how to draw a rectangle to identify character

Question

ahmed 2014-3-29

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/123669-how-to-draw-a-rectangle-to-identify-character

评论： Rik 2021-7-14

This code to draw a rectangle to identify character that I had found (overlay the template in a target).

[name,path] = uigetfile('*.jpg');
image1 = imread([path,name]);
[name,path] = uigetfile('*.jpg');
image2 = imread([path,name]);
if size(image1,3)==3
    image1=rgb2gray(image1);
end
if size(image2,3)==3
    image2=rgb2gray(image2);
end
% check which one is target and which one is template using their size
if size(image1)>size(image2)
    Target=image1;
    Template=image2;
else
    Target=image2;
    Template=image1;
end
% find both images sizes
[r1,c1]=size(Target);
[r2,c2]=size(Template);
% mean of the template
image22=Template-mean(mean(Template));
%corrolate both images
corrMat=[];
for i=1:(r1-r2+1)
    for j=1:(c1-c2+1)
        Nimage=Target(i:i+r2-1,j:j+c2-1);
        Nimage=Nimage-mean(mean(Nimage));  % mean of image part under mask
        corr=sum(sum(Nimage.*image22));
        corrMat(i,j)=corr;
    end 
end

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Image Analyst 2014-3-29

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

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Answer 1

Image Analyst 2014-3-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/123669-how-to-draw-a-rectangle-to-identify-character#answer_131318

That's a dangerous way to use size(). Looks like someone needs to read Steve's blog on the use of the size function.

Anyway, I'm not sure what your question is. Do you want to draw a rectangle in the overlay above the image? If so, use plot() or rectangle().

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Image Analyst 2014-3-29

编辑：Image Analyst 2014-3-29

normxcorr2_demo.m

Anyway, you can't find a template in a target by correlation, at least not robustly. Think about it and if you don't know why, ask. You'll need to use normalized cross correlation, as shown in my attached demo.

raha boolat 2021-7-14

It was a wonderful program. Bravo

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Answer 2

ahmed 2014-3-29

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https://ww2.mathworks.cn/matlabcentral/answers/123669-how-to-draw-a-rectangle-to-identify-character#answer_131321

编辑：ahmed 2014-3-29

i want to draw a rectangle in a overlay the full image illuster to identify the character

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Image Analyst 2014-3-30

Invert your image so that the letters are white and then run the normalized cross correlation code I gave you.

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Answer 3

raha boolat 2021-7-14

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https://ww2.mathworks.cn/matlabcentral/answers/123669-how-to-draw-a-rectangle-to-identify-character#answer_746643

编辑：Rik 2021-7-14

在 MATLAB Online 中打开

function obj_det(img_name)
f=imread (img_name);
if (size(f,3) >1)
    f=rgb2gray(f);
    f_bw=~im2bw(f,graythresh(f));
else
    f_bw=~im2bw(f,graythresh(f));
end
f_bw=imfill(f_bw,'holes');
s=bwconncomp(f_bw);
imshow(f);
for i=1:s.NumObjects
    ind=s.PixelIdxList{i};
    [r,c]=ind2sub(size(f),ind);
    min_r=min(r,[],1);
    max_r=max(r,[],1);
    min_c=min(c,[],1);
    max_c=max(c,[],1);
    hy=max_r - min_r;
    hx=max_c - min_c;
    rectangle('position',[min_c,min_r,hx,hy],'EdgeColor','r');
end
end