Correction: A novel gray-scale image watermarking framework using harmony search algorithm optimization of multiple scaling factors

A Digital image watermarking is a cutting-edge problem that deals with copyright protection, content authentication and ownership identification. Precisely due to this reason, it is quite clear to the media industry. Particularly for images and videos, falling under un-compressed and compressed domain, it deals with minimizing the trade-off between two essential performance evaluation metrics – Visual Quality of the signal and the Robustness criteria. Although several metaheuristic technqiues have been applied to this problem, we are yet to apply new nature inspired techniques to develop watermarking applications for images and video. In this paper, we propose a novel watermark embedding scheme for gray-scale images using Harmony Search Algorithm (HSA). The HSA optimizes the Objective Function which in turn produces the best Multiple Scaling Factors (MSFs) to be used for embedding the watermark coefficients in the most suitable image coefficients in hybrid transform domain. On signed and attacked images, the PSNR show that their visual quality is very good. This scheme is also found to be very robust against common image processing operations except cropping attack of different variants. It is concluded that the proposed scheme is well optimized in terms of aforesaid performance evaluation metrics and proves improvement over other similar state of the art methods.