Image Ownership Veri?cation Via UnitaryTransform of Conjuga Conjugate Quadrature Filterte

摘要

A wavelet-based watermarking system is described for ownershiprnverification of digital images. The wavelet filters used in this systemrnare constructed by unitary transform of two-dimensional conjugaternquadrature filter (CQF). Tensor-product wavelet filters are only specialrncases of this construction. This construction provides more ways to randomlyrngenerate perfect reconstruction filters, and will increase the difficultyrnfor counterfeiters to gain the exact knowledge of our watermark.rnFurthermore, the watermark is insert inserted into several middle-frequencyrned sub-bands and the existence of the watermark is asserted if any one ofrnthe correlation values is greater than a pre-determined threshold. Experimentalrnresults show that the proposed algorithm achieves invisibility,rnblind, and robustness to noising, sharpening, cropping etc.