org.openimaj.image.feature.local.detector.pyramid

Class BasicOctaveExtremaFinder

java.lang.Object

org.openimaj.image.feature.local.detector.pyramid.AbstractOctaveInterestPointFinder<OCTAVE,FImage>

org.openimaj.image.feature.local.detector.pyramid.AbstractOctaveExtremaFinder<GaussianOctave<FImage>>

org.openimaj.image.feature.local.detector.pyramid.BasicOctaveExtremaFinder

All Implemented Interfaces:

OctaveProcessor<GaussianOctave<FImage>,FImage>, OctaveInterestPointFinder<GaussianOctave<FImage>,FImage>

Direct Known Subclasses:

InterpolatingOctaveExtremaFinder

@Reference(type=Article,author="David Lowe",title="Distinctive image features from scale-invariant keypoints",year="2004",journal="IJCV",pages={"91","110"},month="January",number="2",volume="60") @Reference(type=Inproceedings,author="David Lowe",title="Object recognition from local scale-invariant features",year="1999",booktitle="Proc. of the International Conference on Computer Vision {ICCV}",pages={"1150","1157"})
public class BasicOctaveExtremaFinder
extends AbstractOctaveExtremaFinder<GaussianOctave<FImage>>

A basic concrete implementation of an AbstractOctaveExtremaFinder that searches for local extrema in scale space. If detected extrema pass a series of tests (namely those described in AbstractOctaveExtremaFinder) and a final test that tests the absolute value of the interest point pixel against a threshold, then the listener object will be informed that a point has been detected.

Author:

Jonathon Hare (jsh2@ecs.soton.ac.uk)

Field Summary

Fields

Modifier and Type	Field and Description
static float	DEFAULT_MAGNITUDE_THRESHOLD The default threshold for the magnitude of interest points
protected float	magnitudeThreshold
protected float	normMagnitudeScales
protected float	scales

Fields inherited from class org.openimaj.image.feature.local.detector.pyramid.AbstractOctaveExtremaFinder

DEFAULT_EIGENVALUE_RATIO, eigenvalueRatio

Fields inherited from class org.openimaj.image.feature.local.detector.pyramid.AbstractOctaveInterestPointFinder

currentScaleIndex, listener, octave

Constructor Summary

Constructors

Constructor and Description
BasicOctaveExtremaFinder() Default constructor using DEFAULT_MAGNITUDE_THRESHOLD for the magnitude threshold and AbstractOctaveExtremaFinder.DEFAULT_EIGENVALUE_RATIO for the Eigenvalue ratio threshold.
BasicOctaveExtremaFinder(float magnitudeThreshold) Construct with the given magnitude threshold and AbstractOctaveExtremaFinder.DEFAULT_EIGENVALUE_RATIO for the Eigenvalue ratio threshold.
BasicOctaveExtremaFinder(float magnitudeThreshold, float eigenvalueRatio) Construct with the given magnitude and Eigenvalue thresholds

Method Summary

Modifier and Type	Method and Description
protected void	beforeProcess(GaussianOctave<FImage> octave) Called at the start of AbstractOctaveExtremaFinder#process(OCTAVE)
protected boolean	firstCheck(float val, int x, int y, int s, FImage[] dogs) Perform the first of the checks that determine whether a point is a valid interest point.
protected void	processExtrema(FImage[] dogs, int s, int x, int y, float octSize) Perform any additional checks on the point, and then inform the listener that a point has been found.

Methods inherited from class org.openimaj.image.feature.local.detector.pyramid.AbstractOctaveExtremaFinder

getCurrentScaleIndex, getOctave, isLocalExtremum, isNotEdge, process

Methods inherited from class org.openimaj.image.feature.local.detector.pyramid.AbstractOctaveInterestPointFinder

getOctaveInterestPointListener, setOctaveInterestPointListener

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_MAGNITUDE_THRESHOLD

public static final float DEFAULT_MAGNITUDE_THRESHOLD

The default threshold for the magnitude of interest points

See Also:

Constant Field Values

magnitudeThreshold

protected float magnitudeThreshold

scales

protected float scales

normMagnitudeScales

protected float normMagnitudeScales

Constructor Detail

BasicOctaveExtremaFinder

public BasicOctaveExtremaFinder()

Default constructor using DEFAULT_MAGNITUDE_THRESHOLD for the magnitude threshold and AbstractOctaveExtremaFinder.DEFAULT_EIGENVALUE_RATIO for the Eigenvalue ratio threshold.

BasicOctaveExtremaFinder

public BasicOctaveExtremaFinder(float magnitudeThreshold)

Construct with the given magnitude threshold and AbstractOctaveExtremaFinder.DEFAULT_EIGENVALUE_RATIO for the Eigenvalue ratio threshold.

Parameters:

magnitudeThreshold - the magnitude threshold

BasicOctaveExtremaFinder

public BasicOctaveExtremaFinder(float magnitudeThreshold,
                                float eigenvalueRatio)

Construct with the given magnitude and Eigenvalue thresholds

Parameters:

magnitudeThreshold - the magnitude threshold

eigenvalueRatio - the Eigenvalue threshold

Method Detail

beforeProcess

protected void beforeProcess(GaussianOctave<FImage> octave)

Description copied from class: AbstractOctaveExtremaFinder

Called at the start of AbstractOctaveExtremaFinder#process(OCTAVE)

Overrides:

beforeProcess in class AbstractOctaveExtremaFinder<GaussianOctave<FImage>>

Parameters:

octave - the octave being processed

firstCheck

protected boolean firstCheck(float val,
                             int x,
                             int y,
                             int s,
                             FImage[] dogs)

Description copied from class: AbstractOctaveExtremaFinder

Perform the first of the checks that determine whether a point is a valid interest point. This can be overridden to allow for cheaper tests to occur before more expensive ones.

Overrides:

firstCheck in class AbstractOctaveExtremaFinder<GaussianOctave<FImage>>

Parameters:

val - the value at the point.

x - the x-coordinate of the point.

y - the y-coordinate of the point.

s - the scale index at which the point was found

dogs - the scale images

Returns:

true if the point is potentially an interest point; false otherwise.

processExtrema

protected void processExtrema(FImage[] dogs,
                              int s,
                              int x,
                              int y,
                              float octSize)

Description copied from class: AbstractOctaveExtremaFinder

Perform any additional checks on the point, and then inform the listener that a point has been found.

Specified by:

processExtrema in class AbstractOctaveExtremaFinder<GaussianOctave<FImage>>

Parameters:

dogs - the stack of images in this octave

s - the interest-point scale

x - the x-coordinate of the interest-point

y - the y-coordinate of the interest-point