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Circular image plot (MATLAB) 
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#1
Jul2711, 04:26 AM

P: 1,212

Hi,
Just came across this as an image in a book/monograph and it looks very MATLABesque, except I cannot figure out how to possibly create a circular image Say I have a 500x500 matrix and want to plot it as a colour image in this way. Does anyone know how? I've been rereading the same help files again and again with no progress. 


#2
Jul2711, 08:41 PM

Sci Advisor
PF Gold
P: 1,469

transform the x and y coordinates to polar coordinates and plot the new coordinates,
plot3(cos(x), sin(y)); 


#3
Jul2911, 03:39 AM

P: 1,212

Thanks for the reply, I don't fully understand how to apply it to my problem (never been strong on plot tools), my image has no coordinates, it's just a 500x500 matrix. I don't need the axis, just for the plotter to not plot anything outside a circular region. Currently I'm using pcolor with "EdgeAlpha" to zero so it looks very similar to that image I linked, but it's a square.



#4
Nov1511, 06:35 AM

P: 1,212

Circular image plot (MATLAB)
Hi, just need to bump this, I still don't understand how to do this.



#5
Apr2612, 11:09 AM

P: 1,212

One more bump, I still can't find an answer, thanks
I really just need to know how to make the noncircle area white, at the moment I'm fiddling around with colour maps and manually changing the values to force it to look white, but it has sideeffects. 


#6
Jun512, 05:42 AM

P: 1,212

Bumping to say I solved the problem.
The solution lies in the alpha data of the object. For example you can use a ROI to make part of the object transparent, using set(gco,'AlphaDataMapping','scaled','AlphaData',ROI) Where ROI = 1 the image will stay opaque and where it is 0 the image will be transparent. 


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