PSNR计算

purpose_857

im1=imread('lena2.bmp');
%im1=im2double(im1);
1 |7 _% i! K  Mim2=imread('lena_rbhv.bmp');
. r9 K4 G- I) T, X( e%im2=im2double(im2);
   
9 y. K/ G/ A& Iif (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);
3 A8 i/ A$ z( |    B = double(im2);
    D = sum( sum( (A-B).^2 ) );%||A-B||^2
    MSE = D / (m * n);
7 C1 J8 x' f3 k/ \4 eif  D == 0
: o1 d" v3 |( O2 B, o( p    error('两幅图像完全一样');
    PSNR = 200;
else
* [5 f, M! |6 _    PSNR = 10*log10( (255^2) / MSE );                                                        
end
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2 F( L! T  H7 Y5 |
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
' d& j; _% g% ]$ D1 Z' `" d5 f??? Subscript indices must either be real positive integers or logicals.
6 @" N8 Q! @9 V8 B- _' s
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()
  o( Q# V/ x, {  f( Iclc; close all;
  g! I! Q) i5 g: \0 T, iI=imread('cameraman.tif'); %用的是原图
I1=imnoise(I,'gaussian',0,0.01);
figure;
) \) h1 t! x  ^" a! P- asubplot(1, 2, 1); imshow(I); title('原图像');
" v) N% B  S0 {) Xsubplot(1, 2, 2); imshow(I1); title('加噪声图像');
$ t* ]' e- ~# H7 @' T  {% v% e[PSNR, MSE] = psnr(I, I1)
4 T7 q3 l4 ]9 w! m# q% 图像峰值信噪比PSNR、均方根误差MSE
8 J0 l' Q9 q% B) |% l. d2 ~, Afunction [PSNR, MSE] = psnr(X, Y)
2 }( O5 V$ \- g, _% 计算峰值信噪比PSNR、均方根误差MSE
2 B8 F" j  y8 M3 b! ~& y: J% 如果输入Y为空，则视为X与其本身来计算PSNR、MSE

9 L0 [: B; {7 S6 P7 M% I$ Xif nargin<2
6 }. \7 a( a( O6 H7 `    D = X;
else
    if any(size(X)~=size(Y))
        error('The input size is not equal to each other!');
/ b0 G% U" T9 ?+ x    end
1 |$ e: ^, S1 J- `& E/ p# C1 H    D = X-Y;
end
  H& ?$ b! U! o- t0 m* l5 i/ rMSE = sum(D(: ).*D(: ))/prod(size(X));
  S) q$ \. I6 _) {PSNR = 10*log10(255^2/MSE);
4 G/ I! k5 y8 }) W9 o/ yfunction main()
clc; close all;
+ s7 h7 _9 A, K* m& R1 iI=imread('cameraman.tif'); %用的是原图
I1=imnoise(I,'gaussian',0,0.01);
figure;
5 t# l- y% b, w$ I% x9 Csubplot(1, 2, 1); imshow(I); title('原图像');
subplot(1, 2, 2); imshow(I1); title('加噪声图像');
[PSNR, MSE] = psnr(I, I1)
5 l5 C5 r- s" W; K( \; h; q6 K1 p$ U% 图像峰值信噪比PSNR、均方根误差MSE
) N3 Y) x6 d# c4 Wfunction [PSNR, MSE] = psnr(X, Y)
6 I3 g) m6 U4 r, J3 W% 计算峰值信噪比PSNR、均方根误差MSE
3 b) h& V+ A5 C( e* e- i% 如果输入Y为空，则视为X与其本身来计算PSNR、MSE

; r! }. ?3 l4 s, Dif nargin<2
) ?) Z5 F# ^* G3 z    D = X;
0 U( u) Q  Y' \1 zelse
1 J+ r0 P6 r% r5 l) Z$ N    if any(size(X)~=size(Y))
, h. [. W* Z0 ]9 c/ c/ a# ?        error('The input size is not equal to each other!');
    end
    D = X-Y;
end
MSE = sum(D(: ).*D(: ))/prod(size(X));
PSNR = 10*log10(255^2/MSE);
$ I- n7 J+ v) g9 n9 k8 U用这个算法算下吧，I为原图 I1为加噪图像
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