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  • Thesis

  • Authors: Liu, Yi-Wen (2005)

  • "Digital Watermarking" refers to the hiding of binary information in signals such as audio record¬ings, images, or video clips. While the dominating technologies utilize small masked changes in the amplitude to hide information in audio, in an alternate approach, this thesis presents a scheme based on frequency modulation. From an input signal, salient sinusoids are identified in its short-time spectra and parametrized by slowly time-varying frequency envelopes. To bear a watermark, the frequency envelopes are modified by quantization index modulation (QIM), a technique that rounds values to signaling grids. Frequency shifts due to QIM are intended to be not objectionable, if noticeable. To this end, the sensitivity of human ears to pitch changes is carefully considered in the desig...

  • Thesis

  • Authors: Yang, Danny Bon-Ray (2005)

  • Advances in CMOS fabrication have enabled low-cost camera nodes with limited communication and computation capabilities. By combining these capabilities within a small form-factor device, multi-camera networks can readily be built. However, cameras are high-data-rate devices, and many computer vision algorithms are computationally expensive, while these camera nodes are communication and computation constrained. In this dissertation, we present lightweight techniques for distributed scene analysis in such resource-constrained camera networks. We show that in this setting we can compute global aggregates from distributed local measurements. In particular we use the camera network to count and localize targets. Counting and localizing are useful in many applications in surveillance, ...