The constructor

extractor = cv.BOWImgDescriptorExtractor(dextractor, dmatcher)
extractor = cv.BOWImgDescriptorExtractor({dextractor, 'key',val,...}, {dmatcher, 'key',val,...})

Input

• dextractor Descriptor extractor that is used to compute descriptors for an input image and its keypoints. It can be specified by a string containing the type of descriptor extractor, such as 'SIFT' or 'SURF'. See cv.DescriptorExtractor.DescriptorExtractor for possible types.
• dmatcher Descriptor matcher that is used to find the nearest word of the trained vocabulary for each keypoint descriptor of the image. It can be spacified by a string specifying the type of descriptor extractor, such as 'BruteForce' or 'BruteForce-L1'. See cv.DescriptorMatcher.DescriptorMatcher for possible types. default 'BruteForce'

In the first variant, it creates descriptor extractor/matcher of the given types using default parameters (by calling the default constructors).

In the second variant, it creates descriptor extractor/matcher of the given types using the specified options. Each algorithm type takes optional arguments. Each of the extractor/matcher are specified by a cell-array that starts with the type name followed by option arguments, as in: {'Type', 'OptionName',optionValue, ...}. Refer to the individual extractor/matcher functions to see a list of possible options of each algorithm.

Example

% first variant
extractor = cv.BOWImgDescriptorExtractor('ORB', 'BruteForce');

% second variant
extractor = cv.BOWImgDescriptorExtractor(...
    {'FastFeatureDetector', 'Threshold',10}, ...
    {'BFMatcher', 'NormType','L2'});