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Author

Alan C. Bovik

Bio: Alan C. Bovik is an academic researcher from University of Texas at Austin. The author has contributed to research in topics: Image quality & Video quality. The author has an hindex of 102, co-authored 837 publications receiving 96088 citations. Previous affiliations of Alan C. Bovik include University of Illinois at Urbana–Champaign & University of Sydney.


Papers
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Journal ArticleDOI
TL;DR: A systematic evaluation of ‘visually lossless’ (VL) threshold selection for H.264/AVC (Advanced Video Coding) compressed natural videos spanning a wide range of content and motion shows a mapping from ‘perceptually relevant’ statistical video features that capture visual lossless-ness, to statistically determined VL threshold.
Abstract: We performed a systematic evaluation of ‘visually lossless’ (VL) threshold selection for H.264/AVC (Advanced Video Coding) compressed natural videos spanning a wide range of content and motion. A psychovisual study was conducted using a two alternative forced choice task design, where by a series of reference vs. compressed video pairs were displayed to the subjects, where bit rates were varied to achieve a spread in the amount of compression. A statistical analysis was conducted on these data to estimate the VL threshold. Based on the visual thresholds estimated from the observed human ratings, we learn a mapping from ‘perceptually relevant’ statistical video features that capture visual lossless-ness, to statistically determined VL threshold. Using this VL threshold, we derive an H.264 compressibility index. This new Compressibility Index is shown to correlate well with human subjective judgments of VL thresholds. We have also made the code for compressibility index available online (Moorthy, A.K. and Bovik, A.C. (2010). H.264 Visually Lossless Compressibility Index (HVLCI), Software Release. http://live.ece.utexas.edu/research/quality/hvlci.zip.) for its use in practical applications and facilitate future research in this area.

9 citations

Proceedings ArticleDOI
13 Nov 1994
TL;DR: The technique of serial optical sectioning by laser scanning confocal microscopy (LSCM), in conjunction with off-line digital image analysis, was used to quantize the morphological changes occurring during angiogenesis and revascularization of pancreatic islets transplanted at the renal subcapsular site in rats.
Abstract: The technique of serial optical sectioning by laser scanning confocal microscopy (LSCM), in conjunction with off-line digital image analysis, was used to quantize the morphological changes occurring during angiogenesis and revascularization of pancreatic islets transplanted at the renal subcapsular site in rats. The process consisted of in-vivo imaging of the microvasculature which was optically enhanced by the administration of a fluorescent probe into the circulating blood. Serial two-dimensional (2-D) optical sections were obtained through the vascular bed at varying z-intervals in order to perform a computer reconstruction of the complete three-dimensional (3-D) morphology. Image processing algorithms such as gray level thresholding, median filtering, skeletonization, region labeling and template matching were applied to compute the vessel density, lengths and diameters of the neovasculature, and the tortuosity index. >

9 citations

Proceedings ArticleDOI
03 Nov 1996
TL;DR: A new theory of multidimensional AM- FM image modeling is presented and algorithms for extracting AM-FM sub-image information from digital images and dramatic examples where the essential structure of natural images is successfully recovered from their computed Am-FM representations are presented.
Abstract: We present a new theory of multidimensional AM-FM image modeling and derive algorithms for extracting AM-FM sub-image information from digital images. In contrast to Fourier components, AM-FM image functions admit arbitrarily varying amplitude and phase modulations. Thus, they are inherently capable of efficiently capturing essential nonstationary image structures. Often, such nonstationarities contribute significantly to visual perception and interpretation. We describe a practical approach for computing AM-FM image representations using nonlinear demodulation operators. A Gabor filterbank isolates components locally, and optimal filters based on a statistical state-space component model are used to trade image multi-components across the filterbank channel responses. We present dramatic examples where the essential structure of natural images is successfully recovered from their computed AM-FM representations.

9 citations

Proceedings ArticleDOI
03 Jul 2013
TL;DR: It is conjecture that sufficiently fast and coherent motions near the gaze point mask or `silence' the perception of flicker distortions in naturalistic videos in agreement with a recently observed `motion silencing' effect on synthetic stimuli.
Abstract: Motion can reduce the visibility of flicker distortions. We performed human subjective tests to investigate how motion influences the visibility of flicker distortions in naturalistic videos. Forty three naive subjects participated in two tasks (“follow the moving object” and “view freely”) and reported their percepts on 36 test videos. Flicker distortions were simulated by periodic changes of video frames at different quality levels and flicker frequencies. An eye tracker was used to monitor each subject's gaze. The results indicate that the visibility of flicker distortions is strongly reduced when the speed of coherent motion is large, and the effect is more pronounced when the video quality is poor. We conjecture that sufficiently fast and coherent motions near the gaze point mask or `silence' the perception of flicker distortions in naturalistic videos in agreement with a recently observed `motion silencing' effect on synthetic stimuli.

9 citations

Posted Content
TL;DR: This work constructs a proxy network, which mimics the perceptual model while serving as a loss layer of the network, and experimentally demonstrates how this optimization framework can be applied to train an end-to-end optimized image compression network.
Abstract: Mean squared error (MSE) and $\ell_p$ norms have largely dominated the measurement of loss in neural networks due to their simplicity and analytical properties However, when used to assess visual information loss, these simple norms are not highly consistent with human perception Here, we propose a different proxy approach to optimize image analysis networks against quantitative perceptual models Specifically, we construct a proxy network, which mimics the perceptual model while serving as a loss layer of the networkWe experimentally demonstrate how this optimization framework can be applied to train an end-to-end optimized image compression network By building on top of a modern deep image compression models, we are able to demonstrate an averaged bitrate reduction of $287\%$ over MSE optimization, given a specified perceptual quality (VMAF) level

9 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, a structural similarity index is proposed for image quality assessment based on the degradation of structural information, which can be applied to both subjective ratings and objective methods on a database of images compressed with JPEG and JPEG2000.
Abstract: 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/.

40,609 citations

Book
01 Jan 1998
TL;DR: An introduction to a Transient World and an Approximation Tour of Wavelet Packet and Local Cosine Bases.
Abstract: 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.

17,693 citations

Proceedings ArticleDOI
21 Jul 2017
TL;DR: Conditional adversarial networks are investigated as a general-purpose solution to image-to-image translation problems and it is demonstrated that this approach is effective at synthesizing photos from label maps, reconstructing objects from edge maps, and colorizing images, among other tasks.
Abstract: 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.

11,958 citations

Posted Content
TL;DR: Conditional Adversarial Network (CA) as discussed by the authors is a general-purpose solution to image-to-image translation problems, which can be used to synthesize photos from label maps, reconstructing objects from edge maps, and colorizing images, among other tasks.
Abstract: 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.

11,127 citations

Journal ArticleDOI
01 Apr 1988-Nature
TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: 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

9,929 citations