net.imglib2.algorithm.hough

Class HoughTransforms<T extends net.imglib2.type.numeric.RealType<T> & Comparable<T>>

java.lang.Object

net.imglib2.algorithm.hough.HoughTransforms<T>

Type Parameters:

T - the data type of the input image.

public class HoughTransforms<T extends net.imglib2.type.numeric.RealType<T> & Comparable<T>>
extends Object

This class provides static methods used to detect imperfect shapes in two-dimensional images through the use of the Hough Transform.

Author:

Larry Lindsey, Yili Zhao, Gabe Selzer

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_THETA

Constructor Summary

Constructors

Constructor and Description
HoughTransforms()

Method Summary

Modifier and Type	Method and Description
static double	getIntercept(long rho, long theta) Method used to convert the {rho, theta} output of the voteLines(net.imglib2.RandomAccessibleInterval<T>, net.imglib2.RandomAccessibleInterval<U>) algorithm into a more useful y-intercept value.
static double	getSlope(long theta) Method used to convert the {rho, theta} output of the voteLines(net.imglib2.RandomAccessibleInterval<T>, net.imglib2.RandomAccessibleInterval<U>) algorithm into a more useful slope value.
static long[]	getVotespaceSize(net.imglib2.Dimensions dimensions) Returns the size of the vote space output image given an input RandomAccessibleInterval.
static long[]	getVotespaceSize(net.imglib2.Dimensions dimensions, int nTheta) Returns the size of the vote space output image given an input RandomAccessibleInterval.
static long[]	getVotespaceSize(int nRho, int nTheta) Returns the size of the voteSpace output image given desired nRho and nTheta values.
static <T extends net.imglib2.type.numeric.IntegerType<T>> List<net.imglib2.Point>	pickLinePeaks(net.imglib2.RandomAccessibleInterval<T> voteSpace, long threshold) Pick vote space peaks with a LocalExtrema.
static <T extends Comparable<T>> List<net.imglib2.Point>	pickLinePeaks(net.imglib2.RandomAccessibleInterval<T> voteSpace, T minPeak) Pick vote space peaks with a LocalExtrema.
static <T extends Comparable<T>,U extends net.imglib2.type.numeric.IntegerType<U>> void	voteLines(net.imglib2.RandomAccessibleInterval<T> input, net.imglib2.RandomAccessibleInterval<U> votespace) Runs a Hough Line Tranform on an image and populates the vote space parameter with the results.
static <T extends Comparable<T>,U extends net.imglib2.type.numeric.IntegerType<U>> void	voteLines(net.imglib2.RandomAccessibleInterval<T> input, net.imglib2.RandomAccessibleInterval<U> votespace, int nTheta) Runs a Hough Line Tranform on an image and populates the vote space parameter with the results.
static <T extends Comparable<T>,U extends net.imglib2.type.numeric.IntegerType<U>> void	voteLines(net.imglib2.RandomAccessibleInterval<T> input, net.imglib2.RandomAccessibleInterval<U> votespace, int nTheta, int nRho) Runs a Hough Line Tranform on an image and populates the vote space parameter with the results.
static <T,U extends net.imglib2.type.numeric.IntegerType<U>> void	voteLines(net.imglib2.RandomAccessibleInterval<T> input, net.imglib2.RandomAccessibleInterval<U> votespace, int nTheta, int nRho, Predicate<T> filter) Runs a Hough Line Tranform on an image and populates the vote space parameter with the results.
static <T extends Comparable<T>,U extends net.imglib2.type.numeric.IntegerType<U>> void	voteLines(net.imglib2.RandomAccessibleInterval<T> input, net.imglib2.RandomAccessibleInterval<U> votespace, int nTheta, int nRho, T threshold) Runs a Hough Line Tranform on an image and populates the vote space parameter with the results.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_THETA

public static final int DEFAULT_THETA

See Also:

Constant Field Values

Constructor Detail

HoughTransforms

public HoughTransforms()

Method Detail

getVotespaceSize

public static long[] getVotespaceSize(net.imglib2.Dimensions dimensions)

Returns the size of the vote space output image given an input RandomAccessibleInterval.

Parameters:

dimensions - - the Dimensions over which the Hough Line Transform will be run

Returns:

long[] - the dimensions of the vote space image

getVotespaceSize

public static long[] getVotespaceSize(net.imglib2.Dimensions dimensions,
                                      int nTheta)

Returns the size of the vote space output image given an input RandomAccessibleInterval.

Parameters:

dimensions - - the Dimensions over which the Hough Line Transform will be run

nTheta - - the number of theta bins.

Returns:

long[] - the dimensions of the vote space image

getVotespaceSize

public static long[] getVotespaceSize(int nRho,
                                      int nTheta)

Returns the size of the voteSpace output image given desired nRho and nTheta values.

Parameters:

nRho - - the number of bins for rho resolution

nTheta - - the number of bins for theta resolution

Returns:

long[] - the dimensions of the vote space image.

pickLinePeaks

public static <T extends net.imglib2.type.numeric.IntegerType<T>> List<net.imglib2.Point> pickLinePeaks(net.imglib2.RandomAccessibleInterval<T> voteSpace,
                                                                                                        long threshold)

Pick vote space peaks with a LocalExtrema.

Parameters:

voteSpace - - the RandomAccessibleInterval containing the output of a Hough Transform vote

threshold - - the IntegerType at and below which maxima will be ignored

Returns:

List<Point> - a list of all of the local maxima of the voteSpace

pickLinePeaks

public static <T extends Comparable<T>> List<net.imglib2.Point> pickLinePeaks(net.imglib2.RandomAccessibleInterval<T> voteSpace,
                                                                              T minPeak)

Pick vote space peaks with a LocalExtrema.

Parameters:

voteSpace - - the RandomAccessibleInterval containing the output of a Hough Transform vote

minPeak - - the Comparable at and below which maxima will be ignored

Returns:

List<Point> - a list of all of the local maxima of the voteSpace.

voteLines

public static <T extends Comparable<T>,U extends net.imglib2.type.numeric.IntegerType<U>> void voteLines(net.imglib2.RandomAccessibleInterval<T> input,
                                                                                                         net.imglib2.RandomAccessibleInterval<U> votespace)

Runs a Hough Line Tranform on an image and populates the vote space parameter with the results.

Parameters:

input - - the RandomAccessibleInterval to run the Hough Line Transform over

votespace - - the RandomAccessibleInterval in which the results are stored

voteLines

public static <T extends Comparable<T>,U extends net.imglib2.type.numeric.IntegerType<U>> void voteLines(net.imglib2.RandomAccessibleInterval<T> input,
                                                                                                         net.imglib2.RandomAccessibleInterval<U> votespace,
                                                                                                         int nTheta)

Runs a Hough Line Tranform on an image and populates the vote space parameter with the results.

Parameters:

input - - the RandomAccessibleInterval to run the Hough Line Transform over

votespace - - the RandomAccessibleInterval in which the results are stored

nTheta - - the number of bins for theta resolution

voteLines

public static <T extends Comparable<T>,U extends net.imglib2.type.numeric.IntegerType<U>> void voteLines(net.imglib2.RandomAccessibleInterval<T> input,
                                                                                                         net.imglib2.RandomAccessibleInterval<U> votespace,
                                                                                                         int nTheta,
                                                                                                         int nRho)

Runs a Hough Line Tranform on an image and populates the vote space parameter with the results.

Parameters:

input - - the RandomAccessibleInterval to run the Hough Line Transform over

votespace - - the RandomAccessibleInterval in which the results are stored

nTheta - - the number of bins for theta resolution

nRho - - the number of bins for rho resolution

voteLines

public static <T extends Comparable<T>,U extends net.imglib2.type.numeric.IntegerType<U>> void voteLines(net.imglib2.RandomAccessibleInterval<T> input,
                                                                                                         net.imglib2.RandomAccessibleInterval<U> votespace,
                                                                                                         int nTheta,
                                                                                                         int nRho,
                                                                                                         T threshold)

Runs a Hough Line Tranform on an image and populates the vote space parameter with the results.

Parameters:

input - - the RandomAccessibleInterval to run the Hough Line Transform over

votespace - - the RandomAccessibleInterval in which the results are stored

nTheta - - the number of bins for theta resolution

nRho - - the number of bins for rho resolution

threshold - - the minimum value allowed by the populator. Any input less than this value will be disregarded by the populator.

voteLines

public static <T,U extends net.imglib2.type.numeric.IntegerType<U>> void voteLines(net.imglib2.RandomAccessibleInterval<T> input,
                                                                                   net.imglib2.RandomAccessibleInterval<U> votespace,
                                                                                   int nTheta,
                                                                                   int nRho,
                                                                                   Predicate<T> filter)

Runs a Hough Line Tranform on an image and populates the vote space parameter with the results.

Vote space here has two dimensions: rho and theta. theta is measured in radians [-pi/2 pi/2), rho is measured in [-rhoMax, rhoMax).

Lines are modeled as

 l(t) = | x | = rho * |  cos(theta) | + t * | sin(theta) |
        | y |         | -sin(theta) |       | cos(theta) |
 

In other words, rho represents the signed minimum distance from the image origin to the line, and theta indicates the angle between the row-axis and the minimum offset vector.

For a given point, then, votes are placed along the curve

 rho = y * sin( theta ) + x * cos( theta )
 

It is important to note that the interval of the first dimension of the vote space image is NOT [-maxRho, maxRho) but instead [0, maxRho * 2); the same applies to the second dimension of the vote space as well. Thus if pickLinePeaks(net.imglib2.RandomAccessibleInterval<T>, long) is not used to retrieve the maxima from the vote space, the vote space will have to be translated by -maxRho in dimension 0 to get the correct rho and theta values from the vote space.

Parameters:

input - - the RandomAccessibleInterval to run the Hough Line Transform over

votespace - - the RandomAccessibleInterval in which the results are stored

nTheta - - the number of bins for theta resolution

nRho - - the number of bins for rho resolution

filter - - a Predicate judging whether or not the a value is above the minimum value allowed by the populator. Any input less than or equal to this value will be disregarded by the populator.

getIntercept

public static double getIntercept(long rho,
                                  long theta)

Method used to convert the {rho, theta} output of the voteLines(net.imglib2.RandomAccessibleInterval<T>, net.imglib2.RandomAccessibleInterval<U>) algorithm into a more useful y-intercept value. Used with getSlope(long) to create line equations.

Parameters:

rho - - the rho of the line

theta - - the theta of the line

Returns:

double - the y-intercept of the line

getSlope

public static double getSlope(long theta)

Method used to convert the {rho, theta} output of the voteLines(net.imglib2.RandomAccessibleInterval<T>, net.imglib2.RandomAccessibleInterval<U>) algorithm into a more useful slope value. Used with getIntercept(long, long) to create line equations.

Parameters:

theta - - the theta of the line

Returns:

double - the y-intercept of the line