trex.Algo
Class StegoAlgoFFT

java.lang.Object
  |
  +--trex.Algo.StegoAlgo
        |
        +--trex.Algo.StegoAlgoFFT

public class StegoAlgoFFT

extends StegoAlgo

This algorithm stores data in the frequency domain.

Version:

$Revision: 1.4 $

Author:

Bastian Friedrich <bastian@bastian-friedrich.de>

Field Summary

Fields inherited from class trex.Algo.StegoAlgo

passPhrase

Constructor Summary

StegoAlgoFFT()

Method Summary

protected javax.media.jai.PlanarImage	cropImage(Object img, int width, int height) After the inverse DFT, the image can be cropped to the original image's size with this function.
int	defaultAmplification() Return the default amplification of this algorithm for the combinedPanel.
protected javax.media.jai.PlanarImage	embedData(String data, javax.media.jai.PlanarImage img, int w, int h) Embed data into image.
protected String	extractData(javax.media.jai.PlanarImage img, int w, int h) Get actual data from image.
protected javax.media.jai.PlanarImage	FormatTransformed(javax.media.jai.PlanarImage src, BufferedImage template) Reformat the image to "TYPE_BYTE" so it can be displayed.
Component	getConfigDialog() Return the config dialog.
String	getDecrypted(ImageIcon img) Get embedded data from image.
ImageIcon	getEncrypted(String data, ImageIcon img) This method is called from the application's StegData object.
String	getInfo() Static info.
boolean	hasConfigDialog() Algorithm has a config dialog.
boolean	hasPassPhrase() Algorithm doesn't have a pass phrase - uses a config dialog instead.
boolean	pictureLargeEnough(ImageIcon img, String data) Algorithm currently does not know how big an image has to be.
protected javax.media.jai.PlanarImage	squaredImage(Object img, int width, int height) As FFT needs Images of the dimension n^2 x m^2 for any natural n and m, the image is converted to an image of that size beforehand with this method.
boolean	validConfig() Config is valid when it's "I know it's senseless" button is checked.

Methods inherited from class trex.Algo.StegoAlgo

setPassPhrase

Methods inherited from class java.lang.Object

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

Constructor Detail

StegoAlgoFFT

public StegoAlgoFFT()

Method Detail

pictureLargeEnough

public boolean pictureLargeEnough(ImageIcon img,
                                  String data)

Algorithm currently does not know how big an image has to be.

Specified by:

pictureLargeEnough in class StegoAlgo

Parameters:

img - Image to hide data in

data - data to hide

Returns:

true.

hasPassPhrase

public boolean hasPassPhrase()

Algorithm doesn't have a pass phrase - uses a config dialog instead.

Specified by:

hasPassPhrase in class StegoAlgo

Returns:

false.

hasConfigDialog

public boolean hasConfigDialog()

Algorithm has a config dialog.

Specified by:

hasConfigDialog in class StegoAlgo

Returns:

true.

validConfig

public boolean validConfig()

Config is valid when it's "I know it's senseless" button is checked.

Specified by:

validConfig in class StegoAlgo

Returns:

config validity.

extractData

protected String extractData(javax.media.jai.PlanarImage img,
                             int w,
                             int h)
                      throws DecryptImpossibleException

Get actual data from image.

Parameters:

img - (idft) Image to get data from.

w - Image width

h - Image height

Returns:

contained string.

DecryptImpossibleException

getDecrypted

public String getDecrypted(ImageIcon img)
                    throws DecryptImpossibleException

Get embedded data from image.

Specified by:

getDecrypted in class StegoAlgo

Parameters:

img - Image to get data from.

Returns:

Contained data.

DecryptImpossibleException

getConfigDialog

public Component getConfigDialog()

Return the config dialog. Construct it beforehand if necessary.

Specified by:

getConfigDialog in class StegoAlgo

Returns:

An instance of the config dialog.

See Also:

StegoAlgo.hasConfigDialog(), StegoAlgo.hasPassPhrase()

getInfo

public String getInfo()

Static info.

Specified by:

getInfo in class StegoAlgo

Returns:

"LSB in frequency domain (Fourier transformed)"

FormatTransformed

protected javax.media.jai.PlanarImage FormatTransformed(javax.media.jai.PlanarImage src,
                                                        BufferedImage template)

Reformat the image to "TYPE_BYTE" so it can be displayed.

Parameters:

src - Image to transform.

template - Image to take sample- and color model from.

Returns:

The transformed image.

embedData

protected javax.media.jai.PlanarImage embedData(String data,
                                                javax.media.jai.PlanarImage img,
                                                int w,
                                                int h)

Embed data into image. Currently a NOP.

Parameters:

data - Data to embed.

img - Envelope image.

w - Image width.

h - Image height.

Returns:

Stego-image containing the data.

squaredImage

protected javax.media.jai.PlanarImage squaredImage(Object img,
                                                   int width,
                                                   int height)

As FFT needs Images of the dimension n^2 x m^2 for any natural n and m, the image is converted to an image of that size beforehand with this method. It utilizes JAI's BorderExtenderWrap class, as Fourier transformation inherently works on periodic data. After embedding and idft, the image is cropped to it's original size with the cropImage(java.lang.Object, int, int) function.

Parameters:

img - Image to resize. Any format recognized by JAI is allowed.

width - Original image width.

height - Original image height.

Returns:

The resized image.

cropImage

protected javax.media.jai.PlanarImage cropImage(Object img,
                                                int width,
                                                int height)

After the inverse DFT, the image can be cropped to the original image's size with this function.

Parameters:

img - Image to crop.

width - New image width.

height - New image height.

Returns:

The cropped Image.

getEncrypted

public ImageIcon getEncrypted(String data,
                              ImageIcon img)

This method is called from the application's StegData object. It calls the JAI DFT/IDFT operations and starts the data embedding via the embedData(java.lang.String, javax.media.jai.PlanarImage, int, int) method.

Specified by:

getEncrypted in class StegoAlgo

Parameters:

data - Data to hide.

img - Envelope image.

Returns:

The ImageIcon hiding the data.

defaultAmplification

public int defaultAmplification()

Return the default amplification of this algorithm for the combinedPanel.

Specified by:

defaultAmplification in class StegoAlgo

Returns:

Default amplification: 255.