How to plot a circular Image?

Question

ramin bba 2014-7-21

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/142713-how-to-plot-a-circular-image

评论： ramin bba 2014-7-21

采纳的回答： Image Analyst

I want to plot a binary image like this:

However, I only want the red region to be shown in the figure.How can I do this?

tnx in advance

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Geoff Hayes 2014-7-21

Ramin - what exactly are your inputs to draw the above? Do you determine the radius of the red circle? Do you decide on the number of solid black balls that fill the red region? Do you decide on the radius of each solid black ball?

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Image Analyst 2014-7-21

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/142713-how-to-plot-a-circular-image#answer_145884

You can draw only the red circle by using rectangle().

For other approaches to drawing circles, see the FAQ on circles, or see my attached demos.

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

ramin bba 2014-7-21

tnx a lot. All of them came in handy!

请先登录，再进行评论。

Answer 2

Robert Cumming 2014-7-21

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/142713-how-to-plot-a-circular-image#answer_145868

在 MATLAB Online 中打开

A couple of options for you:

% First create an axes and some data:

ax = axes;
ang=0:0.01:2*pi; 
xp=1*cos(ang);
yp=1*sin(ang);
patch ( xp, yp, 'w', 'parent', ax )
axis ( ax, 'equal' )

% option 1 - hide the axes to leave your image:

set ( ax, 'visible', 'off' )

% option 2 - set the background of your image to be the same as the parent:

set ( ax, 'color', get ( get ( ax, 'parent' ), 'color' ) )

2 个评论
显示无隐藏无

ramin bba 2014-7-21

thanks Robert. A question:

should I use the above after I have read my image? 'cause it is not working properly! it actually puts a disk on my current image and hides a circular portion of it! here is what I do:

a=imread('...');

imshow(a);

ax = axes;

ang=0:0.01:2*pi;

xp=1*cos(ang);

yp=1*sin(ang);

patch ( xp, yp, 'w', 'parent', ax )

axis ( ax, 'equal' )

set ( ax, 'color', get ( get ( ax, 'parent' ), 'color' ) )

Robert Cumming 2014-7-21

My example draws a circle as an example. You would need to remove that part. You only need the last part which hides the axes, or changes the background colour.

请先登录，再进行评论。