,v5,2/4] ipa: ipu3: Add a histogram class","commit_ref":null,"pull_url":null,"state":"accepted","archived":false,"hash":"57ad1593c4fce13ba9faf1abf28a61abcaceb664","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/11959/mbox/","series":[{"id":1938,"url":"https://patchwork.libcamera.org/api/1.1/series/1938/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=1938","date":"2021-04-16T07:49:05","name":"Implement IPA algorithms and demo with IPU3","version":5,"mbox":"https://patchwork.libcamera.org/series/1938/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/11959/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/11959/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 33FFDBD235\n\tfor ;\n\tFri, 16 Apr 2021 07:49:16 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 55ADC68816;\n\tFri, 16 Apr 2021 09:49:15 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id A47576880E\n\tfor ;\n\tFri, 16 Apr 2021 09:49:13 +0200 (CEST)","from localhost.localdomain (unknown\n\t[IPv6:2a01:e0a:169:7140:5b63:445c:7960:347a])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 4C7DB5A5;\n\tFri, 16 Apr 2021 09:49:13 +0200 (CEST)"],"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=\"kqgen6xY\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1618559353;\n\tbh=l1kyhlXZo2JexfDP6i3vOBsI/GZ1w7A+8gwJ8PpQrEE=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=kqgen6xYmxpYG9c9otdszwscR6EPWcpwV0qZDk4Lmdeq5RFTmiHYpv7Rvi6gF3iBf\n\tddc5FnlBskKYsTEgR8GmSENKMJNWkx3Eilo9zQlruRupUSmC6r5LlrJRq+VrqXVmFp\n\tYE6AV2zErgZElSJgs7A0iKOMD7epm1bJU90d5Rbg=","From":"Jean-Michel Hautbois ","To":"libcamera-devel@lists.libcamera.org","Date":"Fri, 16 Apr 2021 09:49:07 +0200","Message-Id":"<20210416074909.24218-3-jeanmichel.hautbois@ideasonboard.com>","X-Mailer":"git-send-email 2.27.0","In-Reply-To":"<20210416074909.24218-1-jeanmichel.hautbois@ideasonboard.com>","References":"<20210416074909.24218-1-jeanmichel.hautbois@ideasonboard.com>","MIME-Version":"1.0","Subject":"[libcamera-devel] [PATCH v5 2/4] ipa: ipu3: Add a histogram class","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","Content-Type":"multipart/mixed;\n\tboundary=\"===============4270139658514000556==\"","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"This class will be used at least by AGC algorithm when quantiles are\nneeded for example. It stores a cumulative frequency histogram. Going from\ncumulative frequency back to per-bin values is a single subtraction, while\ngoing the other way is a loop.\n\nSigned-off-by: Jean-Michel Hautbois \n---\n src/ipa/libipa/histogram.cpp | 150 +++++++++++++++++++++++++++++++++++\n src/ipa/libipa/histogram.h | 40 ++++++++++\n src/ipa/libipa/meson.build | 2 +\n 3 files changed, 192 insertions(+)\n create mode 100644 src/ipa/libipa/histogram.cpp\n create mode 100644 src/ipa/libipa/histogram.h","diff":"diff --git a/src/ipa/libipa/histogram.cpp b/src/ipa/libipa/histogram.cpp\nnew file mode 100644\nindex 00000000..b92d8305\n--- /dev/null\n+++ b/src/ipa/libipa/histogram.cpp\n@@ -0,0 +1,150 @@\n+/* SPDX-License-Identifier: BSD-2-Clause */\n+/*\n+ * Copyright (C) 2019, Raspberry Pi (Trading) Limited\n+ *\n+ * histogram.cpp - histogram calculations\n+ */\n+#include \"histogram.h\"\n+\n+#include \n+\n+#include \"libcamera/internal/log.h\"\n+\n+/**\n+ * \\file histogram.h\n+ * \\brief Class to represent Histograms and manipulate them\n+ */\n+\n+namespace libcamera {\n+\n+namespace ipa {\n+\n+/**\n+ * \\class Histogram\n+ * \\brief The base class for creating histograms\n+ *\n+ * This class stores a cumulative frequency histogram, which is a mapping that\n+ * counts the cumulative number of observations in all of the bins up to the\n+ * specified bin. It can be used to find quantiles and averages between quantiles.\n+ */\n+\n+/**\n+ * \\brief Create a cumulative histogram\n+ * \\param[in] data A pre-sorted histogram to be passed\n+ */\n+Histogram::Histogram(Span data)\n+{\n+\tcumulative_.reserve(data.size());\n+\tcumulative_.push_back(0);\n+\tfor (const uint32_t &value : data)\n+\t\tcumulative_.push_back(cumulative_.back() + value);\n+}\n+/**\n+ * \\fn Histogram::bins()\n+ * \\brief Retrieve the number of bins currently used by the Histogram\n+ * \\return Number of bins\n+ */\n+/**\n+ * \\fn Histogram::total()\n+ * \\brief Retrieve the total number of values in the data set\n+ * \\return Number of values\n+ */\n+\n+/**\n+ * \\brief Cumulative frequency up to a (fractional) point in a bin.\n+ * \\param[in] bin The bin up to which to cumulate\n+ *\n+ * With F(p) the cumulative frequency of the histogram, the value is 0 at\n+ * the bottom of the histogram, and the maximum is the number of bins.\n+ * The pixels are spread evenly throughout the “bin” in which they lie, so that\n+ * F(p) is a continuous (monotonically increasing) function.\n+ *\n+ * \\return The cumulative frequency from 0 up to the specified bin\n+ */\n+uint64_t Histogram::cumulativeFrequency(double bin) const\n+{\n+\tif (bin <= 0)\n+\t\treturn 0;\n+\telse if (bin >= bins())\n+\t\treturn total();\n+\tint b = static_cast(bin);\n+\treturn cumulative_[b] +\n+\t (bin - b) * (cumulative_[b + 1] - cumulative_[b]);\n+}\n+\n+/**\n+ * \\brief Return the (fractional) bin of the point through the histogram\n+ * \\param[in] q the desired point (0 <= q <= 1)\n+ * \\param[in] first low limit (default is 0)\n+ * \\param[in] last high limit (default is UINT_MAX)\n+ *\n+ * A quantile gives us the point p = Q(q) in the range such that a proportion\n+ * q of the pixels lie below p. A familiar quantile is Q(0.5) which is the median\n+ * of a distribution.\n+ *\n+ * \\return The fractional bin of the point\n+ */\n+double Histogram::quantile(double q, uint32_t first, uint32_t last) const\n+{\n+\tif (last == UINT_MAX)\n+\t\tlast = cumulative_.size() - 2;\n+\tASSERT(first <= last);\n+\n+\tuint64_t item = q * total();\n+\t/* Binary search to find the right bin */\n+\twhile (first < last) {\n+\t\tint middle = (first + last) / 2;\n+\t\t/* Is it between first and middle ? */\n+\t\tif (cumulative_[middle + 1] > item)\n+\t\t\tlast = middle;\n+\t\telse\n+\t\t\tfirst = middle + 1;\n+\t}\n+\tASSERT(item >= cumulative_[first] && item <= cumulative_[last + 1]);\n+\n+\tdouble frac;\n+\tif (cumulative_[first + 1] == cumulative_[first])\n+\t\tfrac = 0;\n+\telse\n+\t\tfrac = (item - cumulative_[first]) / (cumulative_[first + 1] - cumulative_[first]);\n+\treturn first + frac;\n+}\n+\n+/**\n+ * \\brief Calculate the mean between two quantiles\n+ * \\param[in] lowQuantile low Quantile\n+ * \\param[in] highQuantile high Quantile\n+ *\n+ * Quantiles are not ideal for metering as they suffer several limitations.\n+ * Instead, a concept is introduced here: inter-quantile mean.\n+ * It returns the mean of all pixels between lowQuantile and highQuantile.\n+ *\n+ * \\return The mean histogram bin value between the two quantiles\n+ */\n+double Histogram::interQuantileMean(double lowQuantile, double highQuantile) const\n+{\n+\tASSERT(highQuantile > lowQuantile);\n+\t/* Proportion of pixels which lies below lowQuantile */\n+\tdouble lowPoint = quantile(lowQuantile);\n+\t/* Proportion of pixels which lies below highQuantile */\n+\tdouble highPoint = quantile(highQuantile, static_cast(lowPoint));\n+\tdouble sumBinFreq = 0, cumulFreq = 0;\n+\n+\tfor (double p_next = floor(lowPoint) + 1.0;\n+\t p_next <= ceil(highPoint);\n+\t lowPoint = p_next, p_next += 1.0) {\n+\t\tint bin = floor(lowPoint);\n+\t\tdouble freq = (cumulative_[bin + 1] - cumulative_[bin]) * (std::min(p_next, highPoint) - lowPoint);\n+\n+\t\t/* Accumulate weigthed bin */\n+\t\tsumBinFreq += bin * freq;\n+\t\t/* Accumulate weights */\n+\t\tcumulFreq += freq;\n+\t}\n+\t/* add 0.5 to give an average for bin mid-points */\n+\treturn sumBinFreq / cumulFreq + 0.5;\n+}\n+\n+} /* namespace ipa */\n+\n+} /* namespace libcamera */\ndiff --git a/src/ipa/libipa/histogram.h b/src/ipa/libipa/histogram.h\nnew file mode 100644\nindex 00000000..e06f1884\n--- /dev/null\n+++ b/src/ipa/libipa/histogram.h\n@@ -0,0 +1,40 @@\n+/* SPDX-License-Identifier: BSD-2-Clause */\n+/*\n+ * Copyright (C) 2019, Raspberry Pi (Trading) Limited\n+ *\n+ * histogram.h - histogram calculation interface\n+ */\n+#ifndef __LIBCAMERA_IPA_LIBIPA_HISTOGRAM_H__\n+#define __LIBCAMERA_IPA_LIBIPA_HISTOGRAM_H__\n+\n+#include \n+#include \n+#include \n+\n+#include \n+\n+#include \n+\n+namespace libcamera {\n+\n+namespace ipa {\n+\n+class Histogram\n+{\n+public:\n+\tHistogram(Span data);\n+\tsize_t bins() const { return cumulative_.size() - 1; }\n+\tuint64_t total() const { return cumulative_[cumulative_.size() - 1]; }\n+\tuint64_t cumulativeFrequency(double bin) const;\n+\tdouble quantile(double q, uint32_t first = 0, uint32_t last = UINT_MAX) const;\n+\tdouble interQuantileMean(double lowQuantile, double hiQuantile) const;\n+\n+private:\n+\tstd::vector cumulative_;\n+};\n+\n+} /* namespace ipa */\n+\n+} /* namespace libcamera */\n+\n+#endif /* __LIBCAMERA_IPA_LIBIPA_HISTOGRAM_H__ */\ndiff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build\nindex 1819711d..038fc490 100644\n--- a/src/ipa/libipa/meson.build\n+++ b/src/ipa/libipa/meson.build\n@@ -2,10 +2,12 @@\n \n libipa_headers = files([\n 'algorithm.h',\n+ 'histogram.h'\n ])\n \n libipa_sources = files([\n 'algorithm.cpp',\n+ 'histogram.cpp'\n ])\n \n libipa_includes = include_directories('..')\n","prefixes":["libcamera-devel","v5","2/4"]}