如何使用matlab进行圆形裁剪？ [英] How to do circular crop using matlab?

问题描述

我通常使用 imcrop 来裁剪rectanguler图像，但我想创建圆形裁剪。怎么做？

I usually use imcrop to crop rectanguler image but i wat to create circular crop. How to do it?

我知道还有另外一个关于此的问题，这里是链接：

I know there is another quetion about this, here the link:

1. MATLAB：如何从图像中裁剪出圆圈

[xx,yy] = ndgrid((1:imageSize(1))-ci(1),(1:imageSize(2))-ci(2));
mask = (xx.^2 + yy.^2)<ci(3)^2;

以及 imshow（掩码）的结果是带有白色背景的矩形

and the result of imshow(mask) is rectangle with white background

在MATLAB中的一个点周围裁剪感兴趣的圆形区域

错误 roimaskcc

http://www.mathworks.com/matlabcentral/newsreader/view_thread/242489

[xx,yy]=ndgrid(1:size(X,1), 1:size(X,2));
CroppingMask= ( (xx-Xcenter).^2+(yy-Ycenter).^2<=Radius^2 );
X=X.*CroppingMask;

imshow（CroppingMask）的结果是矩形，黑色背景，矩形中心有小白色圆形。当我运行第3行时，它显示错误。

The result of imshow(CroppingMask) is a rectangle with black background with small white circular at the center of the rectangle. When I run line 3 it shows an error.

请帮助我，一步一步，因为我是初学者。

Please help me, step by step because I'm a beginner.

这是我的形象： https://www.dropbox.com/s/5plqzqgyb1ej6gh/patricia.jpg 。分辨率为480x640。

Here is my image: https://www.dropbox.com/s/5plqzqgyb1ej6gh/patricia.jpg. It resolution is 480x640.

推荐答案

解决方案（1）运行良好。以下是使用您的图片的完整工作示例。

Solution (1) works perfectly well. Here is a complete working example using your image.

I = imread('patricia.jpg');
imageSize = size(I);
ci = [250, 300, 100];     % center and radius of circle ([c_row, c_col, r])
[xx,yy] = ndgrid((1:imageSize(1))-ci(1),(1:imageSize(2))-ci(2));
mask = uint8((xx.^2 + yy.^2)<ci(3)^2);
croppedImage = uint8(zeros(size(I)));
croppedImage(:,:,1) = I(:,:,1).*mask;
croppedImage(:,:,2) = I(:,:,2).*mask;
croppedImage(:,:,3) = I(:,:,3).*mask;
imshow(croppedImage);

它产生以下图像。

我希望这能澄清事情。可能有一种更好的方法来重新组合裁剪的图像，但这是我能想到的最好的方法。

I hope this clarifies things. There is probably a better way of re-assembling the cropped image, but this was what I could come up with off the top of my head.

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