PSNR计算

purpose_857

im1=imread('lena2.bmp');
%im1=im2double(im1);
9 |+ l% p0 p/ s# l  r6 i, q6 [5 aim2=imread('lena_rbhv.bmp');
8 ]0 q5 ~+ P) \/ `! ^%im2=im2double(im2);
9 w' W& f9 ~* t1 K+ S8 N   
if (size(im1))~=(size(im2))
) \  M3 C: _) }4 X    error('错误：两个输入图象的大小不一致');
end
+ `+ V% q* L, s$ v
( @. T; g* v* W' i1 Q" l    [m,n] = size(im1);
    A = double(im1);
% |/ o7 J" z1 [4 _: z    B = double(im2);
    D = sum( sum( (A-B).^2 ) );%||A-B||^2
    MSE = D / (m * n);
if  D == 0
    error('两幅图像完全一样');
( c5 K0 S: r9 K( [! R- M    PSNR = 200;
else
2 E" v( E5 \6 b2 t8 i& W    PSNR = 10*log10( (255^2) / MSE );                                                        
4 q2 x6 W( n# T! F& Aend
+ h1 x# u9 X, ^
' n& w1 d* h3 c$ r
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
; K/ D$ n( \7 C+ d1 U8 B??? Subscript indices must either be real positive integers or logicals.
7 ~0 x; B9 I4 Y$ Z% L+ D
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()
clc; close all;
I=imread('cameraman.tif'); %用的是原图
$ \3 L. u% E2 ]/ d0 b% s- @7 Q) g% |I1=imnoise(I,'gaussian',0,0.01);
figure;
) y) i' K  l' Z3 hsubplot(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 w* W" y1 D% ]2 {% 图像峰值信噪比PSNR、均方根误差MSE
function [PSNR, MSE] = psnr(X, Y)
% 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
) S2 q, }4 I' D, `! _
0 F9 H; S( P- C% gif nargin<2
    D = X;
, v+ d" X' W2 H* D, ^  ]( F) g; delse
2 N  O4 _5 u! ]3 ]) X    if any(size(X)~=size(Y))
        error('The input size is not equal to each other!');
    end
    D = X-Y;
; V1 }$ U6 c4 P' ]) Aend
: @+ R/ ?$ x1 OMSE = sum(D(: ).*D(: ))/prod(size(X));
1 w9 M! \! ]8 z: RPSNR = 10*log10(255^2/MSE);
function main()
clc; close all;
8 C0 v+ F3 @- U8 q/ eI=imread('cameraman.tif'); %用的是原图
/ Y. q* Y5 X4 l0 QI1=imnoise(I,'gaussian',0,0.01);
figure;
subplot(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)
% 图像峰值信噪比PSNR、均方根误差MSE
function [PSNR, MSE] = psnr(X, Y)
% 计算峰值信噪比PSNR、均方根误差MSE
$ m- m0 l# x9 W7 C0 B+ Q% w% 如果输入Y为空，则视为X与其本身来计算PSNR、MSE
3 U+ Y. C# p& \& i% a$ o
6 H' X) @1 {8 ]% D6 ?$ [6 Cif nargin<2
6 y- l) s. J$ X& r8 c    D = X;
/ |- F& l* Z+ q! s8 \4 N* Selse
    if any(size(X)~=size(Y))
- B1 B% w1 J0 l        error('The input size is not equal to each other!');
    end
& P1 b( T1 i/ W8 }. ]" ^2 M9 x    D = X-Y;
end
, B3 x8 E* s% V: {4 }! y/ KMSE = sum(D(: ).*D(: ))/prod(size(X));
PSNR = 10*log10(255^2/MSE);
0 x) i0 M$ p+ {3 @, _  v/ y用这个算法算下吧，I为原图 I1为加噪图像