Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Differential Invariant for Zooming   This paper presents an invariant under scaling and linear brightness change.
The invariant is based on differentials and therefore is a local feature.
Rotationally invariant 2-d differential Gaussian operators up to third order
are proposed for the implementation of the invariant. The performance is
analyzed by simulating a camera zoom-out.

6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph