Improved block encoding method for an image self-recovery approach
K. Sreenivas, V. Kamakshi Prasad · 2016
The paper proposes a modified self-embedding watermarking scheme of the Fan Chen & Hongjie He [4] that improves the quality of the recovered image. The watermarking bits are of variable length that best approximates 5 MSB of the pixel values of a 2 × 2 block of original image compared to average intensity of the block. There are 7 different schemes that help to calculate the watermarking bits for a 2 × 2 block, including the average intensity of the block. That is, when the watermarking bits of a 2 × 2 block survive an attack, the greatest deviation of the recovered block from the original block is not greater than the deviation when the block is recovered using its average intensity. Thus the PSNR between the original and recovered image is relatively higher compared with the one when image recovery used only the average intensity of the block. The experimental results confirm this fact.