how to plot axes onto an image

Hi,

I have a binary image, a set of contour points, and the coordinate of center of gravity. I want to plot an axis with the origin (0,0) set to the center of gravity. And the axes should be in polar coordinate since I want to have the angle in which the contour points with maximum radius exists.

Can anyone help me with this problem? thanks before

Regards, Vga

Answer 1

[Sarah Wait Zaranek]

This should help you to start with the problem. Everything is centered at the origin (0,0) but that could be adjusted by changing the position values.

% generating random "image" data
a = rand(100,100);

% initial axis
h = axes('position',[0  0  1  1]);
colormap bone

%plotting image
f1 = imagesc(a);

% add axis
h2 = axes('position',[0  0  1  1]);
t = 0:.01:2*pi;

% make polar plot
f2 = polar(h2,t,sin(2*t).*cos(2*t),'r');

% removing background of polar plot - so image shows through
ph=findall(h2,'type','patch');
set(ph,'FaceColor','none')

[Tyler]

hi, your answer is really helpful! but i want to plot(scatter) some points over an image, in a new axis, but the background of the new axis is white, so i can't see the image, Can you help me with this problem? thank you !!!

Answer 2

[Philip]

Just what I needed!