boofcv.alg.transform.fft

Class DiscreteFourierTransformOps

java.lang.Object

boofcv.alg.transform.fft.DiscreteFourierTransformOps

public class DiscreteFourierTransformOps
extends Object

Various functions related to DiscreteFourierTransform.

Author:

Peter Abeles

Constructor Summary

Constructors

Constructor and Description
DiscreteFourierTransformOps()

Method Summary

Methods

Modifier and Type	Method and Description
static void	checkImageArguments(ImageBase image, ImageInterleaved transform) Checks to see if the image and its transform are appropriate sizes .
static DiscreteFourierTransform<ImageFloat32,InterleavedF32>	createTransformF32() Creates a DiscreteFourierTransform for images of type ImageFloat32.
static DiscreteFourierTransform<ImageFloat64,InterleavedF64>	createTransformF64() Creates a DiscreteFourierTransform for images of type ImageFloat64.
static boolean	isPowerOf2(int x) true if the number provided is a power of two
static void	magnitude(InterleavedF32 transform, ImageFloat32 magnitude) Computes the magnitude of the complex image: magnitude = sqrt( real2 + imaginary2 )
static void	magnitude(InterleavedF64 transform, ImageFloat64 magnitude) Computes the magnitude of the complex image: magnitude = sqrt( real2 + imaginary2 )
static void	multiplyComplex(InterleavedF32 complexA, InterleavedF32 complexB, InterleavedF32 complexC) Performs element-wise complex multiplication between two complex images.
static void	multiplyComplex(InterleavedF64 complexA, InterleavedF64 complexB, InterleavedF64 complexC) Performs element-wise complex multiplication between two complex images.
static void	multiplyRealComplex(ImageFloat32 realA, InterleavedF32 complexB, InterleavedF32 complexC) Performs element-wise complex multiplication between a real image and a complex image.
static void	multiplyRealComplex(ImageFloat64 realA, InterleavedF64 complexB, InterleavedF64 complexC) Performs element-wise complex multiplication between a real image and a complex image.
static int	nextPow2(int x) Returns the closest power-of-two number greater than or equal to x.
static void	phase(InterleavedF32 transform, ImageFloat32 phase) Computes the phase of the complex image: phase = atan2( imaginary , real )
static void	phase(InterleavedF64 transform, ImageFloat64 phase) Computes the phase of the complex image: phase = atan2( imaginary , real )
static void	realToComplex(ImageFloat32 real, InterleavedF32 complex) Converts a regular image into a complex interleaved image with the imaginary component set to zero.
static void	realToComplex(ImageFloat64 real, InterleavedF64 complex) Converts a regular image into a complex interleaved image with the imaginary component set to zero.
static void	shiftZeroFrequency(InterleavedF32 transform, boolean forward) Moves the zero-frequency component into the image center (width/2,height/2).
static void	shiftZeroFrequency(InterleavedF64 transform, boolean forward) Moves the zero-frequency component into the image center (width/2,height/2).

Methods inherited from class java.lang.Object

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

Constructor Detail

DiscreteFourierTransformOps

public DiscreteFourierTransformOps()

Method Detail

createTransformF32

public static DiscreteFourierTransform<ImageFloat32,InterleavedF32> createTransformF32()

Creates a DiscreteFourierTransform for images of type ImageFloat32.

Returns:

DiscreteFourierTransform

See Also:

GeneralPurposeFFT_F32_2D

createTransformF64

public static DiscreteFourierTransform<ImageFloat64,InterleavedF64> createTransformF64()

Creates a DiscreteFourierTransform for images of type ImageFloat64.

Returns:

DiscreteFourierTransform

See Also:

GeneralPurposeFFT_F64_2D

isPowerOf2

public static boolean isPowerOf2(int x)

true if the number provided is a power of two

Parameters:

x - number

Returns:

true if it is a power of two

nextPow2

public static int nextPow2(int x)

Returns the closest power-of-two number greater than or equal to x.

Parameters:

x -

Returns:

the closest power-of-two number greater than or equal to x

checkImageArguments

public static void checkImageArguments(ImageBase image,
                       ImageInterleaved transform)

Checks to see if the image and its transform are appropriate sizes . The transform should have twice the width and twice the height as the image.

Parameters:

image - Storage for an image

transform - Storage for a Fourier Transform

shiftZeroFrequency

public static void shiftZeroFrequency(InterleavedF32 transform,
                      boolean forward)

Moves the zero-frequency component into the image center (width/2,height/2). This function can be called to undo the transform.

Parameters:

transform - the DFT which is to be shifted.

forward - If true then it does the shift in the forward direction. If false then it undoes the transforms.

shiftZeroFrequency

public static void shiftZeroFrequency(InterleavedF64 transform,
                      boolean forward)

Moves the zero-frequency component into the image center (width/2,height/2). This function can be called to undo the transform.

Parameters:

transform - the DFT which is to be shifted.

forward - If true then it does the shift in the forward direction. If false then it undoes the transforms.

magnitude

public static void magnitude(InterleavedF32 transform,
             ImageFloat32 magnitude)

Computes the magnitude of the complex image:
magnitude = sqrt( real² + imaginary² )

Parameters:

transform - (Input) Complex interleaved image

magnitude - (Output) Magnitude of image

magnitude

public static void magnitude(InterleavedF64 transform,
             ImageFloat64 magnitude)

Computes the magnitude of the complex image:
magnitude = sqrt( real² + imaginary² )

Parameters:

transform - (Input) Complex interleaved image

magnitude - (Output) Magnitude of image

phase

public static void phase(InterleavedF32 transform,
         ImageFloat32 phase)

Computes the phase of the complex image:
phase = atan2( imaginary , real )

Parameters:

transform - (Input) Complex interleaved image

phase - (output) Phase of image

phase

public static void phase(InterleavedF64 transform,
         ImageFloat64 phase)

Computes the phase of the complex image:
phase = atan2( imaginary , real )

Parameters:

transform - (Input) Complex interleaved image

phase - (output) Phase of image

realToComplex

public static void realToComplex(ImageFloat32 real,
                 InterleavedF32 complex)

Converts a regular image into a complex interleaved image with the imaginary component set to zero.

Parameters:

real - (Input) Regular image.

complex - (Output) Equivalent complex image.

realToComplex

public static void realToComplex(ImageFloat64 real,
                 InterleavedF64 complex)

Converts a regular image into a complex interleaved image with the imaginary component set to zero.

Parameters:

real - (Input) Regular image.

complex - (Output) Equivalent complex image.

multiplyRealComplex

public static void multiplyRealComplex(ImageFloat32 realA,
                       InterleavedF32 complexB,
                       InterleavedF32 complexC)

Performs element-wise complex multiplication between a real image and a complex image.

Parameters:

realA - (Input) Regular image

complexB - (Input) Complex image

complexC - (Output) Complex image

multiplyRealComplex

public static void multiplyRealComplex(ImageFloat64 realA,
                       InterleavedF64 complexB,
                       InterleavedF64 complexC)

Performs element-wise complex multiplication between a real image and a complex image.

Parameters:

realA - (Input) Regular image

complexB - (Input) Complex image

complexC - (Output) Complex image

multiplyComplex

public static void multiplyComplex(InterleavedF32 complexA,
                   InterleavedF32 complexB,
                   InterleavedF32 complexC)

Performs element-wise complex multiplication between two complex images.

Parameters:

complexA - (Input) Complex image

complexB - (Input) Complex image

complexC - (Output) Complex image

multiplyComplex

public static void multiplyComplex(InterleavedF64 complexA,
                   InterleavedF64 complexB,
                   InterleavedF64 complexC)

Performs element-wise complex multiplication between two complex images.

Parameters:

complexA - (Input) Complex image

complexB - (Input) Complex image

complexC - (Output) Complex image