基于DCT的信息隐藏实验

function [Y_waterMarked]=embed(S_Y_P_source,row,column,blocksize,message_pad) % 嵌入规则:对于各8×8块，DCT变换后以step为步长量化，以S取模。 % if message bit is 0,coefficient+s/4; % if message bit is 1,coefficient+3*s/4; step=1;%量化步长 s=15;%模值 for y=0:(row/blocksize-1) for x=0:(column/blocksize-1) % transform block using DCT dct_block=dct2(S_Y_P_source((y*blocksize+1):(y+1)*blocksize,(x*blocksize+1):(x+1)*blocksize)); dct_block_WM=dct_block; % DCT变换后以step为步长量化，以S取模。 messured_dct_block=dct_block/step; relaxed_messured_dct_block=messured_dct_block-mod(messured_dct_block,s); % if message bit is 0　elseif message bit is 1 if (message_pad(y*column/blocksize+x+1) == 0) dct_block_WM(1,2)=relaxed_messured_dct_block(1,2)+s/4; dct_block_WM(3,1)=relaxed_messured_dct_block(3,1)+s/4; dct_block_WM(4,4)=relaxed_messured_dct_block(4,4)+s/4; elseif (message_pad(y*column/blocksize+x+1) == 1) dct_block_WM(1,2)=relaxed_messured_dct_block(1,2)+3*s/4; dct_block_WM(3,1)=relaxed_messured_dct_block(3,1)+3*s/4; dct_block_WM(4,4)=relaxed_messured_dct_block(4,4)+3*s/4; end % transform block back into spatial domain Y_waterMarked( y*blocksize+1:(y+1)*blocksize,x*blocksize+1:(x+1)*blocksize)=idct2(dct_block_WM); end end