Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Digital Watermarking Approach Based on DCT Domain Combining QR Code
  and Chaotic Theory   This paper proposes a robust watermarking approach based on Discrete Cosine
Transform domain that combines Quick Response Code and chaotic system.

7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat