Watermark Embedding and Extraction Based on LSB and Four-Step Phase Shift Method

Abstract

A method of color watermark embedding and extraction based on LSB and four-step phase shift method is proposed for information hiding. The method firstly decomposes the color watermark into three primary colors, and decomposes them into grayscale images of R, G, and B channel image. The four-step phase shift method respectively generates four computer-generated hologram (CGH) for each grayscale images, and one of the CGH will be embedded into the corresponding channel image of the color carrier image by the LSB algorithm; the watermark carrier image is decomposed into the R, G, and B channel images, the CGH is extracted from the channel image and The channel images are reconstructed from the CGH by the four-step phase shift method, the original watermark image is synthesized by the channel images, and the watermark recovery is completed. This watermark embedding extraction method based on LSB and the four-step phase shift improves the security during the watermark embedding process.