From 0db2c8dc75e466e7648dc1b95380495c6a126349 Mon Sep 17 00:00:00 2001 From: Naushir Patuck Date: Sun, 3 May 2020 16:48:42 +0100 Subject: libcamera: ipa: Raspberry Pi IPA Initial implementation of the Raspberry Pi (BCM2835) libcamera IPA and associated libraries. All code is licensed under the BSD-2-Clause terms. Copyright (c) 2019-2020 Raspberry Pi Trading Ltd. Signed-off-by: Naushir Patuck Acked-by: Laurent Pinchart Signed-off-by: Laurent Pinchart --- src/ipa/raspberrypi/controller/histogram.cpp | 64 ++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 src/ipa/raspberrypi/controller/histogram.cpp (limited to 'src/ipa/raspberrypi/controller/histogram.cpp') diff --git a/src/ipa/raspberrypi/controller/histogram.cpp b/src/ipa/raspberrypi/controller/histogram.cpp new file mode 100644 index 00000000..103d3f60 --- /dev/null +++ b/src/ipa/raspberrypi/controller/histogram.cpp @@ -0,0 +1,64 @@ +/* SPDX-License-Identifier: BSD-2-Clause */ +/* + * Copyright (C) 2019, Raspberry Pi (Trading) Limited + * + * histogram.cpp - histogram calculations + */ +#include +#include + +#include "histogram.hpp" + +using namespace RPi; + +uint64_t Histogram::CumulativeFreq(double bin) const +{ + if (bin <= 0) + return 0; + else if (bin >= Bins()) + return Total(); + int b = (int)bin; + return cumulative_[b] + + (bin - b) * (cumulative_[b + 1] - cumulative_[b]); +} + +double Histogram::Quantile(double q, int first, int last) const +{ + if (first == -1) + first = 0; + if (last == -1) + last = cumulative_.size() - 2; + assert(first <= last); + uint64_t items = q * Total(); + while (first < last) // binary search to find the right bin + { + int middle = (first + last) / 2; + if (cumulative_[middle + 1] > items) + last = middle; // between first and middle + else + first = middle + 1; // after middle + } + assert(items >= cumulative_[first] && items <= cumulative_[last + 1]); + double frac = cumulative_[first + 1] == cumulative_[first] ? 0 + : (double)(items - cumulative_[first]) / + (cumulative_[first + 1] - cumulative_[first]); + return first + frac; +} + +double Histogram::InterQuantileMean(double q_lo, double q_hi) const +{ + assert(q_hi > q_lo); + double p_lo = Quantile(q_lo); + double p_hi = Quantile(q_hi, (int)p_lo); + double sum_bin_freq = 0, cumul_freq = 0; + for (double p_next = floor(p_lo) + 1.0; p_next <= ceil(p_hi); + p_lo = p_next, p_next += 1.0) { + int bin = floor(p_lo); + double freq = (cumulative_[bin + 1] - cumulative_[bin]) * + (std::min(p_next, p_hi) - p_lo); + sum_bin_freq += bin * freq; + cumul_freq += freq; + } + // add 0.5 to give an average for bin mid-points + return sum_bin_freq / cumul_freq + 0.5; +} -- cgit v1.2.1