PSNR计算

purpose_857

im1=imread('lena2.bmp');
7 E4 D* k( _3 S$ {%im1=im2double(im1);
: O& t$ i8 \* p: W+ b# dim2=imread('lena_rbhv.bmp');
%im2=im2double(im2);
( R; V1 q) u1 [4 A; n. d" V9 A) F   
9 C5 N' G- P7 s% Jif (size(im1))~=(size(im2))
& h% Z; |& T, a% A+ ]    error('错误：两个输入图象的大小不一致');
end

    [m,n] = size(im1);
3 \$ g& T1 t* o9 h- P; W    A = double(im1);
" t; }, d9 }3 U5 p& s1 O' B    B = double(im2);
! r& _+ w+ d5 ?    D = sum( sum( (A-B).^2 ) );%||A-B||^2
- m: u. D6 M' U1 |8 l    MSE = D / (m * n);
& ?: }7 @6 Z5 Z. j  mif  D == 0
    error('两幅图像完全一样');
3 G4 \' Y; {7 Q5 ~7 _; L7 N    PSNR = 200;
else
/ ^( J. x! X" G2 L8 T; |    PSNR = 10*log10( (255^2) / MSE );                                                        
end
1 [4 J4 {# {3 p: J0 G( J6 Z1 ?
8 G4 R& y# [) U
4 ~1 E% p' ~1 v. ~  B' o7 W# ?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.

8 l9 F  o: e9 o0 l! R& a" v1 tError in ==> PSNR_ERRO at 14
3 ~: Z  ~" u7 |+ N3 L    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;
+ _) R# a7 s, F. Z' s3 Z# j% r. LI=imread('cameraman.tif'); %用的是原图
I1=imnoise(I,'gaussian',0,0.01);
: s& c. n) [- f' t3 X5 c5 s. nfigure;
4 q+ i& z8 v$ z! s! Q- L' asubplot(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)
5 a6 }4 H& d# k) u' e. _% 计算峰值信噪比PSNR、均方根误差MSE
  I0 A0 e5 v2 J# h) i! v5 W% 如果输入Y为空，则视为X与其本身来计算PSNR、MSE
* i9 M: u( a- O% K5 k5 \5 x
' h* M/ F1 `3 ]1 W" n/ Bif nargin<2
    D = X;
- L8 Z' C/ {  @, N. |5 N! m) e( Selse
3 P9 ~% o! G* ]4 ?# [. {; p    if any(size(X)~=size(Y))
        error('The input size is not equal to each other!');
    end
2 g$ g4 O; }4 D7 ~8 E3 [    D = X-Y;
& i; q2 p! v6 a2 dend
1 a2 L5 _8 ]2 X2 ~$ W' [MSE = sum(D(: ).*D(: ))/prod(size(X));
& j& V/ ~" G+ aPSNR = 10*log10(255^2/MSE);
function main()
' J1 y  y: M/ ~. I% g! P( oclc; close all;
I=imread('cameraman.tif'); %用的是原图
- A8 o& s; o& r: M4 j/ PI1=imnoise(I,'gaussian',0,0.01);
figure;
% ?7 f+ Q% f# l, F6 tsubplot(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
% E* q$ g2 }# H) F, k+ c8 @  ufunction [PSNR, MSE] = psnr(X, Y)
- v4 Q$ k; b2 ]- @7 \% 计算峰值信噪比PSNR、均方根误差MSE
* }8 _+ K6 z" Y* E% 如果输入Y为空，则视为X与其本身来计算PSNR、MSE
' L0 t  [3 N9 [; M2 p% @5 J
if nargin<2
4 s, d; F6 o. H    D = X;
9 e6 h: o, l3 f, k/ q# P  W8 [else
    if any(size(X)~=size(Y))
, F" Z6 p8 i" F1 [5 Y        error('The input size is not equal to each other!');
    end
    D = X-Y;
end
  O3 A( A; [  t. z3 H% v; LMSE = sum(D(: ).*D(: ))/prod(size(X));
( V* a3 }9 D# l% p) G/ Z: p4 [PSNR = 10*log10(255^2/MSE);
, g* L7 b3 t# @& S用这个算法算下吧，I为原图 I1为加噪图像