Browsing by Author "Jou, I-Chang"

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Multiple description watermarking based on quantization index modulus modulation
(2007-11-01)
Day, Miin-Luen
;
Lee, Suh-Yin
;
Jou, I-Chang
;
資訊工程學系
;
Department of Computer Science
In this paper, we study the problem of watermarking for error-prone transmission over unreliable network. We try to integrate an oblivious quantization index modulus modulation (QIMM) watermarking technique into the multiple description coding (MDC) framework and we call it multiple description watermarking technique (MDW). It is known that the balanced MDC encodes a signal source into multiple bitstreams (descriptions) of equal importance and equal data rate. Consider a traditional two-description case in a packet transmission network. The computation for watermark embedding is performed using either description. Once chosen, the corresponding values to be modulated for the other description are assigned with the same values as the just watermarked description. In the detection process, the embedded watermark could be extracted no matter either one or both descriptions are received. That is to say, the watermark is still detectable from MDW even with 50% packet loss. Furthermore, in the case of 50% packet loss, the resulting watermark from MDW is still robust to a variety of image processing attacks, including DCT based compression (JPEG), DWT based compression (JPEG-2000), Gaussian filtering, sharpening and median filtering. The experimental results confirmed the competitive performance and the effectiveness of the proposed scheme.
Robust multirate lattice quantization index modulation watermarking resilient to multiple description transmission channel
(2007-03-01)
Day, Miin-Luen
;
Lee, Suh-Yin
;
Jou, I-Chang
;
資訊工程學系
;
Department of Computer Science
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.