boofcv.alg.filter.derivative

Class HessianFromGradient

java.lang.Object

boofcv.alg.filter.derivative.HessianFromGradient

public class HessianFromGradient
extends Object

These functions compute the image hessian by computing the image gradient twice. While about twice as fast as computing the Hessian directly from a larger kernel, it requires additional storage space.

NOTE: A subtle design flaw in many of these operations is that they add more image blur each time the derivative is computed. For example, with the sobel operator is is derived by convolving a blur kernel with a derivative kernel. So applying it twice to computer the second order x-derivative is the same as blurring it twice then applying the derivative operator twice. Thus it is not th true second order derivative. Having said that, this issue is of little practical importance and is hard to detect..

Author:

Peter Abeles

Constructor Summary

Constructors

Constructor and Description
HessianFromGradient()

Method Summary

Methods

Modifier and Type	Method and Description
static void	hessianPrewitt(ImageFloat32 inputDerivX, ImageFloat32 inputDerivY, ImageFloat32 derivXX, ImageFloat32 derivYY, ImageFloat32 derivXY, ImageBorder_F32 border) Computes the hessian given an image's gradient using a Prewitt operator.
static void	hessianPrewitt(ImageSInt16 inputDerivX, ImageSInt16 inputDerivY, ImageSInt16 derivXX, ImageSInt16 derivYY, ImageSInt16 derivXY, ImageBorder_I32 border) Computes the hessian given an image's gradient using a Prewitt operator.
static void	hessianSobel(ImageFloat32 inputDerivX, ImageFloat32 inputDerivY, ImageFloat32 derivXX, ImageFloat32 derivYY, ImageFloat32 derivXY, ImageBorder_F32 border) Computes the hessian given an image's gradient using a Sobel operator.
static void	hessianSobel(ImageSInt16 inputDerivX, ImageSInt16 inputDerivY, ImageSInt16 derivXX, ImageSInt16 derivYY, ImageSInt16 derivXY, ImageBorder_I32 border) Computes the hessian given an image's gradient using a Sobel operator.
static void	hessianThree(ImageFloat32 inputDerivX, ImageFloat32 inputDerivY, ImageFloat32 derivXX, ImageFloat32 derivYY, ImageFloat32 derivXY, ImageBorder_F32 border) Computes the hessian given an image's gradient using a three derivative operator.
static void	hessianThree(ImageSInt16 inputDerivX, ImageSInt16 inputDerivY, ImageSInt16 derivXX, ImageSInt16 derivYY, ImageSInt16 derivXY, ImageBorder_I32 border) Computes the hessian given an image's gradient using a three derivative operator.

Methods inherited from class java.lang.Object

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

Constructor Detail

HessianFromGradient

public HessianFromGradient()

Method Detail

hessianPrewitt

public static void hessianPrewitt(ImageSInt16 inputDerivX,
                  ImageSInt16 inputDerivY,
                  ImageSInt16 derivXX,
                  ImageSInt16 derivYY,
                  ImageSInt16 derivXY,
                  ImageBorder_I32 border)

Computes the hessian given an image's gradient using a Prewitt operator.

Parameters:

inputDerivX - Already computed image x-derivative.

inputDerivY - Already computed image y-derivative.

derivXX - Output second XX partial derivative.

derivYY - Output second YY partial derivative.

derivXY - Output second XY partial derivative.

border - Specifies how the image border is handled. If null the border is not processed.

hessianPrewitt

public static void hessianPrewitt(ImageFloat32 inputDerivX,
                  ImageFloat32 inputDerivY,
                  ImageFloat32 derivXX,
                  ImageFloat32 derivYY,
                  ImageFloat32 derivXY,
                  ImageBorder_F32 border)

Computes the hessian given an image's gradient using a Prewitt operator.

Parameters:

inputDerivX - Already computed image x-derivative.

inputDerivY - Already computed image y-derivative.

derivXX - Output second XX partial derivative.

derivYY - Output second YY partial derivative.

derivXY - Output second XY partial derivative.

border - Specifies how the image border is handled. If null the border is not processed.

hessianSobel

public static void hessianSobel(ImageSInt16 inputDerivX,
                ImageSInt16 inputDerivY,
                ImageSInt16 derivXX,
                ImageSInt16 derivYY,
                ImageSInt16 derivXY,
                ImageBorder_I32 border)

Computes the hessian given an image's gradient using a Sobel operator.

Parameters:

inputDerivX - Already computed image x-derivative.

inputDerivY - Already computed image y-derivative.

derivXX - Output second XX partial derivative.

derivYY - Output second YY partial derivative.

derivXY - Output second XY partial derivative.

border - Specifies how the image border is handled. If null the border is not processed.

hessianSobel

public static void hessianSobel(ImageFloat32 inputDerivX,
                ImageFloat32 inputDerivY,
                ImageFloat32 derivXX,
                ImageFloat32 derivYY,
                ImageFloat32 derivXY,
                ImageBorder_F32 border)

Computes the hessian given an image's gradient using a Sobel operator.

Parameters:

inputDerivX - Already computed image x-derivative.

inputDerivY - Already computed image y-derivative.

derivXX - Output second XX partial derivative.

derivYY - Output second YY partial derivative.

derivXY - Output second XY partial derivative.

border - Specifies how the image border is handled. If null the border is not processed.

hessianThree

public static void hessianThree(ImageSInt16 inputDerivX,
                ImageSInt16 inputDerivY,
                ImageSInt16 derivXX,
                ImageSInt16 derivYY,
                ImageSInt16 derivXY,
                ImageBorder_I32 border)

Computes the hessian given an image's gradient using a three derivative operator.

Parameters:

inputDerivX - Already computed image x-derivative.

inputDerivY - Already computed image y-derivative.

derivXX - Output second XX partial derivative.

derivYY - Output second YY partial derivative.

derivXY - Output second XY partial derivative.

border - Specifies how the image border is handled. If null the border is not processed.

hessianThree

public static void hessianThree(ImageFloat32 inputDerivX,
                ImageFloat32 inputDerivY,
                ImageFloat32 derivXX,
                ImageFloat32 derivYY,
                ImageFloat32 derivXY,
                ImageBorder_F32 border)

Computes the hessian given an image's gradient using a three derivative operator.

Parameters:

inputDerivX - Already computed image x-derivative.

inputDerivY - Already computed image y-derivative.

derivXX - Output second XX partial derivative.

derivYY - Output second YY partial derivative.

derivXY - Output second XY partial derivative.

border - Specifies how the image border is handled. If null the border is not processed.