PSNR计算

purpose_857

im1=imread('lena2.bmp');
/ E- n6 n1 o$ w4 C6 e8 v' e5 z& O%im1=im2double(im1);
im2=imread('lena_rbhv.bmp');
; j. b3 v, N1 k3 q9 L. g%im2=im2double(im2);
   
3 {# P8 s* A# v6 k% S1 K! Yif (size(im1))~=(size(im2))
    error('错误：两个输入图象的大小不一致');
6 s) T; n5 P( n" M& E9 o: Gend
4 G% Q, A' s0 ^
+ }( U, \/ V) G/ O    [m,n] = size(im1);
    A = double(im1);
2 H9 l3 X( R  X  x4 [1 k' G    B = double(im2);
    D = sum( sum( (A-B).^2 ) );%||A-B||^2
    MSE = D / (m * n);
if  D == 0
. ^7 x3 G, q* g$ ^    error('两幅图像完全一样');
! H) D1 X3 X, V$ L3 r2 n6 f3 j    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
??? Subscript indices must either be real positive integers or logicals.
/ X7 I5 G) I& a7 A: J1 N  \. P, b
Error in ==> PSNR_ERRO at 14
6 q9 U5 U. j( F7 s+ x: _" _! y' l    D = sum( sum( (A-B).^2 ) );%||A-B||^2

peerless2021

function main()
! Y' K' `* C6 O9 }clc; close all;
I=imread('cameraman.tif'); %用的是原图
I1=imnoise(I,'gaussian',0,0.01);
figure;
' {9 l  D/ t, _subplot(1, 2, 1); imshow(I); title('原图像');
subplot(1, 2, 2); imshow(I1); title('加噪声图像');
6 f# x- q2 p4 E* ?[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)
- a3 b* H5 L$ e, C" T% ^% 计算峰值信噪比PSNR、均方根误差MSE
- L: ~, K/ B1 I& \& s% 如果输入Y为空，则视为X与其本身来计算PSNR、MSE
' Q4 y  U  }- r; r2 ]8 f
/ e0 v2 M5 ]0 t* ?if nargin<2
    D = X;
else
    if any(size(X)~=size(Y))
  Q" u8 J2 k0 Q6 A  O% T        error('The input size is not equal to each other!');
    end
! X8 |' V: e8 W- j8 _/ u    D = X-Y;
8 f' i3 {* s  ^# h/ H' a$ Send
( u. Z4 L% t" n: [# LMSE = sum(D(: ).*D(: ))/prod(size(X));
PSNR = 10*log10(255^2/MSE);
) ~1 p% p. T/ O; jfunction main()
+ v/ r9 r( e2 G6 k0 I! U! a7 v9 ^, G7 @clc; close all;
" x. x0 Q8 W& A8 EI=imread('cameraman.tif'); %用的是原图
8 M  Q7 {4 [" S5 W5 Q$ {, RI1=imnoise(I,'gaussian',0,0.01);
% W- t7 Y* Y# [0 B" d2 ifigure;
subplot(1, 2, 1); imshow(I); title('原图像');
8 E" Z3 Y3 f) b$ C' E) J+ `# i7 [" msubplot(1, 2, 2); imshow(I1); title('加噪声图像');
# a/ W* O$ `, [( P2 A0 `[PSNR, MSE] = psnr(I, I1)
8 @5 \. C5 M( O* @6 s% 图像峰值信噪比PSNR、均方根误差MSE
/ |7 l( C+ L9 y( g( Ufunction [PSNR, MSE] = psnr(X, Y)
% 计算峰值信噪比PSNR、均方根误差MSE
% z2 h" j9 \1 a% 如果输入Y为空，则视为X与其本身来计算PSNR、MSE

if nargin<2
( @6 u- \6 v) J) g/ E1 A7 \    D = X;
( u. ]# c  i( m% pelse
    if any(size(X)~=size(Y))
        error('The input size is not equal to each other!');
    end
4 b! p, f3 z& \5 X8 T  i  v    D = X-Y;
end
MSE = sum(D(: ).*D(: ))/prod(size(X));
PSNR = 10*log10(255^2/MSE);
3 }! W( S$ t4 q' H# d用这个算法算下吧，I为原图 I1为加噪图像

I_believe

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