Learning OpenCV 4 Computer Vision with Python 3 - Third Edition

Defining features

What is a feature, exactly? Why is a particular area of an image classifiable as a feature, while others are not? Broadly speaking, a feature is an area of interest in the image that is unique or easily recognizable. Corners and regions with a high density of textural detail are good features, while patterns that repeat themselves a lot and low-density regions (such as a blue sky) are not. Edges are good features as they tend to divide two regions of an image. A blob (a region of an image that greatly differs from its surrounding areas) is also an interesting feature.

Most feature detection algorithms revolve around the identification of corners, edges, and blobs, with some also focusing on the concept of a ridge, which ...