An approach to symbolic contour extraction will be described that consists of three stages: enhancement, detection, and extraction of contours and corners. Contours and corners are enhanced by models of monkey cortical complex and endstopped cells. Detection of corners and local contour maxima is performed by selection of local maxima in both contour and corner enhanced images. These maxima for...

Over the last decade or so a great deal of psychophysical research has attempted to delineate the principles by which local orientations and motions are combined across space to facilitate the detection of simple spatial contours. This has led to the development of "association field" models of contour detection which suggest that the strength of linking between neighbouring elements in an imag...

a r t i c l e i n f o We present an overview of various edge and line oriented approaches to contour detection that have been proposed in the last two decades. By edge and line oriented we mean methods that do not rely on segmentation. Distinction is made between edges and contours. Contour detectors are divided in local and global operators. The former are mainly based on differential analysis...

In the Ehrenstein grid, bright illusory patches delineated by illusory contours are seen. In order to assess whether the illusory patches possess shape constancy, the Ehrenstein grid was viewed straight on and at various angles of slant with respect to the observer. Observers matched the apparent shape of the illusory patches with a circle or an ellipse defined by real lines in a reference stim...

In order to investigate the development of color mechanisms in infants we fitted elliptical detection contours to psychophysically-derived contrast thresholds plotted in L- and M-cone contrast space. Detection ellipses were obtained for 47 infants (ages 2-5 months of age), and were compared to those of six adults tested under nearly identical conditions. The parameters of the fitted ellipses al...

In order to detect the spatial conflicts in the process of spatial database updating, a refined description of spatial relationships is needed. This paper presents a topological chain model for refined line-line spatial relationships. The model integrates the topological relationships and order relationships with the metric relationships, such as intersecting angles, number of intersection poin...

The human visual system can undertake a specialized form of motion integration, one that enables the presence of extended spatial contours to be disambiguated from their backgrounds. We have shown previously that the visual system can selectively integrate local motion signals when their directions are along spatial contours and its efficiency is inversely related to the curvature of the contou...