Utah State University Department of Computer Science April, 2009
Contour extraction Image
Contours
Computational Geometry Convex Hull
Voronoi Diagram
Metamorphosis of the Cube http://erikdemaine.org/metamorphosis/
Algorithm
Algorithm
General stages
Geometric algorithms
1
4/6/2009
Pre-processing
Clustering
• Extract “edge” pixels from digital image
• Clean up – Reduce number of points – Prevent multiple parallel lines for a single contour
– Using Sobel edge detector – Based on intensity difference with neighbor pixels
• Merge close points with similar angle
• Convert pixels to “directed” points
– “Parallel” (blue) but not “collinear” (red) – Average out coordinates and angles
– Each pixel has an angle associated with it (direction of change)
• Continue until minimum distance is at least some value.
Linking
Simplification
• Connect points based on distance and angle
• Simplified path: subset of original path, including extreme points • Optimize ratio of original path length to simplified path length • Keep as many points as possible without letting the distance from simplified paths to original paths be too large
– Closer and similar angle is better
• Start with “good” pair of points and extend in both directions • Repeat until there are no more good pairs
Applications • Image segmentation • Object recognition and classification • Computer vision • Image compression • Maps • Animation Original video: Metamorphosis of the Cube http://erikdemaine.org/metamorphosis/ Used with permission
Apr 6, 2009 - Based on intensity difference with neighbor pixels. ⢠Convert pixels to âdirectedâ points. â Each pixel has an angle associated with it (direction.
ABSTRACT. We propose a novel unsupervised learning algorithm to ex- tract the layout of an image by learning latent object-related aspects. Unlike traditional ...
from the Caltech face dataset [9]. As in [7], images are re- sized to around 200 Ã 140 and converted to grayscale. A random subset of 50 face and 50 non-face ...
The application on building product data extraction on the Web is called the Wimex-Bot. Key words: image, web, data extraction, context-based image indexing.
Jul 25, 2010 - Which is the best method to extract Web. Image Context? ... Evaluation framework to measure and compare performance of WICE. â» Large ...
Faculty of Computer Science and Engineering ..... Conics have been used previously in computer vision .... and Temple University, USA for providing the.
when compared to other wavelet-based invariants. Also ... provides experimental results and comparisons .... of the above framework is that the invariants are.
email: [email protected] ..... 3377-3390. Lira, J., and Frulla, L., 1998, An automated region growing algorithm for segmentation of texture regions ...
Faculty of Computer Science and Engineering, GIK Institute of Engineering Sciences & Technology, NWFP, Pakistan. The paper ... removing noise from the contour data points. Then ... a generative model as it describes the process of mixing ...
the illustration of the process of prediction and updating in particle filters. The .... fine the classes of the part segments according to the length percentage. CLi.
Jun 7, 2006 - A post-processing step could be needed to close segment boundaries. The active contour techniques look for the optimum position of a closed boundary by minimizing an energy function [6]. The watershed approach grows regions from a gradi
In practice, the fitting process is started by fitting a log- normal distribution to ..... must be somewhere on the sphere in the u-space with a radius. 5.4. = β . By now ...
... and Information Engineering,. Huazhong University of Science and Technology, Wuhan 430074, China ... Temple University, Philadelphia, PA 19122, USA ... described a frame integrates top-down with bottom-up segmentation, in which ... The partial sh
Active contour modeling is a powerful technique for modeling object boundaries. Various methods .... close to the input data, the learning parameters of. TASOM ...
contours and does not call for any other constraint, so that it is particularly suitable ... mented in the same way (di erent number of segments with their endpoints at di ..... In Conference on Computer Vision and Pattern. Recognition, pages 202 ...
