libcamera v0.4.0
Supporting cameras in Linux since 2019
 
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pwl.h
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1/* SPDX-License-Identifier: BSD-2-Clause */
2/*
3 * Copyright (C) 2019, Raspberry Pi Ltd
4 *
5 * Piecewise linear functions interface
6 */
7#pragma once
8
9#include <algorithm>
10#include <functional>
11#include <string>
12#include <utility>
13#include <vector>
14
15#include "vector.h"
16
17namespace libcamera {
18
19namespace ipa {
20
21class Pwl
22{
23public:
25
26 struct Interval {
27 Interval(double _start, double _end)
28 : start(_start), end(_end) {}
29
30 bool contains(double value)
31 {
32 return value >= start && value <= end;
33 }
34
35 double clamp(double value)
36 {
37 return std::clamp(value, start, end);
38 }
39
40 double length() const { return end - start; }
41
42 double start, end;
43 };
44
45 Pwl();
46 Pwl(const std::vector<Point> &points);
47 Pwl(std::vector<Point> &&points);
48
49 void append(double x, double y, double eps = 1e-6);
50
51 bool empty() const { return points_.empty(); }
52 size_t size() const { return points_.size(); }
53
54 Interval domain() const;
55 Interval range() const;
56
57 double eval(double x, int *span = nullptr,
58 bool updateSpan = true) const;
59
60 std::pair<Pwl, bool> inverse(double eps = 1e-6) const;
61 Pwl compose(const Pwl &other, double eps = 1e-6) const;
62
63 void map(std::function<void(double x, double y)> f) const;
64
65 static Pwl
66 combine(const Pwl &pwl0, const Pwl &pwl1,
67 std::function<double(double x, double y0, double y1)> f,
68 double eps = 1e-6);
69
70 Pwl &operator*=(double d);
71
72 std::string toString() const;
73
74private:
75 static void map2(const Pwl &pwl0, const Pwl &pwl1,
76 std::function<void(double x, double y0, double y1)> f);
77 void prepend(double x, double y, double eps = 1e-6);
78 int findSpan(double x, int span) const;
79
80 std::vector<Point> points_;
81};
82
83} /* namespace ipa */
84
85} /* namespace libcamera */
Describe a univariate piecewise linear function in two-dimensional real space.
Definition pwl.h:22
std::string toString() const
Assemble and return a string describing the piecewise linear function.
Definition pwl.cpp:410
void append(double x, double y, double eps=1e-6)
Append a point to the end of the piecewise linear function.
Definition pwl.cpp:135
void map(std::function< void(double x, double y)> f) const
Apply function to (x, y) values at every control point.
Definition pwl.cpp:333
static Pwl combine(const Pwl &pwl0, const Pwl &pwl1, std::function< double(double x, double y0, double y1)> f, double eps=1e-6)
Combine two Pwls.
Definition pwl.cpp:383
Pwl compose(const Pwl &other, double eps=1e-6) const
Compose two piecewise linear functions together.
Definition pwl.cpp:284
bool empty() const
Check if the piecewise linear function is empty.
Definition pwl.h:51
double eval(double x, int *span=nullptr, bool updateSpan=true) const
Evaluate the piecewise linear function.
Definition pwl.cpp:202
Interval domain() const
Get the domain of the piecewise linear function.
Definition pwl.cpp:172
std::pair< Pwl, bool > inverse(double eps=1e-6) const
Compute the inverse function.
Definition pwl.cpp:243
Vector< double, 2 > Point
Describe a point in two-dimensional real space.
Definition pwl.h:24
size_t size() const
Retrieve the number of points in the piecewise linear function.
Definition pwl.h:52
Pwl & operator*=(double d)
Multiply the piecewise linear function.
Definition pwl.cpp:399
Pwl()
Construct an empty piecewise linear function.
Definition pwl.cpp:99
Interval range() const
Get the range of the piecewise linear function.
Definition pwl.cpp:181
Vector class.
Definition vector.h:36
The IPA (Image Processing Algorithm) namespace.
Definition af.cpp:58
Top-level libcamera namespace.
Definition backtrace.h:17
double clamp(double value)
Clamp a value such that it is within the interval.
Definition pwl.h:35
double start
Start of the interval.
Definition pwl.h:42
Interval(double _start, double _end)
Construct an interval.
Definition pwl.h:27
double end
End of the interval.
Definition pwl.h:42
bool contains(double value)
Check if a given value falls within the interval.
Definition pwl.h:30
double length() const
Compute the length of the interval.
Definition pwl.h:40
Vector class.