org.openimaj.image.processing.convolution

Class FImageGradients

java.lang.Object

org.openimaj.image.processing.convolution.FImageGradients

All Implemented Interfaces:

ImageAnalyser<FImage>

public class FImageGradients
extends Object
implements ImageAnalyser<FImage>

Image processor for calculating gradients and orientations using finite-differences. Both signed (+/- PI) orientations and unsigned (+/- PI/2) are computable.

Author:

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

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FImageGradients.Mode Modes of operation for signed and unsigned orientations

Field Summary

Fields

Modifier and Type	Field and Description
FImage	magnitudes The gradient magnitudes
FImageGradients.Mode	mode The orientation mode
FImage	orientations The gradient orientations

Constructor Summary

Constructors

Constructor and Description
FImageGradients() Default constructor using FImageGradients.Mode.Signed mode.
FImageGradients(FImageGradients.Mode mode) Construct using the given FImageGradients.Mode.

Method Summary

Modifier and Type	Method and Description
void	analyseImage(FImage image) Analyse an image.
static FImageGradients	getGradientMagnitudesAndOrientations(FImage image) Static helper to create a new FImageGradients and call analyseImage(FImage) with the image.
static FImageGradients	getGradientMagnitudesAndOrientations(FImage image, FImageGradients.Mode mode) Static helper to create a new FImageGradients and call analyseImage(FImage) with the image.
static void	gradientMagnitudesAndOrientations(FImage image, FImage magnitudes, FImage orientations) Estimate gradients magnitudes and orientations by calculating pixel differences.
static void	gradientMagnitudesAndQuantisedOrientations(FImage image, FImage[] magnitudes) Estimate gradients magnitudes and orientations by calculating pixel differences.
static void	gradientMagnitudesAndQuantisedOrientations(FImage image, FImage[] magnitudes, boolean interp, FImageGradients.Mode mode) Estimate gradients magnitudes and orientations by calculating pixel differences.
static void	gradientMagnitudesAndUnsignedOrientations(FImage image, FImage magnitudes, FImage orientations) Estimate gradients magnitudes and orientations by calculating pixel differences.

Methods inherited from class java.lang.Object

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

Field Detail

magnitudes

public FImage magnitudes

The gradient magnitudes

orientations

public FImage orientations

The gradient orientations

mode

public FImageGradients.Mode mode

The orientation mode

Constructor Detail

FImageGradients

public FImageGradients()

Default constructor using FImageGradients.Mode.Signed mode.

FImageGradients

public FImageGradients(FImageGradients.Mode mode)

Construct using the given FImageGradients.Mode.

Parameters:

mode - the mode

Method Detail

analyseImage

public void analyseImage(FImage image)

Description copied from interface: ImageAnalyser

Analyse an image.

Specified by:

analyseImage in interface ImageAnalyser<FImage>

Parameters:

image - The image to process in place.

getGradientMagnitudesAndOrientations

public static FImageGradients getGradientMagnitudesAndOrientations(FImage image)

Static helper to create a new FImageGradients and call analyseImage(FImage) with the image.

Parameters:

image - the image

Returns:

a FImageGradients for the image

getGradientMagnitudesAndOrientations

public static FImageGradients getGradientMagnitudesAndOrientations(FImage image,
                                                                   FImageGradients.Mode mode)

Static helper to create a new FImageGradients and call analyseImage(FImage) with the image.

Parameters:

image - the image

mode - the orientation mode

Returns:

a FImageGradients for the image

gradientMagnitudesAndOrientations

public static void gradientMagnitudesAndOrientations(FImage image,
                                                     FImage magnitudes,
                                                     FImage orientations)

Estimate gradients magnitudes and orientations by calculating pixel differences. Edges get special treatment. The resultant gradients and orientations are returned though the gradients and orientations parameters respectively. The images represented by the gradients and orientations parameters are assumed to be initialized to the same size as the input image. Gradients are computed using the atan2 function and will be in the range +/-PI.

Parameters:

image - the input image

magnitudes - the output gradient magnitudes

orientations - the output gradient orientations

gradientMagnitudesAndUnsignedOrientations

public static void gradientMagnitudesAndUnsignedOrientations(FImage image,
                                                             FImage magnitudes,
                                                             FImage orientations)

Estimate gradients magnitudes and orientations by calculating pixel differences. Edges get special treatment. The resultant gradients and orientations are returned though the gradients and orientations parameters respectively. The images represented by the gradients and orientations parameters are assumed to be initialized to the same size as the input image. Gradients are computed using the atan function and will be in the range +/- PI/2.

Parameters:

image - the input image

magnitudes - the output gradient magnitudes

orientations - the output gradient orientations

gradientMagnitudesAndQuantisedOrientations

public static void gradientMagnitudesAndQuantisedOrientations(FImage image,
                                                              FImage[] magnitudes)

Estimate gradients magnitudes and orientations by calculating pixel differences. Edges get special treatment.

The orientations are quantised into magnitudes.length bins and the magnitudes are spread to the adjacent bin through linear interpolation. The magnitudes parameter must be fully allocated as an array of num orientation bin images, each of the same size as the input image.

Parameters:

image -

magnitudes -

gradientMagnitudesAndQuantisedOrientations

public static void gradientMagnitudesAndQuantisedOrientations(FImage image,
                                                              FImage[] magnitudes,
                                                              boolean interp,
                                                              FImageGradients.Mode mode)

Estimate gradients magnitudes and orientations by calculating pixel differences. Edges get special treatment.

The orientations are quantised into magnitudes.length bins. Magnitudes are optionally spread to the adjacent bin through linear interpolation. The magnitudes parameter must be fully allocated as an array of num orientation bin images, each of the same size as the input image.

Parameters:

image -

magnitudes -

interp -

mode -