• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.1
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• pp.37-43
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• 2023

Compressed still image or video bitstreams require protection from channel errors in a wireless channel. Embedded Zerotree Coding(EZW), SPIHT could have provided unprecedented high performance in image compression with low complexity. If bit error is generated by dint of wireless channel transmission problem, the loss of synchronization on between encoder and decoder causes serious performance degradation. But wavelet zerotree coding algorithms are producing variable-length codewords, extremely sensitive to bit errors. The idea is to partition the lifting coefficients. A many partition of lifting transform coefficients distributes channel error from wireless channel to each partition. Therefore synchronization problem that caused quality deterioration in still image and video stream was improved.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.75-80
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• 2023

We show the design of fast invertible block transforms that can replace the DCT in future wireless and portable computing application. This is called binDCT. In binDCT, both the forward and the inverse transforms can be implemented using only binary shift and addition operation. And the binDCT inherits all desirable DCT characteristics such as high coding gain, no DC leakage, symmetric basis functions, and recursive construction. The binDCT also inherits all lifting properties such as fast implementations, invertible integer-to-integer mapping, in-place computation. Thus, this method has advantage of fast implementation for complex DCT calculations. In this paper, we present computation costs and performance analysis between DCT and binDCT using Shapiro's EZW.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.313-316
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• 2000

Wavelet transform has specific properties for image coding. The property used at this Paper is clustering of significant coefficients across subband. These coefficients are classified in significant coefficient and insignificant coefficient on a threshold value, and symbolized EZW decreases symbol-position information using zero-trees, but threshold value fall for raising resolution, then coding cost of significant coefficients is expensive. To avoid this fact, this paper uses quad-tree representing coefficient-position information. a magnitude of significant coefficient is represented on matrix used at EZW. the proposed algorithm is hoped for raising a coding cost.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.3
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• pp.23-33
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• 2011

In this paper, the wavelet image coder, that can encode the bit-level information of wavelet coefficients, is proposed. The proposed coder is used the modified EZW algorithm and significant coefficient array that has bit level information of the wavelet coefficients to reduce the memory requirement in coding process. The significant coefficient array is two dimensional data structure that has bit level information of the wavelet coefficients. The proposed algorithm performs the coding of the significance coefficients and coding of bit level information of wavelet coefficients at a time by using the significant coefficient array. Experimental results show a better or similar performance of the proposed method when compared with conventional embedded wavelet coding algorithm. Especially, the proposed algorithm performs stably without image distortion at various bit rates with minimum memory usage by using the significant coefficient array.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.97-100
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• 2002

In this paper, we propose a watermarking technique that embeds a digital watermark into digital images for the proof of owner or copyright protection. Proposed algorithm is based on discrete wavelet transform. Zerotree structure defined by Shapiro's embedded zerotree wavelet(EZW) algorithm is used. In the proposed algorithm, a digital watermark is embedded on only significant wavelet coefficients chosen by QSWT for the robustness of the algorithm. In other words, only the values of significant wavelet coefficients are modified in accordance with the given watermark pattern. We use the relationship among neighboring coefficients when modifying chosen coefficients to keep good image quality. Visual recognizable patterns such as binary images are used as a watermark. The experimental results show that the proposed algorithm has robustness under a variety of attacks such as JPEG compression, sharpening and blurring and also show that it has a better performance in PSNR comparing with other algorithms.

• Journal of Korea Multimedia Society
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• v.8 no.7
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• pp.916-923
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• 2005

In recent times, mobile phones that play an important role in voice communication have became increasingly exciting due to the ability to transmit multimedia contents. However, user's communication cost and service usage fees for digital context exchange are still prohibitive. In this paper, we consider the task of transmitting a facial image in the context of mobile avatar generation. We present image compression as a useful technique to reduce service usage costs of data exchange in mobile communications. In view of this we propose an image compression algorithm that performs better than existing techniques. The suggested algorithm in this paper uses the location of significant coefficient on the wavelet image by detecting facial region as well as the spatial correlation between decomposed bands by wavelet transformation. The algorithm perform well and archives an efficient compression ratio. The proposed method recognizes location information of significant coefficient in advance, thus it is more suitable than existing general compression methods for mobile avatar generation systems.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.51-53
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• 2021

본 논문에서는 초고해상도를 갖는 복소 홀로그램을 압축하기 위한 전용 코덱에서 SPIHT(set partitioning in hierarchical trees)를 사용할 경우에 발생할 수 있는 문제점을 해결하기 위한 방법을 제안한다. 복소 홀로그램을 위한 코덱의 개발은 크게 전용 압축 방법을 만드는 방법과 HEVC 및 JPEG2000과 같은 앵커 코덱을 이용하고 전후처리 기법을 추가하는 방법으로 구분될 수 있다. 전용 압축 방법을 만드는 경우에, 복소 홀로그램의 공간적인 특성이 매우 독특하기 때문에 이 신호를 해석하기 위한 별도의 변환 도구가 필요하다. 많은 연구들에서 웨이블릿 변환이 여기에 좋은 대안이 될 수 있다는 것을 보여왔다. 웨이블릿 변환을 사용할 경우에 압축을 위해서 EZW, EBCOT 그리고 SPIHT를 사용할 수 있다. EBCOT의 경우에 복잡도가 너무 높고, EZW으 경우에는 성능이 좋지 않다. 따라서 SPIHT는 좋은 대안이 될 수 있을 것이다. 그러나 EZW와 SPIHT 같은 부대역 단위의 제로트리 기반의 알고리즘들은 고해상도의 영상에 대해서 고압축으로 코딩할 경우에 비트스트림 제어 시 온전한 부대역의 정보가 제대로 전송되지 못하는 문제점을 갖는다. 본 논문에서는 웨이블릿 부대역의 분할 방법을 이용하여 이와 같은 문제를 해결하기 위한 시도를 하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.211-214
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• 2002

Recently efficient image coding using zerotree have been proposed. In these methods, the locations of nonzero wavelet coefficient are enrolled with a tree structure, called zerotree, which ran exploit the self-similarity of the wavelet pyramid decomposition across different scales. These are very especially in low bit rate image coding. In this paper, two zerotree image rolling algorithm, EZW and SPHIT are briefly introduced, and a new zerotree searching scheme is proposed to emphasize the significance of a wavelet coefficient by its orientation as well as its scale.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.161-164
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• 2000

Recently efficient image coding using zerotree have been proposed. In these methods, the locations of nonzero wavelet coefficient are encoded with a tree structure, called zerotree, which can exploit the self-similarity of the wavelet pyramid decomposition across different scales. These are very especially in low bit rate image coding. In this paper, two zerotree image coding algorithm, EZW and SPHIT are briefly introduced, and a new zerotree searching scheme is proposed to emphasize the significance of a wavelet coefficient by its orientation as well as its scale.

• Journal of Biomedical Engineering Research
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• v.18 no.3
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• pp.223-231
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• 1997

In this paper, an interframe coding method for volumetric medical images is proposed. By treating interslice variations as the motion of bones or tissues, we use the motion compensation (MC) technique to predict the current frame from the previous frame. Instead of a block matching algorithm (BMA), which is the most common motion estimation (ME) algorithm in video coding, image warping with biolinear transformation has been suggested to predict complex interslice object variation in medical images. When an object disappears between slices, however, warping prediction has poor performance. In order to overcome this drawback, an overlapped block motion compensation (OBMC) technique is combined with carping prediction. Motion compensated residual images are then encoded by using an embedded zerotree wavelet (EZW) coder with small modification for consistent quality of reconstructed images. The experimental results show that the interframe coding suing warping prediction provides better performance compared with interframe coding, and the OBMC scheme gives some additional improvement over the warping-only MC method.