boofcv.alg.feature.detect.intensity

Class FastCornerIntensity<T extends boofcv.struct.image.ImageGray>

java.lang.Object

boofcv.alg.feature.detect.intensity.FastCornerIntensity<T>

All Implemented Interfaces:

FeatureIntensity<T>

Direct Known Subclasses:

ImplFastIntensity10, ImplFastIntensity11, ImplFastIntensity12, ImplFastIntensity9

public abstract class FastCornerIntensity<T extends boofcv.struct.image.ImageGray>
extends java.lang.Object
implements FeatureIntensity<T>

Generic interface for fast corner detection algorithms. The general idea is that at the points in a circle around the center point (see below) should either be above or below the center pixel's intensity value value. With this information candidates corners can be quickly eliminated, see [1].

This implementation works by trying to minimize the number of reads per pixel. Code is auto generated and samples each point in a series of if statements such that the number of possible candidate corners around a pixel are eliminated. A different auto generated implementation is provided for Fast 9 to Fast 12. The number indicates how many continuous pixels are needed for it to be considered a corner.

After a pixel is flagged as a corner then the the intensity the difference between the average exterior pixel value which is part of the corner and the center pixel value. See code for details.

Circle of radius 2 pixels is searched around the center point 'x':

		12	13	14
	11				15
10						16
09			x			01
08						02
	07				03
		06	05	04

See Also:

[1] Edward Rosten, Reid Porter and Tom Drummond. "Faster and better: a machine learning approach to corner detection"

Field Summary

Fields

Modifier and Type	Field and Description
protected FastHelper<T>	helper
protected T	image
protected int[]	offsets
protected static int	radius

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	FastCornerIntensity(FastHelper<T> helper) Constructor

Method Summary

Modifier and Type	Method and Description
protected abstract boolean	checkLower(int index) Checks to see if the specified pixel qualifies as a corner with lower values
protected abstract boolean	checkUpper(int index) Checks to see if the specified pixel qualifies as a corner with upper values
boofcv.struct.QueueCorner	getCandidates()
int	getIgnoreBorder() Size of the region surrounding the image's border in which pixels are not processed.
int	getRadius() Returns the radius of the feature being computed.
void	process(T image, boofcv.struct.image.GrayF32 intensity)

Methods inherited from class java.lang.Object

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

Field Detail

radius

protected static final int radius

See Also:

Constant Field Values

offsets

protected int[] offsets

image

protected T extends boofcv.struct.image.ImageGray image

helper

protected FastHelper<T extends boofcv.struct.image.ImageGray> helper

Constructor Detail

FastCornerIntensity

protected FastCornerIntensity(FastHelper<T> helper)

Constructor

Parameters:

helper - Provide the image type specific helper.

Method Detail

getCandidates

public boofcv.struct.QueueCorner getCandidates()

getRadius

public int getRadius()

Description copied from interface: FeatureIntensity

Returns the radius of the feature being computed. Features are square in shape with a width = 2*radius+1.

Specified by:

getRadius in interface FeatureIntensity<T extends boofcv.struct.image.ImageGray>

Returns:

Radius of detected features.

getIgnoreBorder

public int getIgnoreBorder()

Description copied from interface: FeatureIntensity

Size of the region surrounding the image's border in which pixels are not processed.

Specified by:

getIgnoreBorder in interface FeatureIntensity<T extends boofcv.struct.image.ImageGray>

Returns:

The ignore border around the image.

process

public void process(T image,
                    boofcv.struct.image.GrayF32 intensity)

checkLower

protected abstract boolean checkLower(int index)

Checks to see if the specified pixel qualifies as a corner with lower values

checkUpper

protected abstract boolean checkUpper(int index)

Checks to see if the specified pixel qualifies as a corner with upper values