Circular region in an image

Question

Sordin 2018-1-15

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https://ww2.mathworks.cn/matlabcentral/answers/377192-circular-region-in-an-image

评论： Image Analyst 2018-7-18

I am trying to replace a circular region in one image with the corresponding region in another image. Here is my code so far:

% Sample images:
I=imread('office_1.jpg');
I2=imread('office_5.jpg');
[imageSizeY, imageSizeX,z1] = size(I);
centerX = ceil(imageSizeX/2);
centerY = ceil(imageSizeY/2);
radius = 200;
for i=1:max(imageSizeY,imageSizeX)
      if (((centerY+i) - centerY).^2 ...
              + ((centerX+i) - centerX).^2 <= radius.^2)
          I(centerY:centerY+i, centerX:centerX+i, :) ...
              = I2(centerY:centerY+i, centerX:centerX+i, :);
      end
end
imshow(I)

Unfortunately, my code does not work correctly, and instead of a circle the result is a square (corresponding to only one quadrant of the desired circle):

What are the mistakes here? Any explanation is greatly appreciated.

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Answer 1

Matt J 2018-1-15

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https://ww2.mathworks.cn/matlabcentral/answers/377192-circular-region-in-an-image#answer_300192

编辑：Matt J 2018-1-15

在 MATLAB Online 中打开

I don't really follow the logic of your code, but in any case there are much simpler and more efficient approaches, e.g.,

   [yy,xx,~]=ndgrid(  (1:imageSizeY)-centerY, (1:imageSizeX)-centerX ,1:z1);
   map=(yy.^2+xx.^2<=radius^2);
   I(map)=I2(map);

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Image Analyst 2018-1-16

编辑：Image Analyst 2018-1-16

Does this work for his color image?

Sordin 2018-1-16

Hi Image Analyst, Yes this worked for the color images as well.

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Answer 2

Image Analyst 2018-1-15

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https://ww2.mathworks.cn/matlabcentral/answers/377192-circular-region-in-an-image#answer_300211

See my attached copy and paste demos.

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Answer 3

Prince Masedi 2018-7-18

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https://ww2.mathworks.cn/matlabcentral/answers/377192-circular-region-in-an-image#answer_329309

II. Determine the following statistical parameter using Matlab program (Note you must copy and paste your code on the answer booklet. (1. Error variance, 2. Assume X=Rainfall Y=Runoff fill in the table with respective determined square of (X-Xm) where Xm is the mean of X and determine estimated Y termed as Yest.