Re: [WM]: Re: wavelet based watermarked

[bo zambo <bo_me_bo@yahoo.com>]

thanks Mr/Ms Min-Su KIM
I have done what you told and the max value of alpha to  have watermark image as same as the original visually is only 0.1, Is it
ok? is it to small for robustness? is it because I use db filter for dwt? or it because the pseudorandom binary sequence that I use?
I generate it just like that, no rules and other just a sequence of 1 and -1. Do I have to use the pseudorandom binary sequence with
zero mean and variance 1? thank you very much!

Bo

--- Min-Su KIM <speedyminsu@gmail.com> wrote:

> after forward WT, did you insert a bit like THIS?
> W = W + M ?
> ,where W is detail coefficient, M is your random bits.
> 
> and if you did so, maybe, it was too big to be invisible.
> 
> Try like THIS,
> 
> W = W + alpha * M,
> 
> , where 0.0 < alpha <1.0
> 
> you can control the strength of your watermark more invisible with 
> alpha.
> 
> or you can also try like THIS,
> 
>  W = W + alpha * M * W,
> 
> , where 0.0 < alpha <1.0.
> 
> You can see our BIBLE book, DIGITAL WATERMARKING from the the COX, the 
> MILLER, and the BLOOM . :)
> 
> ----- Original Message -----
> From: "bo zambo" <bo_me_bo@yahoo.com>
> To: <watermarking@watermarkingworld.org>
> Sent: Wednesday, August 24, 2005 5:41 PM
> Subject: [WM]: wavelet based watermarked
> 
> 
> > dear watermarkers
> > 
> > I'm working on a wavelet based watermarked...I'm
> really new in this field and I have lot to ask...
> > I try a simple wavelet based watermarked just
> decomposed the image and change the details coeffecients of the lowest 
> level by adding
> > it with 1 or -1 (randomly) after that inverse DWT,
> the problem is...the watermarked image is not perceptual 
> invisibility...can
> > antone tell me why and rceptual invisibility...can how to fix this. 
> >I follow the step from some papers
> but the result is not the same. Am I miss some step?
> Ok
> > thanks. please don't laugh,,I really new in these
> field,,,ok you can laugh but please answer my question.
> > 
> > regau can laugh but please answer my question.
> >rds
> > Bo


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