Combined manipulation of blur, line length and contrast reveal two distinct processes involved in curvature detection. When line length is small relative to blur, thresholds are almost directly proportional to blur and independent of line length. When line length is large relative to blur thresholds are directly proportional to line length and independent of blur. The aspect ratio (line length/...

Subthreshold summation between physical target lines and illusory contours induced by edges such as those produced in the Kanizsa illusion has been reported in previous studies. Here, we investigated the ability of line-induced illusory contours, using Ehrenstein figures, to produce similar subthreshold summation. In the first experiment, three stimulus conditions were presented. The target lin...

Stereopsis relies principally on the extraction of horizontal retinal disparities. As such, we assume that the vertical contours (i.e., horizontal contrast energy) are of principle import for stereopsis. Yet there are theoretical reasons for believing that horizontal contours should be involved in binocular matching (if not stereopsis proper) as well. First, they would facilitate the computatio...

We used visual search to explore whether attention could be guided by Kanizsa-type subjective contours and by subjective contours induced by line ends. Unlike in previous experiments, we compared search performance with subjective contours against performance with real, luminance contours, and we had observers search for orientations or shapes produced by subjective contours, rather than search...

Feature extraction algorithms delivering accurate results are computational intensive and cannot keep up with the demanded processing times on single processor systems in automated micropart assembly tasks. For this case an improved contour tracer for real-time edge-line extraction, using adaptive local thresholds, is introduced. In combination with an effective start point search, that concent...

We have constructed a computer algorithm that finds the contours of the dorsal and ventral portions of the images of ribs in chest radiographs. The following are a few of the expected uses for the automatic detection of rib contours: 1. Rib images contribute false positives in tumor-detection algorithms. Hence> detecting the rib contours should f a c i l i t a t e removal of these lalse posltiv...

Finger vein patterns are considered as one of the most promising biometric authentication methods for its security and convenience. Most of the current available finger vein recognition methods utilize features from a segmented blood vessel network. As an improperly segmented network may degrade the recognition accuracy, binary pattern based methods are proposed, such as Local Binary Pattern (L...