How to plot a circular Image?

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ramin bba
ramin bba 2014-7-21
评论： ramin bba 2014-7-21
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
Geoff Hayes
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?

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采纳的回答

Image Analyst
Image Analyst 2014-7-21
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.

更多回答（1 个）

Robert Cumming
Robert Cumming 2014-7-21
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
ramin bba
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
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.

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