Package org.opencv.xfeatures2d

Class BOWImgDescriptorExtractor

java.lang.Object

org.opencv.xfeatures2d.BOWImgDescriptorExtractor

public class BOWImgDescriptorExtractor
extends java.lang.Object

Class to compute an image descriptor using the *bag of visual words*. Such a computation consists of the following steps: 1. Compute descriptors for a given image and its keypoints set. 2. Find the nearest visual words from the vocabulary for each keypoint descriptor. 3. Compute the bag-of-words image descriptor as is a normalized histogram of vocabulary words encountered in the image. The i-th bin of the histogram is a frequency of i-th word of the vocabulary in the given image.

Field Summary

Fields

Modifier and Type	Field	Description
protected long	nativeObj

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	BOWImgDescriptorExtractor(long addr)
	BOWImgDescriptorExtractor(Feature2D dextractor, DescriptorMatcher dmatcher)	The constructor.

Method Summary

Modifier and Type	Method	Description
static BOWImgDescriptorExtractor	__fromPtr__(long addr)
void	compute(Mat image, MatOfKeyPoint keypoints, Mat imgDescriptor)
int	descriptorSize()	Returns an image descriptor size if the vocabulary is set.
int	descriptorType()	Returns an image descriptor type.
protected void	finalize()
long	getNativeObjAddr()
Mat	getVocabulary()	Returns the set vocabulary.
void	setVocabulary(Mat vocabulary)	Sets a visual vocabulary.

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

BOWImgDescriptorExtractor

protected BOWImgDescriptorExtractor(long addr)

BOWImgDescriptorExtractor

public BOWImgDescriptorExtractor(Feature2D dextractor,
                                 DescriptorMatcher dmatcher)

The constructor.

Parameters:

dextractor - Descriptor extractor that is used to compute descriptors for an input image and its keypoints.

dmatcher - Descriptor matcher that is used to find the nearest word of the trained vocabulary for each keypoint descriptor of the image.

Method Detail

getNativeObjAddr

public long getNativeObjAddr()

__fromPtr__

public static BOWImgDescriptorExtractor __fromPtr__(long addr)

setVocabulary

public void setVocabulary(Mat vocabulary)

Sets a visual vocabulary.

Parameters:

vocabulary - Vocabulary (can be trained using the inheritor of BOWTrainer ). Each row of the vocabulary is a visual word (cluster center).

getVocabulary

public Mat getVocabulary()

Returns the set vocabulary.

Returns:

automatically generated

compute

public void compute(Mat image,
                    MatOfKeyPoint keypoints,
                    Mat imgDescriptor)

Parameters:

imgDescriptor - Computed output image descriptor. pointIdxsOfClusters[i] are keypoint indices that belong to the i -th cluster (word of vocabulary) returned if it is non-zero.

image - automatically generated

keypoints - automatically generated

descriptorSize

public int descriptorSize()

Returns an image descriptor size if the vocabulary is set. Otherwise, it returns 0.

Returns:

automatically generated

descriptorType

public int descriptorType()

Returns an image descriptor type.

Returns:

automatically generated

finalize

protected void finalize()
                 throws java.lang.Throwable

Overrides:

finalize in class java.lang.Object

Throws:

java.lang.Throwable