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Print-Scan Resilient Data Hiding

People

K. Solanki, U. Madhow, B.S.Manjunath, S. Chandrasekaran

Objective

In this project, our goal is to develop methods for hiding information in images in a manner that is robust to printing and scanning. Print-scan resilient data hiding finds many important applications as outlined below.

  1. Image copyright protection: Many pictures appear on magazines and newspapers everyday. With availability of inexpensive high resolution scanners, the image can be conveniently converted into a digital form and the ownership of the image may be claimed by someone else. To counter this, information can be hidden into these images before they are printed and the ownership can be verified in the digital format.
  2. E-commerce of digital images: With the availability of affordable digital cameras, more and more images are created in a digital form. The potential of e-commerce for digital images cannot be realized unless a system for owner identification is in place. In this scenario, it is desirable that the hidden ownership information does not get destroyed if the image is printed.
  3. Protecting critical documents: Security information (such as fingerprints, signature, or passport number) can be imperceptibly embedded into a picture in documents such as passports, drivers licenses, or ID cards. Only specific devices, which have access to a secret key, can decode and authenticate the hidden information. Forgery of such documents become extremely difficult because the embedded data is inseparable from the picture.

Print-Scan Resilient Data Hiding: The SELF Hiding Scheme

The method is based on embedding in the transform domain, with synchronization and error correction using powerful turbo-like channel codes. The design is based on an experimental understanding of the effects of the print-scan operation. The method, named selective embedding in low frequencies (SELF) is based on embedding dynamically into low frequency DFT coefficients. We employ turbo-like error and erasure correcting codes in a novel fashion to counter the synchronization problem caused due to the adaptive hiding. This also provides robustness to the hidden data against a variety of other attacks such as those in Stirmark, e.g., heavy JPEG compression, scaling or aspect ratio change, Gaussian or median filtering, rows and/or columns removal, and random bending.

Estimating and Undoing Rotation after Scanning

The scanned digital image is preprocessed by an automated algorithm for estimating and undoing the rotation caused by random placement of the printed image in the scanner. The method is based on the fact that laser printers use an ordered digital halftoning algorithm for printing. There is no penalty in hiding rate for achieving robustness against rotation. In fact, the estimation and automatic derotation allows more information to be hidden (as compared to manual placing of image printout on the scanner flatbed) because of its accurate estimation of the rotation angle.

» Presentation: "Estimating and Undoing Rotation for Print-Scan Resilient Data Hiding." (2.8 Mb)

Modeling the Print-Scan Process

A model for print-scan process is proposed, which has three main components.

  1. Effects due to mild cropping:  At the time of scanning, the image part must be cropped out from the background, either manually or automatically. At this point, some mild cropping of the image is inevitable.
  2. Colored high-frequency noise: High-frequency noise gets added to the image as a result of the digital halftoning and the printing process. This affects the high frequency spectrum of the image, so that the high frequency coefficients cannot be used for data embedding.
  3. Non-linear effects: Both printing and scanning processes introduce non-linearity, which includes the gamma correction that happens at the time of scanning.

Examples

Acknowledgements

This research is supported by a grant from ONR #N00014-01-1-0380. Program manager: Dr. Ralph Wachter

Publications

    2006

  1. K. Solanki, U. Madhow, B. S. Manjunath, S. Chandrasekaran and I. El-Khalil,
    "'Print and Scan' Resilient Data Hiding in Images"
    IEEE Transactions on Information Forensics and Security, vol. 1, no. 4, pp. 464-478, Dec. 2006.
    [abstract] [PDF] [BibTex]

    Abstract preview: "Print-scan resilient data hiding finds important applications in document security and image copyright protection. This paper proposes methods to hide information into images that achieve robustness a..." [more]

  2. 2005

  3. K. Solanki, U. Madhow, B. S. Manjunath and S. Chandrasekaran,
    "Modeling the Print-Scan Process for Resilient Data Hiding"
    Proc. SPIE Security, Steganography, and Watermarking of Multimedia Contents VII, Edward J. Delp III, Ping W. Wong (Editors), vol. 5681, pp. 418-429, Mar. 2005.
    VRL ID: 143, [abstract] [PDF] [BibTex]

    Abstract preview: "Print-scan resilient data hiding finds important applications in document security, and image copyright protection. In this paper, we build upon our previous work on print-scan resilient data hiding w..." [more]

  4. 2004

  5. K. Solanki, U. Madhow, B. S. Manjunath, and S. Chandrasekaran,
    "Estimating and Undoing Rotation for Print-Scan Resilient Data Hiding"
    Proc. IEEE International Conference on Image Processing, Singapore, Oct. 2004.
    IBM Student Paper Award
    VRL ID: 137, [abstract] [PDF] [BibTex]

    Abstract preview: "This paper proposes a method to hide information into images that achieves robustness against printing and scanning with blind decoding. A significant contribution of this paper is a technique to esti..." [more]

  6. 2003

  7. K. Solanki, O. Dabeer, U. Madhow, B. S. Manjunath and Shiv Chandrasekaran,
    "Robust Image-Adaptive Data Hiding: Modeling, Source Coding, and Channel Coding"
    41st Allerton Conference on Communications, Control, and Computing, Oct. 2003.
    VRL ID: 125, [abstract] [PDF] [BibTex]

    Abstract preview: "This paper provides a summary of our work over the past two years on robust, high-volume data hiding in images. We first present a basic framework for image-adaptive hiding, which allows selection of ..." [more]