Goal
The goal of this project is to identify and empirically study of cues in shaded images that give rise to a ground bias in figure-ground organization.
Motivation
The shaded side appears to be figural and closer in the left image. Some modifications to the shaded part of an image made it appear farther from the viewer, i.e. more ground-like.
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Definitions
The shaded side appears to be figural and closer in the left image. Some modifications to the shaded part of an image made it appear farther from the viewer, i.e. more ground-like.
Experiment 1: Influence of Angle ELC
The strength of GC as a ground cue was tested for many different angle ELCs, when pitted against an extremal edge. Results show that the figural bias drops exponentially as the angle between the shared edge and equiluminant contours changes from zero. The data is coded as the percentage of times the gradient cut side was chosen as figural. In the examples shown on the axis, the gradient cut side is the on the left of the shared contour.
Experiment 2: Influence of Alignment of edge with minima & maxima of the shading gradient.
Other than angle ELC the alignment between light and dark striations of a shading gradient and the minima and maxima of the edge seems to affect figure-ground organization. In the following figure angle ELC is same for all images but the alignment of the edge with the shading gradient is different.
The results were as follows:
Experiment 3: Which is more influential – the Arrow, Y- or T- junctions?
In the previous experiment light arrows are always paired with dark-Ys and dark arrows with light-Ys. In this experiment this confound was removed by using asymmetrical edges. The results showed that the presence of dark-Y junctions bias a region to be appear figural and closer.
The data demonstrate that gradient cuts and type of alignment of egdes with the shading gradient both play a role in deciding relative depth across a contour and to figure-ground organization.
Last updated by Tandra Ghose , February 2009