2697231
Lossless compression of color mosaic images
We present a low complexity algorithm for lossless compression of color mosaic images generated by a Bayer CCD color filter array. This algorithm is based on an interesting use of the integer wavelet transform followed by a fast adaptive context-based Golomb-Rice coding. The lossless compression performance of the proposed algorithm is apparently the best reported in the literature so far for color mosaic images.
14301513
On multirate optimality of JPEG2000 code stream
Arguably, the most important and defining feature of the JPEG2000 image compression standard is its R-D optimized code stream of multiple progressive layers. This code stream is an interleaving of many scalable code streams of different sample blocks. In this paper, we reexamine the R-D optimality of JPEG2000 scalable code streams under an expected multirate distortion measure (EMRD), which is defined to be the average distortion weighted by a probability distribution of operational rates in a given range, rather than for one or few fixed rates. We prove that the JPEG2000 code stream constructed by embedded block coding of optimal truncation is almost optimal in the EMRD sense for uniform rate distribution function, even if the individual scalable code streams have nonconvex operational R-D curves. We also develop algorithms to optimize the JPEG2000 code stream for exponential and Laplacian rate distribution functions while maintaining compatibility with the JPEG2000 standard. Both of our analytical and experimental results lend strong support to JPEG2000 as a near-optimal scalable image codec in a fairly general setting.
2090063
Primary-consistent soft-decision color demosaic for digital cameras
Bayer color mosaic sampling scheme is widely used in digital cameras. Given the resolution of CCD sensor arrays, the image quality of digital cameras using Bayer sampling mosaic largely depends on the performance of the color demosaic process. A common and serious weakness shared by all existing color demosaic algorithms is an inconsistency of sample interpolations in different primary color components, which is the culprit for the most objectionable color artifacts. To cure the problem we propose a primary-consistent color demosaic algorithm. The performance of this algorithm is further enhanced by a soft-decision sample interpolation scheme. Experiments demonstrate that the proposed framework of primary-consistent soft-decision color demosaic can significantly improve the image quality of digital cameras.
41726157
Lossless compression of color mosaic images
We present a low complexity algorithm for lossless compression of color mosaic images generated by a Bayer CCD color filter array. This algorithm is based on an interesting use of the integer wavelet transform followed by a fast adaptive context-based Golomb-Rice coding. The lossless compression performance of the proposed algorithm is apparently the best reported in the literature so far for color mosaic images.
11164895
Primary-consistent soft-decision color demosaicking for digital cameras (patent pending)
Color mosaic sampling schemes are widely used in digital cameras. Given the resolution of CCD sensor arrays, the image quality of digital cameras using mosaic sampling largely depends on the performance of the color demosaicking process. A common problem with existing color demosaicking algorithms is an inconsistency of sample interpolations in different primary color channels, which is the cause of the most objectionable color artifacts. To cure the problem, we propose a new primary-consistent soft-decision framework (PCSD) of color demosaicking. In the PCSD framework, we make multiple estimates of a missing color sample under different hypotheses on edge or texture directions. The estimates are made via a primary consistent interpolation, meaning that all three primary components of a color are interpolated in the same direction. The final estimate of a color sample is obtained by testing different interpolation hypotheses in the reconstructed full-resolution color image and selecting the best via an optimal statistical decision or inference process. A concrete color demosaicking method of the PCSD framework is presented. This new method eliminates certain types of color artifacts of existing color demosaicking methods. Extensive experimental results demonstrate that the PCSD approach can significantly improve the image quality of digital cameras in both subjective and objective measures. In some instances, our gain over the competing methods can be as much as 7dB.
15693719
Context-based Arithmetic Coding Reexamined for DCT Video Compression
This paper presents a new context modeling technique for arithmetic coding of DCT coefficients in video compression. A key feature of the new technique is the inclusion of all previously coded coefficient magnitudes in a DCT block in context modeling. This enables adaptive arithmetic coding to exploit the redundancy of the high-order Markov process in the DCT domain with a few conditioning states. In addition, a context weighting technique is used to further improve the coding efficiency. The complexity of the new arithmetic coding scheme is slightly lower than that of context-based adaptive binary arithmetic coding (CABAC) of H.264. Moreover, the scheme is made compatible to the AVS baseline profile. It achieves on average 13% improvement in compression ratio over context-based two dimension variable length coding (C2DVLC) designed for the DCT domain, and a similar coding efficiency as the CABAC technique in H.264.
15419167
VISSIM-Based Simulation of the Left-Turn Waiting Zone at Signalized Intersection
In order to simulate traffic movements of the left-turn waiting zone (LWZ) at signalized intersection to quantitatively evaluate the operational performances after the implementation of the LWZ, following the introduction of the concept of the LWZ, its application environment were recommended, the modeling method of the LWZ was established, and the simulation evaluation indexes were introduced. Based on the data investigation, the simulation model was applied to a typical signalized intersection with the LWZ by micro-simulation software VISSIM to evaluate the efficiency of the traffic operation. It is found that compared with the layout of lacking LWZ, the left-turn traffic capacity at signalized intersection increased by 5.9, 4.3 and 6.7 percent in three different periods of traffic levels respectively after using the LWZ. The result shows that optimizing the layout of the intersection by using the LWZ can improve the operation efficiency without affecting the traffic safety.
18850818
A Fast Algorithm for the Chirp Rate Estimation
A fast algorithm for the chirp rate estimation is presented in this paper. By the computation of the cubic phase transform (CPT) of the signal, it is shown that the CPT is concentrated along the frequency rate law of the signal, and the peak of the CPT yields the estimate of the chirp rate. The proposed algorithm is fast in that it requires only one-dimensional (1-D) maximizations. The asymptotic statistical result is derived for the chirp rate estimation, and the computer simulation demonstrates that, when the input signal-to-noise ratio (SNR) is higher than -2 dB, the simulation results and the theoretical analyses are well matched, and the mean-square error (MSE) approaches optimality as the SNR tends to infinity.
36024332
L-∞ constrained micronoise filtering for high-fidelity image compression
Imaging apparatus inevitably impose undesirable noises onto acquired images during real imaging process. Usually these noises are too faint to cause unpleasing visual effects, however, they degrade image fidelity and significantly lower the compression ratio of lossless coding. More baffling, in this case, there leaves little room for traditional noise filtering methods to work. This paper will introduce some of our efforts trying to weaken the effect of such Micro Noise during near-lossless compression. Experimental results on ISO test images and micro Gaussian noises demonstrate that with potentiality of filtering micro noise, an improved near-lossless coder can not only achieve obviously higher compression ratio but also provide better image fidelity (measured by mean squared error) than lossless coding.
5525123
FIX: feature-based indexing technique for XML documents
Indexing large XML databases is crucial for efficient evaluation of XML twig queries. In this paper, we propose a feature-based indexing technique, called FIX, based on spectral graph theory. The basic idea is that for each twig pattern in a collection of XML documents, we calculate a vector of features based on its structural properties. These features are used as keys for the patterns and stored in a B+tree. Given an XPath query, its feature vector is first calculated and looked up in the index. Then a further refinement phase is performed to fetch the final results. We experimentally study the indexing technique over both synthetic and real data sets. Our experiments show that FIX provides great pruning power and could gain an order of magnitude performance improvement for many XPath queries over existing evaluation techniques.
17598350
Certified e-mail delivery with DSA receipts
In this paper we present two variant protocols DSA-CEMD1 and DSA-CEMD2 for certified e-mail delivery with DSA receipts. The protocols are based on a cryptographic primitive called Verifiable and Recoverable Encryption of a Signature (VRES) and are capable of achieving non-repudiation and strong fairness security properties. The novel design of the VRES primitive allows efficiency improvements in comparison with the related certified e-mail delivery protocols based on similar primitives. The protocols employ the services of an off-line and invisible trusted third party (TTP) only in case of dispute. In DSA-CEMD1 the content of the e-mail message is not revealed to the TTP during possible recovery and this is achieved at the cost of some additional cryptographic operations. In DSA-CEMD2 the confidentiality of the message is not protected from the TTP, but the protocol is slightly more efficient.