Embedding invisible watermark in digital image using interpolation and histogram shifting

Watermarking or embedding of watermark is a technique to embed the useful information in a digital media for copyright protection, authentication, broadcast monitoring etc. This paper describes a data hiding method based on interpolation which calculates the interpolation error and the residual histogram of the interpolation errors of the host image to hide secret data. The residual image is obtained by interpolation and histogram shifting is applied to obtain the watermarked image. The major advantages of this method are higher image quality and smaller computational cost as compared to other data hiding techniques. Image quality is evaluated in terms of peak to signal ratio (PSNR). Experimental results show that quality of watermarked image is higher for this scheme as compared to other existing watermarking schemes. This watermarking technique gives higher embedding capacity than other histogram based methods.