PSNR计算

purpose_857

im1=imread('lena2.bmp');
%im1=im2double(im1);
im2=imread('lena_rbhv.bmp');
/ P0 V; e( u1 n' f%im2=im2double(im2);
   
* G5 q- ?' }; ^& Y+ u9 ?1 G. c5 qif (size(im1))~=(size(im2))
    error('错误：两个输入图象的大小不一致');
end

    [m,n] = size(im1);
    A = double(im1);
    B = double(im2);
1 P7 R; m1 C6 t5 Z4 J4 D9 d9 q* n8 P  T    D = sum( sum( (A-B).^2 ) );%||A-B||^2
    MSE = D / (m * n);
& e* q, G: a0 @# q7 T$ tif  D == 0
6 b8 d, C* _( J5 K5 S    error('两幅图像完全一样');
3 p1 }6 _2 }/ w+ \    PSNR = 200;
else
    PSNR = 10*log10( (255^2) / MSE );                                                        
end


从网上COPY了下 稍微改了下  我不知道这一行为什么出错  请指教
* ~4 j& k- i2 i# \& u8 w! T& ~9 Q1 [??? Subscript indices must either be real positive integers or logicals.
0 B4 l5 h5 U2 Y6 A  T
1 w9 [. v  h; a2 R9 _) ^Error in ==> PSNR_ERRO at 14
    D = sum( sum( (A-B).^2 ) );%||A-B||^2

I_believe

D = sum( sum( (A-B).^2 ) );指的是什么，为什么有两从sum？

peerless2021

function main()
+ c8 x% `! x; Z0 W" A$ @clc; close all;
I=imread('cameraman.tif'); %用的是原图
1 V9 V5 \8 O- ^! J  {) {I1=imnoise(I,'gaussian',0,0.01);
% ~# Y  b( |) U2 u* [; _3 N  pfigure;
& p0 E+ s# W% v8 usubplot(1, 2, 1); imshow(I); title('原图像');
subplot(1, 2, 2); imshow(I1); title('加噪声图像');
% P. [* V" f- X0 B. @6 P[PSNR, MSE] = psnr(I, I1)
& H5 V5 l+ \9 g# `, y7 }% 图像峰值信噪比PSNR、均方根误差MSE
7 p& L: `. ^5 k0 R# G1 |- ofunction [PSNR, MSE] = psnr(X, Y)
, F: p$ n# Z- c: T% a/ D, [$ T% 计算峰值信噪比PSNR、均方根误差MSE
  {8 q: A; d* t3 Y  z% 如果输入Y为空，则视为X与其本身来计算PSNR、MSE

9 [; |* Y9 V: K& Lif nargin<2
    D = X;
else
    if any(size(X)~=size(Y))
+ N8 H" W" c' H0 B( C1 h  A0 x* Y        error('The input size is not equal to each other!');
4 C0 B# q( j0 H    end
    D = X-Y;
6 E, K; |9 ^" k" Pend
MSE = sum(D(: ).*D(: ))/prod(size(X));
8 X" ?" {% s$ m; KPSNR = 10*log10(255^2/MSE);
function main()
clc; close all;
I=imread('cameraman.tif'); %用的是原图
- x9 ]- N1 W1 L/ j/ ~I1=imnoise(I,'gaussian',0,0.01);
6 ~1 E1 D0 i2 Q  k( \5 y6 cfigure;
subplot(1, 2, 1); imshow(I); title('原图像');
subplot(1, 2, 2); imshow(I1); title('加噪声图像');
7 d7 }+ r, c+ `; Q' u" s9 V[PSNR, MSE] = psnr(I, I1)
% 图像峰值信噪比PSNR、均方根误差MSE
function [PSNR, MSE] = psnr(X, Y)
* q0 G- d, ?7 `% 计算峰值信噪比PSNR、均方根误差MSE
% 如果输入Y为空，则视为X与其本身来计算PSNR、MSE
( N" A3 ?+ I2 I" b" \
if nargin<2
    D = X;
else
    if any(size(X)~=size(Y))
/ k" b- v, J5 w7 |        error('The input size is not equal to each other!');
    end
    D = X-Y;
6 y" f( y, ]. ?  Q9 i5 Cend
; ~$ y" z! w& AMSE = sum(D(: ).*D(: ))/prod(size(X));
& z1 Y+ N  q; X* {# F: lPSNR = 10*log10(255^2/MSE);
用这个算法算下吧，I为原图 I1为加噪图像