I'm working on a project to hide simple string inside a 255x255 Image using Wavelet transform, The problem is that,

When i used Haar Wavelet the result is successful, This is what I've done,

  • Decompose the image into its approximation and details(Vertical,Horizontal,Diognal)
  • then Hiding message in the details of the Image,
  • Reconstructing the Image with Hidden message,
  • Applying same wavelet on the Reconstructed Image.
  • Decoding the algorithms applied for the encoding of the Message.

but when i tried these Wavelets,

Coiflets 'coif1', ... , 'coif5'

Symlets'sym2', ... , 'sym8', ... ,'sym45'

Discrete Meyer'dmey'

Biorthogonal'bior1.1', 'bior1.3', 'bior1.5'
'bior2.2', 'bior2.4', 'bior2.6', 'bior2.8'
'bior3.1', 'bior3.3', 'bior3.5', 'bior3.7'
'bior3.9', 'bior4.4', 'bior5.5', 'bior6.8'

Reverse Biorthogonal'rbio1.1', 'rbio1.3', 'rbio1.5'
'rbio2.2', 'rbio2.4', 'rbio2.6', 'rbio2.8'
'rbio3.1', 'rbio3.3', 'rbio3.5', 'rbio3.7'
'rbio3.9', 'rbio4.4', 'rbio5.5', 'rbio6.8'

I am getting weird characters rather than my original Hidden Message. What does that mean ? How would i know which Wavelet should i suppose to use when the message is totally random ?

  • 1
    $\begingroup$ Do you mean steganography or stenography? $\endgroup$ – Dilip Sarwate Mar 14 '13 at 2:30
  • $\begingroup$ If you transform forward and back on the original image (no hiding) a few times, does it change? $\endgroup$ – geometrikal Mar 14 '13 at 4:13
  • $\begingroup$ no it isn't, it remains intact. $\endgroup$ – Sufiyan Ghori Mar 14 '13 at 9:25
  • 1
    $\begingroup$ What does 'hiding' mean? Changing the coefficients of the DW transformed signal and transforming back? If you change the coefficients by a fixed amount, e.g. +10%, does it work? $\endgroup$ – geometrikal Mar 14 '13 at 10:53

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