Robust multirate lattice quantization index modulation watermarking resilient to multiple description transmission channel

Abstract

Multiple-description (MD) transmission results in nonlinear value-metric (value-scaling) distortion in the case when some of the sent descriptions are not received. An acceptable image can still be received in the above situation due to the characteristic of MD. However, it is quite damaging to the traditional quantization-based watermarking technique for payload detection. To overcome the problem, a straightforward approach would be to increase the quantization step size in watermark embedding so as to keep the distortion within the tolerant range. However, as a larger quantization step size in watermark embedding would result in a worsened watermarked image, it is not feasible to adopt it without further consideration. The proposed multirate lattice quantization index modulation (MRL-QIM) encodes two watermark bits into each of the four co-set points of a lattice (so-called multirate). Compared to traditional vector-based quantization encoding or combined spread spectrum-quantization encoding, it significantly increases the payload (capacity) and enhances the robustness of watermark detection while preserving the fidelity of the watermarked image. Comprehensive experiments have confirmed that the overall performance and the effectiveness of the proposed scheme are superior to previous approaches. (C) 2007 Society of Photo-Optical Instrumentation Engineers.