Circular region in an image

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Sordin on 15 Jan 2018
Commented: Image Analyst on 18 Jul 2018
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:
[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, :);
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.

Accepted Answer

Matt J
Matt J on 15 Jan 2018
Edited: Matt J on 15 Jan 2018
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);
Sordin on 16 Jan 2018
Hi Image Analyst, Yes this worked for the color images as well.

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More Answers (2)

Prince Masedi
Prince Masedi on 18 Jul 2018
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.
  1 Comment
Image Analyst
Image Analyst on 18 Jul 2018
How does this answer the original question about pasting circular regions into an image?

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