Skip to main content
Kent Academic Repository

Recovering sign bits of DCT coefficients in digital images as an optimization problem

Lin, Ruiyuan, Liu, Sheng, Jiang, Jun, Li, Shujun, Li, Chengqing, Kuo, C.-C. Jay (2024) Recovering sign bits of DCT coefficients in digital images as an optimization problem. Journal of Visual Communication and Image Representation, 98 . Article Number 104045. ISSN 1047-3203. (doi:10.1016/j.jvcir.2023.104045) (KAR id:106082)


Recovering unknown, missing, damaged, distorted, or lost information in DCT coefficients is a common task in multiple applications of digital image processing, including image compression, selective image encryption, and image communication. This paper investigates the recovery of sign bits in DCT coefficients of digital images, by proposing two different approximation methods to solve a mixed integer linear programming (MILP) problem, which is NP-hard in general. One method is a relaxation of the MILP problem to a linear programming (LP) problem, and the other splits the original MILP problem into some smaller MILP problems and an LP problem. We considered how the proposed methods can be applied to JPEG-encoded images and conducted extensive experiments to validate their performances. The experimental results showed that the proposed methods outperformed other existing methods by a substantial margin, both according to objective quality metrics and our subjective evaluation.

Item Type: Article
DOI/Identification number: 10.1016/j.jvcir.2023.104045
Uncontrolled keywords: Discrete cosine transform (DCT); Sign bit recovery; Optimization; Integer programming; Linear programming; Selective encryption
Subjects: Q Science > QA Mathematics (inc Computing science) > QA 75 Electronic computers. Computer science
Q Science > QA Mathematics (inc Computing science) > QA 76 Software, computer programming, > QA76.575 Multimedia systems
T Technology > TK Electrical engineering. Electronics. Nuclear engineering > TK5101 Telecommunications > TK5102.9 Signal processing
Divisions: Divisions > Division of Computing, Engineering and Mathematical Sciences > School of Computing
University-wide institutes > Institute of Cyber Security for Society
Funders: National Natural Science Foundation of China (
Depositing User: Shujun Li
Date Deposited: 24 May 2024 17:36 UTC
Last Modified: 28 May 2024 11:36 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

  • Depositors only (login required):

Total unique views for this document in KAR since July 2020. For more details click on the image.