OpenCV 4 with Python Blueprints - Second Edition

Obtaining feature descriptors with SURF

The process of extracting features from an image with OpenCV using SURF is also a single step. It is done by the compute method of our feature extractor. The latter accepts an image and the keypoints of the image as arguments:

key_query, desc_query = self.f_extractor.compute(img_query, key_query)

Here, desc_query is a NumPY ndarray with shape (num_keypoints, descriptor_size). You can see that each descriptor is a vector in an n-dimensional space (n-length array of numbers). Each vector describes the corresponding key point and provides some meaningful information about our complete image.

Hence, we have completed our feature extraction algorithm that had to provide meaningful information about our image ...