org.opencv.core
Class Algorithm

java.lang.Object
  org.opencv.core.Algorithm

Direct Known Subclasses:

BackgroundSubtractor, EM, FaceRecognizer

public class Algorithm
extends java.lang.Object

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:

#include "opencv2/opencv.hpp"

// C++ code:

#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

protected long

nativeObj

Constructor Summary

protected

Algorithm(long addr)

Method Summary

protected void	finalize()
boolean	getBool(java.lang.String name)
double	getDouble(java.lang.String name)
int	getInt(java.lang.String name)
Mat	getMat(java.lang.String name)
java.util.List<Mat>	getMatVector(java.lang.String name)
java.lang.String	getString(java.lang.String name)
java.lang.String	paramHelp(java.lang.String name)
int	paramType(java.lang.String name)
void	setBool(java.lang.String name, boolean value) Sets the algorithm parameter The method sets value of the particular parameter.
void	setDouble(java.lang.String name, double value) Sets the algorithm parameter The method sets value of the particular parameter.
void	setInt(java.lang.String name, int value) Sets the algorithm parameter The method sets value of the particular parameter.
void	setMat(java.lang.String name, Mat value) Sets the algorithm parameter The method sets value of the particular parameter.
void	setMatVector(java.lang.String name, java.util.List<Mat> value) Sets the algorithm parameter The method sets value of the particular parameter.
void	setString(java.lang.String name, java.lang.String value) Sets the algorithm parameter The method sets value of the particular parameter.

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

finalize

protected void finalize()
                 throws java.lang.Throwable

Overrides:

finalize in class java.lang.Object

Throws:

java.lang.Throwable

getBool

public boolean getBool(java.lang.String name)

getDouble

public double getDouble(java.lang.String name)

getInt

public int getInt(java.lang.String name)

getMat

public Mat getMat(java.lang.String name)

getMatVector

public java.util.List<Mat> getMatVector(java.lang.String name)

getString

public java.lang.String getString(java.lang.String name)

paramHelp

public java.lang.String paramHelp(java.lang.String name)

paramType

public int paramType(java.lang.String name)

setBool

public void setBool(java.lang.String name,
                    boolean value)

Sets the algorithm parameter

The method sets value of the particular parameter. Some of the algorithm parameters may be declared as read-only. If you try to set such a parameter, you will get exception with the corresponding error message.

Parameters:

name - The parameter name.

value - The parameter value.

See Also:

org.opencv.core.Algorithm.set

setDouble

public void setDouble(java.lang.String name,
                      double value)

Sets the algorithm parameter

The method sets value of the particular parameter. Some of the algorithm parameters may be declared as read-only. If you try to set such a parameter, you will get exception with the corresponding error message.

Parameters:

name - The parameter name.

value - The parameter value.

See Also:

org.opencv.core.Algorithm.set

setInt

public void setInt(java.lang.String name,
                   int value)

Sets the algorithm parameter

The method sets value of the particular parameter. Some of the algorithm parameters may be declared as read-only. If you try to set such a parameter, you will get exception with the corresponding error message.

Parameters:

name - The parameter name.

value - The parameter value.

See Also:

org.opencv.core.Algorithm.set

setMat

public void setMat(java.lang.String name,
                   Mat value)

Sets the algorithm parameter

The method sets value of the particular parameter. Some of the algorithm parameters may be declared as read-only. If you try to set such a parameter, you will get exception with the corresponding error message.

Parameters:

name - The parameter name.

value - The parameter value.

See Also:

org.opencv.core.Algorithm.set

setMatVector

public void setMatVector(java.lang.String name,
                         java.util.List<Mat> value)

Sets the algorithm parameter

The method sets value of the particular parameter. Some of the algorithm parameters may be declared as read-only. If you try to set such a parameter, you will get exception with the corresponding error message.

Parameters:

name - The parameter name.

value - The parameter value.

See Also:

org.opencv.core.Algorithm.set

setString

public void setString(java.lang.String name,
                      java.lang.String value)

Sets the algorithm parameter

The method sets value of the particular parameter. Some of the algorithm parameters may be declared as read-only. If you try to set such a parameter, you will get exception with the corresponding error message.

Parameters:

name - The parameter name.

value - The parameter value.

See Also:

org.opencv.core.Algorithm.set