Macromolecules comprise only 2% of vitreous, yet are responsible for its gel state, transparency, and physiologic function(s) within the eye. Myopia and aging alter collagen and hyaluronan ...association causing concurrent gel liquefaction and fibrous degeneration. The resulting vitreous opacities and collapse of the vitreous body during posterior vitreous detachment are the most common causes for the visual phenomenon of vitreous floaters. Previously considered innocuous, the vitreous opacities that cause floaters sometimes impact vision by profoundly degrading contrast sensitivity function and impairing quality-of-life. While many people adapt to vitreous floaters, clinically significant cases can be diagnosed with Vision Degrading Myodesopsia based upon echographic assessment of vitreous structure and by measuring contrast sensitivity function. Perhaps due to the ubiquity of floaters, the medical profession has to date largely ignored the plight of those with Vision Degrading Myodesopsia. Improved diagnostics will enable better disease staging and more accurate identification of severe cases that merit therapy. YAG laser treatments may occasionally be slightly effective, but vitrectomy is currently the definitive cure. Future developments will usher in more informative diagnostic approaches as well as safer and more effective therapeutic strategies. Improved laser treatments, new pharmacotherapies, and possibly non-invasive optical corrections are exciting new approaches to pursue. Ultimately, enhanced understanding of the underlying pathogenesis of Vision Degrading Myodesopsia should result in prevention, the ultimate goal of modern Medicine.
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•Vitreous fills the center of the eye with a clear solid gel during youth.•Myopia in youth and posterior vitreous detachment in aging cause vitreous floaters.•Degradation in contrast sensitivity function impacts vision and quality of life.•Vitrectomy normalizes vision and improves quality of life cost-effectively.•Laser therapies or pharmacologic vitreolysis might replace surgery in the future.
Recent development of the quick contrast sensitivity function (qCSF) method has made it possible to obtain accurate, precise, and efficient contrast sensitivity function (CSF) assessment. To improve ...statistical inference on CSF changes in a within-subject design, we developed a hierarchical Bayesian model (HBM) to compute the joint distribution of CSF parameters and hyperparameters at test, subject, and population levels, utilizing information within- and between-subjects and experimental conditions. We evaluated the performance of the HBM relative to a non-hierarchical Bayesian inference procedure (BIP) on an existing CSF dataset of 112 subjects obtained with the qCSF method in three luminance conditions (Hou, Lesmes, Kim, Gu, Pitt, Myung, & Lu, 2016). We found that the average d's of the area under log CSF (AULCSF) and CSF parameters between pairs of luminance conditions at the test-level from the HBM were 33.5% and 103.3% greater than those from the BIP analysis of AULCSF. The increased d' resulted in greater statistical differences between experimental conditions across subjects. In addition, simulations showed that the HBM generated accurate and precise CSF parameter estimates. These results have strong implications for the application of HBM in clinical trials and patient care.
High-bit images can show more detail than low-bit images do. False contours in the low-bit images should be suppressed when converting low-bit images to high-bit ones. In this paper, a contrast-aware ...bit depth enhancement (BDE) module is proposed based on the visual perceptual feature which models the relationship of contrast sensitivity and image bit depth. And a bit depth enhancement network is constructed by the cascade of this module. The experimental results show that the bit depth enhancement algorithm based on this network structure has the best or second-best peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) metrics when compared with the related algorithms, and on average, our PSNR (40.20 dB) is only 1.03% and SSIM (0.9681) is only 0.11% lower than that of the state-of-the-arts, but uses 6.7% fewer parameters (11.2M). And visual comparisons show that our algorithm can effectively suppress false contours and color distortions, resulting in high-bit images with better quality.
•Apply contrast sensitivity function (CSF) to bit-depth enhancement.•Propose a contrast-aware bit-depth enhancement (BDE) module.•Propose a lightweight bit-depth enhancement algorithm.
The size of the pupil has a large effect on visual function, and pupil size depends mainly on the adapting luminance, modulated by other factors. Over the last century, a number of formulas have been ...proposed to describe this dependence. Here we review seven published formulas and develop a new unified formula that incorporates the effects of luminance, size of the adapting field, age of the observer, and whether one or both eyes are adapted. We provide interactive demonstrations and software implementations of the unified formula.
In this paper, we propose a method to reduce a flicker (1/f) noise upconversion in voltage-biased RF oscillators. Excited by a harmonically rich tank current, a typical oscillation voltage waveform ...is observed to have asymmetric rise and fall times due to even-order current harmonics flowing into the capacitive part, as it presents the lowest impedance path. The asymmetric oscillation waveform results in an effective impulse sensitivity function of a nonzero dc value, which facilitates the 1/f noise upconversion into the oscillator's 1/f3 phase noise. We demonstrate that if the ω 0 tank exhibits an auxiliary resonance at 2ω 0 , thereby forcing this current harmonic to flow into the equivalent resistance of the 2ω 0 resonance, then the oscillation waveform would be symmetric and the flicker noise upconversion would be largely suppressed. The auxiliary resonance is realized at no extra silicon area in both inductor-and transformer-based tanks by exploiting different behaviors of inductors and transformers in differential-and common-mode excitations. These tanks are ultimately employed in designing modified class-D and class-F oscillators in 40 nm CMOS technology. They exhibit an average flicker noise corner of less than 100 kHz.
This paper presents a millimeter-wave (mmW) frequency generation stage aimed at minimizing phase noise (PN) via waveform shaping and harmonic extraction while suppressing flicker noise upconversion ...via proper harmonic terminations. A 2nd-harmonic resonance is assisted by a proposed embedded decoupling capacitor inside a transformer for explicit common-mode current return path. Class-F operation with 3rd-harmonic boosting and extraction techniques allow maintaining high quality factor of a 10-GHz tank at the 30-GHz frequency generation. We further propose a comprehensive quantitative analysis method of flicker noise upconversion mechanism exploiting latest insights into the flicker noise mechanisms in nanoscale short-channel transistors, and it is numerically verified against foundry models. The proposed 27.3to 31.2-GHz oscillator is implemented in TSMC 28-nm CMOS. It achieves PN of -106 dBc/Hz at 1-MHz offset and figure-of-merit (FoM) of -184 dBc/Hz at 27.3 GHz. Its flicker phase-noise (1/f 3 ) corner of 120 kHz is an order-of-magnitude better than currently achievable at mmW.
•A method of designing robust superdirective beamformers for arbitrary sensor arrays is proposed.•The optimal weighting vector is transformed into an equivalent form based on the eigen–decomposition ...of the noise correlation matrix.•The beampattern, directivity factor, and error sensitivity function can be expressed as functions of the parameter.•The closed–form expression of the parameter can be derived given a desired directivity factor or error sensitivity function.•The proposed method provides flexible schemes to designing robust broadband superdirective beamformers for arbitrary arrays in simulations and experiments.
This paper presents a method of designing robust superdirective beamformers for arbitrary sensor arrays. First, the optimal weighting vector is transformed into an equivalent form based on the eigen–decomposition of the noise correlation matrix in an isotropic uniform noise field, and its entries will be indexed using mode orders instead of element numbers. Second, a parameter is weighted at the maximum–order entry in the modified weighting vector. The beampattern, directivity factor, and error sensitivity function can be expressed as functions of the parameter. Adjusting the parameter will achieve arbitrary–order superdirective beampatterns with different directivity factors or error sensitivity functions. Third, the closed–form expression of the parameter can be derived given a desired directivity factor or error sensitivity function. The final robust broadband superdirective beampatterns can then be readily synthesized. The proposed method, which is an extension of that previously proposed for circular sensor arrays, provides flexible schemes to designing robust broadband superdirective beamformers for arbitrary arrays in simulations and experiments.
This paper presents a hyperspectral image (HSI) reconstruction technique based on physics-driven optimization of multispectral filter array (MSFA) patterns. The encoding of HSIs using an MSFA and ...their decoding through deep learning has gained increasing attention. However, previous studies have seldom explored pattern optimization from a physical perspective during the encoding process. In this paper, we apply a spectral sensitivity function (SSF) response model to generate the MSFA, and the goal of encoder optimization extends from SSF to physical structural parameters. To fully utilize spatial and spectral information in the decoding process, we design an end-to-end dual-branch spatial-spectral fusion network (DSFNet). By jointly optimizing the MSFA with the SSF response model and DSFNet, the proposed method significantly improves the reconstruction accuracy of HSI. When compared with existing HSI reconstruction methods, our proposed approach achieves state-of-the-art performance in both metric and visual quality.
Objective quality assessment of distorted stereoscopic images is a challenging problem, especially when the distortions in the left and right views are asymmetric. Existing studies suggest that ...simply averaging the quality of the left and right views well predicts the quality of symmetrically distorted stereoscopic images, but generates substantial prediction bias when applied to asymmetrically distorted stereoscopic images. In this paper, we first build a database that contains both single-view and symmetrically and asymmetrically distorted stereoscopic images. We then carry out a subjective test, where we find that the quality prediction bias of the asymmetrically distorted images could lean toward opposite directions (overestimate or underestimate), depending on the distortion types and levels. Our subjective test also suggests that eye dominance effect does not have strong impact on the visual quality decisions of stereoscopic images. Furthermore, we develop an information content and divisive normalization-based pooling scheme that improves upon structural similarity in estimating the quality of single-view images. Finally, we propose a binocular rivalry-inspired multi-scale model to predict the quality of stereoscopic images from that of the single-view images. Our results show that the proposed model, without explicitly identifying image distortion types, successfully eliminates the prediction bias, leading to significantly improved quality prediction of the stereoscopic images.
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