org.opencv.core

Class Algorithm

java.lang.Object

org.opencv.core.Algorithm

Direct Known Subclasses:

BackgroundSubtractor, CLAHE, EM, FaceRecognizer

public class Algorithm
extends Object

class CV_EXPORTS_W Algorithm

// C++ code:

public:

Algorithm();

virtual ~Algorithm();

string name() const;

template typename ParamType<_Tp>.member_type get(const string& name) const;

template typename ParamType<_Tp>.member_type get(const char* name) const;

CV_WRAP int getInt(const string& name) const;

CV_WRAP double getDouble(const string& name) const;

CV_WRAP bool getBool(const string& name) const;

CV_WRAP string getString(const string& name) const;

CV_WRAP Mat getMat(const string& name) const;

CV_WRAP vector getMatVector(const string& name) const;

CV_WRAP Ptr getAlgorithm(const string& name) const;

void set(const string& name, int value);

void set(const string& name, double value);

void set(const string& name, bool value);

void set(const string& name, const string& value);

void set(const string& name, const Mat& value);

void set(const string& name, const vector& value);

void set(const string& name, const Ptr& value);

template void set(const string& name, const Ptr<_Tp>& value);

CV_WRAP void setInt(const string& name, int value);

CV_WRAP void setDouble(const string& name, double value);

CV_WRAP void setBool(const string& name, bool value);

CV_WRAP void setString(const string& name, const string& value);

CV_WRAP void setMat(const string& name, const Mat& value);

CV_WRAP void setMatVector(const string& name, const vector& value);

CV_WRAP void setAlgorithm(const string& name, const Ptr& value);

template void setAlgorithm(const string& name, const Ptr<_Tp>& value);

void set(const char* name, int value);

void set(const char* name, double value);

void set(const char* name, bool value);

void set(const char* name, const string& value);

void set(const char* name, const Mat& value);

void set(const char* name, const vector& value);

void set(const char* name, const Ptr& value);

template void set(const char* name, const Ptr<_Tp>& value);

void setInt(const char* name, int value);

void setDouble(const char* name, double value);

void setBool(const char* name, bool value);

void setString(const char* name, const string& value);

void setMat(const char* name, const Mat& value);

void setMatVector(const char* name, const vector& value);

void setAlgorithm(const char* name, const Ptr& value);

template void setAlgorithm(const char* name, const Ptr<_Tp>& value);

CV_WRAP string paramHelp(const string& name) const;

int paramType(const char* name) const;

CV_WRAP int paramType(const string& name) const;

CV_WRAP void getParams(CV_OUT vector& names) const;

virtual void write(FileStorage& fs) const;

virtual void read(const FileNode& fn);

typedef Algorithm* (*Constructor)(void);

typedef int (Algorithm.*Getter)() const;

typedef void (Algorithm.*Setter)(int);

CV_WRAP static void getList(CV_OUT vector& algorithms);

CV_WRAP static Ptr _create(const string& name);

template static Ptr<_Tp> create(const string& name);

virtual AlgorithmInfo* info() const / * TODO: make it = 0;* / { return 0; }

};

This is a base class for all more or less complex algorithms in OpenCV, especially for classes of algorithms, for which there can be multiple implementations. The examples are stereo correspondence (for which there are algorithms like block matching, semi-global block matching, graph-cut etc.), background subtraction (which can be done using mixture-of-gaussians models, codebook-based algorithm etc.), optical flow (block matching, Lucas-Kanade, Horn-Schunck etc.).

The class provides the following features for all derived classes:

• so called "virtual constructor". That is, each Algorithm derivative is registered at program start and you can get the list of registered algorithms and create instance of a particular algorithm by its name (see Algorithm.create). If you plan to add your own algorithms, it is good practice to add a unique prefix to your algorithms to distinguish them from other algorithms.
• setting/retrieving algorithm parameters by name. If you used video capturing functionality from OpenCV highgui module, you are probably familar with cvSetCaptureProperty(), cvGetCaptureProperty(), VideoCapture.set() and VideoCapture.get(). Algorithm provides similar method where instead of integer id's you specify the parameter names as text strings. See Algorithm.set and Algorithm.get for details.
• reading and writing parameters from/to XML or YAML files. Every Algorithm derivative can store all its parameters and then read them back. There is no need to re-implement it each time.

Here is example of SIFT use in your application via Algorithm interface:

// C++ code:

#include "opencv2/opencv.hpp"

#include "opencv2/nonfree/nonfree.hpp"...

initModule_nonfree(); // to load SURF/SIFT etc.

Ptr sift = Algorithm.create("Feature2D.SIFT");

FileStorage fs("sift_params.xml", FileStorage.READ);

if(fs.isOpened()) // if we have file with parameters, read them

sift->read(fs["sift_params"]);

fs.release();

else // else modify the parameters and store them; user can later edit the file to use different parameters

sift->set("contrastThreshold", 0.01f); // lower the contrast threshold, compared to the default value

WriteStructContext ws(fs, "sift_params", CV_NODE_MAP);

sift->write(fs);

Mat image = imread("myimage.png", 0), descriptors;

vector keypoints;

(*sift)(image, noArray(), keypoints, descriptors);

See Also:

org.opencv.core.Algorithm

Field Summary

Fields

Modifier and Type	Field and Description
protected long	nativeObj

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Algorithm(long addr)

Method Summary

Modifier and Type	Method and Description
protected void	finalize()
boolean	getBool(String name)
double	getDouble(String name)
int	getInt(String name)
Mat	getMat(String name)
List<Mat>	getMatVector(String name)
String	getString(String name)
String	paramHelp(String name)
int	paramType(String name)
void	setBool(String name, boolean value)
void	setDouble(String name, double value)
void	setInt(String name, int value)
void	setMat(String name, Mat value)
void	setMatVector(String name, List<Mat> value)
void	setString(String name, String value)

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

nativeObj

protected final long nativeObj

Constructor Detail

Algorithm

protected Algorithm(long addr)

Method Detail

getBool

public boolean getBool(String name)

getDouble

public double getDouble(String name)

getInt

public int getInt(String name)

getMat

public Mat getMat(String name)

getMatVector

public List<Mat> getMatVector(String name)

getString

public String getString(String name)

paramHelp

public String paramHelp(String name)

paramType

public int paramType(String name)

setBool

public void setBool(String name,
                    boolean value)

setDouble

public void setDouble(String name,
                      double value)

setInt

public void setInt(String name,
                   int value)

setMat

public void setMat(String name,
                   Mat value)

setMatVector

public void setMatVector(String name,
                         List<Mat> value)

setString

public void setString(String name,
                      String value)

finalize

protected void finalize()
                 throws Throwable

Overrides:

finalize in class Object

Throws:

Throwable