Transform Domain Fragile Watermarking Using Fermat Number Transform

This paper presents a transform domain fragile watermarking technique based on Fermat number transform (FNT). This transform domain is very simple and efficient in terms of computational complexity and speed. FNT is a true digital transform, which makes the watermarking method free from round-off errors. In this method, the image is divided into non-overlapping blocks and FNT is applied on each block. The transformed coefficients are then quantized and embedded by the watermark bits. Finally, inverse FNT is taken and all the blocks are combined together. This method has eight variations depending on the fragility requirements. Depending upon the requirement of fragility and PSNR different variants of this method can be used.