Module imagingbook.spectral

Package imagingbook.spectral.dft

Class Dft1dFast

java.lang.Object

imagingbook.spectral.dft.Dft1dFast

All Implemented Interfaces:

Dft1d

Direct Known Subclasses:

Dft1dFast.Double, Dft1dFast.Float

public abstract class Dft1dFast
extends Object

FFT (fast) implementation of the DFT, based on the JTransforms package by Piotr Wendykier (see https://github.com/wendykierp/JTransforms). Note that this class has no public constructor - instantiate sub-class Dft1dFast.Float or Dft1dFast.Double instead, as shown below. See Sec. 18.4.2 of [1] for additional details.

Usage example (for float data):

 float[] re = {1, 2, 3, 4, 5, 3, 0};
 float[] im = {0, 0, 0, 0, 0, 0, 0};
 Dft1d.Float dft = new Dft1dFast.Float(re.length);
 dct.forward(re, im);  // re/im now is the DFT spectrum
 dct.inverse(re, im);  // re/im now is the original signal 
 ...
 

[1] W. Burger, M.J. Burge, Digital Image Processing – An Algorithmic Introduction, 3rd ed, Springer (2022).

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Dft1dFast.Double	One-dimensional FFT implementation using double data.
static class	Dft1dFast.Float	One-dimensional FFT implementation using float data.

Method Summary

Modifier and Type	Method	Description
ScalingMode	getScalingMode()	Returns the scaling mode of this DFT (see ScalingMode).
int	getSize()	Returns the size of this DFT (length of data vectors).

Methods inherited from class java.lang.Object

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

Method Details

getSize

public int getSize()

Description copied from interface: Dft1d

Returns the size of this DFT (length of data vectors).

Specified by:

getSize in interface Dft1d

Returns:

the size of this DFT

getScalingMode

public ScalingMode getScalingMode()

Description copied from interface: Dft1d

Returns the scaling mode of this DFT (see ScalingMode).

Specified by:

getScalingMode in interface Dft1d

Returns:

the scaling mode of this DFT.