Summation of perceptual cues in natural visual scenes

Abstract

Natural visual scenes are rich in information, and any neural system analysing them must piece together the many messages from large arrays of diverse feature detectors. It is known how threshold detection of compound visual stimuli (sinusoidal gratings) is determined by their components' thresholds. We investigate whether similar combination rules apply to the perception of the complex and suprathreshold visual elements in naturalistic visual images. Observers gave magnitude estimations (ratings) of the perceived differences between pairs of images made from photographs of natural scenes. Images in some pairs differed along one stimulus dimension such as object colour, location, size or blur. But, for other image pairs, there were composite differences along two dimensions (e.g. both colour and object-location might change). We examined whether the ratings for such composite pairs could be predicted from the two ratings for the respective pairs in which only one stimulus dimension had changed. We found a pooling relationship similar to that proposed for simple stimuli: Minkowski summation with exponent 2.84 yielded the best predictive power (rZ0.96), an exponent similar to that generally reported for compound grating detection. This suggests that theories based on detecting simple stimuli can encompass visual processing of complex, suprathreshold stimuli.

A Visual-Attention Model Using Earth Mover's Distance-Based Saliency Measurement and Nonlinear Feature Combination

“…1. In [42], this nonlinear operator was called Minkowski summation. However, in mathematics, Minkowski summation usually indicates the dilation of two sets in geometry.…”

“…In this paper, we consider three basic features of color, intensity, and orientation as in most previous visualattention models and as suggested in [42], set the summating exponent m ¼ 2:8 in constructing super features. We construct two super features:…”

“…In [42], To et al used the L m -norm 1 for combining the perception of the complex and suprathreshold visual elements in naturalistic visual images. Specifically, the L m -norm [39], [42] over n real numbers a i , i ¼ 1; 2; .…”

Multi-level visual alphabets

“…Humans and animals process the visual world by combining a rich set of cues such as size, shape, color, lightness, motion, depth into a useful representation of the natural environment [17]. Early models from both computer and human vision * At the time this research was conducted, the author was affiliated with VicarVision, Amsterdam, The Netherlands.…”

Psychophysical Methods and the Evasion of Introspection

“…In a series of experiments published recently (To et al 2008, Tolhurst et al 2010 subjects were presented with nearly 300 pairs of photographsan original and a modified version -and were asked to rate how similar the pairs were on a scale from 0 (completely identical) to any arbitrarily high value (see fig.…”