SIFT (1)

2D feature extracted, satisfy:

1. scale invarient;

2. rotation invarient.

Naive Thinking: Minimal point or Maximum Point, Local;

Now you are given a grey img. Just a Matrix with element value range from 0,1,.., to255.

It is a finite discrete set.

The details looks like this:

SIFT (1)

原文：http://www.cnblogs.com/stevenxiu/p/5565099.html