[WM]: algorithm DCT need help

[Gomper <gomper@wp.pl>]

hi watermarkers!

Im  trying  implement DCT to my fragile image watermarking. Problem is that I can't/don't know how embedd watermark to image :(.

Im doing this:

matlab code:
[obraz,map] = imread('lena_256.bmp');
obraz = double(obraz);
A_dct = dct2(obraz);

and  values of A_dct are '+' and '-' . If I think corectly I need all values  of  A_dct  convert to binary and then modify some bits
with my watermark.
But  I  dont  know  what  to  do with negative values of A_dct? How to convert  them  to  binary values?  How and where im supposed
to embedd watermark then?

For ANY help Im really grateful.
Looking foreward your suggestions.
Great thanks


--
best regards,
 Gomper


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