Recent work on depth map compression has revealed the importance of incorporating a description of discontinuity boundary geometry into the compression scheme. We propose a novel compression strategy for depth maps that incorporates geometry information while achieving the goals of scalability and embedded representation. Our scheme involves two separate image pyramid structures, one for breakpoints and the other for sub-band samples produced by a breakpoint-adaptive transform. Breakpoints capture geometric attributes, and are amenable to scalable coding. We develop a rate-distortion optimization framework for determining the presence and precision of breakpoints in the pyramid representation. We employ a variation of the EBCOT scheme to produce embedded bit-streams for both the breakpoint and sub-band data. Compared to JPEG 2000, our proposed scheme enables the same the scalability features while achieving substantially improved rate-distortion performance at the higher bit-rate range and comparable performance at the lower rates.

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Recent work highlights the importance of incorporating geometry information into the compression of depth maps. For many applications, features such as resolution scalability and embedded coding are also highly desirable. JPEG 2000 offers these scalability features but suffers from poor compression performance in the vicinity of strong discontinuities. We propose a novel compression strategy for depth maps that incorporates geometry information while retaining the highly scalable coding properties of JPEG 2000. Our scheme involves two separate image pyramid structures, one for arc breakpoints and other for sub-band samples produced by a breakpoint-adaptive transform. Breakpoints capture geometric attributes and are also amenable to scalable coding. We develop an R-D optimization framework for the breakpoint data. We also use a variation of the EBCOT scheme to produce embedded bit-streams for both the breakpoint and sub-band data, allowing them to be independently and incrementally sequenced based on R-D considerations

Existing video coders anchor motion fields at frames that are to be predicted. In this paper, we demonstrate how changing the anchoring of motion fields to reference frames has some important advantages over conventional anchoring. We work with piecewise-smooth motion fields, and use breakpoints to signal discontinuities at moving object boundaries. We show how discontinuity information can be used to resolve double mappings arising when motion is warped from reference to target frames. We present an analytical model that allows to determine weights for texture, motion, and breakpoints to guide the rate-allocation for scalable encoding. Compared with the conventional way of anchoring motion fields, the proposed scheme requires fewer bits for the coding of motion; furthermore, the reconstructed video frames contain fewer ghosting artefacts. The experimental results show the superior performance compared with the traditional anchoring, and demonstrate the high scalability attributes of the proposed method.

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Aim:To study the efficacy of pterygopalatine fossa (PPF) block with 2% xylocaine and 1:80,000 adrenaline on bleeding during endoscopic sinus surgery (ESS). Materials and methods:Single-blinded prospective comparative study was conducted on patients who underwent bilateral functional endoscopic sinus surgery after obtaining written informed consent. The effect of PPF infiltration was tested by injecting 2% xylocaine with adrenaline on test side, and saline on the control side. The test and the control side were determined by block randomization technique. The surgeon was blinded as to which side the test and control drug was to be given. The surgical field was assessed and graded every 15 minutes on both sides according to Boezaart and Vander Merwe scoring system, and the results were compared and analyzed using Mann-Whitney U test.Results: Thirty-two patients were included in the study, of whom 59.4% were males. Ethmoidal polyposis was the most common diagnosis (50%). The median computed tomography grade and the endoscopic grade of disease in test side and control side were comparable. The mean blood loss grade on test side was 9.0 ± 3.5 and in control side was 10.9 ± 3.5, and the difference was statistically significant. Significant positive correlation was observed between preoperative endoscopic grade of the disease and blood loss during surgery. A statistically significant correlation was also observed between the vital parameters and blood loss. Conclusion:Pterygopalatine fossa infiltration with 2% xylocaine and 1:80,000 adrenaline reduces bleeding during ESS. Clinical significance:This study is pivotal in devising an additional method for providing a clear bloodless operative field which to date is one of the major challenges faced by the otorhinolaryngologist.