org.openimaj.image.feature.local.descriptor.gradient

Interface GradientFeatureProvider

All Superinterfaces:

FeatureVectorProvider<OrientedFeatureVector>, LocalFeatureProvider<OrientedFeatureVector>

All Known Implementing Classes:

IrregularBinningSIFTFeatureProvider, SIFTFeatureProvider

public interface GradientFeatureProvider
extends LocalFeatureProvider<OrientedFeatureVector>

Interface for classes capable of building local descriptors from the gradient (magnitude and orientation) information in an image patch. The model for the construction of various concrete feature extractors that implement this interface is that some external code will provide individual pixel samples (consisting of both magnitude and orientation values) and their relative positions within a unit sampling patch (or slightly beyond if interpolation is used; see Interpolation.bilerp(double, double, double, double, double, double)).

The general contract for methods using this interface is as follows:

f = new GradientBasedLocalFeatureExtractorImpl()
f.setPatchOrientation(orientation)
for (pixels in patch)
f.addSample(normalised-pixel-position, pixel-magnitude, pixel-orientation)


Author:

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

Method Summary

Modifier and Type	Method and Description
void	addSample(float x, float y, float gradmag, float gradori) Add a sample to the feature.
OrientedFeatureVector	getFeatureVector() Get the FeatureVector associated with this object.
void	setPatchOrientation(float patchOrientation) Set the primary orientation of the sample patch in the image being processed.

Methods inherited from interface org.openimaj.image.feature.local.descriptor.LocalFeatureProvider

getOversamplingAmount

Method Detail

setPatchOrientation

void setPatchOrientation(float patchOrientation)

Set the primary orientation of the sample patch in the image being processed. This might be used by concrete implementations to provide rotation invariance. This method should only be called once by calling code, and the call should be before any calls to addSample(float, float, float, float) are made.

Parameters:

patchOrientation - the actual orientation of the square in the image

addSample

void addSample(float x,
               float y,
               float gradmag,
               float gradori)

Add a sample to the feature. The x and y coordinates are given in terms of a unit index square (i.e. 0<=x<=1 and 0<=y<=1).

Parameters:

x - x-coordinate within the unit indexing square

y - y-coordinate within the unit indexing square

gradmag - the gradient magnitude at the given coordinate

gradori - the gradient direction at the given coordinate

getFeatureVector

OrientedFeatureVector getFeatureVector()

Description copied from interface: FeatureVectorProvider

Get the FeatureVector associated with this object.

Specified by:

getFeatureVector in interface FeatureVectorProvider<OrientedFeatureVector>

Returns:

the feature vector.