Contemporary Affirmation of SPIHT Improvements in Image Coding

Set partitioning in hierarchal trees (SPIHT) is actually a widely-used compression algorithm for wavelet altered images. On most algorithms developed, SPIHT algorithm from the time its introduction in 1996 for image compression has got lots of interest. Though SPIHT is considerably simpler and efficient than several present compression methods since it's a completely inserted codec, provides good image quality, large PSNR, optimized for modern image transmission, efficient conjunction with error defense, form information on demand and hence element powerful error correction decreases from starting to finish but still it has some downsides that need to be taken away for its better use therefore since its development it has experienced many adjustments in its original model. This document presents a survey on several different improvements in SPIHT in certain fields as velocity, redundancy, quality, error resilience, sophistication, and compression ratio and memory requirement

Massively Extended Modular Monitoring and a Second Life for Upper Stages

Launching science and technology experiments to space is expensive. Although commercial spaceflight has resulted in a drop of prices, the cost for a launch is still significant. However, most of theweight that is needed to conduct experiments in space belongs to the spacecraft’s bus and it is responsiblefor power distribution, thermal management, orbital control and communications. An upper stage, on the other hand, includes all the necessary subsystems andhas to be launched in any case. Many upper stages (e.g. ARIANE5) will even stay in orbit for severalyears after their nominal mission with all their subsystems intact but passivated.We proposea compact system based on a protective container and high-performance Commercial-off-the-Shelf (COTS) hardwarethat allows cost-efficient launching oftechnology experiments by reusing the launcher’s upper stage and its subsystems. Addingacquisition channels for various sensors gives the launch provider the ability to exploitthe computational power of the COTS hardwareduring the nominal mission. In contrast to existing systems,intelligent and mission-dependent data selection and compression can beapplied to the sensor data.In this paper, we demonstrate the implementation and qualification of a payload bussystem based on COTScomponentsthat is minimallyinvasive to the launcher(ARIANE5)and its nominal missionwhile offering computational power to both the launch provider and a potential payloaduser. The reliability of the COTS-based system is improvedby radiation hardening techniques and software-based self-test detecting and counteracting faults during the mission

Advances in Mass Spectrometers for Flyby Space Missions for the Analysis of Biosignatures and Other Complex Molecules

Spacecraft flybys provide access to the chemical composition of the gaseous envelope of the planetary object. Typical relative encounter velocities range from km/s to tens of km/s in flybys. For speeds exceeding about 5 km/s, modern mass spectrometers analyzing the rapidly encountering gas suffer from intrinsic hypervelocity impact-induced fragmentation processes causing ambiguous results when analyzing complex molecules. In this case, instruments use an antechamber, inside which the incoming species collide many times with the chamber wall. These collisions cause the desired deceleration and thermalization of the gas molecules. However, these collisions also dissociate molecular bonds, thus fragmenting the molecules, and possibly forming new ones precluding scientists from inferring the actual chemical composition of the sampled gas. We developed a novel time-of-flight mass spectrometer that handles relative encounter velocities of up to 20 km/s omitting an antechamber and its related fragmentation. It analyzes the complete mass range of m/z 1 to 1000 at an instance. This innovation leads to unambiguous analysis of complex (organic) molecules. Applied to Enceladus, Europa or Io, it will provide reliable chemical composition datasets for exploration of the Solar System to determine its status, origin and evolution

Cost-effective Hardware Design of a SPIHT Compression Algorithm

학위논문 (석사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 2. Jae Ha Kim.Set Partitioning In Hierarchical Trees (SPIHT) is one of most popular embedded coding algorithms applied for wavelet coding images. It allows progressive transmission of information and gives high coding efficiency. In addition, it can omit entropy coding of the bit stream by arithmetic code with only small loss in performance. Thus it offers a cheaper and faster hardware design. In this dissertation, a cost-effective design of a SPIHT-based algorithm is proposed. In this algorithm, an image is partitioned into 1x64 blocks, each of which is transformed by DWT to generate wavelet coefficients. The wavelet coefficients are coded by SPIHT to generate bit-stream. Due to the mismatch of the data structure between DWT and SPIHT, the large buffers are required. In order to reduce buffers, a new data structure of wavelet coefficients and partitioned SPIHT are proposed. A wavelet-based block is partitioned into small sub-blocks each of which is compressed independently. To minimize distortion due to the sub-block-based compression, a bit-allocation scheme is proposed. The proposed design is implemented in both software and hardware. Experimental results show that the proposed design reduces the buffer size while minimizing the degradation of the rate-distortion performance. It is proved that the proposed design outperforms previous designs in hardware cost.Chapter Ⅰ. Introduction 1 Chapter Ⅱ. Basic Architecture of the compression algorithm 5 Chapter Ⅲ. A Partitioned NLS Algorithm 17 Chapter Ⅳ. Adjustment of the target bit lengths for individual sub-blocks Chapter Ⅴ. Experimental Results 35 Chapter Ⅵ. Conclusion 48 References 50 Abstract 52 초록 53Maste

Compression Efficiency for Combining Different Embedded Image Compression Techniques with Huffman Encoding

This thesis presents a technique for image compression which uses the different embedded Wavelet based image coding in combination with Huffman- encoder(for further compression). There are different types of algorithms available for lossy image compression out of which Embedded Zerotree Wavelet(EZW), Set Partitioning in Hierarchical Trees (SPIHT) and Modified SPIHT algorithms are the some of the important compression techniques. EZW algorithm is based on progressive encoding to compress an image into a bit stream with increasing accuracy. The EZW encoder was originally designed to operate on 2D images, but it can also use to other dimensional signals. Progressive encoding is also called as embedded encoding. Main feature of ezw algorithm is capability of meeting an exact target bit rate with corresponding rate distortion rate(RDF). Set Partitioning in Hierarchical Trees (SPIHT) is an improved version of EZW and has become the general standard of EZW. SPIHT is a very efficient image compression algorithm that is based on the idea of coding groups of wavelet coefficients as zero trees. Since the order in which the subsets are tested for significance is important in a practical implementation the significance information is stored in three ordered lists called list of insignificant sets (LIS) list of insignificant pixels (LIP) and list of significant pixels (LSP). Modified SPIHT algorithm and the preprocessing techniques provide significant quality (both subjectively and objectively) reconstruction at the decoder with little additional computational complexity as compared to the previous techniques. This proposed method can reduce redundancy to a certain extend. Simulation results show that these hybrid algorithms yield quite promising PSNR values at low bitrates

디스플레이 장치를 위한 고정 비율 압축 하드웨어 설계

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2016. 2. 이혁재.디스플레이 장치에서의 압축 방식은 일반적인 비디오 압축 표준과는 다른 몇 가지 특징이 있다. 첫째, 특수한 어플리케이션을 목표로 한다. 둘째, 압축 이득, 소비 전력, 실시간 처리 등을 위해 하드웨어 크기가 작고, 목표로 하는 압축률이 낮다. 셋째, 래스터 주사 순서에 적합해야 한다. 넷째, 프레임 메모리 크기를 제한시키거나 임의 접근을 하기 위하여 압축 단위당 목표 압축률을 실시간으로 정확히 맞출 수 있어야 한다. 본 논문에서는 이와 같은 특징을 만족시키는 세 가지 압축 알고리즘과 하드웨어 구조를 제안하도록 한다. LCD 오버드라이브를 위한 압축 방식으로는 BTC(block truncation coding) 기반의 압축 방식을 제안하도록 한다. 본 논문은 압축 이득을 증가시키기 위하여 목표 압축률 12에 대한 압축 방식을 제안하는데, 압축 효율을 향상시키기 위하여 크게 두 가지 방법을 이용한다. 첫 번째는 이웃하는 블록과의 공간적 연관성을 이용하여 비트를 절약하는 방법이다. 그리고 두 번째는 단순한 영역은 2×16 코딩 블록, 복잡한 영역은 2×8 코딩 블록을 이용하는 방법이다. 2×8 코딩 블록을 이용하는 경우 목표 압축률을 맞추기 위하여 첫 번째 방법으로 절약된 비트를 이용한다. 저비용 근접-무손실 프레임 메모리 압축을 위한 방식으로는 1D SPIHT(set partitioning in hierarchical trees) 기반의 압축 방식을 제안하도록 한다. SPIHT은 고정 목표 압축률을 맞추는데 매우 효과적인 압축 방식이다. 그러나 1D 형태인 1D SPIHT은 래스터 주사 순서에 적합함에도 관련 연구가 많이 진행되지 않았다. 본 논문은 1D SPIHT의 가장 큰 문제점인 속도 문제를 해결할 수 있는 하드웨어 구조를 제안한다. 이를 위해 1D SPIHT 알고리즘은 병렬성을 이용할 수 있는 형태로 수정된다. 인코더의 경우 병렬 처리를 방해하는 의존 관계가 해결되고, 파이프라인 스케쥴링이 가능하게 된다. 디코더의 경우 병렬로 동작하는 각 패스가 디코딩할 비트스트림의 길이를 미리 예측할 수 있도록 알고리즘이 수정된다. 고충실도(high-fidelity) RGBW 컬러 이미지 압축을 위한 방식으로는 예측 기반의 압축 방식을 제안하도록 한다. 제안 예측 방식은 두 단계의 차분 과정으로 구성된다. 첫 번째는 공간적 연관성을 이용하는 단계이고, 두 번째는 인터-컬러 연관성을 이용하는 단계이다. 코딩의 경우 압축 효율이 높은 VLC(variable length coding) 방식을 이용하도록 한다. 그러나 기존의 VLC 방식은 목표 압축률을 정확히 맞추는데 어려움이 있었으므로 본 논문에서는 Golomb-Rice 코딩을 기반으로 한 고정 길이 압축 방식을 제안하도록 한다. 제안 인코더는 프리-코더와 포스터-코더로 구성되어 있다. 프리-코더는 특정 상황에 대하여 실제 인코딩을 수행하고, 다른 모든 상황에 대한 예측 인코딩 정보를 계산하여 포스터-코더에 전달한다. 그리고 포스트-코더는 전달받은 정보를 이용하여 실제 비트스트림을 생성한다.제 1 장 서론 1 1.1 연구 배경 1 1.2 연구 내용 4 1.3 논문 구성 8 제 2 장 이전 연구 9 2.1 BTC 9 2.1.1 기본 BTC 알고리즘 9 2.1.2 컬러 이미지 압축을 위한 BTC 알고리즘 10 2.2 SPIHT 13 2.2.1 1D SPIHT 알고리즘 13 2.2.2 SPIHT 하드웨어 17 2.3 예측 기반 코딩 19 2.3.1 예측 방법 19 2.3.2 VLC 20 2.3.3 예측 기반 코딩 하드웨어 22 제 3 장 LCD 오버드라이브를 위한 BTC 24 3.1 제안 알고리즘 24 3.1.1 비트-절약 방법 25 3.1.2 블록 크기 선택 방법 29 3.1.3 알고리즘 요약 31 3.2 하드웨어 구조 33 3.2.1 프레임 메모리 인터페이스 34 3.2.2 인코더와 디코더의 구조 37 3.3 실험 결과 44 3.3.1 알고리즘 성능 44 3.3.2 하드웨어 구현 결과 49 제 4 장 저비용 근접-무손실 프레임 메모리 압축을 위한 고속 1D SPIHT 54 4.1 인코더 하드웨어 구조 54 4.1.1 의존 관계 분석 및 제안하는 파이프라인 스케쥴 54 4.1.2 분류 비트 재배치 57 4.2 디코더 하드웨어 구조 59 4.2.1 비트스트림의 시작 주소 계산 59 4.2.2 절반-패스 처리 방법 63 4.3 하드웨어 구현 65 4.4 실험 결과 73 제 5 장 고충실도 RGBW 컬러 이미지 압축을 위한 고정 압축비 VLC 81 5.1 제안 알고리즘 81 5.1.1 RGBW 인터-컬러 연관성을 이용한 예측 방식 82 5.1.2 고정 압축비를 위한 Golomb-Rice 코딩 85 5.1.3 알고리즘 요약 89 5.2 하드웨어 구조 90 5.2.1 인코더 구조 91 5.2.2 디코더 구조 95 5.3 실험 결과 101 5.3.1 알고리즘 실험 결과 101 5.3.2 하드웨어 구현 결과 107 제 6 장 압축 성능 및 하드웨어 크기 비교 분석 113 6.1 압축 성능 비교 113 6.2 하드웨어 크기 비교 120 제 7 장 결론 125 참고문헌 128 ABSTRACT 135Docto

Rate scalable image compression in the wavelet domain

This thesis explores image compression in the wavelet transform domain. This the- sis considers progressive compression based on bit plane coding. The rst part of the thesis investigates the scalar quantisation technique for multidimensional images such as colour and multispectral image. Embedded coders such as SPIHT and SPECK are known to be very simple and e cient algorithms for compression in the wavelet do- main. However, these algorithms require the use of lists to keep track of partitioning processes, and such lists involve high memory requirement during the encoding process. A listless approach has been proposed for multispectral image compression in order to reduce the working memory required. The earlier listless coders are extended into three dimensional coder so that redundancy in the spectral domain can be exploited. Listless implementation requires a xed memory of 4 bits per pixel to represent the state of each transformed coe cient. The state is updated during coding based on test of sig- ni cance. Spectral redundancies are exploited to improve the performance of the coder by modifying its scanning rules and the initial marker/state. For colour images, this is done by conducting a joint the signi cant test for the chrominance planes. In this way, the similarities between the chrominance planes can be exploited during the cod- ing process. Fixed memory listless methods that exploit spectral redundancies enable e cient coding while maintaining rate scalability and progressive transmission. The second part of the thesis addresses image compression using directional filters in the wavelet domain. A directional lter is expected to improve the retention of edge and curve information during compression. Current implementations of hybrid wavelet and directional (HWD) lters improve the contour representation of compressed images, but su er from the pseudo-Gibbs phenomenon in the smooth regions of the images. A di erent approach to directional lters in the wavelet transforms is proposed to remove such artifacts while maintaining the ability to preserve contours and texture. Imple- mentation with grayscale images shows improvements in terms of distortion rates and the structural similarity, especially in images with contours. The proposed transform manages to preserve the directional capability without pseudo-Gibbs artifacts and at the same time reduces the complexity of wavelet transform with directional lter. Fur-ther investigation to colour images shows the transform able to preserve texture and curve.EThOS - Electronic Theses Online ServiceGBUnited Kingdo