Contrast sensitivity and the detection of moving patterns and features

O’Carroll, David C.; Wiederman, Steven D.

doi:10.1098/rstb.2013.0043

Cited by 63 publications

(53 citation statements)

References 36 publications

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“…This rivals the remarkable sensitivity for low-contrast targets of the insect visual system upon which it is based [9].…”

Section: Discussionmentioning

confidence: 97%

“…These 'small target motion detector' (STMD) neurons of the insect lobula (third optic neuropil) are selective for tiny targets, on the same scale as the optical resolution of the eye. STMDs are velocity-tuned, contrast-sensitive and respond robustly to targets even against the motion of high-contrast background features [6][7][8][9]. Individual STMDs may have very small receptive fields, corresponding to just a few dozen facets of the compound eye, or view an entire visual hemisphere, suggesting a complex hierarchy in their contributions to underlying control systems for target pursuit [6][7][8]10].…”

Section: Introductionmentioning

confidence: 99%

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Properties of neuronal facilitation that improve target tracking in natural pursuit simulations

Bagheri

Wiederman

Cazzolato

et al. 2015

J. R. Soc. Interface.

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Although flying insects have limited visual acuity (approx. 18) and relatively small brains, many species pursue tiny targets against cluttered backgrounds with high success. Our previous computational model, inspired by electrophysiological recordings from insect 'small target motion detector' (STMD) neurons, did not account for several key properties described from the biological system. These include the recent observations of response 'facilitation' (a slow build-up of response to targets that move on long, continuous trajectories) and 'selective attention', a competitive mechanism that selects one target from alternatives. Here, we present an elaborated STMD-inspired model, implemented in a closed loop target-tracking system that uses an active saccadic gaze fixation strategy inspired by insect pursuit. We test this system against heavily cluttered natural scenes. Inclusion of facilitation not only substantially improves success for even short-duration pursuits, but it also enhances the ability to 'attend' to one target in the presence of distracters. Our model predicts optimal facilitation parameters that are static in space and dynamic in time, changing with respect to the amount of background clutter and the intended purpose of the pursuit. Our results provide insights into insect neurophysiology and show the potential of this algorithm for implementation in artificial visual systems and robotic applications.

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“…This rivals the remarkable sensitivity for low-contrast targets of the insect visual system upon which it is based [9].…”

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Properties of neuronal facilitation that improve target tracking in natural pursuit simulations

Bagheri

Wiederman

Cazzolato

et al. 2015

J. R. Soc. Interface.

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“…When addressing questions of inherent contrast of an object at a fixed distance, as was the case with this study, either Michelson or Weber contrast formulae may be used (Johnsen, 2012). Weber contrast is often preferred to calculate attenuation of contrast with distance of small objects (Johnsen, 2012) or for sensitivity modeling of animals viewing eyeshine (O'Carroll and Wiederman, 2014). Since our objective was not designed to model the visibility of larval eyes to hypothetical viewers, but rather to test the inherent contrast of stomatopod larval eyes with the background environment, we chose to calculate the Michelson contrast (C M ) of our subject with the background:…”

Section: Image Analysismentioning

confidence: 99%

Hiding opaque eyes in transparent organisms: a potential role for larval eyeshine in stomatopod crustaceans

Feller

Cronin

2014

Journal of Experimental Biology

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Opaque screening pigments are a fundamental requisite for preserving resolution in image-forming eyes. Possession of any type of image-forming eye in a transparent, pelagic animal will thus undermine the ability of that animal to be invisible in the water column. Transparent, pelagic animals must therefore deal with the trade-off between the ability to see and the ability of other animals to see them. Stomatopod larvae, like many transparent crustaceans, possess specialized optics in their compound eyes that minimize the volume of the opaque retina. Though the volumes of these retinas are reduced, their opacity remains conspicuous to an observer. The light reflected from structures overlying the retinas of stomatopod crustacean larval eyes, referred to here as eyeshine, is hypothesized to further reduce the visibility of opaque retinas. Blue or green wavelengths of light are most strongly reflected in stomatopod larval eyeshine, suggesting a putative spectral matching to the light environment against which the larval eyes are viewed. We tested the efficacy of stomatopod crustacean larval eyeshine as an ocular camouflaging mechanism by photographing larvae in their natural light environment and analysing the contrast of eyes with the background light. To test for spectral matching between stomatopod larval eyeshine and the background light environment, we characterized the spectrum of eyeshine and calculated its performance using radiometric measurements collected at the time of each photographic series. These results are the first to demonstrate an operative mirror camouflage matched in both spectrum and radiance to the pelagic background light environment.

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“…5), as opposed to an attraction effect or an effect of feature size independent of expansion. For example, the avian visual system may be tuned to particular feature sizes or spatial frequencies that may be easy to resolve visually and track (5,18,29,30). Additional studies that directly manipulate expansion are needed to test these alternatives.…”

Section: Discussionmentioning

confidence: 99%

Visual guidance of forward flight in hummingbirds reveals control based on image features instead of pattern velocity

Dakin

Fellows

Altshuler

2016

Proc. Natl. Acad. Sci. U.S.A.

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Information about self-motion and obstacles in the environment is encoded by optic flow, the movement of images on the eye. Decades of research have revealed that flying insects control speed, altitude, and trajectory by a simple strategy of maintaining or balancing the translational velocity of images on the eyes, known as pattern velocity. It has been proposed that birds may use a similar algorithm but this hypothesis has not been tested directly. We examined the influence of pattern velocity on avian flight by manipulating the motion of patterns on the walls of a tunnel traversed by Anna's hummingbirds. Contrary to prediction, we found that lateral course control is not based on regulating nasal-to-temporal pattern velocity. Instead, birds closely monitored feature height in the vertical axis, and steered away from taller features even in the absence of nasalto-temporal pattern velocity cues. For vertical course control, we observed that birds adjusted their flight altitude in response to upward motion of the horizontal plane, which simulates vertical descent. Collectively, our results suggest that birds avoid collisions using visual cues in the vertical axis. Specifically, we propose that birds monitor the vertical extent of features in the lateral visual field to assess distances to the side, and vertical pattern velocity to avoid collisions with the ground. These distinct strategies may derive from greater need to avoid collisions in birds, compared with small insects. The translational motion of images on the eye (hereafter referred to as "pattern velocity") provides a rich source of information about selfmotion and the surrounding environment and has been shown to play a prominent role in the visual guidance strategies of all flying animals studied to date (2-5). Honey bees use pattern velocity for a diverse set of flight controls: they balance pattern velocity on their left and right sides to navigate narrow passageways (6); they regulate pattern velocity to control their flight speed (7) and altitude (8); and they integrate pattern velocity to estimate distances to foraging sites, communicating this information to hivemates (9, 10). Pattern velocity thus represents an elegant solution to insect flight control that is robust to a range of spatial frequencies and contrasts (2, 3, 6, 7).In the first study to ask whether birds also use a similar strategy, Bhagavatula et al. (11) trained five budgerigars to fly repeatedly down a tunnel. The authors found that like bees (6), the budgerigars steered away from vertically oriented gratings that provided strong nasal-to-temporal (fore-aft) pattern velocity, and toward horizontally oriented gratings and blank walls that provided little to no nasal-to-temporal pattern velocity. However, because Bhagavatula et al. (11) used only stationary gratings and did not manipulate pattern velocity directly, the exact mechanism used by birds remains to be confirmed. More recent experiments demonstrate that pattern velocity does not affect the flight speed of budgerigars (12) ...

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Contrast sensitivity and the detection of moving patterns and features

Cited by 63 publications

References 36 publications

Properties of neuronal facilitation that improve target tracking in natural pursuit simulations

Properties of neuronal facilitation that improve target tracking in natural pursuit simulations

Hiding opaque eyes in transparent organisms: a potential role for larval eyeshine in stomatopod crustaceans

Visual guidance of forward flight in hummingbirds reveals control based on image features instead of pattern velocity

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