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

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

We investigate conditional adversarial networks as a general-purpose solution to image-to-image translation problems. These networks not only learn the mapping from input image to output image, but also learn a loss function to train this mapping. This makes it possible to apply the same generic approach to problems that traditionally would require very different loss formulations. We demonstrate that this approach is effective at synthesizing photos from label maps, reconstructing objects from edge maps, and colorizing images, among other tasks. Moreover, since the release of the pix2pix software associated with this paper, hundreds of twitter users have posted their own artistic experiments using our system. As a community, we no longer hand-engineer our mapping functions, and this work suggests we can achieve reasonable results without handengineering our loss functions either.

/pdf/image-to-image-translation-with-conditional-adversarial-5058t24et2.pdf

Image-to-Image Translation with Conditional Adversarial Networks

We investigate conditional adversarial networks as a general-purpose solution to image-to-image translation problems. These networks not only learn the mapping from input image to output image, but also learn a loss function to train this mapping. This makes it possible to apply the same generic approach to problems that traditionally would require very different loss formulations. We demonstrate that this approach is effective at synthesizing photos from label maps, reconstructing objects from edge maps, and colorizing images, among other tasks. Indeed, since the release of the pix2pix software associated with this paper, a large number of internet users (many of them artists) have posted their own experiments with our system, further demonstrating its wide applicability and ease of adoption without the need for parameter tweaking. As a community, we no longer hand-engineer our mapping functions, and this work suggests we can achieve reasonable results without hand-engineering our loss functions either.

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The theoretical vertical horopter is a line passing through the fixation point and perpendicular to the horizontal plane, when the fixation is symmetric and on the horizontal median plane. However, the empirical vertical horopter measured psychophysically deviates from the true vertical, as its top inclines backward with an angle. Thus the two corresponding retinal images of the empirical vertical horopter also deviate from the theoretical corresponding vertical meridians of the two eyes. The average angle between the two empirical vertical meridians is 2 deg, which is called the Helmholtz shear of empirical vertical meridians. Explanations were proposed that this shear has an ecological value by bringing the ground to vertical horopter to aid in navigating the world. Further evidence was found in cats and owls. They have a much larger shear than humans, which matches their typical height and fixation distance.

Relationship between the Helmholtz shear of vertical meridians and disparity statistics in natural scenes

The receptive field profiles of certain simple cells in the visual cortex have recently been shown to approximate the 2-D Gabor functions, which are Gaussian-modulated sinusoidal gratings in the space domain, and shifted Gaussians in the frequency domain (Marcelja 1980; Daugman 1980,1985). The 2-D Gabor functions minimize the space-frequency uncertainty principle, and hence can be defined with narrow frequency and orientation responses while maintaining spatial localization. Physiological evidence indicates that the Gabor receptive fields are often arranged in quadrature pairs (Pollen and Ronner 1981) allowing a novel interpretation of early visual processing whereby highly frequency- or orientation-specific information can be recovered from the ampUtude or phase envelopes of a set of Gabor-filtered images. In particular, this leads to an interpretation of texture as a surface code from which physical information can be derived via appropriate filtering/ demodulation processes.

Experiments with a theory of visual texture segmentation using modulation/demodulation processes

Generalized Deterministic Annealing (GDA) is a useful new tool for computing fast multi-state combinatorial optimization of difficult non-convex problems. By estimating the stationary distribution of simulated annealing (SA), GDA yields equivalent solutions to practical SA algorithms while providing a significant speed improvement. Using the standard GDA, the computational time of SA may be reduced by an order of magnitude, and, with a new implementation improvement, Windowed GDA, the time improvements reach two orders of magnitude with a trivial compromise in solution quality. The fast optimization of GDA has enabled expeditious computation of complex nonlinear image enhancement paradigms, such as the Piecewise Constant (PICO) regression examples used in this paper. To validate our analytical results, we apply GDA to the PICO regression problem and compare the results to other optimization methods. Several full image examples are provided that show successful PICO image enhancement using GDA in the presence of both Laplacian and Gaussian additive noise.

Fast combinatorial optimization using generalized deterministic annealing

We present an overview of AM-FM image analysis techniques. Many nonstationary textured images are multi-partite, and may be considered to comprise several locally narrowband components. We introduce a multi-component AM-FM model useful in describing such images, and show that the components may be demodulated on a spatially local basis using multiband filtering followed by a computationally efficient nonlinear algorithm. We outline practical approaches both for estimating the locally dominant image frequencies and for computing a full AM-FM image representation. Finally, we discuss how the estimated frequencies may be used to compute flow lines.

/pdf/am-fm-image-analysis-techniques-4mx60gyzt7.pdf

Alan C. Bovik

Papers

Relationship between the Helmholtz shear of vertical meridians and disparity statistics in natural scenes

Experiments with a theory of visual texture segmentation using modulation/demodulation processes

Fast combinatorial optimization using generalized deterministic annealing

AM-FM image analysis techniques

Chromaticity as a source of information in the human stereo correspondence process.