Image watermarking using low wavelet subband based on 8×8 sub-block DCT

Currently, digital image watermarking is widely implemented as a tool for copyright protection. Along with technological developments, the technique of theft and manipulation of digital imagery increasingly sophisticated. So research on image watermarking should continue to grow for improved copyright security. This paper proposes the use of Discrete Cosine Transform (DCT) based on 8×8 sub-blocks to convert the original image from spatial to the frequency domain. The DCT transform result will produce AC and DC coefficients. Next, the DC coefficients are collected into a matrix to be transformed with DWT. The result of DWT transformation yield four subbands. Then the LL subband is selected for embedding copyright in the form of a binary image with a certain watermark strength value. The final step inverse the DWT-DCT transform to produce a watermarked image. From the results of this study, high imperceptibility values are evidenced by PSNR and MSE. Image watermark toughness is also measured by NC and is proven to be robust from various attacks mainly from JPEG compression attacks.