dither_test.rar_Score!_matlab watermark_watermark_水印_水印 检测

%************************************************************************** %date :2004_11_18 %Function name:dither_test.m %Function :simplification the grey image form 8bit to 2bit %programer :lj %************************************************************************** function dither_test() %define the function name A=double(imread('d:\lena图像\lena_256x256_gray.jpg')); %input the image lenna (grey,8bit,256X256 pixel) size(A); imshow(A/255),pause, [m,n]=size(A); for i=1:m for j=1:n a=A(i,j); if a<=128 a=a; else a=a-255; end % determind the basic value,when A(i,j)>128,the a is negative;while % A(i,j)<=128,the a is positive if (i<m)&&(j==1) A(i,j+1)=A(i,j+1)+(7*a)/16; A(i+1,j+1)=A(i+1,j+1)+(1*a)/16; A(i+1,j)=A(i+1,j)+(5*a)/16; elseif (i<m)&&(j<n) A(i,j+1)=A(i,j+1)+(7*a)/16; A(i+1,j+1)=A(i+1,j+1)+(1*a)/16; A(i+1,j)=A(i+1,j)+(5*a)/16; A(i+1,j-1)=A(i+1,j-1)+(3*a)/16; elseif (i<m)&&(j==n) A(i+1,j-1)=A(i+1,j-1)+(3*a)/16; A(i+1,j)=A(i+1,j)+(5*a)/16; elseif (i==m)&&(j<n) A(i,j+1)=A(i,j+1)+(7*a)/16; elseif (i==m)&&(j==n) A(i,j)=A(i,j); end end end A=fix(A); % similate the float for i=1:m for j=1:n if A(i,j)<=128 A(i,j)=0; else A(i,j)=1; end end end b=ones(2,2); A=kron(A,b); % B=(imread('lenna_gray.bmp')); % C=dither(B); % D=im2bw(B); %************************************************************************** %Now redfine the matrix of B by four pixel %************************************************************************** E=double(imread('d:\lena图像\lena_256x256_gray.jpg')); for i=1:m for j=1:n if (i<m)&&(j==1) a=(E(i,j)+E(i,j+1)+E(i+1,j+1)+ E(i+1,j))/4; E(i,j)=a; E(i,j+1)=a; E(i+1,j+1)=a; E(i+1,j)=a; elseif (i<m)&&(j<n) a=(E(i,j)+E(i,j+1)+E(i+1,j+1)+ E(i+1,j)+E(i+1,j-1))/5; E(i,j)=a; E(i,j+1)=a; E(i+1,j+1)=a; E(i+1,j)=a; E(i+1,j-1)=a; elseif (i<m)&&(j==n) a=(E(i,j)+E(i+1,j-1)+E(i+1,j))/3; E(i,j)=a; E(i+1,j-1)=a; E(i+1,j)=a; elseif (i==m)&&(j<n) a=(E(i,j)+ E(i,j+1))/2; E(i,j)=a; E(i,j+1)=a; elseif (i==m)&&(j==n) E(i,j)=E(i,j); end end end E=fix(E); % similate the float for i=1:m for j=1:n if E(i,j)<=128 E(i,j)=0; else E(i,j)=1; end end end %************************************************************************** % Now for every pixel,we use a 5X5 Matrix to reconstrcture the image A % The 5X5 Matrix is magic(5) %************************************************************************** %subplot(3,2,1),subimage(B),title('former'); %subplot(3,2,2),subimage(C),title('matlab-dither()'); %subplot(3,2,3),subimage(D),title('matlab-im2bw()'); %subplot(3,2,4),subimage(E),title('Two-values'); %subplot(3,2,5),subimage(A),title('error-diffusion'); imshow(A),title('error-diffusion'), size(A),save lena_dither.mat A