libcamera  v0.3.1+12-19bbca3c
Supporting cameras in Linux since 2019
histogram.h
Go to the documentation of this file.
1 /* SPDX-License-Identifier: BSD-2-Clause */
2 /*
3  * Copyright (C) 2019, Raspberry Pi Ltd
4  *
5  * histogram calculation interface
6  */
7 
8 #pragma once
9 
10 #include <assert.h>
11 #include <limits.h>
12 #include <stdint.h>
13 #include <type_traits>
14 #include <vector>
15 
16 #include <libcamera/base/span.h>
17 #include <libcamera/base/utils.h>
18 
19 namespace libcamera {
20 
21 namespace ipa {
22 
23 class Histogram
24 {
25 public:
26  Histogram() { cumulative_.push_back(0); }
27  Histogram(Span<const uint32_t> data);
28 
29  template<typename Transform,
30  std::enable_if_t<std::is_invocable_v<Transform, uint32_t>> * = nullptr>
31  Histogram(Span<const uint32_t> data, Transform transform)
32  {
33  cumulative_.resize(data.size() + 1);
34  cumulative_[0] = 0;
35  for (const auto &[i, value] : utils::enumerate(data))
36  cumulative_[i + 1] = cumulative_[i] + transform(value);
37  }
38 
39  size_t bins() const { return cumulative_.size() - 1; }
40  uint64_t total() const { return cumulative_[cumulative_.size() - 1]; }
41  uint64_t cumulativeFrequency(double bin) const;
42  double quantile(double q, uint32_t first = 0, uint32_t last = UINT_MAX) const;
43  double interQuantileMean(double lowQuantile, double hiQuantile) const;
44 
45 private:
46  std::vector<uint64_t> cumulative_;
47 };
48 
49 } /* namespace ipa */
50 
51 } /* namespace libcamera */
Top-level libcamera namespace.
Definition: backtrace.h:17
uint64_t total() const
Retrieve the total number of values in the data set.
Definition: histogram.h:40
Histogram(Span< const uint32_t > data, Transform transform)
Create a cumulative histogram.
Definition: histogram.h:31
Transform
Enum to represent a 2D plane transform.
Definition: transform.h:16
Miscellaneous utility functions.
Histogram()
Construct an empty Histogram.
Definition: histogram.h:26
double quantile(double q, uint32_t first=0, uint32_t last=UINT_MAX) const
Return the (fractional) bin of the point through the histogram.
Definition: histogram.cpp:105
The base class for creating histograms.
Definition: histogram.h:23
uint64_t cumulativeFrequency(double bin) const
Cumulative frequency up to a (fractional) point in a bin.
Definition: histogram.cpp:82
double interQuantileMean(double lowQuantile, double hiQuantile) const
Calculate the mean between two quantiles.
Definition: histogram.cpp:142
size_t bins() const
Retrieve the number of bins currently used by the Histogram.
Definition: histogram.h:39