org.openimaj.image.feature.local.interest

Class SubPixelCorners

java.lang.Object

org.openimaj.image.feature.local.interest.SubPixelCorners

public class SubPixelCorners
extends Object

Refines detected corners (i.e. from HarrisIPD or other methods) to an optimised sub-pixel estimate. The method works by iteratively updating the sub-pixel position of a point based on the inverse of the local gradient auto-correlation matrix.

Author:

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

Constructor Summary

Constructors

Constructor and Description
SubPixelCorners(int halfWidth, int halfHeight, int zeroZoneHalfWidth, int zeroZoneHalfHeight, Predicate<IterationState> iter) Construct with the given search window size, zeroed window and predicate to stop the iteration.
SubPixelCorners(int halfWidth, int halfHeight, Predicate<IterationState> iter) Construct with the given search window size and predicate to stop the iteration.

Method Summary

Modifier and Type	Method and Description
Point2dImpl	findSubPixCorner(FImage src, Point2d corner) Find the sub-pixel estimated position of a corner
List<Point2dImpl>	findSubPixCorners(FImage src, List<? extends Point2d> corners) Find the sub-pixel estimated position of each corner

Methods inherited from class java.lang.Object

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

Constructor Detail

SubPixelCorners

public SubPixelCorners(int halfWidth,
                       int halfHeight,
                       Predicate<IterationState> iter)

Construct with the given search window size and predicate to stop the iteration. No zeroing of weights is performed

Parameters:

halfWidth - half the search window width (actual size is 2*halfWidth + 1, centred on point)

halfHeight - half the search window height (actual size is 2*halfHeight + 1, centred on point)

iter - the predicate to stop iteration

SubPixelCorners

public SubPixelCorners(int halfWidth,
                       int halfHeight,
                       int zeroZoneHalfWidth,
                       int zeroZoneHalfHeight,
                       Predicate<IterationState> iter)

Construct with the given search window size, zeroed window and predicate to stop the iteration.

The zeroed window is a dead region in the middle of the search zone over which the summation over gradients is not done. It is used sometimes to avoid possible singularities of the autocorrelation matrix.

Parameters:

halfWidth - half the search window width (actual size is 2*halfWidth + 1, centred on point)

halfHeight - half the search window height (actual size is 2*halfHeight + 1, centred on point)

zeroZoneHalfWidth - the half-width of the zeroed region in the weighting array

zeroZoneHalfHeight - the half-height of the zeroed region in the weighting array

iter - the predicate to stop iteration

Method Detail

findSubPixCorners

public List<Point2dImpl> findSubPixCorners(FImage src,
                                           List<? extends Point2d> corners)

Find the sub-pixel estimated position of each corner

Parameters:

src - the image

corners - the initial corner positions

Returns:

the updated corners

findSubPixCorner

public Point2dImpl findSubPixCorner(FImage src,
                                    Point2d corner)

Find the sub-pixel estimated position of a corner

Parameters:

src - the image

corner - the initial corner position

Returns:

the updated corner position