A Comparison of Watermarking Image Quality Based on Dual Intermediate Significant Bit with Genetic Algorithm

The quality of the watermarked images is considered as one of the most important requirements of any watermarking system. In most applications, the watermarking algorithm embeds the watermark without affecting the quality of the host media. In this study, a comparison of watermarking image quality was performed between two existing methods: Dual Intermediate Significant Bit (DISB) and Genetic Algorithm (GA). The first method focuses on the high quality of the watermarked image based on DISB model and this method requires embedding two bits into every pixel of the original image, while the other six bits are modified so as to immediately assimilate the original pixel. In this case, when the two hidden bits are equal to the original bits, there will be no change to the other remaining bits. However, if the original value is not equal to the embedded one, the nearest pixel to the original one will be chosen as the watermarked image. The second method, GA method is used to embed two bits of watermarking data within every pixel of the original image and to find the optimal value based on the existing DISB. On the other hand, if the two embedded bits are equal to the original bits then this means the watermarked image is still the same as the original one without any changes, while in the other case GA is used in determining the minimum fitness value in which the fittest is the absolute value between the pixel and chromosome and the value of chromosome between 0-255. The results indicate that the two methods produce a high quality watermarked image, but there is a big difference in the processing time, so the DISB method is faster than the GA method.