Package org.opencv.features2d
Class BOWImgDescriptorExtractor
java.lang.Object
org.opencv.features2d.BOWImgDescriptorExtractor
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.
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Field Summary
Fields -
Constructor Summary
ConstructorsModifierConstructorDescriptionprotected
BOWImgDescriptorExtractor
(long addr) BOWImgDescriptorExtractor
(Feature2D dextractor, DescriptorMatcher dmatcher) The constructor. -
Method Summary
Modifier and TypeMethodDescriptionstatic BOWImgDescriptorExtractor
__fromPtr__
(long addr) void
compute
(Mat image, MatOfKeyPoint keypoints, Mat imgDescriptor) int
Returns an image descriptor size if the vocabulary is set.int
Returns an image descriptor type.protected void
finalize()
long
Returns the set vocabulary.void
setVocabulary
(Mat vocabulary) Sets a visual vocabulary.
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Field Details
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nativeObj
protected final long nativeObj
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Constructor Details
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BOWImgDescriptorExtractor
protected BOWImgDescriptorExtractor(long addr) -
BOWImgDescriptorExtractor
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.
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Method Details
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getNativeObjAddr
public long getNativeObjAddr() -
__fromPtr__
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setVocabulary
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).
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getVocabulary
Returns the set vocabulary.- Returns:
- automatically generated
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compute
- Parameters:
image
- automatically generatedkeypoints
- automatically generatedimgDescriptor
- 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.
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descriptorSize
public int descriptorSize()Returns an image descriptor size if the vocabulary is set. Otherwise, it returns 0.- Returns:
- automatically generated
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descriptorType
public int descriptorType()Returns an image descriptor type.- Returns:
- automatically generated
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finalize
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