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Algorithm Class Reference

This is a base class for all more or less complex algorithms in OpenCV. More...

#include <core.hpp>

Inherited by AlignExposures, BackgroundSubtractor, BaseCascadeClassifier, CalibrateCRF, CLAHE, DenseOpticalFlow, DescriptorMatcher, Feature2D [virtual], GeneralizedHough, HistogramCostExtractor, LineSegmentDetector, MergeExposures, MinProblemSolver, StatModel, SVM::Kernel, ShapeDistanceExtractor, ShapeTransformer, StereoMatcher, DenseOpticalFlowExt, SuperResolution, and Tonemap.

Public Member Functions

virtual CV_WRAP void clear ()
 Clears the algorithm state.
virtual void write (FileStorage &fs) const
 Stores algorithm parameters in a file storage.
virtual void read (const FileNode &fn)
 Reads algorithm parameters from a file storage.
virtual bool empty () const
 Returns true if the Algorithm is empty (e.g.
virtual CV_WRAP void save (const String &filename) const
 Saves the algorithm to a file.
virtual CV_WRAP String getDefaultName () const
 Returns the algorithm string identifier.

Static Public Member Functions

template<typename _Tp >
static Ptr< _Tp > read (const FileNode &fn)
 Reads algorithm from the file node.
template<typename _Tp >
static Ptr< _Tp > load (const String &filename, const String &objname=String())
 Loads algorithm from the file.
template<typename _Tp >
static Ptr< _Tp > loadFromString (const String &strModel, const String &objname=String())
 Loads algorithm from a String.

Detailed Description

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.).

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

    #include "opencv2/opencv.hpp"
    #include "opencv2/xfeatures2d.hpp"
    using namespace cv::xfeatures2d;

    Ptr<Feature2D> sift = SIFT::create();
    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->setContrastThreshold(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<KeyPoint> keypoints;
    sift->detectAndCompute(image, noArray(), keypoints, descriptors);

Definition at line 2976 of file core.hpp.


Member Function Documentation

virtual CV_WRAP void clear (  ) [virtual]

Clears the algorithm state.

Reimplemented in DescriptorMatcher, and FlannBasedMatcher.

Definition at line 2984 of file core.hpp.

virtual bool empty (  ) const [virtual]

Returns true if the Algorithm is empty (e.g.

in the very beginning or after unsuccessful read

Reimplemented in Feature2D, DescriptorMatcher, and StatModel.

Definition at line 2996 of file core.hpp.

virtual CV_WRAP String getDefaultName (  ) const [virtual]

Returns the algorithm string identifier.

This string is used as top level xml/yml node tag when the object is saved to a file or string.

static Ptr<_Tp> load ( const String &  filename,
const String &  objname = String() 
) [static]

Loads algorithm from the file.

Parameters:
filenameName of the file to read.
objnameThe optional name of the node to read (if empty, the first top-level node will be used)

This is static template method of Algorithm. It's usage is following (in the case of SVM):

     Ptr<SVM> svm = Algorithm::load<SVM>("my_svm_model.xml");

In order to make this method work, the derived class must overwrite Algorithm::read(const FileNode& fn).

Definition at line 3027 of file core.hpp.

static Ptr<_Tp> loadFromString ( const String &  strModel,
const String &  objname = String() 
) [static]

Loads algorithm from a String.

Parameters:
strModelThe string variable containing the model you want to load.
objnameThe optional name of the node to read (if empty, the first top-level node will be used)

This is static template method of Algorithm. It's usage is following (in the case of SVM):

     Ptr<SVM> svm = Algorithm::loadFromString<SVM>(myStringModel);

Definition at line 3046 of file core.hpp.

static Ptr<_Tp> read ( const FileNode fn ) [static]

Reads algorithm from the file node.

This is static template method of Algorithm. It's usage is following (in the case of SVM):

     Ptr<SVM> svm = Algorithm::read<SVM>(fn);

In order to make this method work, the derived class must overwrite Algorithm::read(const FileNode& fn) and also have static create() method without parameters (or with all the optional parameters)

Reimplemented in DescriptorMatcher, and FlannBasedMatcher.

Definition at line 3008 of file core.hpp.

virtual void read ( const FileNode fn ) [virtual]

Reads algorithm parameters from a file storage.

Reimplemented in DescriptorMatcher, and FlannBasedMatcher.

Definition at line 2992 of file core.hpp.

virtual CV_WRAP void save ( const String &  filename ) const [virtual]

Saves the algorithm to a file.

In order to make this method work, the derived class must implement Algorithm::write(FileStorage& fs).

virtual void write ( FileStorage fs ) const [virtual]

Stores algorithm parameters in a file storage.

Reimplemented in DescriptorMatcher, and FlannBasedMatcher.

Definition at line 2988 of file core.hpp.