Adaptive color image watermarking based on a modified improved pixel-wise masking technique

In this paper, a family of modified wavelet-based watermarking techniques is proposed. This family of techniques is based on the improved pixel-wise (PW) watermarking scheme. The basic proposed algorithm considerably improves the PSNR of the watermarked image (in the range of 2.20–7.28 dB), and is based on selecting specific locations in the three detailed sub-bands of the first level of the DWT decomposition of the image. The selective nature of the modified PW method (denoted as selective PW: SPW) allows the scheme to be adaptive in terms of the imperceptibility and the watermark size. Also, the PW and SPW methods were extended to be implemented with color images: (1) grayscale-wise PW method (G-PW) that embeds the watermark in the Y component of the YCbCr model. (2) Multi spectral-PW method (MS-PW) that embeds the watermark in the R, G, and B layers independently. (3) Multi spectral-SPW method (MS-SPW) that gains high PSNR value compared with MS-SPW, and (4) multi spectral-maximum PW method (MS-MPW) which is proposed to improve the PSNR value as well as the level of watermarking security, when compared with MS-PW method.