Improved watermarking technique based on significant difference of lifting wavelet coefficients

In this paper, a blind watermarking scheme based on significant difference of lifting wavelet transform coefficients has been proposed. The difference between two maximum coefficients in a block is called as significant difference. Embedding of binary watermark has been done based on the largest coefficient of randomly shuffled blocks of CH3 sub-band. This sub-band is quantized using the predefined threshold value by comparing the significant difference value with the average of significant difference value of all blocks. The watermarked image shows no perceptual degradation as the PSNR value exceeds 42 dB. An adaptive-thresholding-based method is used for watermark extraction. In the proposed technique, the benefit of using lifting wavelet over traditional wavelet is the maximum energy compaction property, which helps in resisting different attacks. The simulation results show higher performance of the proposed technique as compared to the similar existing techniques under different geometric and nongeometric attacks such as amplification, median filtering, sharpening, scaling, rotation, Gaussian noise, salt and paper noise, Gaussian filter and JPEG compression.