• Journal of Information Processing Systems
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• v.13 no.1
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• pp.40-56
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• 2017

Since the progress of digital medical imaging techniques, it has been needed to compress the variety of medical images. In medical imaging, reversible compression of image's region of interest (ROI) which is diagnostically relevant is considered essential. Then, improving the global compression rate of the image can also be obtained by separately coding the ROI part and the remaining image (called background). For this purpose, the present work proposes an efficient reversible discrete cosine transform (RDCT) based embedded image coder designed for lossless ROI coding in very high compression ratio. Motivated by the wavelet structure of DCT, the proposed rearranged structure is well coupled with a lossless embedded zerotree wavelet coder (LEZW), while the background is highly compressed using the set partitioning in hierarchical trees (SPIHT) technique. Results coding shows that the performance of the proposed new coder is much superior to that of various state-of-art still image compression methods.

• Journal of Internet Computing and Services
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• v.10 no.6
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• pp.219-228
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• 2009

The increased popularity of multimedia applications places a great demand on efficient data storage and transmission techniques. Some methods have been proposed to combine compression and encryption together to reduce the overall processing time, but they are either insecure or intensive computationally. specially, they are unsuitable to wireless communication of mobile device. We propose a novel solution called partial encryption, We introduce quadtree and zerotree wavelet image compression in this paper, it reduces computation for date transmission in mobile device, and does not reduce the compression rate. In conclusion, the proposed partial encryption schemes are fast, secure, and do not reduce the compression performance of underlying compression algorithm.

• 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.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06b
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• pp.189-194
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• 1998

We introduce a new zerotree scheme that effectively exploits the inter-scale self-similarities found in the octave decomposition by a wavelet transform. A zerotree is useful to efficiently code wavelet coefficients and its efficiency was proved by Shapiro's EZW. In the coding scheme, wavelet coefficients are symbolized and entropy-coded for more compression. The entropy per symbol is determined from the produced symbols and the final coded size is calculated by multiplying the entropy and the total number of symbols. In this paper, were analyze produced symbols from the EZW and discuss the entropy per symbol. Since the entropy depends on the produced symbols, we modify the procedure of symbolic streaming out for the purpose. First, we extend the relation between a parent and children used in the EZW to raise a probability that a significant parent has significant children. The proposed relation is flexibly extended according to the fact that a significant coefficient is highly addressed to have significant coefficients in its neighborhood. The extension way is reasonable because an image is decomposed by convolutions with a wavelet filter and thus neighboring coefficients are not independent with each other.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.653-656
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• 2001

웨이블렛 변환을 이용한 영상 압축의 방법에 있어서 최근 우수한 압축 성능을 보이는 비트 평면 부호화 방법이 많이 발전되어 왔다. 본 논문에서는 블록 기반 제로트리와 사진나무구조를 이용하여 비트 평면을 효율적으로 부호화함으로써 우수한 압축 성능을 보이는 부호기를 제안한다. 블록 기반 제로트리는 주파수 대역에 걸쳐 상관성을 보이며 존재하는 중요하지 않은 계수를 효과적으로 부호화하며, 사진나무구조는 블록 안에 있는 중요한 계수를 찾아내어 부호화한다. 제안하는 부호기의 성능은 기존의 우수한 비트 평면 부호기에 필적하는 성능을 보이며, 특히 낮은 피라미드 레벨과 저비트율에서의 성능이 더 우수함을 보인다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.223-226
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• 2001

In this paper, we propose a robust and fragile watermarking technique for tamper proofing of still images. Robust watermarks are embedded by quantization with a robust quantization step-size, and it is imperceptible value for human visual system. Fragile watermarks are embedded by thresholding and quantization with EW(Embedded Zerotree Wavelet) algorithm. The proposed method enables us to distinguish malicious change from non-malicious change. Futhermore this technique enables us to find tampering regions and degrees.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.412-415
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• 2003

본 논문에서는 영상 검색에 있어서 객체의 특징치를 추출하는데 많은 시간과 비용이 따르므로 수행속도를 향상시키기 위해 영상의 공간적인 정보를 이용한 영상의 압축을 이용하는 내용기반 영상 검색을 제안하고자 한다. 압축 성능이 뛰어나며 영상의 위치 정보와 주파수 정보를 가지는 EZW(Embedded Zerotree Wavelet)알고리즘을 이용하여 영상을 김색하는 방안으로 EZW 변환 후 얻어지는 저 대역 부 밴드에서의 공간적인 특성을 고려한 특징 값을 이용하여 정지영상의 대표 특징들을 형태와 질감으로 빠르게 영상 검색하고자 한다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.234-234
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• 2004

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05a
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• pp.23-26
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• 2003

본 논문은 웨이블릿 변환 과정을 통해서 분해한 영상을 Shapiro가 제안한 효율적인 영상 압축 방법인 EZW(Embedded Zerotree Wavelet)알고리즘을 하드웨어로 설계하였다. 이를 위한 하드웨어 구조를 제시하고 VHDL로 모델링 하여 FPGA를 통해 검증하였다.

• The KIPS Transactions:PartB
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• v.10B no.4
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• pp.367-372
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• 2003

The existing watermarking techniques for copyright protection of a digital image are fragile in geometric distortion and it is hard to detect whether it was manipulated artificially. In this paper, we proposed the new copyright protection system that can authorize a digital mage and :an embed or extract a robust watermark in a artificial manipulation in order to solve these problems. In a watermarking part, the proposed a watermarking technique embeds a watermark in a phase component after a Complex Wavelet Transform (CWT) with an original image, and a watermark is extracted from an watermarked image by stages. A copyright about an image can be insisted on than a threshold after comparing a correlation of an original watermark with an extracted watermark if large. In an authentication part of a digital image, EZW (Embedded Zerotree Wavelet) is used, and an authentication cord of an watermarked image is generated. An authentication code of an image to have been distribute to is compared with a generated authentication cord, and artificial operation isn´t than a threshold if large. The proposed copyright protection system through performance evaluation display that it was robust in geometric distortion and a artificial operation was able to be detected.