It is now accepted that the visual system integrates local orientation information across space to define spatial contours [Vision Research 33 (1993) 173]. More recently, it has been shown that similar integration occurs for the direction of local motion signals, in different parts of the visual field, if they are aligned along the axis of a spatial contour [Vision Research 42 (2002) 653]. Here...

Given a directed graph G and a parameter k, the Long Directed Cycle (LDC) problem asks whether G contains a simple cycle on at least k vertices, while the k-Path problems asks whether G contains a simple path on exactly k vertices. Given a deterministic (randomized) algorithm for k-Path as a black box, which runs in time t(G, k), we prove that LDC can be solved in deterministic time O(max{t(G, ...

The arrival of appearance-based image features has dramatically influenced the field of visual object recognition. Previous work has shown, however, that contour curvature and junctions are important for shape representation and detection. We investigate a local representation of contours for object detection that complements appearance-based information, such as texture. We present a non-param...

most of the erythrocyte related diseases are detectable by hematology images analysis. at the first step of this analysis, segmentation and detection of blood cells are inevitable. in this study, a novel method using a line operator and watershed algorithm is rendered for erythrocyte detection and segmentation in blood smear images, as well as reducing over-segmentation in watershed algorithm t...

Research has shown that contour detection is impaired in the visual periphery for snake-shaped Gabor contours but not for circular and elliptical contours. This discrepancy in findings could be due to differences in intrinsic shape properties, including shape closure and curvature variation, as well as to differences in stimulus predictability and familiarity. In a detection task using only cir...

Polygonal objects are prevalent in man-made scenes. Early approaches to detecting them relied mainly on geometry while subsequent ones also incorporated appearance-based cues. It has recently been shown that this could be done fast by searching for cycles in graphs of line-fragments, provided that the cycle scoring function can be expressed as additive terms attached to individual fragments. In...