A reinforcement learning method for decision making process of watermark strength in still images

Summary of the embedding and extracting procedures. Embedding procedure Compute the DCT of the whole image; Select the middle frequency coefficients; Embed the watermark according to Equation 5; Compute the inverse DCT of the result to obtain the watermarked image. Detection procedure Compute the DCT of watermarked image; Select the middle frequency coefficients; Compute NCC between the coefficients and original watermark; Compare the NCC with the predefined threshold; Decide the image is watermarked or not. without loss of the robustness against signal processing operations (Liang, 2008). Then, the watermark is scaled according to the watermark strength of the particular frequency component. The vector Xc { xK 1, xK 2, , xKc M } with the marked DCT coefficients is computed according to the following rule: c K  1 Ox K  i wi (5) action Where i 1,2, ,M and O is the watermark strength. Finally, Xc is reinserted in the zig-zag scan and the inverse DCT is performed, thus obtaining the watermarked image