Fractal Image Compression
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Information and Compression Introduction Summary of Course
Information and compression Introduction ■ We will be looking at what information is Information and Compression ■ Methods of measuring it ■ The idea of compression ■ 2 distinct ways of compressing images Paul Cockshott Faraday partnership Summary of Course Agenda ■ At the end of this lecture you should have ■ Encoding systems an idea what information is, its relation to ■ BCD versus decimal order, and why data compression is possible ■ Information efficiency ■ Shannons Measure ■ Chaitin, Kolmogorov Complexity Theory ■ Relation to Goedels theorem Overview Connections ■ Data coms channels bounded ■ Simple encoding example shows different ■ Images take great deal of information in raw densities possible form ■ Shannons information theory deals with ■ Efficient transmission requires denser transmission encoding ■ Chaitin relates this to Turing machines and ■ This requires that we understand what computability information actually is ■ Goedels theorem limits what we know about compression paul 1 Information and compression Vocabulary What is information ■ information, ■ Information measured in bits ■ entropy, ■ Bit equivalent to binary digit ■ compression, ■ Why use binary system not decimal? ■ redundancy, ■ Decimal would seem more natural ■ lossless encoding, ■ Alternatively why not use e, base of natural ■ lossy encoding logarithms instead of 2 or 10 ? Voltage encoding Noise Immunity Binary voltage ■ ■ ■ 5v Digital information BINARY DECIMAL encoded as ranges of ■ 2 values 0,1 ■ 10 values 0..9 continuous variables 1 ■ 1 isolation band ■ -
An Improved Fast Fractal Image Compression Coding Method
Rev. Téc. Ing. Univ. Zulia. Vol. 39, Nº 9, 241 - 247, 2016 doi:10.21311/001.39.9.32 An Improved Fast Fractal Image Compression Coding Method Haibo Gao, Wenjuan Zeng, Jifeng Chen, Cheng Zhang College of Information Science and Engineering, Hunan International Economics University, Changsha 410205, Hunan, China Abstract The main purpose of image compression is to use as many bits as possible to represent the source image by eliminating the image redundancy with acceptable restoration. Fractal image compression coding has achieved good results in the field of image compression due to its high compression ratio, fast decoding speed as well as independency between decoding image and resolution. However, there is a big problem in this method, i.e. long coding time because there are considerable searches of fractal blocks in the coding. Based on the theoretical foundation of fractal coding and fractal compression algorithm, this paper researches every step of this compression method, including block partition, block search and the representation of affine transformation coefficient, in order to come up with optimization and improvement strategies. The simulation result shows that the algorithm of this paper can achieve excellent effects in coding time and compression ratio while ensuring better image quality. The work on fractal coding in this paper has made certain contributions to the research of fractal coding. Key words: Image Compression, Fractal Theory, Coding and Decoding. 1. INTRODUCTION Image compression is aimed to use as many bytes as possible to represent and transmit the original big image and to have a better quality in the restored image. -
How to Exploit the Transferability of Learned Image Compression to Conventional Codecs
How to Exploit the Transferability of Learned Image Compression to Conventional Codecs Jan P. Klopp Keng-Chi Liu National Taiwan University Taiwan AI Labs [email protected] [email protected] Liang-Gee Chen Shao-Yi Chien National Taiwan University [email protected] [email protected] Abstract Lossy compression optimises the objective Lossy image compression is often limited by the sim- L = R + λD (1) plicity of the chosen loss measure. Recent research sug- gests that generative adversarial networks have the ability where R and D stand for rate and distortion, respectively, to overcome this limitation and serve as a multi-modal loss, and λ controls their weight relative to each other. In prac- especially for textures. Together with learned image com- tice, computational efficiency is another constraint as at pression, these two techniques can be used to great effect least the decoder needs to process high resolutions in real- when relaxing the commonly employed tight measures of time under a limited power envelope, typically necessitating distortion. However, convolutional neural network-based dedicated hardware implementations. Requirements for the algorithms have a large computational footprint. Ideally, encoder are more relaxed, often allowing even offline en- an existing conventional codec should stay in place, ensur- coding without demanding real-time capability. ing faster adoption and adherence to a balanced computa- Recent research has developed along two lines: evolu- tional envelope. tion of exiting coding technologies, such as H264 [41] or As a possible avenue to this goal, we propose and investi- H265 [35], culminating in the most recent AV1 codec, on gate how learned image coding can be used as a surrogate the one hand. -
Chapter 9 Image Compression Standards
Fundamentals of Multimedia, Chapter 9 Chapter 9 Image Compression Standards 9.1 The JPEG Standard 9.2 The JPEG2000 Standard 9.3 The JPEG-LS Standard 9.4 Bi-level Image Compression Standards 9.5 Further Exploration 1 Li & Drew c Prentice Hall 2003 ! Fundamentals of Multimedia, Chapter 9 9.1 The JPEG Standard JPEG is an image compression standard that was developed • by the “Joint Photographic Experts Group”. JPEG was for- mally accepted as an international standard in 1992. JPEG is a lossy image compression method. It employs a • transform coding method using the DCT (Discrete Cosine Transform). An image is a function of i and j (or conventionally x and y) • in the spatial domain. The 2D DCT is used as one step in JPEG in order to yield a frequency response which is a function F (u, v) in the spatial frequency domain, indexed by two integers u and v. 2 Li & Drew c Prentice Hall 2003 ! Fundamentals of Multimedia, Chapter 9 Observations for JPEG Image Compression The effectiveness of the DCT transform coding method in • JPEG relies on 3 major observations: Observation 1: Useful image contents change relatively slowly across the image, i.e., it is unusual for intensity values to vary widely several times in a small area, for example, within an 8 8 × image block. much of the information in an image is repeated, hence “spa- • tial redundancy”. 3 Li & Drew c Prentice Hall 2003 ! Fundamentals of Multimedia, Chapter 9 Observations for JPEG Image Compression (cont’d) Observation 2: Psychophysical experiments suggest that hu- mans are much less likely to notice the loss of very high spatial frequency components than the loss of lower frequency compo- nents. -
Image Compression Using Discrete Cosine Transform Method
Qusay Kanaan Kadhim, International Journal of Computer Science and Mobile Computing, Vol.5 Issue.9, September- 2016, pg. 186-192 Available Online at www.ijcsmc.com International Journal of Computer Science and Mobile Computing A Monthly Journal of Computer Science and Information Technology ISSN 2320–088X IMPACT FACTOR: 5.258 IJCSMC, Vol. 5, Issue. 9, September 2016, pg.186 – 192 Image Compression Using Discrete Cosine Transform Method Qusay Kanaan Kadhim Al-Yarmook University College / Computer Science Department, Iraq [email protected] ABSTRACT: The processing of digital images took a wide importance in the knowledge field in the last decades ago due to the rapid development in the communication techniques and the need to find and develop methods assist in enhancing and exploiting the image information. The field of digital images compression becomes an important field of digital images processing fields due to the need to exploit the available storage space as much as possible and reduce the time required to transmit the image. Baseline JPEG Standard technique is used in compression of images with 8-bit color depth. Basically, this scheme consists of seven operations which are the sampling, the partitioning, the transform, the quantization, the entropy coding and Huffman coding. First, the sampling process is used to reduce the size of the image and the number bits required to represent it. Next, the partitioning process is applied to the image to get (8×8) image block. Then, the discrete cosine transform is used to transform the image block data from spatial domain to frequency domain to make the data easy to process. -
Task-Aware Quantization Network for JPEG Image Compression
Task-Aware Quantization Network for JPEG Image Compression Jinyoung Choi1 and Bohyung Han1 Dept. of ECE & ASRI, Seoul National University, Korea fjin0.choi,[email protected] Abstract. We propose to learn a deep neural network for JPEG im- age compression, which predicts image-specific optimized quantization tables fully compatible with the standard JPEG encoder and decoder. Moreover, our approach provides the capability to learn task-specific quantization tables in a principled way by adjusting the objective func- tion of the network. The main challenge to realize this idea is that there exist non-differentiable components in the encoder such as run-length encoding and Huffman coding and it is not straightforward to predict the probability distribution of the quantized image representations. We address these issues by learning a differentiable loss function that approx- imates bitrates using simple network blocks|two MLPs and an LSTM. We evaluate the proposed algorithm using multiple task-specific losses| two for semantic image understanding and another two for conventional image compression|and demonstrate the effectiveness of our approach to the individual tasks. Keywords: JPEG image compression, adaptive quantization, bitrate approximation. 1 Introduction Image compression is a classical task to reduce the file size of an input image while minimizing the loss of visual quality. This task has two categories|lossy and lossless compression. Lossless compression algorithms preserve the contents of input images perfectly even after compression, but their compression rates are typically low. On the other hand, lossy compression techniques allow the degra- dation of the original images by quantization and reduce the file size significantly compared to lossless counterparts. -
Hardware Architecture for Elliptic Curve Cryptography and Lossless Data Compression
Hardware architecture for elliptic curve cryptography and lossless data compression by Miguel Morales-Sandoval A thesis presented to the National Institute for Astrophysics, Optics and Electronics in partial ful¯lment of the requirement for the degree of Master of Computer Science Thesis Advisor: PhD. Claudia Feregrino-Uribe Computer Science Department National Institute for Astrophysics, Optics and Electronics Tonantzintla, Puebla M¶exico December 2004 Abstract Data compression and cryptography play an important role when transmitting data across a public computer network. While compression reduces the amount of data to be transferred or stored, cryptography ensures that data is transmitted with reliability and integrity. Compression and encryption have to be applied in the correct way: data are compressed before they are encrypted. If it were the opposite case the result of the cryptographic operation would be illegible data and no patterns or redundancy would be present, leading to very poor or no compression. In this research work, a hardware architecture that joins lossless compression and public-key cryptography for secure data transmission applications is discussed. The architecture consists of a dictionary-based lossless data compressor to compress the incoming data, and an elliptic curve crypto- graphic module that performs two EC (elliptic curve) cryptographic schemes: encryp- tion and digital signature. For lossless data compression, the dictionary-based LZ77 algorithm is implemented using a systolic array aproach. The elliptic curve cryptosys- tem is de¯ned over the binary ¯eld F2m , using polynomial basis, a±ne coordinates and the binary method to compute an scalar multiplication. While the model of the complete system was implemented in software, the hardware architecture was described in the Very High Speed Integrated Circuit Hardware Description Language (VHDL). -
A Review of Data Compression Technique
International Journal of Computer Science Trends and Technology (IJCST) – Volume 2 Issue 4, Jul-Aug 2014 RESEARCH ARTICLE OPEN ACCESS A Review of Data Compression Technique Ritu1, Puneet Sharma2 Department of Computer Science and Engineering, Hindu College of Engineering, Sonipat Deenbandhu Chhotu Ram University, Murthal Haryana-India ABSTRACT With the growth of technology and the entrance into the Digital Age, the world has found itself amid a vast amount of information. Dealing with such enormous amount of information can often present difficulties. Digital information must be stored and retrieved in an efficient manner, in order for it to be put to practical use. Compression is one way to deal with this problem. Images require substantial storage and transmission resources, thus image compression is advantageous to reduce these requirements. Image compression is a key technology in transmission and storage of digital images because of vast data associated with them. This paper addresses about various image compression techniques. There are two types of image compression: lossless and lossy. Keywords:- Image Compression, JPEG, Discrete wavelet Transform. I. INTRODUCTION redundancies. An inverse process called decompression Image compression is important for many applications (decoding) is applied to the compressed data to get the that involve huge data storage, transmission and retrieval reconstructed image. The objective of compression is to such as for multimedia, documents, videoconferencing, and reduce the number of bits as much as possible, while medical imaging. Uncompressed images require keeping the resolution and the visual quality of the considerable storage capacity and transmission bandwidth. reconstructed image as close to the original image as The objective of image compression technique is to reduce possible. -
A Review on Different Lossless Image Compression Techniques
Ilam Parithi.T et. al. /International Journal of Modern Sciences and Engineering Technology (IJMSET) ISSN 2349-3755; Available at https://www.ijmset.com Volume 2, Issue 4, 2015, pp.86-94 A Review on Different Lossless Image Compression Techniques 1Ilam Parithi.T * 2Balasubramanian.R Research Scholar/CSE Professor/CSE Manonmaniam Sundaranar Manonmaniam Sundaranar University, University, Tirunelveli, India Tirunelveli, India [email protected] [email protected] Abstract In the Morden world sharing and storing the data in the form of image is a great challenge for the social networks. People are sharing and storing a millions of images for every second. Though the data compression is done to reduce the amount of space required to store a data, there is need for a perfect image compression algorithm which will reduce the size of data for both sharing and storing. Keywords: Huffman Coding, Run Length Encoding (RLE), Arithmetic Coding, Lempel – Ziv-Welch Coding (LZW), Differential Pulse Code Modulation (DPCM). 1. INTRODUCTION: The Image compression is a technique for effectively coding the digital image by minimizing the numbers of bits needed for representing the image. The aim is to reduce the storage space, transmission cost and to maintain a good quality. The compression is also achieved by removing the redundancies like coding redundancy, inter pixel redundancy, and psycho visual redundancy. Generally the compression techniques are divided into two types. i) Lossy compression techniques and ii) Lossless compression techniques. Compression Techniques Lossless Compression Lossy Compression Run Length Coding Huffman Coding Wavelet based Fractal Compression Compression Arithmetic Coding LZW Coding Vector Quantization Block Truncation Coding Fig. -
Video/Image Compression Technologies an Overview
Video/Image Compression Technologies An Overview Ahmad Ansari, Ph.D., Principal Member of Technical Staff SBC Technology Resources, Inc. 9505 Arboretum Blvd. Austin, TX 78759 (512) 372 - 5653 [email protected] May 15, 2001- A. C. Ansari 1 Video Compression, An Overview ■ Introduction – Impact of Digitization, Sampling and Quantization on Compression ■ Lossless Compression – Bit Plane Coding – Predictive Coding ■ Lossy Compression – Transform Coding (MPEG-X) – Vector Quantization (VQ) – Subband Coding (Wavelets) – Fractals – Model-Based Coding May 15, 2001- A. C. Ansari 2 Introduction ■ Digitization Impact – Generating Large number of bits; impacts storage and transmission » Image/video is correlated » Human Visual System has limitations ■ Types of Redundancies – Spatial - Correlation between neighboring pixel values – Spectral - Correlation between different color planes or spectral bands – Temporal - Correlation between different frames in a video sequence ■ Know Facts – Sampling » Higher sampling rate results in higher pixel-to-pixel correlation – Quantization » Increasing the number of quantization levels reduces pixel-to-pixel correlation May 15, 2001- A. C. Ansari 3 Lossless Compression May 15, 2001- A. C. Ansari 4 Lossless Compression ■ Lossless – Numerically identical to the original content on a pixel-by-pixel basis – Motion Compensation is not used ■ Applications – Medical Imaging – Contribution video applications ■ Techniques – Bit Plane Coding – Lossless Predictive Coding » DPCM, Huffman Coding of Differential Frames, Arithmetic Coding of Differential Frames May 15, 2001- A. C. Ansari 5 Lossless Compression ■ Bit Plane Coding – A video frame with NxN pixels and each pixel is encoded by “K” bits – Converts this frame into K x (NxN) binary frames and encode each binary frame independently. » Runlength Encoding, Gray Coding, Arithmetic coding Binary Frame #1 . -
Why Compression Matters
Computational thinking for digital technologies: Snapshot 2 PROGRESS OUTCOME 6 Why compression matters Context Sarah has been investigating the concept of compression coding, by looking at the different ways images can be compressed and the trade-offs of using different methods of compression in relation to the size and quality of images. She researches the topic by doing several web searches and produces a report with her findings. Insight 1: Reasons for compressing files I realised that data compression is extremely useful as it reduces the amount of space needed to store files. Computers and storage devices have limited space, so using smaller files allows you to store more files. Compressed files also download more quickly, which saves time – and money, because you pay less for electricity and bandwidth. Compression is also important in terms of HCI (human-computer interaction), because if images or videos are not compressed they take longer to download and, rather than waiting, many users will move on to another website. Insight 2: Representing images in an uncompressed form Most people don’t realise that a computer image is made up of tiny dots of colour, called pixels (short for “picture elements”). Each pixel has components of red, green and blue light and is represented by a binary number. The more bits used to represent each component, the greater the depth of colour in your image. For example, if red is represented by 8 bits, green by 8 bits and blue by 8 bits, 16,777,216 different colours can be represented, as shown below: 8 bits corresponds to 256 possible numbers in binary red x green x blue = 256 x 256 x 256 = 16,777,216 possible colour combinations 1 Insight 3: Lossy compression and human perception There are many different formats for file compression such as JPEG (image compression), MP3 (audio compression) and MPEG (audio and video compression). -
Video Compression and Communications: from Basics to H.261, H.263, H.264, MPEG2, MPEG4 for DVB and HSDPA-Style Adaptive Turbo-Transceivers
Video Compression and Communications: From Basics to H.261, H.263, H.264, MPEG2, MPEG4 for DVB and HSDPA-Style Adaptive Turbo-Transceivers by c L. Hanzo, P.J. Cherriman, J. Streit Department of Electronics and Computer Science, University of Southampton, UK About the Authors Lajos Hanzo (http://www-mobile.ecs.soton.ac.uk) FREng, FIEEE, FIET, DSc received his degree in electronics in 1976 and his doctorate in 1983. During his 30-year career in telecommunications he has held various research and academic posts in Hungary, Germany and the UK. Since 1986 he has been with the School of Electronics and Computer Science, University of Southampton, UK, where he holds the chair in telecom- munications. He has co-authored 15 books on mobile radio communica- tions totalling in excess of 10 000, published about 700 research papers, acted as TPC Chair of IEEE conferences, presented keynote lectures and been awarded a number of distinctions. Currently he is directing an academic research team, working on a range of research projects in the field of wireless multimedia communications sponsored by industry, the Engineering and Physical Sciences Research Council (EPSRC) UK, the European IST Programme and the Mobile Virtual Centre of Excellence (VCE), UK. He is an enthusiastic supporter of industrial and academic liaison and he offers a range of industrial courses. He is also an IEEE Distinguished Lecturer of both the Communications Society and the Vehicular Technology Society (VTS). Since 2005 he has been a Governer of the VTS. For further information on research in progress and associated publications please refer to http://www-mobile.ecs.soton.ac.uk Peter J.