Slantlet based hybrid watermarking technique for medical images.

Watermarking techniques are widely used for copyright protection, confidentiality and integrity issues in medical field. Reversibility, robustness, embedding capacity and invisibility are the essential requirements of a watermarking technique. Cogitating the need of security for medical images, this paper proposes a reversible high embedding capacity, high image fidelity, a hybrid robust lossless data hiding technique by using both transform and spatial domains. Proposed technique alters the mean of the selected non-overlapping slantlet transformed blocks of the host image whereas RS vector considers flipping factor for data embedding. The optimum thresholds to select the blocks are calculated through PSO technique and watermark is generated by using patient details, biometric id and region of interest (ROI) blocks of host image. This watermark is further compressed by applying LZW technique and encrypted by AES as well as MD5. The watermark bits are embedded in all three RGB channels of a cover image, to increase the embedding capacity up to 3.3675 bpp. The credibility of the proposed technique in comparison with other medical watermarking techniques is evidenced through experimental results. [ABSTRACT FROM AUTHOR]