- Automatic Refinement Strategies for Manual Initialization of Object Trackers. [Journal Article]
- ITIEEE Trans Image Process 2016 Dec 01
- Tracking objects across multiple frames is a wellinvestigated problem in computer vision. The majority of the existing algorithms assume an accurate initialization is readily available. However, in m...
Tracking objects across multiple frames is a wellinvestigated problem in computer vision. The majority of the existing algorithms assume an accurate initialization is readily available. However, in many real-life settings, in particular for applications where the video is streaming in real-time, the initialization has to be provided by a human operator. This limitation raises an inevitable uncertainty issue. Here, we first collect a large and new dataset of inputs that consists of more than 20K human initialization clicks, called as HIC, by several subjects under three practical user interface scenarios for the popular TB50 tracking benchmark. We analyze the factors and mechanisms of human input, derive statistical models, and show that human input always contains deviations, which exacerbate further when the relative objectcamera motion becomes large. We also design and evaluate alternative refinement schemes, and propose a strategy that refits an object window on the most probable target region after a single click. To compensate for the human initialization errors, our method generates window proposals using objectness cues extracted from color and motion attributes, accumulates them into a likelihood map that is weighted by the initial click position and visual saliency scores, and assigns the final window by the maximum likelihood estimate. Our experiments demonstrate that the presented refinement strategy effectively reduces human input errors.
- The colors of paintings and viewers' preferences. [Journal Article]
- VRVision Res 2016 Nov 29
- One hypothesis to explain the aesthetics of paintings is that it depends on the extent to which they mimic natural image statistics. In fact, paintings and natural scenes share several statistical im...
One hypothesis to explain the aesthetics of paintings is that it depends on the extent to which they mimic natural image statistics. In fact, paintings and natural scenes share several statistical image regularities but the colors of paintings seem generally more biased towards red than natural scenes. Is the particular option for colors in each painting, even if less naturalistic, critical for perceived beauty? Here we show that it is. In the experiments, 50 naïve observers, unfamiliar with the 10 paintings tested, could rotate the color gamut of the paintings and select the one producing the best subjective impression. The distributions of angles obtained are described by normal distributions with maxima deviating, on average, only 7 degrees from the original gamut orientation and full width at half maximum just above the threshold to perceive a chromatic change in the paintings. Crucially, for data pooled across observers and abstract paintings the maximum of the distribution was at zero degrees, i.e., the same as the original. This demonstrates that artists know what chromatic compositions match viewers' preferences and that the option for less naturalistic colors does not constraint the aesthetic value of paintings.
- Uveal melanoma: relatively rare but deadly cancer. [Review]
- EEye (Lond) 2016 Dec 02
- Although it is a relatively rare disease, primarily found in the Caucasian population, uveal melanoma is the most common primary intraocular tumor in adults with a mean age-adjusted incidence of 5.1 ...
Although it is a relatively rare disease, primarily found in the Caucasian population, uveal melanoma is the most common primary intraocular tumor in adults with a mean age-adjusted incidence of 5.1 cases per million per year. Tumors are located either in iris (4%), ciliary body (6%), or choroid (90%). The host susceptibility factors for uveal melanoma include fair skin, light eye color, inability to tan, ocular or oculodermal melanocytosis, cutaneous or iris or choroidal nevus, and BRCA1-associated protein 1 mutation. Currently, the most widely used first-line treatment options for this malignancy are resection, radiation therapy, and enucleation. There are two main types of radiation therapy: plaque brachytherapy (iodine-125, ruthenium-106, or palladium-103, or cobalt-60) and teletherapy (proton beam, helium ion, or stereotactic radiosurgery using cyber knife, gamma knife, or linear accelerator). The alternative to radiation is enucleation. Although these therapies achieve satisfactory local disease control, long-term survival rate for patients with uveal melanoma remains guarded, with risk for liver metastasis. There have been advances in early diagnosis over the past few years, and with the hope survival rates could improve as smaller tumors are treated. As in many other cancer indications, both early detection and early treatment could be critical for a positive long-term survival outcome in uveal melanoma. These observations call attention to an unmet medical need for the early treatment of small melanocytic lesions or small melanomas in the eye to achieve local disease control and vision preservation with the possibility to prevent metastases and improve overall patient survival.Eye advance online publication, 2 December 2016; doi:10.1038/eye.2016.275.
- Group benefit associated with polymorphic trichromacy in a Malagasy primate (Propithecus verreauxi). [Journal Article]
- SRSci Rep 2016 Dec 02; 6:38418
- In some primate lineages, polymorphisms in the X-linked M/LWS opsin gene have produced intraspecific variation in color vision. In these species, heterozygous females exhibit trichromacy, while males...
In some primate lineages, polymorphisms in the X-linked M/LWS opsin gene have produced intraspecific variation in color vision. In these species, heterozygous females exhibit trichromacy, while males and homozygous females exhibit dichromacy. The evolutionary persistence of these polymorphisms suggests that balancing selection maintains color vision variation, possibly through a 'trichromat advantage' in detecting yellow/orange/red foods against foliage. We identified genetic evidence of polymorphic trichromacy in a population of Verreaux's sifaka (Propithecus verreauxi) at Kirindy Mitea National Park in Madagascar, and explored effects of color vision on reproductive success and feeding behavior using nine years of morphological, demographic, and feeding data. We found that trichromats and dichromats residing in social groups with trichromats exhibit higher body mass indices than individuals in dichromat-only groups. Additionally, individuals in a trichromat social group devoted significantly more time to fruit feeding and had longer fruit feeding bouts than individuals in dichromat-only groups. We hypothesize that, due to small, cohesive sifaka social groups, a trichromat advantage in detecting productive fruit patches during the energetically stressful dry season also benefits dichromats in a trichromat's group. Our results offer the first support for the 'mutual benefit of association' hypothesis regarding the maintenance of polymorphic trichromacy in primates.
- A high resolution IR/visible imaging system for the W7-X limiter. [Journal Article]
- RSRev Sci Instrum 2016; 87(11):11D607
- A high-resolution imaging system, consisting of megapixel mid-IR and visible cameras along the same line of sight, has been prepared for the new W7-X stellarator and was operated during Operational P...
A high-resolution imaging system, consisting of megapixel mid-IR and visible cameras along the same line of sight, has been prepared for the new W7-X stellarator and was operated during Operational Period 1.1 to view one of the five inboard graphite limiters. The radial line of sight, through a large diameter (184 mm clear aperture) uncoated sapphire window, couples a direct viewing 1344 × 784 pixel FLIR SC8303HD camera. A germanium beam-splitter sends visible light to a 1024 × 1024 pixel Allied Vision Technologies Prosilica GX1050 color camera. Both achieve sub-millimeter resolution on the 161 mm wide, inertially cooled, segmented graphite tiles. The IR and visible cameras are controlled via optical fibers over full Camera Link and dual GigE Ethernet (2 Gbit/s data rates) interfaces, respectively. While they are mounted outside the cryostat at a distance of 3.2 m from the limiter, they are close to a large magnetic trim coil and require soft iron shielding. We have taken IR data at 125 Hz to 1.25 kHz frame rates and seen that surface temperature increases in excess of 350 °C, especially on leading edges or defect hot spots. The IR camera sees heat-load stripe patterns on the limiter and has been used to infer limiter power fluxes (∼1-4.5 MW/m(2)), during the ECRH heating phase. IR images have also been used calorimetrically between shots to measure equilibrated bulk tile temperature, and hence tile energy inputs (in the range of 30 kJ/tile with 0.6 MW, 6 s heating pulses). Small UFO's can be seen and tracked by the FLIR camera in some discharges. The calibrated visible color camera (100 Hz frame rate) has also been equipped with narrow band C-III and H-alpha filters, to compare with other diagnostics, and is used for absolute particle flux determination from the limiter surface. Sometimes, but not always, hot-spots in the IR are also seen to be bright in C-III light.
- Vanishing point attracts gaze in free-viewing and visual search tasks. [Journal Article]
- JVJ Vis 2016 Nov 01; 16(14):18
- Several structural scene cues such as gist, layout, horizontal line, openness, and depth have been shown to guide scene perception (e.g., Oliva & Torralba, 2001); Ross & Oliva, 2009). Here, to invest...
Several structural scene cues such as gist, layout, horizontal line, openness, and depth have been shown to guide scene perception (e.g., Oliva & Torralba, 2001); Ross & Oliva, 2009). Here, to investigate whether vanishing point (VP) plays a significant role in gaze guidance, we ran two experiments. In the first one, we recorded fixations of 10 observers (six male, four female; mean age 22; SD = 0.84) freely viewing 532 images, out of which 319 had a VP (shuffled presentation; each image for 4 s). We found that the average number of fixations at a local region (80 × 80 pixels) centered at the VP is significantly higher than the average fixations at random locations (t test; n = 319; p < 0.001). To address the confounding factor of saliency, we learned a combined model of bottom-up saliency and VP. The AUC (area under curve) score of our model (0.85; SD = 0.01) is significantly higher than the base saliency model (e.g., 0.8 using attention for information maximization (AIM) model by Bruce & Tsotsos, 2005, t test; p = 3.14e-16) and the VP-only model (0.64, t test; p < 0.001). In the second experiment, we asked 14 subjects (six male, four female; mean age 23.07, SD = 1.26) to search for a target character (T or L) placed randomly on a 3 × 3 imaginary grid overlaid on top of an image. Subjects reported their answers by pressing one of the two keys. Stimuli consisted of 270 color images (180 with a single VP, 90 without). The target happened with equal probability inside each cell (15 times L, 15 times T). We found that subjects were significantly faster (and more accurate) when the target appeared inside the cell containing the VP compared to cells without the VP (median across 14 subjects 1.34 s vs. 1.96 s; Wilcoxon rank-sum test; p = 0.0014). These findings support the hypothesis that vanishing point, similar to face, text (Cerf, Frady, & Koch, 2009), and gaze direction Borji, Parks, & Itti, 2014) guides attention in free-viewing and visual search tasks.
- MACULAR PERIVENOUS RETINAL WHITENING AND PRESUMED RETINO-CILIARY SPARING IN A RECURRENT CENTRAL RETINAL VEIN OCCLUSION ASSOCIATED WITH THE ANTIPHOSPHOLIPID SYNDROME AND CRYOGLOBULINEMIA. [Journal Article]
- RCRetin Cases Brief Rep 2016 Nov 29
- CONCLUSIONS: Macular perivenous retinal whitening should be considered in the differential diagnosis of retinal whitening and occurs in CRVO secondary to hypoperfusion-induced middle retinal ischemia. To our knowledge, this case represents the first description of retino-ciliary venous sparing of the retina in CRVO.
- Erratum: Perceived image quality with simulated segmented bifocal corrections: publisher's note. [Published Erratum]
- BOBiomed Opt Express 2016 Nov 1; 7(11):4620
- [This corrects the article on p. 4388 in vol. 7.].
[This corrects the article on p. 4388 in vol. 7.].
- Perceived image quality with simulated segmented bifocal corrections. [Journal Article]
- BOBiomed Opt Express 2016 Nov 1; 7(11):4388-4399
- Bifocal contact or intraocular lenses use the principle of simultaneous vision to correct for presbyopia. A modified two-channel simultaneous vision simulator provided with an amplitude transmission ...
Bifocal contact or intraocular lenses use the principle of simultaneous vision to correct for presbyopia. A modified two-channel simultaneous vision simulator provided with an amplitude transmission spatial light modulator was used to optically simulate 14 segmented bifocal patterns (+ 3 diopters addition) with different far/near pupillary distributions of equal energy. Five subjects with paralyzed accommodation evaluated image quality and subjective preference through the segmented bifocal corrections. There are strong and systematic perceptual differences across the patterns, subjects and observation distances: 48% of the conditions evaluated were significantly preferred or rejected. Optical simulations (in terms of through-focus Strehl ratio from Hartmann-Shack aberrometry) accurately predicted the pattern producing the highest perceived quality in 4 out of 5 patients, both for far and near vision. These perceptual differences found arise primarily from optical grounds, but have an important neural component.
New Search Next
- Nest covering in plovers: How modifying the visual environment influences egg camouflage. [Journal Article]
- EEEcol Evol 2016; 6(20):7536-7545
- Camouflage is one of the most widespread antipredator defences, and its mechanistic basis has attracted considerable interest in recent years. The effectiveness of camouflage depends on the interacti...
Camouflage is one of the most widespread antipredator defences, and its mechanistic basis has attracted considerable interest in recent years. The effectiveness of camouflage depends on the interaction between an animal's appearance and its background. Concealment can therefore be improved by changes to an animal's own appearance, by behaviorally selecting an optimal background, or by modifying the background to better match the animal's own appearance. Research to date has largely focussed on the first of these mechanisms, whereas there has been little work on the second and almost none on the third. Even though a number of animal species may potentially modify their environment to improve individual-specific camouflage, this has rarely if ever been quantitatively investigated, or its adaptive value tested. Kittlitz's plovers (Charadrius pecuarius) use material (stones and vegetation) to cover their nests when predators approach, providing concealment that is independent of the inflexible appearance of the adult or eggs, and that can be adjusted to suit the local surrounding background. We used digital imaging and predator vision modeling to investigate the camouflage properties of covered nests, and whether their camouflage affected their survival. The plovers' nest-covering materials were consistent with a trade-off between selecting materials that matched the color of the eggs, while resulting in poorer nest pattern and contrast matching to the nest surroundings. Alternatively, the systematic use of materials with high-contrast and small-pattern grain sizes could reflect a deliberate disruptive coloration strategy, whereby high-contrast material breaks up the telltale outline of the clutch. No camouflage variables predicted nest survival. Our study highlights the potential for camouflage to be enhanced by background modification. This provides a flexible system for modifying an animal's conspicuousness, to which the main limitation may be the available materials rather than the animal's appearance.