OpenCV 4 with Python Blueprints - Second Edition

Using SURF descriptor

But wait a minute! In Chapter 3, Finding Objects via Feature Matching and Perspective Transforms, you learned that the SURF descriptor is one of the best and most robust ways to describe images independent of scale or rotations. Can we use this technique to our advantage in a classification task?

Glad you asked! To make this work, we need to adjust SURF so that it returns a fixed number of features per image. By default, the SURF descriptor is only applied to a small list of interesting key points in the image, the number of which might differ on an image-by-image basis. This is unsuitable for our current purposes because we want to find a fixed number of feature values per data sample.

Instead, we need to apply SURF ...