381 research outputs found

    Understanding images in biological and computer vision

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    yesThis issue of Interface Focus is a collection of papers arising out of a Royal Society Discussion meeting entitled ‘Understanding images in biological and computer vision’ held at Carlton Terrace on the 19th and 20th February, 2018. There is a strong tradition of inter-disciplinarity in the study of visual perception and visual cognition. Many of the great natural scientists including Newton [1], Young [2] and Maxwell (see [3]) were intrigued by the relationship between light, surfaces and perceived colour considering both physical and perceptual processes. Brewster [4] invented both the lenticular stereoscope and the binocular camera but also studied the perception of shape-from-shading. More recently, Marr's [5] description of visual perception as an information processing problem led to great advances in our understanding of both biological and computer vision: both the computer vision and biological vision communities have a Marr medal. The recent successes of deep neural networks in classifying the images that we see and the fMRI images that reveal the activity in our brains during the act of seeing are both intriguing. The links between machine vision systems and biology may at sometimes be weak but the similarity of some of the operations is nonetheless striking [6]. This two-day meeting brought together researchers from the fields of biological and computer vision, robotics, neuroscience, computer science and psychology to discuss the most recent developments in the field. The meeting was divided into four themes: vision for action, visual appearance, vision for recognition and machine learning

    Learning a 3-D Visual Light Field: Effects of Exploration on Lightness Constancy

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    The pattern of light across a scene is determined by the lighting, the material properties of objects in the scene, and the three- dimensional (3-D) scene structure. The problem of determining the material properties of an object is therefore a complex one. To do this correctly the relationship between 3-D scene structure and lighting must be understood by the viewer. In this paper we describe experiments which evaluate how exploration of the lightfield [1] within the scene aids the estimation of surface lightness (albedo). We find that the experience of viewing a block moving throughout the 3D scene - illustrating the variations in lightfield – results in lightness constancy, i.e. viewers are able to estimate surface albedo under varying illumination. Exploration of the lightfield facilitated albedo recovery as opposed to simple brightness matching. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

    The many colours of ‘the dress’

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    YesThere has been an intense discussion among the public about the colour of a dress, shown in a picture posted originally on Tumblr (http://swiked. tumblr.com/post/112073818575/ guys-please-help-me-is-this-dress white-and; accessed on 10:56 am GMT on Tue 24 Mar 2015). Some people argue that they see a white dress with golden lace, while others describe the dress as blue with black lace. Here we show that the question “what colour is the dress?” has more than two answers.The full text was made available at the end of the publisher's embargo, 14th May 201

    Endovascular management of a pseudo-aneurysm appeared as a post-surgical complication

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    George Emil Palade University of Medicine, Pharmacy, Science and Technology of Targu Mures, The 8th International Medical Congress for Students and Young Doctors, September 24-26, 2020Background. Renal masses are a biologically heterogeneous group of tumors ranging from benign masses to cancers that can be indolent or aggressive. Frequently, tumors are discovered incidentally and are asymptomatic at presentation. All imaging-enhanced solid renal masses are suspicious for renal cell carcinoma. In the case of a renal tumor, the vascular architecture can be modified. The therapeutic behavior is represented by the surgical techniques (total or partial nephrectomy). The most feared complications are severe bleeding that is difficult to control. Case report. We present a 59-year-old patient known with malignant renal tumor, admitted to Cluj-Napoca Oncological Institute. The patient undergoes surgical treatment, which consisted of anterior renal valve resection and tumor mass resection. Shortly after the intervention, the patient had macroscopic hematuria. A CT scan is performed with contrast substance that reveals vascular lesions suggestive of a pseudoaneurysm / renal arteriovenous fistula. The next step is digital angiography by subtraction (DSA) which indicates the presence of pseudoaneurysm in the renal parenchyma incriminated as a cause of hematuria. Considering the patient's age and the possibility of preserving the kidney, the therapeutic option applied is the endovascular treatment that involves the embolization of the aneurysm. By Zellinger approach is performed the catheterization of the right renal artery and the supraselective catheterization of the aneurysm, followed by embolization using a embolic liquid agent as mixture of Lipidiol and Glubran. The exclusion from the circulation of the aneurysm is obtained and the hemorrhagic (hematuric) source is eliminated. At the control injection the aneurysmal formation is complete ocluded, with very good imaging and clinical result. The control angiography after 6 months shows normal renal vascularization. Conclusions. The therapeutic option of performing a nephrectomy is very aggressive for the patient. Due to the interdisciplinary approach, interventional radiology techniques can offer minimally invasive therapeutic solutions, sometimes unique in rescuing patients

    Object knowledge modulates colour appearance

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    We investigated the memory colour effect for colour diagnostic artificial objects. Since knowledge about these objects and their colours has been learned in everyday life, these stimuli allow the investigation of the influence of acquired object knowledge on colour appearance. These investigations are relevant for questions about how object and colour information in high-level vision interact as well as for research about the influence of learning and experience on perception in general. In order to identify suitable artificial objects, we developed a reaction time paradigm that measures (subjective) colour diagnosticity. In the main experiment, participants adjusted sixteen such objects to their typical colour as well as to grey. If the achromatic object appears in its typical colour, then participants should adjust it to the opponent colour in order to subjectively perceive it as grey. We found that knowledge about the typical colour influences the colour appearance of artificial objects. This effect was particularly strong along the daylight axis

    Ambiguity in high definition: Gaze determines physical interpretation of ambiguous rotation even in the absence of a visual context

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    YesPhysical interactions between objects, or between an object and the ground, are amongst the most biologically relevant for live beings. Prior knowledge of Newtonian physics may play a role in disambiguating an object’s movement as well as foveation by increasing the spatial resolution of the visual input. Observers were shown a virtual 3D scene, representing an ambiguously rotating ball translating on the ground. The ball was perceived as rotating congruently with friction, but only when gaze was located at the point of contact. Inverting or even removing the visual context had little influence on congruent judgements compared with the effect of gaze. Counterintuitively, gaze at the point of contact determines the solution of perceptual ambiguity, but independently of visual context. We suggest this constitutes a frugal strategy, by which the brain infers dynamics locally when faced with a foveated input that is ambiguous.J.S. was funded by a College of Life Sciences studentship from the University of Leicester

    Sensitivity to velocity- and disparity based cues to motion-in-depth with and without spared stereopsis in binocular visual impairment

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    YesPurpose: Two binocular sources of information serve motion-in-depth (MID) perception: changes in disparity over time (CD), and interocular velocity differences (IOVD). While CD requires the computation of small spatial disparities, IOVD could be computed from a much lower-resolution signal. IOVD signals therefore might still be available under conditions of binocular vision impairment (BVI) with limited or no stereopsis, e.g. amblyopia. Methods: Sensitivity to CD and IOVD was measured in adults who had undergone therapy to correct optical misalignment or amblyopia in childhood (n=16), as well as normal vision controls with good stereoacuity (n=8). Observers discriminated the interval containing a smoothly-oscillating MID “test” stimulus from a “control” stimulus in a two-interval forced choice (2IFC) paradigm. Results: Of the BVI observers with no static stereoacuity (n=9), one displayed evidence for sensitivity to IOVD only, while there was otherwise no sensitivity for either CD or IOVD in the group. Generally, BVI observers with measurable stereoacuity (n=7) displayed a pattern resembling the control group: showing a similar sensitivity for both cues. A neutral-density (ND) filter placed in front of the fixing eye in a subset of BVI observers did not improve performance. Conclusions: In one BVI observer there was preserved sensitivity to IOVD but not CD, though overall only those BVI observers with at least gross stereopsis were able to detect disparity-based or velocity-based cues to MID. The results imply that these logically distinct information sources are somehow coupled, and in some cases BVI observers with no stereopsis may still retain sensitivity to IOVD.UK Biotechnology and Biological 498 Sciences Research Council (BBSRC): BB/M002543/1 (Alex R. Wade) BB/M001660/1 (Julie 499 M. Harris) and BB/M001210/1 (Marina Bloj

    Bias effects of short- and long-term color memory for unique objects

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    Are objects remembered with a more saturated color? Some of the evidence supporting this statement comes from research using “memory colors”—the typical colors of particular objects, for example, the green of grass. The problematic aspect of these findings is that many different exemplars exist, some of which might exhibit a higher saturation than the one measured by the experimenter. Here we avoid this problem by using unique personal items and comparing long- and short-term color memory matches (in hue, value, and chroma) with those obtained with the object present. Our results, on average, confirm that objects are remembered as more saturated than they are
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