what is the meaning of intensity order in image processing?

Question

I'm reading this article. This article explains a new feature descriptor such as Sift and Surf and it's name is MROGH.

In a part of this article, there is this sentence:

In our work, sample points are segmented based on their intensity orders
and their gradients are then pooled for each segment.

My question is:

• what is the meaning of intensity order and local intensity of a point in image?

thanks,

---

Edit:

@Yves Daoust linked me here and that is my answer.

Answer 1

The explanation seems to rest in that quote from the paper: "Specifically, we first sort sample points in the support region according to their intensities. Then we divide them into segments equally according to their orders. Finally, gradient information of the sample points in each segment are pooled, and the gradient orientation histograms in these segments are concatenated to form the representation of this support region."