RE: Re: [WM]: human visual system in video

[jd_sun <jd_sun@sina.com>]

Dear Dominique:
     Thank you for your response to my question,first.I think after readi=
ng your letter, I
understand your idea. But I think there must be some measures for the acc=
eleration or the
velocity.
I have read a paper,"perceptually tuned robust watermarking scheme for di=
gital video using
motion entropy masking",in which there are the equations defined by motio=
n vectors and
based on the masking model for images to express the sensitivity to motio=
n. I think it is
reasonable to some extent. How do you think about it?
     I think maybe the motion estimation can reslove the issue caused by
acceleration/velocity,but I am not confirm. What is your opinion?
Best Regards!
                                          Yours Sincerely,
                                                          J.D.Sun
----- Original Message -----
From:"DA Winne, Electrical & Electronic Engineering" <D.Winne@bristol.ac.=
uk>
To:jd_sun <jd_sun@sina.com>
Subject:Re: [WM]: human visual system in video
Date:Mon, 22 Sep 2003 18:15:12 +0800
 >Hi,
 >
 >The watermark strength factor of a video watermarking system has a
 >spatial and a temporal part. There exist good publications which
 >describe the spatial factor*.
 >Some video watermarking papers describe a temporal shape factor as they
 >claim that a benefit can be gained by exploiting the decrease of
 >spatial acuity (sharpness) of a moving object. I argue against the
 >watermark strength factor adaptation to the motion content as prior
 >knowledge of the ability of the viewers visual system to track an
 >object is not available. The spatial acuity is a function of the
 >ability of the visual system to track an object with smooth-pursuit eye
 >movements and does not depend directly on the image velocity. Assuming
 >the availability of this prior knowledge does not solve the
 >perceptibility of the watermark when the sequence is viewed at a slower
 >frame rate or even is stopped, as the moving object will accelerate at
 >a slower pace and makes it easier to track. Therefore a stronger
 >watermark will become perceptible. The only case where a stronger
 >watermark can be embedded imperceptibly is immediately following
 >drastic scene changes. As these frames will be coarser quantized and
 >the visual system needs time to adapt to the new scene. There is only
 >one case where one can embed a stronger watermark into a moving object
 >that is when the acceleration is random and difficult to track.
 >
 >Hope that helps,
 >Dominique
 >
 >* S.Voloshynovskiy, A.Herrigel, N.Baumg=E4rtner, T.Pun, A stochastic
 >approach to content adaptive digital image watermarking,  In
 >International Workshop on Information Hiding, Notes in Computer
 >Science, Ed. Andreas Pfitzmann, Dresden, Germany, September (1999), pp.
 >211-236.
 >On Mon, 22 Sep 2003 10:42:41 +0800 jd_sun <jd_sun@sina.com> wrote:
 >
 >> Hi,every watermarker:
 >>      Would you like to tell me whether there are some papers on human
 >visual masking model
 >> for video? And how to get them? I think there must be some papers on
 >video perceptual
 >> measure or the masking model for video, just like there are so many
 >human visual system
 >> for images.Thanks for any help in advance!
 >>
 >>                                          Yours Sincerely,
 >>                                                           J.D.Sun
 >>
 >>

 >Ph.D. student in Image Communications
 >Dominique Albert Winne, Electrical & Electronic Engineering
 >Room 2.19 MVB, tel: (0044) 0117/9545126
 >D.Winne@bristol.ac.uk (private: winnje@hotmail.com)


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