function?[simPSNR]=kuopin_wangying（yuzhiaattack_styleattack_strength）
%%%attack_style用于設置選擇何種攻擊
%%%yuzhi用于選擇嵌入系數
%%%a用于控制嵌入強度
%%%sim返回相關系數
%%%psnr返回峰值信噪比
%%%attack_strength用于控制攻擊的強弱
%%%%%%%%%%%%%%%%%%%%%讀入原始載體圖像%%%%%%%%%%%%%%%%%%%%%%%%%
[xmap]=imread（‘lena.bmp‘）;
[rowcol]=size（x）;
M=row;
N=col;
MN=col*row;
figure（1）;image（x）colormap（map）;
title（‘原始圖像‘‘Fontsize‘13‘color‘‘yellow‘）;
x_source=x;
fun1=@dct2;%%%分割圖像進行二維DCT變換
J1=blkproc（x[256256]fun1）;
%%%%%%%%%%%%%%%%%%%%產生長度為1000的偽隨機序列作為水印信息%%%%%%%%%%%
mm=normrnd（01[1?1000]）;
MNm=1000;
z=mm;
num=1;
num1=1;
num2=1;
t=1;
%%%%%%%%%%%%%%%%%%%%水印信息嵌入%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
J11=J1;
for?i=1:M
????for?k=1:N
????????if?abs（J1（ik））>yuzhi&&t<=MNm&&（i+k>2）
????????????J11（ik）=J1（ik）*（1+a*z（t））;
????????????t=t+1;
????????end
????end
end
marksize=t-1;
J2=IDCT2（J11）;%%%二維DCT逆變換
imwrite（uint8（round（J2））‘ss_watermarked.bmp‘）;
%%%%%%%%%%%%%%%%%%%%計算合成信號的峰值信噪比%%%%%%%%%%%%%%%%%%%%%%
x_temp1=J2-double（x_source）;
figure（10）imshow（uint8（round（100*x_temp1）））;
imwrite（（uint8（round（100*x_temp1）））‘ss_chazhi.bmp‘）;
x_temp2=x_temp1（:）;
x_temp3=abs（x_temp2）;
x_temp4=x_temp3‘*x_temp3;
d_embed=x_temp4/（M*M）;
SDR1=255*255/d_embed;
PSNR=10*log10（SDR1）;
%%%%%%%%%%%%%%%%%%%%攻擊%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
J2=imread（‘ss_watermarked.bmp‘）;
if?attack_style==1
????%%%（1）放大兩倍的操作（當然提取之前要先縮小兩倍）
xxx1=imresize（J22‘bicubic‘）;
xxx2=imresize（xxx11/2‘bicubic‘）;
yy=double（xxx2）;
end
if?attack_style==2
%%%（1）放大四倍的操作（當然提取之前要先縮小四倍）
xxx1=imresize（J24‘bicubic‘）;
xxx2=imresize（xxx11/4‘bicubic‘）;
yy=double（xxx2）;
end
%（2）縮小1/4的操作
if?attack_style==3
????xxx1=imresize（J23/4‘bicubic‘）;
????xxx2=imresize（xxx14/3‘bicubic‘）;
????yy=double（xxx2）;
end
if?attack_style==4
????xxx1=imresize（J22/4‘bicu