信噪比（PSNR）

function psnr=PSNR(A,B)

%将图像A的大小赋值给变量SizeA

sizeA=size(A);

%将图像B的大小赋值给变量SizeB

sizeB=size(B);

%判断A与B的大小是否相等

if sizeA~=sizeB

error(‘Image A and B are not of the same size’)

end

if A==B

error(‘Image are idential:PSNR has infinite value’)

end

%分别找出A与B中的最大与最小灰度点值

max2_A=max(max(A));

max2_B=max(max(B));

min2_A=min(min(A));

min2_B=min(min(B));

%确定灰度值的范围在0~255

if max2_A>255 || max2_B>255 || min2_A<0 ||min2_B<0

error(‘input matrices must have values in the interval [0,255]’)

end

error_diff=A-B;

psnr=20*log10(255/(sqrt(mean(mean(error_diff)))));

disp(sprintf(‘PSNR’= + %5.2fdB’,psnr))