Descriptors and object matching

Image features by themselves are a bit useless. Yes, we have found unique points on an image. But what did we get? Only pixels values and that's it. If we try to compare those values it will not give us much information. Moreover, if we change the overall image brightness, we will not find the same keypoints on the same image! Taking into account all of this, we need the information which surrounds our key points. Moreover, we need a method to efficiently compare this information. First, we need to describe the image features, which comes from image descriptors. In this part, we will see how those descriptors can be extracted and matched. The tracking.js and JSFeat libraries provide different methods for image descriptors. We will discuss both.

The BRIEF and ORB descriptors

The descriptors theory is focused on changes in an image pixels' intensities. The tracking.js library provides the Binary Robust Independent Elementary Features (BRIEF) descriptors and the...