A Simple Block Based Content Watermarking Scheme for Image Authentication and Tamper Detection
L. Sumalatha1, G. Rosline Nesa Kumari2, V.Vijaya Kumar3

1L. Sumalatha, Associate Professor, Department of Computer Science and Engineering, University College of Engineering, JNTUK, Kakinada, AP, India.
2G. Rosline Nesa Kumari, Associate Professor, Godavari Institute of Engineering and Technology, Rajahmundry, AP, India.
3Dr. V.Vijaya Kumar, Dean of Computer Sciences, Godavari Institute of Engineering and Technology, Rajahmundry, AP, India.
Manuscript received on September 01, 2012. | Revised Manuscript received on September 02, 2012. | Manuscript published on September 05, 2012. | PP: 113-117 | Volume-2 Issue-4, September 2012. | Retrieval Number: D0910072412/2012©BEIESP
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© The Authors. Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Abstract: Digital watermarking techniques have been proposed for handling applications like Copy protection, Content authentication of digital images. Any tiny change to the content is not acceptable in images especially when they are used to store secret information in the form of an invisible digital watermark. To address this present paper proposes a simple block based content checksum watermarking (BCCW) method for image authentication and tamper localization. The proposed BCCW is a hierarchical and block based method. In BCCW the image is divided into sub blocks of size 4×4. Then a hierarchical relationship is established by dividing each 4×4 as a set of four 2×2 blocks. A Checksum of 8 bits is computed from pixels of 4×4 block and the checksum is placed intelligently on the selected 2×2 block pixels. In the proposed BCCW if any block or even a pixel is tampered then the block checksum does not match with the extracted bit sequence. The main advantage of the BCCW scheme is, it can identify effectively in which blocks the tampering has occurred. The experimental results show that the quality of the embedded image is very high, and the positions of the tampered parts are located correctly. The proposed BCCW method is compared with several other methods.
Keywords: Block Based, Content Checksum, Image Authentication