Blind Photograph Watermarking with Robust Defocus-Based JND Model

Algorithm 2

.

Watermarking extraction.

Begin

Input: Watermarked photograph ;

Output: Watermark Image ;

Step 1: Transform the photograph from RGB space to YCbCr space. Select the channel Y as the host photograph;

Step 2: Divide the host photograph into 8 × 8 non-overlapped blocks;

For each block do

1. Obtain the vector and the original quantization step from the watermarked photograph ;

2. Project these two vectors to the given direction and get and ;

3. And one bit of the watermark message is extracted by Equation (20);

End

Return Watermark message ;