A rate-constrained adaptive quantization scheme for wavelet pyramid image coding

Conference theme: Connecting the WorldIt is well known that orthogonal wavelet transform with filters of nonlinear phase gives poor visual results in low bit rate image coding. Biorthogonal wavelet is a good substitute, which is, however essentially nonorthogonal. A greedy steepest descend algorithm is proposed to design an adaptive quantization scheme based on the actual statistics of the input image. Since the L2 norm of the quantization error is not preserved through the nonorthogonal transform, a quantization error estimation formula considering the characteristic value of the reconstruction filters is derived to incorporate the adaptive quantization scheme. Computer simulation results demonstrate significant SNR gains over standard coding technique, and comparable visual improvements.published_or_final_versio

Finite state lattice vector quantization for wavelet-based image coding

IEEE International Symposium on Circuits and Systems, Hong Kong, China, 9-12 June 1997It is well known that there exists strong energy correlation between various subbands of a real-world image. A new powerful technique of Finite State Vector Quantization (FSVQ) has been introduced to fully exploit the self-similarity of the image in wavelet domain across different scales. Lattices in RN have considerable structure, and hence, Lattice VQ offers the promise of design simplicity and reduced complexity encoding. The combination of FSVQ and LVQ gives rise to the so-called FSLVQ, which is proved to be successful in exploiting the energy correlation across scales and simple enough in implementation.published_or_final_versio

A novel entropy-constrained adaptive quantization scheme for wavelet pyramid image coding

The orthogonal wavelet transform with filters of nonlinear phase gives poor visual results in low bit rate image coding. The biorthogonal wavelet is a good substitute, which is, however essentially nonorthogonal. A greedy steepest descent algorithm is proposed to design an adaptive quantization scheme based on the actual statistics of the input image. Since the L2 norm of the quantization error is not preserved through the nonorthogonal transform, a quantization error estimation formula considering the characteristic value of the reconstruction filters is derived to incorporate the adaptive quantization scheme. Computer simulation results demonstrate significant SNR gains over standard coding techniques, and comparable visual improvements.published_or_final_versio

Model-based multirate Kalman filtering approach for optimal two-dimensional signal reconstruction from noisy subband systems

Conventional synthesis filters in subband systems lose their optimality when additive noise (due, for example, to signal quantization) disturbs the subband components. The multichannel representation of subband signals is combined with the statistical model of input signal to derive the multirate state-space model for the filter bank system with additive subband noises. Thus the signal reconstruction problem in subband systems can be formulated as the process of optimal state estimation in the equivalent multirate state-space model. Incorporated with the vector dynamical model, a 2-D multirate state-space model suitable for 2-D Kalman filtering is developed. The performance of the proposed 2-D multirate Kalman filter can be further improved through adaptive segmentation of the object plane. The object plane is partitioned into disjoint regions based on their spatial activity, and different vector dynamical models are used to characterize the nonstationary object-plane distributions. Finally, computer simulations with the proposed 2-D multirate Kalman filter give favorable results. ©1998 Society of Photo-Optical instrumentation Engineers.published_or_final_versio

北宋内臣蓝元震事迹考

Author name used in this publication: 何冠环Title in Traditional Chinese: 北宋內臣藍元震事跡考2008-2009 > Academic research: refereed > Chapter in an edited book (author)Version of RecordPublishe

宋太祖的从龙功臣李处耘 (920—966)

Author name used in this publication: 何冠环Title in Traditional Chinese: 宋太祖的從龍功臣李處耘(920—966)Journal title in Traditional Chinese: 曁南學報. 哲學社會科學版Version of RecordPublishe

Value of gastrografin in adhesive small bowel obstruction after unsuccessful conservative treatment: A prospective evaluation

Aim: Gastrografin is a hyperosmolar water-soluble contrast medium. Besides its predictive value for the need for operative treatment, a potential therapeutic role of this agent in adhesive small bowel obstruction has been suggested. This study aimed at evaluating the effectiveness of gastrografin in adhesive small bowel obstruction when conservative treatment failed. Methods: Patients with adhesive small bowel obstruction were given trial conservative treatment unless there was fear of bowel strangulation. Those responded in the initial 48 h had conservative treatment continued. Patients who showed no improvement in the initial 48 h were given 100 mL of gastrografin through nasogastric tube followed by serial abdominal radiographs. Patients with the contrast appeared in large bowel within 24 h were regarded as having partial obstruction and conservative treatment was continued. Patients in which the contrast failed to reach large bowel within 24 h were considered to have complete obstruction and laparotomy was performed. Results: Two hundred and twelve patients with 245 episodes of adhesive obstruction were included. Fifteen patients were operated on soon after admission due to fear of strangulation. One hundred and eighty-six episodes of obstruction showed improvement in the initial 48 h and conservative treatment was continued. Two patients had subsequent operations because of persistent obstruction. Forty-four episodes of obstruction showed no improvement within 48 h and gastrografin was administered. Seven patients underwent complete obstruction surgery. Partial obstruction was demonstrated in 37 other cases, obstruction resolved subsequently in all of them except one patient who required laparotomy because of persistent obstruction. The overall operative rate in this study was 10%. There was no complication that could be attributed to the use of gastrografin. Conclusion: The use of gastrografin in adhesive small bowel obstruction after unsuccessful conservative treatment is safe and reduces the need for surgical intervention. © 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio

Total mesorectal excision for rectal cancer decreases local recurrence

Conference Theme: Challenges to specialists in the 21st centurypublished_or_final_versio

Socioeconomic Gradient in Childhood Obesity and Hypertension: A Multilevel Population-Based Study in a Chinese Community

published_or_final_versio

Modeling and analysis of piezoelectric transformer using multi-mesh loop matrix circuit under square-wave excitation conditions

K. W. Kwok, X. X. Wang and H. Chan, Department of Applied PhysicsAuthor name used in this publication: K. W. E. ChengAuthor name used in this publication: S. L. HoAuthor name used in this publication: K. W. KwokAuthor name used in this publication: H. ChanAuthor name used in this publication: X. D. XueRefereed conference paper2005-2006 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe