FEATURE-BASED ROBUST IMAGE WATERMARKING SCHEME USING BISPECTRAL INVARIANT

摘要

PURPOSE: A characteristic-based strong image watermark algorithm using invariance of bispectrum is provided to use a bispectrum vector as a watermark, so that the watermark has solidarity in the case of applying RST(Rotation, Scale, Translation). CONSTITUTION: Two-dimensional fast fourier transform is calculated to an original image before mapping the original image on polar coordinates(S1-S2). Phase components are corrected to shape features by using strength parameters for making one feature vector(S3). A key is used to select projection for embedding(S4). The original image mapped on the polar coordinates are mapped on cartesian coordinates by using an inverse FFT(Fast Fourier Transform) to obtain a bispectrum vector(S5). The bispectrum vector is used as a watermark(S6-S8).