• Journal of KIISE:Software and Applications
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• v.30 no.7_8
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• pp.687-695
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• 2003

In this paper, we present a document image compression system based on segmentation, Quincunx downsampling, (5/3) wavelet lifting and subband-oriented SPIHT coding. We reduced the coding time by the adaptation of subband-oriented SPIHT coding and Quincunx downsampling. And to increase compression rate further, we applied arithmetic coding to the bitstream of SPIHT coding output. Finally, we present the reconstructed images for visual comparison and also present the compression rates and PSNR values under various scalar quantization methods.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10b
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• pp.209-211
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• 2000

SPIHT(Set Partitioning In Hierarchical Trees) 부호화 알고리즘은 EXW(Embedded Zerotree Wavelet) 부호와 알고리즘의 부호화 방법을 개선하여 압축 효율을 개선한 알고리즘이다. SPIHT 부호화 알고리즘은 웨이브렛 변환된 영상의 계수 값이 동일한 방향은 갖는 대역 사이에서 상관 관계를 갖는다는 점을 이용한다는 점에서 EZW 부호화 알고리즘과 동일하다. 그러나 zerotree의 부호화 부분에서 계수의 중요도에 따라 부분 집합으로 분할해 가는 과정과 분할된 계수들을 부호화하는 과정을 개선하였다. 이 부호화 과정에서의 significant map은 모든 threshold에 대해서 LSP(List of Insignificant Pixels), LIP(List of Insignificant), LIS(List of Insignificant Sets)의 세가지 리스트를 통하여 구하여 진다. 그리고, 전체 알고리즘은 초기화, Sorting pass, Refinement pass, 양자화 값 갱신의 네 가지 단계로 구성된다. 본 논문에서는 SPIHT 구현에 필요한 자료구조를 제안하고 SPIHT 부호화 모듈을 구현에 대하여 설명한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8A
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• pp.814-821
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• 2002

The SPIHT(set partitioning in hierarchical tree) is efficient and well-known in the zerotree coding algorithm. However SPIHT's high memory requirement is a major difficulty for hardware implementation. In this paper we propose low-memory and fast zerotree algorithm. We present following three methods for reduced memory and fst coding speed. First, wavelet transform by lifting has a low memory requirement and reduced complexity than traditional filter bank implementation. The second method is to divide the wavelet coefficients into a block. Finally, we use NLS algorithm proposed by Wheeler and Pearlman in our codec. Performance of NLS is nearly same as SPIHT and reveals low and fixed memory and fast coding speed.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.3
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• pp.101-109
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• 2004

In this paper, we propose an efficient algerian for wavelet-based sti image coding method that utilizes the rate-distortion (R-D) theory. Since conventional tree-structured image coding schemes do not consider the rate-distortion theory properly, they show reduced coding performance. In this paper, we apply an rate-distortion optimized embedding (RDE) operation into the set partitioning in hierarchical trees (SPIHT) algorithm. In this algorithm, we use the rate-distortion slope as a criterion for the coding order of wavelet coefficients in SPIHT lists. We also describe modified set partitioning and rate-distortion optimized list scan methods. Experimental results demonstrate that the proposed method outperforms the SPIHT algorithm and the rate-distortion optimized embedding algerian with respect to the PSNR (peak signal-to-noise ratio) performance.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.229-232
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• 2001

초저속 전송 통신망에서 비디오 전송을 효율적으로 하기 위한 시스템은 낮은 비디오 전송율에서 높은 압축율을 갖는 부호화 방법들이 사용된다. 현재 저속 통신을 위한 부호화 표준으로 대표적인 ITU-T의 H.263은 DCT기반이므로 낮은 비트율에서 블록화 현상이 발생한다. 본 논문에서 제안하는 다중 가중 인자를 이용한 SPIHT 비디오 부호기는 H.263에 비하여 동영상의 PSNR이 우수한 성능을 보였고 기존 SPIHT 비디오 부호기보다도 PSNR이 우수함을 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.1
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• pp.1-7
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• 2005

We propose an effective Landsat TM image compression method using the classified bidirectional prediction (CBP), the classified KLT and the SPIHT. The SPIHT is used to exploit the spatial redundancy of feature bands selected in the visible range and the infrared range separately. Regions of the prediction bands are classified into three classes in the wavelet domain, and then the CBP is performed to exploit the spectral redundancy. Residual bands that consist of difference values between the original band and the predicted band are decorrelated by the spectral KLT Finally, the three dimensional (3-D) SPIHT is used to encode the decorrelated coefficients. Experiment results show that the proposed method reconstructs higher quality Landsat TM image than conventional methods at the same bit rate.

• Journal of Korea Multimedia Society
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• v.10 no.11
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• pp.1427-1438
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• 2007

Video watermarking technologies are classified into types of four kinds. The first type is to embed the watermark into a raw video signal and to code the watermarked video signal. Most of video watermarking technologies fall into the category of this type. The second type is to apply watermarking to the coding process, such as block DCT and quantization. The third is to directly embed the watermark into the compressed bitstream itself. Generally, it is referred as labelling rather than watermarking. Finally, the fourth is to embed the water mark into MPEG motion vector. This type has the difficulty in real-time process because of the high complexity and has the blocking effects because of DCT-based on coder. In this paper, we proposed the digital video watermarking that embed the watermark in SPIHT video code for I-frame using motion vector analysis. This method can remove the blocking effect occurred at the DCT-based on coder and obtain video data that has progressive transmission property. The proposed method is to select the region for the watermark embedding in I frame using motion vector estimated from the previous P or B frame. And then, it is to perform DWT and embed the watermark based on HVS into the wavelet coefficients in the same subband of DWT as the motion vector direction. Finally, the watermarked video bitstream is obtained by the SPIHT coder. The experimental results verified that the proposed method has the invisibility from the objective and subjective image quality and the robustness against the various SPIHT compression and MPEG re-code.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.417-420
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• 2000

점진적 영상 전송과 저해상도에서도 높은 PSNR를 나타내는 방법으로 EZW(Enbeded Zerotree Wavelet)과 SPIHT(set partitioning in hierarchical tree)를 사용한 보다 향상된 영상 압축방법이 제안되어졌다. 특히 SPIHT는 적응 산술부호화(adaptive arithmetic coding)를 사용하지 않고도 EZW보다 뛰어난 압축률과 효과를 얻을 수 있다. 하지만 부대역(subband)간의 유사성(similarity)을 이용한 제로트리 부호화에서 계층을 나누는 일은 계수 사이의 연결관계를 깰 수 있기 때문에 간단한 일은 아니다. 본 논문에서는 SPIHT의 비트열을 여러개의 계층으로 나누고 각각의 해상도로 복원하는 새로운 정렬 방법을 제안하고, 계층간의 비트열을 균일하게 나눔으로써 보다 효율적으로 전송 할 수 있는 방법을 제안하였다. 또한 복호시에 낮은 해상도일수로 복원시간의 이득을 볼 수 있는 향상된 방법을 제안한다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.113-116
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• 2001

제로트리 부호화 알고리즘 중 효율적이며 잘 알려진 SPIHT는 높은 메모리 요구로 인해 하드웨어 구현에 큰 어려움을 가지고 있다. 이 논문에서는 저 메모리 사용과 빠른 제로트리 부호화 알고리즘을 제안한다. 메모리를 줄이고 빠른 코딩을 위한 방법으로 다음 3가지를 사용한다. 첫 번째, 리프팅을 이용한 웨이블릿 변환은 기존의 필터뱅크 방식의 변환보다 저 메모리와 계산량의 감소를 가진다. 두 번째, 웨이블릿 변환된 계수들은 블럭으로 나누어져 각각 코딩된다. 여기서 블록은 제로트리 구조가 유지되는 STB(spatial tree-based block)이다. 세 번째, Wheeler 와 Pearlman이 제안한 NLS (no list SPIHT)를 이용한 부호화이다. NLS는 효율성에서 SPIHT와 거의 같으며 작고 고정된 메모리와 빠른 부호화 속도를 보여준다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.5
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• pp.486-493
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• 2002

In this paper, we proposed the effective multispectral image compression method using CIBP(classified interband bidrectional prediction) and extended SPIHT(set partition in hierarchical trees) in wavelet domain. We determine separately feature bands that have the highest correlation with other bands in the visible range and in the infrared range of wavelengths. Feature bands are coded to remove the spatial redundancy with SPIHT in the wavelet domain. Prediction bands that have high correlation with feature bands are wavelet transformed and they are classified into one of three classes considering reflection characteristics of the baseband. For Prediction bands, CIBP is performed to reduce the spectral redundancy. for the difference bands between prediction bands and the predicted bands, They are ordered to upgrade the compression efficiency of extended SPIHT with the largest error magnitude. The arranged bands are coded to compensate the prediction error with extended SPIHT. Experiments are carried out on the multispectral images. The results show that the proposed method reconstructs higher quality images than images reconstructed by the conventional methods at the same bit rate.