Sung-Wen Wang

An adaptive edge detection based colorization algorithm and its applications

Colorization is a computer-assisted process for adding colors to grayscale images or movies. It can be viewed as a process for assigning a three-dimensional color vector (YUV or RGB) to each pixel of a grayscale image. In previous works, with some color hints the resultant chrominance value varies linearly with that of the luminance. However, it is easy to find that existing methods may introduce obvious color bleeding, especially, around region boundaries. It then needs extra human-assistance to fix these artifacts, which limits its practicability. Facing such a challenging issue, we introduce a general and fast colorization methodology with the aid of an adaptive edge detection scheme. By extracting reliable edge information, the proposed approach may prevent the colorization process from bleeding over object boundaries. Next, integration of the proposed fast colorization scheme to a scribble-based colorization system, a modified color transferring system and a novel chrominance coding approach are investigated. In our experiments, each system exhibits obvious improvement as compared to those corresponding previous works.

Attained Adult Height in Juvenile Rheumatoid Arthritis with or without Corticosteroid Treatment

Abstract: Growth impairment has been described in patients with juvenile rheumatoid arthritis (JRA). Both the direct action of underlying disease and prolonged corticosteroid usage for disease management may contribute to growth impairment. The purpose of this retrospective study was to evaluate the effect of systemic corticosteroid treatment on attained adult height in patients with JRA. We reviewed patients who first visited our hospital from 1973 to 1995 with a diagnosis of JRA. Adult height (AH) and the reported parental heights of these patients were recorded. Target height (TH) is estimated according to midparental height. Patients who never had or had only transient (less than 1 week) systemic corticosteroid therapy were classified as group 1. Group 2 included patients who had corticosteroid therapy for more than 1 week but never continuously for more than 12 months, and group 3 included patients on long-term steroid treatment (continuously for more than 1 year). Height data were analysed using adult height and the difference between adult height and target height (AH minus TH). Thirty-three patients fulfilling the diagnostic criteria for JRA were reviewed. Fourteen belonged to group 1, 13 to group 2 and six to group 3. The difference between adult height and target height in group 1 was 2.96 ± 4.54 cm, in group 2 0.71 ± 6.08 cm (group 1 vs. group 2, P = 0.28), and in group 3 −11.65 ± 10.71 cm (group 1 vs. group 3, P<0.05). In 15 patients who never received corticosteroid therapy continuously for more than 1 year, AH–TH was statistically correlated neither with the cumulative corticosteroid exposure dose nor with cumulative corticosteroid exposure period by linear regression (P= 0.408, P= 0.278, respectively). We concluded that continuous systemic corticosteroid usage for less than 1 year does not affect attained adult height in JRA patients; however, prolonged corticosteroid treatment for more than 1 year can lead to irreversible growth impairment.

A Multi-core Architecture Based Parallel Framework for H.264/AVC Deblocking Filters

Deblocking filter is one of the most time consuming modules in the H.264/AVC decoder as indicated in many studies. Therefore, accelerating deblocking filter is critical for improving the overall decoding performance. This paper proposes a novel parallel algorithm for H.264/AVC deblocking filter to speed the H.264/AVC decoder up. We exploit pixel-level data parallelism among filtering steps, and observe that results of each filtering step only affect a limited region of pixels. We call this “the limited propagation effect”. Based on this observation, the proposed algorithm could partition a frame into multiple independent rectangles with arbitrary granularity. The proposed parallel deblocking filter algorithm requires very little synchronization overhead, and provides good scalability. Experimental results show that applying the proposed parallelization method to a SIMD optimized sequential deblocking filter achieves up to 95.31% and 224.07% speedup on a two-core and four-core processor, respectively. We have also observed a significant speedup for H.264/AVC decoding, 21% and 34% on a two-core and four-core processor, respectively.

DSP-based multi-format video decoding engine for media adapter applications

There are four major components in a generic digital home framework: media center, set-top box, media adapter and portable viewer. In this paper, we present a DSP-based multi-format video decoding engine for realizing media adapter application. By choosing a powerful DSP core and designing an efficient and configurable software engine, the proposed solution is believed to possess low-cost and high-flexibility advantages at the same time. In our current implementation, the video decoding engine can decode most of the major video formats in the market, such as MPEG-1/2/4, H.264/AVC baseline/main, VC-I and its precedents, and some other MPEG-4-like formats. Simulation results demonstrate the efficiency of the decoding engine: videos up to SD resolution can be decoded seamlessly. The engine has been successfully integrated into an available media adapter module and the corresponding product. Our future work is to enhance the engine performance capable of handling HD contents.

The optimization of H.264/AVC baseline decoder on low-cost TriMedia DSP processor

The emerging video coding standard, H.264/AVC, exhibits the unprecedented coding performance. Comparing to traditional coders, e.g., MPEG-2 and MEPG-4 ASP, about half bitrate saving is shown in the official verification test. Such outstanding performance makes it become the video compression candidate for the upcoming HD-DVD. As a side effect, it was also blamed that H.264/AVC is much more logically complex and requires more computation power than any of the existing standards. A low-cost and efficient implementation of the international standard hence plays an important role of its success. In this paper, we realize an H.264/AVC baseline decoder by a low-cost DSP processor, i.e., Philips’ TriMedia TM-1300, and illustrate that less computation demand for H.264/AVC decoding becomes feasible by using effective software core. To this end, we first consider different approaches and take advantage of SIMD instruction set to optimize critical time-consuming coding modules, such as the fractional motion compensation, spatial prediction and inverse transform. Next, we also present some other optimization approaches for entropy decoding and in-loop deblocking filtering, even though they cannot get benefits from utilizing SIMD. In our experiments, by exploiting appropriate instruction level parallelism and efficient algorithms, the decoding speed can be improved by a factor of 8~10; a CIF video sequence can be decoded at up to 19.74~28.97 fps on a 166-MHz TriMedia TM-1300 processor compared to 2.40~2.98 fps by the standard reference software.

A Parallel Algorithm for H.264/AVC Deblocking Filter Based on Limited Error Propagation Effect

In this paper, we propose a parallel algorithm for H.264/AVC deblocking filter which is scalable to the number of processors. Unlike the conventional approach, which is limited by the independent data units, the designed algorithm allows issuing dependent data units concurrently to decrease the penalty from synchronization of data units. For the general-purpose dual-core processors, experimental results show that our method speeds up 1.72 and 1.39 times as compared with optimized sequential method and the well-known wavefront parallelizing method, respectively.

Memory Efficient Hierarchical Lookup Tables for Mass Arbitrary-Side Growing Huffman Trees Decoding

This paper addresses the optimization problem of minimizing the number of memory access subject to a rate constraint for any Huffman decoding of various standard codecs. We propose a Lagrangian multiplier based penalty-resource metric to be the targeting cost function. To the best of our knowledge, there is few related discussion, in the literature, on providing a criterion to judge the approaches of entropy decoding under resource constraint. The existing approaches which dealt with the decoding of the single-side growing Huffman tree may not be memory-efficient for arbitrary-side growing Huffman trees adopted in current codecs. By grouping the common prefix part of a Huffman tree, in stead of the commonly used single-side growing Huffman tree, we provide a memory efficient hierarchical lookup table to speed up the Huffman decoding. Simulation results show that the proposed hierarchical table outperforms previous methods. A Viterbi-like algorithm is also proposed to efficiently find the optimal hierarchical table. More importantly, the Viterbi-like algorithm obtains the same results as that of the brute-force search algorithm.

Boundary-energy sensitive visual de-blocking for H.264/AVC coder

Finding out the better parameter set (OffsetA and OffsetB) for conducting the de-blocking process of H.264/AVC, is capable of improving visual quality, said eliminating the resultant blocking artifact. Identifying which edges belong to blocking regions relies on the perceptual judging process of human beings. In fact, this subjective assessment may not exactly match existing objective assessing measurements, and the meaning of high PSNR does not always stand for less blocking artifacts. In this paper, we first introduce a new criterion for measuring the block boundary distortion by comparing the source video and the reconstructed video prior to the deblocking process. By jointly optimizing the objective picture quality and the blocky energy, the deblocking parameters decision process can find out a good balance between signal matching and blocky elimination, and therefore, maximize the effect of the built-in deblocking process. In our experiments, the proposed method can efficiently pick a better deblocking parameter set from all 169 possibilities for each coded frame and result in a better visual quality.

An Efficient Memory Construction Scheme for an Arbitrary Side Growing Huffman Table

By grouping the common prefix of a Huffman tree, in stead of the commonly used single-side rowing Huffman tree (SGH-tree), we construct a memory efficient Huffman table on the basis of an arbitrary-side growing Huffman tree (AGH-tree) to speed up the Huffman decoding. Simulation results show that, in Huffman decoding, an AGH-tree based Huffman table is 2.35 times faster that of the Hashemians method (an SGH-tree based one) and needs only one-fifth the corresponding memory size. In summary, a novel Huffman table construction scheme is proposed in this paper which provides better performance than existing construction schemes in both decoding speed and memory usage

Motion Transitive Based Fast Multi-Frame Motion Estimation Algorithm For MPEG-4 AVC/H.264

The complexity of conducting motion estimation in multiple reference frames is much higher than that of a single reference frame. Generally, we know that temporally neighboring frames have strong correlations with each other. In this paper, the interframe motion correlations are used to estimate motion vectors in multiple reference frames mode efficiently. Our method reuses the pre-coded motion vectors without requiring additional information. The proposed method takes only 23.06% execution time as compared with the approach applying the full search in all the reference frames. Meanwhile, the coding efficiency and visual quality of the proposed method are still comparable to those of the full search.