Forward Modified Histogram Shifting based Reversible Watermarking with Reduced Pixel Shifting and High Embedding Capacity

The modified histogram shifting method proposed by Hong et. al.(2010) is best method of reversible watermarking[16]. The shifting of pixels are more in Hong et. al.(2010) method. Even Hong et. al.(2010) method of modified histogram shifting has less embedding capacity and do not provide enough quality for general purpose image. Our forward modified histogram shifting method overcomes all these drawbacks of Hong et. al.(2010) method. Generally PSNR decreases when embedding capacity increases and shifting pixels also increases. But our modified histogram shifting method optimizes all these factors. Our forward modified histogram shifting method shifts required pixel values to right by ‘n-1’ numbers. ‘n-1’ may be 1,2,3 and so on. This also increases embedding capacity approximately to (n-1) times maximum number of pixels in the histogram. The complexity of our forward modified histogram shifting method is same as that of Hong et. al. (2010) modified histogram shifting method as both scans image twice during processing.