A novel quantization-based data-hiding method, named Rational Dither Modulation (ROM), is presented. This method amounts to simple modifications of the well-known Dither Modulation (OM) scheme, which is largely vulnerable to scaling attacks. With such modifications, RDM becomes invariant to those attacks. Since RDM does not work by trying to estimate the step-size of the quantizers, it does not need any pilot-sequence.Moreover, ROM is suitable for a scalar operation, thus avoiding the cumbersome constructions of spherical codes. It is also shown that ROM approaches the performance of DM as)mptotically with the size of the memory needed for the method to operate. Simulation results show the accuracy of our theoretical analysis and the superiority of ROM compared to the Improved Spread Spectrum method.
Abstract. In this paper we study the positive Borel measures µ on the unit disc D in C for which the Bloch space B is continuously included in L p (dµ), 0 < p < ∞. We call such measures p-Bloch-Carleson measures. We give two conditions on a measure µ in terms of certain logarithmic integrals one of which is a necessary condition and the other a sufficient condition for µ being a p-Bloch-Carleson measure. We also give a complete characterization of the p-Bloch-Carleson measures within certain special classes of measures. It is also shown that, for p > 1, the p-Bloch-Carleson measures are exactly those for which the Toeplitz operator T µ , defined by T µ (f )(z) =
The aim of this paper is to show that univalent functions in several classical function spaces can be characterized by integral conditions involving the maximum modulus function. For a suitable choice of parameters, the established condition or its appropriate variant reduces to a known characterization of univalent functions in the Hardy or weighted Bergman space and gives a new characterization of univalent functions in several Möbius invariant function spaces, such as BMOA, Qp or the Bloch space. It is proved, for example, that univalent functions in the Dirichlet type space D p p+α are the same as the univalent functions in H p α and S p α if p ≥ 2. Moreover, it is shown that there is in a sense a much smaller Möbius invariant subspace of the Bloch space than Qp still containing all univalent Bloch functions.
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