Biobjective NSGA-II for optimal spread spectrum watermarking of color frames: Evaluation study

In this work, a spread spectrum watermarking optimization algorithm is explored for digital color images using biobjective genetic algorithms and full-frame discrete-cosine transform. The aim of optimization is to generate the trade-off curve, a.k.a. optimal Pareto points, of watermark imperceptibility and robustness. The watermark imperceptibility is evaluated using the Structural SIMilarity (SSIM) index between the original image and the watermarked image whereas the watermark robustness is evaluated in terms of the Normalized Correlation Coefficient (NCC) between the original watermark and the recovered watermark. The watermarked image is susceptible to various types of attacks or processing distortions such as additive Gaussian noise, pepper-and-salt noise, JPEG compression, camera motion and median filtering. For the biobjective genetic algorithm, we used the fast elitist Non-dominated Sorting Genetic Algorithm (NSGA-II). We reviewed related work and investigated two color spaces (YCbCr and HSV) in addition to gray scale images where embedding is conducted in different frames and various distortions are applied before the extraction of the watermark. The results are compared for various cases under similar conditions.