hough transform
DESCRIPTION
Hough Transform. Omri Zorea and Alon LipnikGroup #11. Introduction. Technique to find imperfect instances of object within a certain class of shapes. (i.e. lines, cycles, ellipses, parabolas etc.). Use in image analysis, computer vision and digital image processing. - PowerPoint PPT PresentationTRANSCRIPT
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Hough Transform
Omri Zorea and Alon Lipnik Group #11
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Technique to find imperfect instances of object within a certain class of shapes. (i.e. lines, cycles, ellipses, parabolas etc.).
Use in image analysis, computer vision and digital image processing. Was invented by Richard Duda and Peter Hart in 1972 (patent of Paul Hough, 1962).
Introduction
Hough Transform
1. Aerial photo 2. X-Y plane 3. Hough plane
detecting transform
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Hough Transform Find lines in picture (y = -mx + b).
Match dots on the picture to lines and match line to a dot.
The slope (m) can goes to infinity (unbounded domain) polar coordinates.
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Hough Transform
Hough Transform
Detect arbitrary shapes in picture.
Each point in Image space is now a sinusoid:
ρ = x cosθ + y sinθ
For each edge point on image it compute his gradient and know
which shape is it.
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Hough Transform
Hough Transform
Detect arbitrary shapes in picture.
Accumulator matrix - find lines with maximum points. determines Threshold values in matrix.
the values are the points-density of shape.
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Parallel Algorithm
Hough Transform
The image is divided into rows with
the same number of columns.
PVM is a programming tool used for
the message routing, data
conversion and task scheduling.
Complexity of O(m*n^2).m – different
theta values.nxn – image
size
(* Algorithm LARPBS – linear array reconfigurable pipeline bus system)
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Parallel Algorithm
Hough Transform
Speed Up:
Check on 4, 8, 16 and 32 processors.
Two different algorithms.
Image density range 5% - 15%.
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Parallel Algorithm
Hough Transform
Efficiency:
Image density range from 5% to 25%.
Check on 4, 8, 12, 16 and 32 processors (process 0 is
the master).
Trade-Off (processors and image density).
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Parallel algorithms for Hough Transform, Fevzi Oktay Ozbek : http://preserve.lehigh.edu/cgi/viewcontent.cgi?article=1073&context=etd A fast efficient parallel HT algorithm on LARPBS:
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.99.8684&rep=rep1&type=pdf
Guillermo Sapiro of Duke university :https://www.youtube.com/watch?v=kMK8DjdGtZo
References