block matching image issue

Question

Blob 2023-4-8

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1943879-block-matching-image-issue

评论： Walter Roberson 2023-4-10

When I did blockmatching algorithm on the tennis man image, and did a comparaison between the original and reconstructed image I got this black boxes, why?

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Blob 2023-4-8

编辑：Walter Roberson 2023-4-8

在 MATLAB Online 中打开

clc
 clear all
close all
load('f1.mat');
load('f2.mat');
figure;
subplot 121
imagesc(F1);
title('image 1');
subplot 122
imagesc(F2);
title('image 2');
colormap gray
 load('e1.mat');
load('e2.mat');
 figure;
subplot 121
imagesc(e1);
title('image 1');
subplot 122
imagesc(e2);
title('image 2');
colormap gray
 [M N]=size(F1);
T=16;
nbr_l=M/T;
nbr_c=N/T;
indbloc_x=1:nbr_l;
indbloc_y=1:nbr_c;
L=length(indbloc_x);
Q=length(indbloc_y);
F2_recons = zeros(size(F2));
for i=1:L
    for j=1:Q
        X=indbloc_x(i);
        Y=indbloc_y(j);
        if i==L
            1+1
        end
        %for n=1:T
        %         bloc2=F2(X:X+T-1,Y:Y+T-1);
        bloc2=F2((1:16)+(i-1)*16,(1:16)+(j-1)*16);
        eqm=inf(15, 15);
        mineqm = inf;
        for i1=-7:7
            for i2=-7:7
                condition = (X+i1) >=1 & (Y+i2) >=1;
                condition2 = ((16+(i-1)*16+i1)<=M) & ((16+(j-1)*16+i2)<=N);
                if ~(condition&&condition2)
                    continue
                else
                    bloc1=F1((1:16)+(i-1)*16+i1,(1:16)+(j-1)*16+i2);
                    eqm(i1+8, i2+8)=(1/(nbr_l*nbr_l))*(sum(sum(bloc2-bloc1).^2));
                    if eqm(i1+8, i2+8)< mineqm
                        %stocke bloc1 et les indices qui correspondent
                        mineqm = eqm(i1+8, i2+8);
                        indx=i1;
                        indy=i2;
                        bloc1min = bloc1;
                    end
                end
            end
        end
        F2_recons((1:16)+(i-1)*16,(1:16)+(j-1)*16) = bloc1min;
    end
end
figure
imshow(uint8(F2_recons))

Blob 2023-4-8

These are the files @Walter Roberson

Walter Roberson 2023-4-8

在 MATLAB Online 中打开

(Just showing the output, not trying to debug the problem)

Untitled5

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Answer 1

Walter Roberson 2023-4-8

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1943879-block-matching-image-issue#answer_1212164

在 MATLAB Online 中打开

Your attached code (but not your posted code) has

imshow (F2_recons - e1)

where both of those arrays are double precision and happen to contain integer values. The difference between the two arrays ranges between -255 and +206 . You are passing that array of values -255 to +206 to imshow() as a double precision array. By default, when passed a double precision array, imshow() assumes that the valuable part of the data is the range 0 to 1, and that anything below 0 should be treated as 0 and anything above 1 should be treated as 1. So you more or less end up binarizing the difference array.

You should be considering using

imagesc(F2_recons - e1);
colormap(gray)

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Blob 2023-4-10

@Walter Roberson thank you, I have one more request, could you please show me how to plot the vectors of motion?

Walter Roberson 2023-4-10

Sorry, no, I do not see anything in your code that corresponds to vectors of motion, or anything that corresponds to motion at all. I cannot tell what you are calculating at all.

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