Effect of Different Places in Applying Laplacian Filter on the Recovery Algorithm in Spatial Domain Watermarking

Generally, Laplacian filter is used to make an image more defined and enhanced. In this study, a comparison is toke place between the effects of different places of performing Laplacian filter on the power of the watermark recovery in spatial domain image watermarking. This filter is applied in two different places in the watermark recovery algorithm; before performing the watermark recovery and before take the correlation in the middle of recovery algorithm. The distinction between the watermark and UN water marked parts of the image are increased by this filter. Thus, watermark could recover significantly better by recovery algorithm. We intend to determine which of these places is more appropriate to apply this filter. A typical correlation based method is used as a representative of spatial domain watermarking methods. Several experiment are done to compare the effect of different places in applying proposed filter on quality of extracted watermark in correlation based watermarking algorithm.