ILFeature Interface Reference

This interface provide functionalities of the image features, which is used for feature extraction from image in machine learning technology. More...

Inheritance diagram for ILFeature:

Properties
BOOL	Enabled [get, set]
	Whether the feature is enabled. The disabled feature is skipped in feature extraction.
LPVFeatureType	Type [get, set]
	The type of the feature. Changing the type will reset the feature to default.
Properties inherited from ILParameterized
BOOL	ParamBool (LString paramName) [get, set]
	The boolean parameter.
double	ParamF (LString paramName) [get, set]
	The floating double parameter.
int	ParamI (LString paramName) [get, set]
	The integer parameter.
LSize	ParamSize (LString paramName) [get, set]
	The size parameter.

Additional Inherited Members
Public Member Functions inherited from ILObject
ILObject *	Copy ()
LPVErrorCode	Load (LString filename)
void	Reset ()
LPVErrorCode	Save (LString filename)
BOOL	Valid ()

Detailed Description

This interface provide functionalities of the image features, which is used for feature extraction from image in machine learning technology.

You should firstly create the image feature with specified type via Create(), then adjust its parameters via ILParameterized interface.
Currently, we support following features:

Feature	Usage and Parameters
ORB	Oriented FAST and Rotated BRIEF Parameter Name Usage Type Range Default "count" Count of vocabulary in Bag-of-Words Integer 8 ~ 2048 64 "patch size" Size of each patch Integer 4 ~ 256 32 "scale factor" Scale factor for the pyramid Double 1 ~ 2 1.2 "scale-down level" Total level count of the scale-down pyramid Integer > 0 5 "random point pair count" The number of points that produce each element of ORB Integer 2 ~ 4 2
HOG	Histogram of Oriented Gradients Parameter Name Usage Type Range Default "cell size" Size of a cell that build the histogram Size @math_eq{2 \times 2} ~ @math_eq{128 \times 128} must be @math_eq{2^x} @math_eq{4 \times 4} "bin size" Bins of histogram, should be factor of 360 or 180, depending on whether gradient is signed Integer 1 ~ 60 9 "cell in block" Count of cells in a block Size @math_eq{1 \times 1} ~ @math_eq{64 \times 64} @math_eq{2 \times 2} "cell in block stride" Count of cells in a block stride Size @math_eq{1 \times 1} ~ @math_eq{64 \times 64} @math_eq{1 \times 1} "block stride step" Count of stride block Size @math_eq{1 \times 1} "signed gradient" Use signed gradient or not, directions are analyzed in 360 or 180 degree Bool false
AKAZE	Accelerated-KAZE Parameter Name Usage Type Range Default "count" Count of vocabulary in Bag-of-Words Integer 8 ~ 2048 64 "rotation invariant" Whether this feature is rotation-invariant Bool true "accept threshold" Threshold to accept key point Double > 0 10 "octave" Maximum octave evolution Integer 1 ~ 5 3 "sub-level" Number of sub-levels per scale level(octave) Integer > 0 4 "conductivity" Conductivity coefficient Integer see LPVConductivity G2

Example Code

C++

// create a HOG feature
ILFeaturePtr hog = LFeature::Create();
hog->Type = LPVFeatureType::LPVFeatureHOG;
// change its parameters
hog->PutParamSize(L"cell size", LSize{ 8, 8 });
hog->PutParamI(L"bin size", 5);
hog->PutParamSize(L"cell in block", LSize{ 4, 4 });
llc->AddFeature(hog); // add it to the classifier

C#

// create a HOG feature
LFeature hog = new LFeature();
hog.Type = LPVFeatureType.LPVFeatureHOG;
// change its parameters
hog.ParamSize["cell size"] = new LSize{ w = 8, h = 8 };
hog.ParamI["bin size"] = 5;
hog.ParamSize["cell in block"] = new LSize { w = 4, h = 4 };
llc.AddFeature(hog); // add it to the classifier

COM

// create a HOG feature
ILFeaturePtr hog = LFeature::Create();
// or, ILFeaturePtr hog(__uuidof(LFeature)), for absence of built-in Create functions (before 2.2.0)
hog->Type = LPVFeatureType::LPVFeatureHOG;
// change its parameters
hog->ParamSize[L"cell size"] = LSize{ 8, 8 };
hog->ParamI[L"bin size"] = 5;
hog->ParamSize[L"cell in block"] = LSize{ 4, 4 };
llc->AddFeature(hog); // add it to the classifier