OpenCV 4.11.0-pre
Open Source Computer Vision
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cv::Algorithm Class Reference

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

#include <opencv2/core.hpp>

Collaboration diagram for cv::Algorithm:

Public Member Functions

 Algorithm ()
 
virtual ~Algorithm ()
 
virtual void clear ()
 Clears the algorithm state.
 
virtual bool empty () const
 Returns true if the Algorithm is empty (e.g. in the very beginning or after unsuccessful read.
 
virtual String getDefaultName () const
 
virtual void read (const FileNode &fn)
 Reads algorithm parameters from a file storage.
 
virtual void save (const String &filename) const
 
void write (const Ptr< FileStorage > &fs, const String &name=String()) const
 
virtual void write (FileStorage &fs) const
 Stores algorithm parameters in a file storage.
 
void write (FileStorage &fs, const String &name) const
 

Static Public Member Functions

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

Protected Member Functions

void writeFormat (FileStorage &fs) const
 

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 SimpleBlobDetector use in your application via Algorithm interface:

Ptr<Feature2D> sbd = SimpleBlobDetector::create();
FileStorage fs_read("SimpleBlobDetector_params.xml", FileStorage::READ);
if (fs_read.isOpened()) // if we have file with parameters, read them
{
sbd->read(fs_read.root());
fs_read.release();
}
else // else modify the parameters and store them; user can later edit the file to use different parameters
{
fs_read.release();
FileStorage fs_write("SimpleBlobDetector_params.xml", FileStorage::WRITE);
sbd->write(fs_write);
fs_write.release();
}
Mat result, image = imread("../data/detect_blob.png", IMREAD_COLOR);
vector<KeyPoint> keypoints;
sbd->detect(image, keypoints, Mat());
drawKeypoints(image, keypoints, result);
for (vector<KeyPoint>::iterator k = keypoints.begin(); k != keypoints.end(); ++k)
circle(result, k->pt, (int)k->size, Scalar(0, 0, 255), 2);
imshow("result", result);
waitKey(0);

Constructor & Destructor Documentation

◆ Algorithm()

cv::Algorithm::Algorithm ( )

◆ ~Algorithm()

virtual cv::Algorithm::~Algorithm ( )
virtual

Member Function Documentation

◆ clear()

virtual void cv::Algorithm::clear ( )
inlinevirtual
Python:
cv.Algorithm.clear() -> None

◆ empty()

virtual bool cv::Algorithm::empty ( ) const
inlinevirtual
Python:
cv.Algorithm.empty() -> retval

◆ getDefaultName()

◆ load()

template<typename _Tp >
static Ptr< _Tp > cv::Algorithm::load ( const String & filename,
const String & objname = String() )
inlinestatic

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");
static Ptr< _Tp > load(const String &filename, const String &objname=String())
Loads algorithm from the file.
Definition core.hpp:3255
std::shared_ptr< _Tp > Ptr
Definition cvstd_wrapper.hpp:23

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

Here is the call graph for this function:

◆ loadFromString()

template<typename _Tp >
static Ptr< _Tp > cv::Algorithm::loadFromString ( const String & strModel,
const String & objname = String() )
inlinestatic

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):

static Ptr< _Tp > loadFromString(const String &strModel, const String &objname=String())
Loads algorithm from a String.
Definition core.hpp:3276
Here is the call graph for this function:

◆ read() [1/2]

◆ read() [2/2]

template<typename _Tp >
static Ptr< _Tp > cv::Algorithm::read ( const FileNode & fn)
inlinestatic
Python:
cv.Algorithm.read(fn) -> None

Reads algorithm from the file node.

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

cv::FileStorage fsRead("example.xml", FileStorage::READ);
Ptr<SVM> svm = Algorithm::read<SVM>(fsRead.root());
virtual void read(const FileNode &fn)
Reads algorithm parameters from a file storage.
Definition core.hpp:3219
XML/YAML/JSON file storage class that encapsulates all the information necessary for writing or readi...
Definition persistence.hpp:261
@ READ
value, open the file for reading
Definition persistence.hpp:266

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)

◆ save()

virtual void cv::Algorithm::save ( const String & filename) const
virtual
Python:
cv.Algorithm.save(filename) -> None

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

◆ write() [1/3]

void cv::Algorithm::write ( const Ptr< FileStorage > & fs,
const String & name = String() ) const
Python:
cv.Algorithm.write(fs) -> None
cv.Algorithm.write(fs, name) -> None

◆ write() [2/3]

◆ write() [3/3]

void cv::Algorithm::write ( FileStorage & fs,
const String & name ) const
Python:
cv.Algorithm.write(fs) -> None
cv.Algorithm.write(fs, name) -> None

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ writeFormat()

void cv::Algorithm::writeFormat ( FileStorage & fs) const
protected

The documentation for this class was generated from the following file: