A blind block based DCT watermarking technique for gray level images using one dimensional Walsh coding

In this paper a new complete technique using one dimensional Walsh coding to improve the robustness of watermarking in digital images is presented. The proposed technique inserts bits of binary handwritten signatures in the DCT blocks of a digital image. In the proposed method, the 1-D Walsh functions are used to encode the signature before being embedded in the cover image. The 1-D Walsh coding can be applied either horizontally or vertically. The work was carried out using the horizontal 1-D Walsh coding. By utilizing this type of coding, each row of the signature´s vectors will be replaced by the Walsh code and queue them horizontally to get the modulated signal. In the decoding process, the original signature´s bits are identified by the use of odd and even functions. The proposed technique gives good image quality and is robust against JPEG compression.