Objective methods for assessing perceptual image quality traditionally attempted to quantify the visibility of errors (differences) between a distorted image and a reference image using a variety of known properties of the human visual system. Under the assumption that human visual perception is highly adapted for extracting structural information from a scene, we introduce an alternative complementary framework for quality assessment based on the degradation of structural information. As a specific example of this concept, we develop a structural similarity index and demonstrate its promise through a set of intuitive examples, as well as comparison to both subjective ratings and state-of-the-art objective methods on a database of images compressed with JPEG and JPEG2000. A MATLAB implementation of the proposed algorithm is available online at http://www.cns.nyu.edu//spl sim/lcv/ssim/.

/pdf/image-quality-assessment-from-error-visibility-to-structural-1rlwcqe34t.pdf

Image quality assessment: from error visibility to structural similarity

There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Introduction to a Transient World. Fourier Kingdom. Discrete Revolution. Time Meets Frequency. Frames. Wavelet Zoom. Wavelet Bases. Wavelet Packet and Local Cosine Bases. An Approximation Tour. Estimations are Approximations. Transform Coding. Appendix A: Mathematical Complements. Appendix B: Software Toolboxes.

http://ahvazdownload.persiangig.com/document/article/39.pdf

A wavelet tour of signal processing

Embedded zerotree wavelet (EZW) coding, introduced by Shapiro (see IEEE Trans. Signal Processing, vol.41, no.12, p.3445, 1993), is a very effective and computationally simple technique for image compression. We offer an alternative explanation of the principles of its operation, so that the reasons for its excellent performance can be better understood. These principles are partial ordering by magnitude with a set partitioning sorting algorithm, ordered bit plane transmission, and exploitation of self-similarity across different scales of an image wavelet transform. Moreover, we present a new and different implementation based on set partitioning in hierarchical trees (SPIHT), which provides even better performance than our previously reported extension of EZW that surpassed the performance of the original EZW. The image coding results, calculated from actual file sizes and images reconstructed by the decoding algorithm, are either comparable to or surpass previous results obtained through much more sophisticated and computationally complex methods. In addition, the new coding and decoding procedures are extremely fast, and they can be made even faster, with only small loss in performance, by omitting entropy coding of the bit stream by the arithmetic code.

http://dns2.asia.edu.tw/~ysho/YSHO-English/2000%20Engineering/PDF/IEE%20Tra%20Cir%20Sys%20Vid%20Tec6,%20243.pdf

A new, fast, and efficient image codec based on set partitioning in hierarchical trees

The embedded zerotree wavelet algorithm (EZW) is a simple, yet remarkably effective, image compression algorithm, having the property that the bits in the bit stream are generated in order of importance, yielding a fully embedded code The embedded code represents a sequence of binary decisions that distinguish an image from the "null" image Using an embedded coding algorithm, an encoder can terminate the encoding at any point thereby allowing a target rate or target distortion metric to be met exactly Also, given a bit stream, the decoder can cease decoding at any point in the bit stream and still produce exactly the same image that would have been encoded at the bit rate corresponding to the truncated bit stream In addition to producing a fully embedded bit stream, the EZW consistently produces compression results that are competitive with virtually all known compression algorithms on standard test images Yet this performance is achieved with a technique that requires absolutely no training, no pre-stored tables or codebooks, and requires no prior knowledge of the image source The EZW algorithm is based on four key concepts: (1) a discrete wavelet transform or hierarchical subband decomposition, (2) prediction of the absence of significant information across scales by exploiting the self-similarity inherent in images, (3) entropy-coded successive-approximation quantization, and (4) universal lossless data compression which is achieved via adaptive arithmetic coding >

http://dns2.asia.edu.tw/~ysho/YSHO-English/2000%20Engineering/PDF/IEE%20Tra%20Sig%20Pro41,%203445.pdf

Embedded image coding using zerotrees of wavelet coefficients

A hexagonally sampled image is split into a low passband and nine passbands of one octave width and 60 deg angular orientation. The conditions to be satisfied by the filter banks for perlect reconstruction are presented. The human visual system's response to stimuli at differing spatial frequencies is then employed to shape the coding noise spectrum. Rate is allocated under a frequency-weighted mean-square-error distortion measure. A framework is presented employing either the power spectral density of the image or the variance of the subbands. Both adaptive and nonadaptive entropy coding simulations are carried out under a Laplacian source distribution. Transparent coding results are presented at rates below 1 bit/pixel.

Hexagonal subband image coding with perceptual weighting

Set partition coding (SPC) has shown tremendous success in image compression. Despite its popularity, the lack of error resilience remains a significant challenge to the transmission of images in error-prone environments. In this paper, we propose a novel data representation called the progressive significance map (prog-sig-map) for error-resilient SPC. It structures the significance map (sig-map) into two parts: a high-level summation sig-map and a low-level complementary sig-map (comp-sig-map). Such a structured representation of the sig-map allows us to improve its error-resilient property at the price of only a slight sacrifice in compression efficiency. For example, we have found that a fixed-length coding of the comp-sig-map in the prog-sig-map renders 64% of the coded bitstream insensitive to bit errors, compared with 40% with that of the conventional sig-map. Simulation results have shown that the prog-sig-map can achieve highly competitive rate-distortion performance for binary symmetric channels while maintaining low computational complexity. Moreover, we note that prog-sig-map is complementary to existing independent packetization and channel-coding-based error-resilient approaches and readily lends itself to other source coding applications such as distributed video coding.

Progressive Significance Map and Its Application to Error-Resilient Image Transmission

In this paper we consider the problem of faded wireless image and video transmission schemes over multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) channels that are energy and the bandwidth constrained. A computationally inexpensive analytic mean square error (MSE) distortion rate (D-R) estimator for progressive wavelet coders which generates an exact D-R (distortion rate) function for 2-D and 3-D SPIHT algorithm is utilized from our previous work. Using the D-R function, a joint source-channel coding scheme using optimal equal error protection (EEP) is presented. Both analytic and Monte-Carlo simulations are presented for image and video sources. A system that uses two transmit antennas and two receive antennas expends 12 dB less in energy per bit for the same performance as a SISO system. Our results are also significantly better than outage probability JSCC schemes used by other authors. The joint source-channel coding (JSCC) scheme demonstrates that MIMO OFDM can achieve real-time high quality video transmission in low energy regions and the system is robust against the delay spread and Doppler frequency shift.

Real-Time Video Transmission over MIMO OFDM Channels Using Space-Time Block Codes

With the increase of remote sensing images, fast access to some features of the image is becoming critical This access could be some part of the spectrum, some area of the image, high spatial resolution An adaptation of 3D-SPIHT image compression algorithm is presented to allow random access to some part of the image, whether spatial or spectral Resolution scalability is also available, enabling the decoding of different resolution images from the compressed bitstream of the hyperspectral data Final spatial and spectral resolutions are chosen independently From the same compressed bitstream, various resolutions and quality images can be extracted while reading a minimum amount of bits from the coded data All this is done while reducing the memory necessary during the compression

/pdf/three-dimensional-spiht-coding-of-hyperspectral-images-with-4pvi3tk1pi.pdf

Three-dimensional SPIHT Coding of Hyperspectral Images with Random Access and Resolution Scalability

We address multiresolutional encoding and decoding within the embedded zerotree wavelet (EZW) framework for both images and video By varying a resolution parameter, one can obtain decoded images at different resolutions from one single encoded bitstream, which is already rate scalable for EZW coders Similarly one can decode video sequences at different rates and different spatial and temporal resolutions from one bitstream Furthermore, a layered bitstream can be generated with multiresolutional encoding, from which the higher resolution layers can be used to increase the spatial/temporal resolution of the images/video obtained from the low resolution layer In other words, we have achieved full scalability in rate and partial scalability in space and time This added spatial/temporal scalability is significant for emerging multimedia applications such as fast decoding, image/video database browsing, telemedicine, multipoint video conferencing, and distance learning

William A. Pearlman

Papers

Hexagonal subband image coding with perceptual weighting

Progressive Significance Map and Its Application to Error-Resilient Image Transmission

Real-Time Video Transmission over MIMO OFDM Channels Using Space-Time Block Codes

Three-dimensional SPIHT Coding of Hyperspectral Images with Random Access and Resolution Scalability

Multiresolutional encoding and decoding in embedded image and video coders