watermark performance standard & algorithms

standard:

1) imperceptibility   2)robustness   3)capacity     4)security    5)false -arlarm rate   

algorithms: 

    1) patchwork:   divide image into two collections with equal size

                               if w=1, add 1 to the first colletion,while decrease 1 to the other

                               if w=0,decrease 1 to the first collection,while add 1 to the other/

statistic: compare the two collections ,if the first is more than the  other, represents w=1,which is inserted.

questions: how are  the two collections is divided? how to identify which is which?

    2)Generate Guassian:   make  noise  N   with the same dimension to image I

                then: if w=1, I'= I+N;

                             w=0,I'=I-N;

                            c=I' * N

statistic: check out the c is more than 0;

question: what's the dimension means? why c must be the multiply of i' and N?

    3)spread spectrum: 1) perform DCT to image

                                      2)Generate  Guassian-like noise vextor x;

                                      3)select 1000 max DCT coefficients;

                              then vi=vi(1+aXi)

                                       SUM( X,X*)

               question: vextor?

    4)LSB:  Generate m sequence

                  Compress original image to 128 color using adaptive histogram algorithm

                  Insert m-sequence to LSB of image

      Detection: correlation of LSB to m-sequence

    5) predictive coding:

        Generate a difference table with key

        Modify pixel with smallest change so that the difference of two adjacent corresponds to current inserted bit.

   6)QIM:

   7)Salient point:

   8) Chaos based

   9) RST -invariant