Finite Ridgelet Transform in Digital Watermarking

Existing watermarking algorithms in finite ridgelet transform domain usually work by modulating the transform coefficients in the direction of maximum energy.However,how to select suitable coefficients for watermark embedding is still an open question.In this work,a study on finite ridgelet transform in digital watermarking is carried out.At first,edges are detected by Roberts operator,followed by finite ridgelet transform on the obtained edge image.Then based on Laplacian probability distribution function(PDF),the suitable finite ridgelet transform coefficients are obtained by adopting maximum a posterior(MAP) estimation principle.Finally the watermark is embedded adaptively in those coefficients.Experimental results demonstrate the good robustness and invisibility of our proposed approach.