[WM]: Regarding implementation of STDM (QIM)

[shalini priti <shalini_priti@yahoo.co.in>]

Hello Watermarkers,

 

I need your kind concern or advice. I am trying to implement STDM (spread-transform dither modulation) watermarking algorithm as a part of research.

 

I have implemented the same with directional vector (also called projection vector), randomly generated with uniform distribution in the unit interval [-0.5, 0.5].

 

I have read some papers describing that the same can yeild better results if implemented in the direction of least perceptual distortion. Can someone suggest me how do I measure the perceptual distortion for an image. how do i incorporate it in my  vector generation method.

 

Thanks

Shalini