Understanding images in biological and computer vision

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

The many colours of ‘the dress’

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

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

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

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

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

The effect of adherence to spectacle wear on early developing literacy: a longitudinal study based in a large multi-ethnic city, Bradford, UK

YesObjectives: To determine the impact of adherence to spectacle wear on visual acuity (VA) and developing literacy following vision screening at age 4–5 years. Design: Longitudinal study nested within the Born in Bradford birth cohort. Setting and participants: Observation of 944 children: 432 had failed vision screening and were referred (treatment group) and 512 randomly selected (comparison group) who had passed (<0.20 logarithm of the minimum angle of resolution (logMAR) in both eyes). Spectacle wear was observed in school for 2 years following screening and classified as adherent (wearing spectacles at each assessment) or non-adherent. Main outcome measures: Annual measures of VA using a crowded logMAR test. Literacy was measured by Woodcock Reading Mastery Tests-Revised subtest: letter identification. Results: The VA of all children improved with increasing age, −0.009 log units per month (95% CI −0.011 to −0.007) (worse eye). The VA of the adherent group improved significantly more than the comparison group, by an additional −0.008 log units per month (95% CI −0.009 to −0.007) (worse eye) and −0.004 log units per month (95% CI −0.005 to −0.003) in the better eye. Literacy was associated with the VA, letter identification (ID) reduced by −0.9 (95% CI −1.15 to −0.64) for every one line (0.10 logMAR) fall in VA (better eye). This association remained after adjustment for socioeconomic and demographic factors (−0.33, 95% CI −0.54 to −0.12). The adherent group consistently demonstrated higher letter-ID scores compared with the non-adherent group, with the greatest effect size (0.11) in year 3. Conclusions: Early literacy is associated with the level of VA; children who adhere to spectacle wear improve their VA and also have the potential to improve literacy. Our results suggest failure to adhere to spectacle wear has implications for the child’s vision and education.AB is funded by a National Institute for Health Research Post- Doctoral Fellowship Award (PDF-2013-06-050). The Born in Bradford study presents independent research commissioned by the National Institute for Health Research Collaboration for Applied Health Research and Care (NIHR CLAHRC) and the Programme Grants for Applied Research funding scheme (RP-PG-0407-10044)

Prevalence of, and Risk Factors for, Presenting Visual Impairment : Findings from a vision screening programme based on UK NSC guidance in a multi-ethnic population

YesPurpose: To determine presenting visual acuity levels and explore the factors associated with failing vision screening in a multi-ethnic population of UK children aged 4–5 years. Methods: Visual acuity (VA) using the logMAR Crowded Test was measured in 16,541 children in a population-based vision screening programme. Referral for cycloplegic examination was based on national recommendations (>0.20logMAR in one or both eyes). Presenting visual impairment (PVI) was defined as VA >0.3logMAR in the better eye. Multivariable logistic regression was used to assess the association of ethnicity, maternal, and early-life factors with failing vision screening and PVI in participants of the Born in Bradford birth cohort. Results: In total, 2467/16,541 (15%) failed vision screening, 732 (4.4%) had PVI. Children of Pakistani (OR: 2.49; 95% CI: 1.74–3.60) and other ethnicities (OR: 2.00; 95% CI: 1.28–3.12) showed increased odds of PVI compared to white children. Children born to older mothers (OR: 1.63; 95% CI: 1.19–2.24) and of low birth weight (OR: 1.52; 95% CI: 1.00–2.34) also showed increased odds. Follow-up results were available for 1068 (43.3%) children, 993 (93%) were true positives; 932 (94%) of these had significant refractive error. Astigmatism (>1DC) (44%) was more common in children of Pakistani ethnicity and hypermetropia (>3.0DS) (27%) in white children (Fisher’s exact, p < 0.001). Conclusions: A high prevalence of PVI is reported. Failing vision screening and PVI were highly associated with ethnicity. The positive predictive value of the vision screening programme was good, with only 7% of children followed up confirmed as false positives.National Institute for Health Research Post-Doctoral Fellowship Award (PDF-2013-06-050); The Born in Bradford study presents independent research commissioned by the National Institute for Health Research Collaboration for Applied Health Research and Care (NIHR CLAHRC) and the Programme Grants for Applied Research funding scheme (RP-PG-0407-10044)

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

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

Learning to Use Illumination Gradients as an Unambiguous Cue to Three Dimensional Shape

The luminance and colour gradients across an image are the result of complex interactions between object shape, material and illumination. Using such variations to infer object shape or surface colour is therefore a difficult problem for the visual system. We know that changes to the shape of an object can affect its perceived colour, and that shading gradients confer a sense of shape. Here we investigate if the visual system is able to effectively utilise these gradients as a cue to shape perception, even when additional cues are not available. We tested shape perception of a folded card object that contained illumination gradients in the form of shading and more subtle effects such as inter-reflections. Our results suggest that observers are able to use the gradients to make consistent shape judgements. In order to do this, observers must be given the opportunity to learn suitable assumptions about the lighting and scene. Using a variety of different training conditions, we demonstrate that learning can occur quickly and requires only coarse information. We also establish that learning does not deliver a trivial mapping between gradient and shape; rather learning leads to the acquisition of assumptions about lighting and scene parameters that subsequently allow for gradients to be used as a shape cue. The perceived shape is shown to be consistent for convex and concave versions of the object that exhibit very different shading, and also similar to that delivered by outline, a largely unrelated cue to shape. Overall our results indicate that, although gradients are less reliable than some other cues, the relationship between gradients and shape can be quickly assessed and the gradients therefore used effectively as a visual shape cue